It is now well recognised that adverse local tissue reaction (so called pseudotumor or ALTR) may follow the use of metal-on-metal arthroplasty, the source of the metal being the primary bearing surface (the articulation itself) or a modular junction within the construct, such as the trunnion. This is more likely seen if a large femoral head has been used. We are aware of this risk and have implemented surveillance systems worldwide to facilitate its early diagnosis and prompt management. Less well known, and silent in its initial development, is adverse local reaction following metal-on-polyethylene hip replacement.

Initially the problem is unknown to the patient and the surgeon. Typically there follows unexplained pain (due to synovitis), loss of motion, sometimes the development of a mass, followed by increasing dysfunction as the inflammatory, destructive process invades the surrounding soft tissues. Radiographic features are late to follow (focal osteolysis), unless cross-sectional imaging is considered (ultrasound and/or metal suppressed MRI) early in the process. Serum metal ions are an important adjunct in its diagnosis, and it is now acknowledged that the previously used level of 7 ppb is much higher than that required to recognise the entity. Typically there is a reverse of the usual CrCo ratio, and a recent study has suggested that a raised serum Co alone is adequate to assist in the diagnosis

Four important lessons have been learned at our center in recent years and will be demonstrated in this case-based presentation designed for surgeons in practice. It is hoped that the cases and supportive literature will prove useful in advancing the early diagnosis of this troublesome and often silent condition.

Total hip arthroplasty (THA) is effective, reproducible, and durable in the treatment of hip joint arthritis. While improvements in polyethylene materials have significantly reduced wear rates and osteolysis, aseptic loosening of implants remains one of the leading causes of revision THA. Additionally, fears of dislocation and instability have driven the increase in the utilization of larger diameter femoral heads in primary THA which can lead to increased wear when coupled with a polyethylene articulation. Finally, the increasing number of younger and active patients undergoing THA raises questions with regards to the ability of modern conventional bearings to provide durability and longevity beyond second and third decades following joint implantation.

Ceramic-on-ceramic articulations are ideally suited for today's young and high demand patients undergoing primary THA. It has the lowest in-vitro wear properties of any bearing couple and the wear characteristics further improved by its wettability and lubrication particularly when larger heads are utilised. Additionally, improvements in material properties and prosthesis design have significantly decreased fracture rates and increased the reliability of these implants. Furthermore, reported outcomes and longevity of modern ceramic-on-ceramic THAs in younger patients have all shown excellent survivorship despite patients achieving and maintaining a very high level of activity and function. In short, it is the bearing couple most in tune with current market demands and utilization trends.

While registry data and meta-analyses of published literature have failed to show the superiority of ceramic-on-ceramic articulations compared to conventional bearings at 10 years, there is evidence that even highly crosslinked polyethylene (HXPE) is not immune to wear. Selvarajah et al. reported steady, in-vivo wear rates of HXPE exceeding 0.1 mm/year threshold in young THA patients with 36 mm ceramic ball heads. Additionally, small osteolytic lesions have been observed in hips with HXPE bearings at 12–14 years follow up. Finally, analysis of all controlled randomised studies have shown less osteolysis of ceramic-on-ceramic hips compared to polyethylene articulations. The significance of these lesions are unclear but the question remains: Can HXPE as a bearing be able to provide over 30 years of service needed to outlast patients younger than 60 years?

Concerns with cost, squeaking, and fractures do not make ceramic-on-ceramic bearings suitable for all patients undergoing primary THA. However, in young, healthy and active patients, a modern ceramic-on-ceramic articulation is most likely to provide the lowest wear rates, lowest risk of osteolysis, and greatest chance for life-long durability.

In 1998, lysis / wear were the biggest concerns in THR. 3 distinct tacks emerged: Alternatives to polyethylene: Ceramic / Ceramic; Metal / Metal; Make a better polyethylene

MOM story is well known: bad ending!!

Large adoption of Ceramic / Ceramic: positives: low wear, benign MR findings, even low dislocation rates !! negatives: fractures still occurred, noise generation, liner malseating, metal transfer (edge effects)

Crosslinked Polyethylene: Update: 13–15 year follow-up of 1st generation XLPE with remelted product: Annual wear rates of 0.004 (metal heads) 0.002 (ceramic heads)!

No lysis!! Wear rates for “standard” heads and large heads both low approaching the lower limits of detection!!

CONCLUSION: Crosslinked Polyethylene with Ceramic Heads: The Winner and Still Champion!

Increasing data is emerging, consistently demonstrating a more rapid recovery for patients undergoing direct anterior approach (DAA) surgery. In one study, objective findings of early recovery including timed up and go tests, Functional Independence Measures are significantly faster in the first 2 weeks, and normalise by 6 weeks. A more recent randomised study shows a quicker achievement of the functional milestones of discontinuing walking aids, discontinuing opioids, stair ascent, and walking 6 blocks, as well as accelerometer measures of activity in the first 2 weeks after surgery. In both of these studies, seasoned surgeons well beyond their learning curves performed the surgeries.

A prospective MRI study of volume before and after surgery has shown full recovery or mild hypertrophy of most muscles at an average of 24 weeks from surgery, but a sustained loss of muscle volume for the obturator internus muscle in the DAA, and sustained loss of muscle volume for obturator internus, obturator externus, piriformis, and quadratus femoris in the posterior approach patients. The muscles that are released in the surgeries recover incompletely.

Prospective assessment of muscle strength demonstrated loss of flexion strength in the DAA group and loss of external rotation strength in the Posterior group at 6 weeks. By 3 months, the DAA group had returned to normal in their strength, while the Posterior group had persistent external rotation weakness.

Prospective assessment of gait, pre-operatively and at 6 months showed similar improvements in frontal and sagittal plane range of movement in gait, with a similar improvement in transverse plane movement (internal and external rotation) in the DAA group, but no change in the Posterior cohort.

The precision of socket placement, after undergoing a learning curve, was greater with the use of fluoroscopy in the DAA.

Cutting and subsequently repairing a muscle can have a clinically insignificant, but nonetheless objectively measurable effect on the function of that muscle.

Observed downsides of DAA include a higher prevalence of wound complications in obese patients, and possibly a higher risk of periprosthetic fractures in elderly, thin women. Recent larger registry data would also suggest that there is no difference in dislocation rate between the 2 referenced approaches, and possibly a higher femoral revision rate for the DAA. These may be honest and real depictions of a large learning curve as we further understand and disseminate the subtleties of proper execution of DAA surgery.

There are numerous examples in medicine where “eminence trumps evidence.” The direct anterior approach (DA) is no exception. Its meteoric rise has largely been driven by industry and surgeon promotion. This surgical approach continues to garner interest, but this interest is largely for marketing purposes, as emerging data would suggest a high risk, low reward operation. In addition, factors such as selection bias and impact bias, have substantially swayed peoples interest into making an inferior operation look better.

There are several factors related to the direct anterior approach that should give us pause. Those include the surgeon learning curve, limited functional benefit and increased complications. There is no question the DA approach for total hip arthroplasty (THA) has a long and steep learning curve. The majority of studies would suggest at minimum, 50–100 cases before a surgeon is comfortable with this approach and some studies would suggest the technical difficulties of this approach remain an issue even with increasing experience. This proves difficult with an attempted rapid adoption of this technique by a surgeon who may perform less than 50 THAs per year but feel the need to offer this approach to their patients for marketing purposes.

One of the many touted benefits of the DA approach is the perception of improved functional outcomes. Many of the early studies showed early improvement in gait, pain and mobility. However, these studies compared the DA approach to an anterolateral approach. Even when compared to the anterolateral approach, considered the most invasive and least muscle sparing, the benefits of the DA approach were only short term (6 weeks). The majority of retrospective studies, prospective randomised studies and meta-analyses comparing DA to a posterior approach show little, if any, benefit of one approach over another with regards to functional benefit. Another touted benefit includes a low or no dislocation risk associated with the posterior approach. On the contrary many studies have failed to demonstrate lower dislocation rates with the DA approach compared to a contemporary posterior approach. A recent registry study from the Michigan Arthroplasty Registry Quality Initiative (MARQI) showed equal dislocation rates between the DA and posterior approach.

Concerns have also been raised regarding unique and more frequent complications with the DA approach compared to other surgical approaches for total hip arthroplasty. Unique complications such as ankle fractures and a high incidence of nerve injury, especially damage to the lateral femoral cutaneous nerve, have been reported. In addition, the data now clearly show a higher incidence of complications on the femoral side, including early loosening and periprosthetic fracture.

As responsible surgeons, if we want to say the DA approach is different, then fine, we can say it's different. Claims of superiority of one approach over another have not been born our in the literature and in fact much of the data would suggest a high risk no reward operation for the DA approach compared to other surgical approaches for total hip arthroplasty.

Length of hospital stay has been decreased to the point where the next logical progression in arthroplasty surgery is outpatient arthroplasty procedures. This trend has already happened for procedures formerly regarded as “inpatient” procedures such as upper extremity surgery, arthroscopy, anterior cruciate ligament reconstruction, foot and ankle procedures, and rotator cuff repair. Refinement of surgical techniques, anesthesia protocols, and patient selection has facilitated this transformation. Today, hip, knee and shoulder arthroplasty can be performed safely as outpatient procedures by implementing surgical and protocol refinements. Understanding and addressing, safely, the reasons that surgeons and patients believe they “need” a hospital admission is the cornerstone to outpatient arthroplasty. This program can be highly beneficial to patients, surgeons, anesthesia, ambulatory surgery centers, and payors as arthroplasty procedures shift to the outpatient space. It will always cost more to perform these procedures in hospitals therefore opening up significant opportunities. The less efficiently run hospital in-patient setting demands over-treatment of each patient to fit him or her into the mold of inpatient surgery. Patient satisfaction is very high in the outpatient setting. Patients can recover in their own home with reduced inpatient services and by utilizing outpatient physical therapy. The surgeon efficiently controls the local environment, and thus the overall patient experience and satisfaction are improved in the outpatient setting. The surgeon's role changes from commoditised technician in the hospital setting to coordinator of the entire care experience including pre-operative care, imaging, anesthesia, peri-operative care mapping, post-operative care, and enhanced coordination with therapy providers. An outpatient arthroplasty program involves multiple individuals and specialised protocols for pre-operative, peri-operative, and post-operative care. These include patient selection and education, anesthesia and analgesia, and minimally invasive surgical techniques. By implementing these protocols and a minimally invasive Watson-Jones approach, one study has reported 77% utilization of outpatient THA, 99% success with day of surgery discharge, and a 1% readmission or complication rate.

Outpatient arthroplasty is safe, it's better for us and our patients, and it is here now. In an outpatient environment the surgeon actually spends more time with the patients and family in a friendly environment. Patients feel safe and well cared for, and are highly satisfied with their arthroplasty experience. In a typical day a surgeon can perform 6–8 outpatient arthroplasty procedures with multiple interactions with each patient and their family throughout the day.

Avoidance of narcotics with peripheral and local blocks will increase the eligibility for outpatient surgery and decrease the need for overnight hospitalization. The singular focus on the patient and the avoidance of over-treatment will become the standard of care for total hip and total knee arthroplasty in much the same way as for other procedures once deemed “inpatient” surgeries.

An outpatient total hip arthroplasty (THA) will be defined as a THA performed at an ambulatory care facility where the patient is discharged the same day as the procedure. Such procedures are being done in the United States and the hypothesis is that a “same day” THA will lead to reduced costs and improved outcomes. However, there are no appropriately powered randomised controlled trials evaluating outcomes in this group of patients to support this hypothesis.

It appears that a “same day” THA is here to stay. Therefore, the selection criteria for patients that undergo the procedure needs to be carefully defined. The safety of this regimen needs to be confirmed.

In an evaluation of the NSQIP database, Otero et al. compared outcomes in patients discharged on POD 0 and POD 1 and noted that THA patients in the POD 0 group had increased rates of complications. Risk factors for complications included age >70, smoking, COPD, CAD and hematocrit less than 36. In addition, the patients discharged on POD 0 had higher rates of diabetes, steroid use and lower hematocrit. Clearly, the selection criteria for this procedure needs to be defined.

In two separate studies, Goyal et al. and Dorr et al. noted that approximately 25% of patients were unable to leave the hospital on POD 0 usually because of nausea and/or hypertension.

Issues to consider before developing a same day discharge program include: 1) Is the patient healthy enough to go home the same day as the surgery?; 2) Does the patient live close enough to the hospital to be discharged the same day?; 3) Can the family provide the appropriate care for the patient at home?; 4) Is it really better for the patient or just better for the surgeon?

If a surgeon embarks on a same day discharge program, rigorous selection criteria must be instituted and followed. In addition, the patient must have free choice with respect to a same day discharge versus a 24-hour stay.

Do we need new polyethylene? Is there a clinical problem with first generation crosslinked polyethylene (XLPE)? Are we being duped into believing that doped polyethylene will solve a problem?

Clinical failures of polyethylene bearing total hip replacements are related to wear and the mechanical properties of the polyethylene. Wear is primarily related to crosslinking. Wear failures are secondary to periprosthetic osteolysis while mechanical failure causes cracking of thin polyethylene. Use of large femoral heads that reduce dislocation may increase wear and mechanical failure in the second decade of XLPE use.

There is no question that XLPE has reduced 2-dimensional (2D) head penetration, volumetric penetration and periprosthetic osteolysis with traditional 28 mm head sizes. Reported 2D penetration rates are 0.03–0.07 mm/year and clinically important polyethylene wear induced osteolysis is nonexistent. However, larger heads with the same 2D head penetration will generate more volumetric debris and could cause osteolysis.

There is no question that retrieved XLPE components have low levels of oxidation at the time of explant. While this is unexpected, the levels are well below levels reported with traditional polyethylene. It remains to be seen if these levels of oxidation will cause mechanical failures.

Currently available versions of polyethylene have focused on eliminating oxidation induced mechanical property reduction and not additional wear reduction. This is accomplished with Vitamin E doping or blending. While the local effects of Vitamin E polyethylene particles at the cellular level have been studied the clinical effect of these chemically new particles remains to be seen.

This author believes that long term volumetric wear with large head size is a greater concern than reduced mechanical properties secondary to in-vivo oxidation. New polyethylene development needs to focus on additional wear reduction. Can we afford to pay more for a new polyethylene in a value based healthcare environment?

A large body of the orthopaedic literature clearly indicates that the cement mantle surrounding the femoral component of a cemented total hip arthroplasty should be at least 2 mm thick. In the early 1970s, another concept was introduced and is still in use in France consisting of implanting a canal filling femoral component line-to-line associated with a thin cement mantle. This principle has been named the “French paradox”. An explanation to this phenomenon has been provided by in-vitro studies demonstrating that a thin cement mantle in conjunction with a canal filling stem was supported mainly by cortical bone and was subjected to low stresses. We carried out a study to evaluate the in-vivo migration patterns of 164 primary consecutive Charnley-Kerboull total hip replacements. All prosthesis in the current series combined an all-polyethylene socket and a 22.2 mm stainless steel femoral head. The monobloc double tapered (5.9 degrees) femoral component was made of 316L stainless steel with a highly polished surface (Ra = 0.04 μm), a quadrangular section, and a neck-stem angle of 130 degrees. The stem was available in six sizes with a stem length (shoulder to tip) ranging from 110 mm to 160 mm, and a neck length ranging from 24 mm to 56 mm. For each size, the femoral component was available in two to four different diameters to adapt the implant to the medullary canal. Hence the whole range comprised a total of 18 standard femoral components. The femoral preparation included removal of diaphyseal cancellous bone to obtain primary rotational and varus/valgus stability of the stem prior to the line-to-line cementation. We used the Ein Bild Roentgen Analyse Femoral Component (EBRA-FCA) method to assess the subsidence of the femoral component. At the minimum 15-year follow-up, 73 patients were still alive and had not been revised at a mean of 17.3 years, 8 patients had been revised, 66 patients were deceased, and 8 patients were lost to follow-up. The mean subsidence of the entire series was 0.63 ± 0.49 mm (0 – 1.94 mm). When using a 1.5 mm threshold, only four stems were considered to have subsided. With revision of either component for any reason as the endpoint, the cumulative survival rate at 17 years was 90.5 ± 3.2% (95% CI, 84.2% to 96.8%). With radiological loosening of the femoral component as the endpoint, the cumulative survival rate at 17 years was 96.8 ± 3.1% (95% CI, 93.2% to 100%). This study demonstrated that, in most cases, a highly polished double tapered stem cemented line-to-line does not subside up to 18-year follow-up.

In recent years, cementless stems have dominated the North American market. There are several categories of cementless stems, but in the past 20 years, the two most popular designs in the United States have been the extensively coated cylindrical cobalt-chrome (CoCr) stem and the proximally coated tapered titanium stem, which in recent years has become the most common. The 10-year survival for both stem types has been over 95% with a distinction made on factors other than stem survival, including thigh pain, stress shielding, complications of insertion, and ease of revision. Conventional wisdom holds that proximally coated titanium stems have less stress shielding, less thigh pain, and a higher quality clinical result. Recent studies, however, including randomised clinical trials have found that the incidence of thigh pain and clinical result is essentially equivalent between the stem types, however, there is a modest advantage in terms of stress shielding for a tapered titanium stem over an extensively coated CoCr stem. One study utilizing pain drawings did establish that if a CoCr cylindrical stem was utilised, superior clinical results in terms of pain score and pain drawings were obtained with a fully coated versus a proximally coated stem. In spite of the lack of a clinically proven advantage in randomised trials, tapered titanium stems have been favored because of the occasional occurrence of substantial stress shielding, the increased clinical observation of thigh pain severe enough to warrant surgical intervention, ease of use of shorter tapered stems that involve removal of less trochanteric bone and less risk of fracture both at the trochanter and the diaphysis due to the shorter, and greater ease of insertion through more limited approaches, especially anterior approaches. When tapered stems are utilised, there may be an advantage to a more rectangular stem cross-section in patients with type C bone. In spite of the numerous clinical advantages of tapered titanium stems, there still remains a role for more extensively coated cylindrical stems in patients that have had prior surgery of the proximal femur, particularly for a hip fracture, which makes proximal fixation, ingrowth, and immediate mechanical stability difficult to assure consistently. Cement fixation should also be considered in these cases. While the marketplace and the clinical evidence strongly support routine use of tapered titanium proximally coated relatively short stems with angled rather than straight proximal lateral geometry in the vast majority of cases, there still remains a role for more extensively coated cylindrical and for specific indications.

Distal neck modularity places a modular connection at a mechanically critical location, which is also the location that confers perhaps the greatest clinical utility. The benefits of increased clinical options at that location must be weighed against the potential risks of adding an additional junction to the construct. Those risks include prosthetic neck fracture, taper corrosion, metal hypersensitivity, and adverse local tissue reaction. Further, in-vitro testing of ultimate or fatigue strength of femoral component designs has repeatedly failed to predict behavior in-vivo, raising questions about the utility of in-vitro testing that does not incorporate the effect of mechanically assisted crevice corrosion into the test design.

The material properties of Ti alloy and CoCr alloy place limits on design considerations in the proximal femur. The smaller taper junctions that are necessary for primary reconstruction are particularly vulnerable to failure whereas larger taper junctions commonly used in revision modular femoral component designs have greater opportunity for success. Modular junctions of CoCr alloy on conventional Ti alloy have been shown to have a greater incidence of clinically significant mechanically assisted crevice corrosion and adverse reaction. Designs that have proven clinical strength and utility universally have larger, more robust junctions, that extend into the metaphysis of the femur. While these designs are primarily designed for revision total hip replacement (THR), they are occasionally indicated for primary THR. Overall, however, while design options at the neck-stem junction have unmatched clinical utility, no design that does not extend into the metaphysis has proven to be universally reliable. While routine use of modular neck components for primary THR does not appear to be clinically indicated based on current evidence, modular designs with proven successful proximal junctions appear to be indicated for revision THR and rare primary THR with extreme version or other anatomical circumstances.

For primary hip arthroplasty contemporary acetabular component options available from across multiple manufacturers have evolved over the years to provide several common and widely available features and a few unique options designed to address the main clinical problems that have plagued hip arthroplasty in the past. These include the main causes of failure of THA generally, and of acetabular components in particular: fixation, wear, instability, and infection. The design and implant options that have been made available vary in how effectively they have “solved” the problem in question and occasionally have created new problems or have been associated with major tradeoffs and disadvantages.

Fixation: Cementless fixation of the socket has largely supplanted cemented fixation in North America. First generation ingrowth materials for cementless sockets including beads, plasma spraying, and wire mesh, have given way to enhanced more highly porous materials. The advent of rapid prototyping and 3-D printing of highly porous titanium (and other) materials has sparked a wave of various new orthopaedic implant designs including for the acetabulum.

Wear: Polyethylene wear and the resulting osteolysis problems seen in hip arthroplasty in the 1980's and 90's spawned a competition between 3 technologies over the optimal enhanced wear couple for THA: Metal-on-Metal (MOM), Ceramic-on-Ceramic, and Metal/Ceramic-on-Highly Crosslinked Polyethylene. Metal-on-Metal surface replacement and MOM THA were designed to reduce wear and also allow very large heads and potentially enhanced hip stability. Unfortunately, after wide adoption, subsequent problems occurred and this ongoing disaster has resulted in the rapid disappearance of virtually all MOM designs. Ceramic-on-Ceramic articulations achieve very low wear rates, but with lower tolerances for imperfect implant positioning. The potential for stripe wear, audible squeaking, rare breakage problems, and much greater expense have limited usage in the US, though this articulation is still preferred by some surgeons for selected very young patients. Ceramic- or Chrome Cobalt-on-Highly Crosslinked Polyethylene has emerged as the most widely used articulation in the US and has excellent wear performance with no demonstrable osteolysis over the first decade. More recent modifications of crosslinking methods and use of Vitamin E as an antioxidant, it is hoped, will further improve wear performance and mechanical properties.

Instability: Instability of the hip (subluxation or frank dislocation) remains one of the most common complications of THA, especially early. Acetabular component and insert options available to prevent instability (or treat it in the revision setting) include: 1) Optimal cup version and inclination (so called “safe zone”); 2) Prevent femoral component impingement against socket or liner rim; 3) Face changing elevated liner; 4) Liner to allow large fixed head (32 mm or > depending on cup size); 5) Dual mobility liner; 6) Tripolar construct (small bipolar inside a matched liner for a 40 mm or larger head); 7) Constrained liner (various designs).

Infection: There are currently a very limited number of acetabular component or liner options available to attempt to reduce the risk of infection or assist as adjunctive measures in treating the infected arthroplasty, but this is an area of active research and implant design effort.

Both the patient and the surgeon want hip and knee arthroplasties to last a lifetime. As a result, many patients have been told to defer arthroplasty as long as possible. After arthroplasty, many patients have been advised to limit physical activity. Such management strategies prioritise longevity but compromise lifestyle. Given that the technical aspects of the arthroplasty are satisfactory, modern total hip and knee prostheses have demonstrated remarkable durability. Quantitative studies of patient activity have measured up to 48 million cycles in-vivo, with impact, without evidence of loosening, osteolysis, or other impending failure. These data suggest that with current technology, an active lifestyle is compatible with implant longevity.

This session will be practically oriented, focusing on important surgical decisions and on technical tips to avoid complications. The panel will be polled concerning individual preferences as regards the following issues in primary total hip arthroplasty: 1.) Peri-operative antibiotics; 2.) Blood management and tranexamic acid protocols; 3.) Surgical indications: High BMI patients; 4.) Surgical approach for primary total hip arthroplasty: indications or preferences for direct anterior, anterolateral, posterior; 5.) Acetabular fixation; 6.) Tips for optimizing acetabular component orientation; 7.) Femoral fixation: (a) Indications for cemented and uncemented implants. (b) Is there still a role for hip resurfacing?; 8.) Femoral material and size: (a) Preferred head sizes and materials in different situations. (b) Is there a role for dual mobility implants in primary THA?; 9.) Bearing surface: Present role of different bearings. 10.) Tips for optimizing intra-operative hip stability; 11.) Tips for optimizing leg length; 12.) Post-operative venous thromboembolism prophylaxis; 13.) Heterotopic bone prophylaxis; 14.) Post-operative pain management; 15.) Hospital discharge: Is there a role for outpatient surgery?; 16.) Post-operative rehabilitation protocol: weight bearing, role of physical therapy; 17.) Post-operative activity restrictions; hip dislocation precautions; 18.) Is there value to physical therapy as outpatient after THA?; and 19.) Long-term antibiotic prophylaxis for procedures.

Few will disagree that the best femoral head that a young patient can have is his or her own, native femoral head. In the active, healthy patient under age 60 with a displaced femoral neck fracture, well-done, timely ORIF presents the best chance of preserving the patient's native femoral head. Arthroplasty is generally reserved for older patients, over age 60, where attempts at ORIF in this setting have demonstrated failure rates over 40%. “Physiologic age” is a somewhat nebulous term that takes into account the health and ambulatory status of the patient. For example, a 52-year-old with end stage renal failure, severe osteoporosis, and a displaced femoral neck fracture may best be treated with arthroplasty. However, in reality, such situations are quite rare. Recent studies have documented that approximately 80% of young patients with displaced femoral neck fractures treated with ORIF will keep their own femoral head for 10 years after injury. The variables under the surgeon's control include timing of fixation, quality of reduction, accurate implant placement and implant selection, and capsulotomy. All of these variables potentially affect outcomes. Fractures in this young age group are frequently high shear angle (vertical) Pauwels type 3 fractures, and benefit from fixed angle fixation. The author prefers anatomic reduction and stabilization with a sliding hip screw and a superiorly placed derotation screw. Careful attention to detail is important to obtain an anatomic reduction, which is the most important variable in the outcome of these challenging injuries.

Despite the best of technique, when faced with a sub-capital or per-trochanteric fracture, inevitably there are failures of proximal fixation. These situations provide unique challenges for the reconstructive surgeon.

While there are specific issues related to either sub-capital or per-trochanteric fractures, there also are many commonalities. The causes of failure are nonunion, malunion, failure of fixation or avascular necrosis. In all cases, it is imperative to rule out infection. Since the surgery is now elective, the patient's medical status must be optimised prior to the intervention.

Basic surgical principles apply to both fracture types. Use the old incision (if possible) and choose an approach that can be extensile. Of course, the old hardware needs to be removed – this task can be quite frustrating, so good preparation and patience is imperative. Retrieve old operative notes to identify the type of hardware so that any special tools needed are available. Hardware can be intra-osseous in location and excavation of the hardware may require bone osteotomy. These patients are at higher risk of post-operative dislocation, so absolute hip stability must be achieved and confirmed in the OR. Bigger heads and dual mobility options improve stability provided that the components are properly positioned and offset and leg length are restored.

Subcapital fractures provide certain specific issues related to stem choice. While, my bias is towards THA because of better chance of complete pain relief, especially in community ambulators, certainly bipolar arthroplasties can be a satisfactory solution. Stem fixation can be either cemented or cementless.

For per-trochanteric fractures in younger patients, repeat osteosynthesis should be considered if the femoral head is viable. Bone deformity – trochanteric overhang, shaft offset – may necessitate an osteotomy as part of the reconstruction. While proximal fixation primary type stems are often possible, distal fixation revision stems may be required. Any bone defects related to screw holes should be bypassed by the femoral component.

Ten to 15% of the pelvic girdle tumors are primary malignant bone tumors, while about 80% are osseous metastases. Due to improved function, enhanced quality of life, and acceptable local recurrence rates, limb salvage surgery has replaced external hemipelvectomies in many cases of primary malignancies. However, large segmental bony defects and poor bone quality due to the disease process itself and subsequent treatment (i.e. chemotherapy and radiation) can make stable implant fixation difficult when performing a total hip arthroplasty (THA) for oncologic periacetabular lesions with concurrent fractures. Various methods are available to reconstruct the hemipelvis, and include large structural allografts, allograft-prosthetic composites (APCs), custom-made endoprostheses, modular saddle prostheses, and modular hemipelvis endoprostheses. However, short- and mid-term results from our institution indicate that tantalum reconstructions with adjuvant screw fixation and supplemental reinforcement cages provide reasonable improvement in clinical outcomes and stable fixation in situations with massive bone loss and compromised bone quality. On the femoral side, cemented fixation remains a viable option (including proximal femoral replacements), but uncemented distal fixation with extensively-porous coated cylindrical stems or modular fluted tapered stems can be considered if the disease process (or subsequent treatment) primarily affects the proximal femur. In addition to long-term fixation, post-operative dislocations remain a significant concern given the often compromised abductor mechanism.

Acetabular fractures, particularly in the geriatric population are on the rise. A recent study indicated a 2.4-fold increase in the incidence of acetabular fractures, with the fastest rising age group, those older than the age of 55. Controversy exists as to the role and indications for total hip arthroplasty (THA), particularly in the acute setting. Three common scenarios require further evaluation and will be addressed. 1.) What is the role of THA in the acute setting for young patients (< 55 years old)? 2.) What is the role and indications for THA in the older patient population (>55 years) and what are surgical tips to address these complex issues? 3.) What are the outcomes of THA in patients with prior acetabular fractures converted to THA?

Acetabular fractures in young patients are often the result of high energy trauma and are a life changing event. In general, preservation of the native hip joint and avoidance of arthroplasty as the first line treatment should be recommended. A recent long-term outcome study of 810 acetabular fractures treated with Open Reduction and Internal Fixation (ORIF) demonstrated 79% survivorship at 20 years with need for conversion to THA as the endpoint. Risk factors for failure were older age, degree of initial fracture displacement, incongruence of the acetabular roof and femoral head cartilage lesions. In selected younger patients, certain fracture types with concomitant injuries to articular surfaces may best be treated by acute THA.

In the elderly patient population, acetabular fractures are more likely the result of low energy trauma but often times result in more displacement, comminution and damage to the articular surface. Osteoporosis and generalised poor bone quality make adequate reduction and fixation a challenge in these acute injuries. As such, the role of acute arthroplasty is becoming more widespread. Consideration should be given to delayed arthroplasty in certain patients to allow time for fracture healing followed by THA. However, early mobilization and weight bearing is important in the elderly population and consideration should be given to acute THA. The challenge remains gaining appropriate acetabular fixation in the fractured, osteoporotic bone. Early results showed high complication rates with acetabular fixation. However, newer fixation surfaces and advances in ORIF techniques have led to improved results. In addition, the need for complex acetabular reconstruction with the use of cages or cup cage constructs may be required in this setting. Appropriate 3-D imaging is essential to evaluate the extent of involvement of the anterior and posterior columns as well as the acetabular walls. Mears et al. reported on 57 patients who underwent THA for acute acetabular fracture and reported results at a mean of 8.1 years. 79% of patient reported good or excellent results and no acetabular cups were revised for loosening.

One of the more common scenarios is the patient that presents with a prior ORIF of an acetabular fracture that has developed post-traumatic arthritis or avascular necrosis of the hip and requires conversion to THA. Challenges in this patient population include dealing with prior hardware that may interfere with THA component fixation, severe stiffness of the joint making exposure difficult and prior heterotopic ossification that may put neurovascular structures at risk. Previous studies have demonstrated lower long-term survivorship of the acetabular component (71% at 20 years) compared to primary THA for osteoarthritis. New acetabular fixation surfaces should mitigate the risk of aseptic loosening in this challenging patient population.

Intra-operative fractures of the femur are on the rise mainly due to the increased use of cementless implants and the desire to get a tight pressfit. The prevalence has been reported to be between 1–5% in cementless total hip arthroplasties (THAs). The key to preventing these fractures is to identify patients at high risk and careful surgical technique. Surgical risk factors include the use of cementless devices, revision hip surgery, the use of flat tapered wedges and MIS surgery. Patient factors that increased risk include increasing age, female gender, osteopenia and rheumatoid arthritis. These risk factors tend to be additive and certainly when more than one is present extra caution needs to be taken.

Surgical technique is critical to avoid these intra-operative fractures. Fractures can occur during exposure and dislocation, during implant removal (in revision THA), during canal preparation and most commonly during stem insertion. In both primary and especially in revision THA, be wary of the stiff hip in association with osteopenia or osteolysis. These patients require a very gentle dislocation. If this cannot be achieved, then alteration of the standard approach and dislocation may be needed. Examples of these include protrusion with an osteopenic femur and revision THA with a very stiff hip with lysis in the femur. Lastly, in cases with retained hardware, dislocate prior to removing plates and screws.

After dislocation, the next challenge is gentle preparation of the femoral canal. A reasonable exposure is required to access the femoral canal safely. MIS procedures do not offer as good access to femoral canal and this probably results in increased risk of fracture during broaching or implant insertion. When broaching, stop when broach will not advance further. When inserting a tapered wedge stem, be worried if stem goes further in than broach.

In revision surgery when taking the stem out from above, make sure the greater trochanter does not overhang the canal. A high speed burr can clear the shoulder for easier access for removal. In revision THA with an ETO place a cerclage wire prior to reaming and retighten prior to stem insertion.

Even with careful surgical technique intra-operative femoral fractures will still occur. When inserting the stem a sudden change in resistance is highly suggestive of fracture. Wide exposure of the entire proximal femur is necessary to confirm the diagnosis. The distal extent of the fracture must be seen. Only on occasion is an intra-operative radiograph needed. Management is directed to ensuring component stability and good fracture fixation. In primary total hip arthroplasty calcar fractures are by far the most common. If using proximal fixation and you are certain the stem is stable, then all that is needed is cerclage wiring. As already mentioned, you must follow the fracture line distally so you are aware of how far down it goes. Often what appears to be a calcar split actually propagates distal to the lesser trochanter. In these cases, one would probably go for distal fixation plus wiring.

In conclusion intra-operative femoral fractures are on the rise. Prevention is the key. If a fracture, exposure is the key to deciding on a treatment plan.

As the incidence of total hip arthroplasty (THA) rises, an increasing prevalence of peri-prosthetic femur fractures has been reported. This is likely due to the growing population with arthroplasties, increasing patient survival and a more active life-style following arthroplasty. It is the 3rd most common reason for THA reoperation (9.5%) and 5th most common reason for revision (5% with fracture risk after primary THA reported at 0.4%-1.1% and after revision at 2.1%-4%).

High quality radiographs are usually sufficient to classify the fracture and plan treatment. Important issues in treatment include stem fixation status and fracture location relative to the stem. Additional comorbidities will also influence treatment choices, of which the most critical is the presence of infection and the quality of bone stock.

The most commonly studied, and reported classification system is the Vancouver. Type A are peri-trochanteric fractures with AL at the lesser and AG at the greater trochanter. B fractures are those around the stem with B1 fractures having a well-fixed stem, B2 a loose stem with adequate bone stock, and B3 representing loose stem and inadequate bone stock. C fractures are distal to the stem.

Type A) Trochanteric Fractures: These are usually associated with lysis. Displaced fractures can be managed adequately with cerclage fixation and cancellous allograft to fill osteolytic defects. Undisplaced fractures usually heal well with symptomatic treatment.

Type B) Fractures Around the Stem: The B1 type has a well-fixed component and is usually treated with extramedullary fixation plus graft. Contemporary plates have been designed specifically for these fractures. Strut allograft may be used to provide a more rigid construct. Spiral and long oblique fractures can be cerclaged while short oblique or transverse fractures require fixation anterior and lateral with cable plates and cortical strut grafts. Screws can be used distal to the implant, and cables used proximally. The B2 type has a loose prosthesis but otherwise good bone stock. In this setting, the fracture line may be extended on the lateral cortex of the femur as an extended osteotomy to provide easy access for cement removal. These fractures can be managed with an extensively coated stem if rotational stability can be obtained in the distal segment. If rotational stability over a 4 cm scratch interference fit of the stem isn't possible, then a fluted tapered modular stem should be used. Strut allografts improve initial stability. The B3 type has both a loose prosthesis and poor bone stock and in the younger patient restoration of bone stock should be a priority. Bulk femoral grafts may be needed. The elderly or low functional demand patient may be treated with a proximal femoral replacement. Because of soft-tissue deficiencies, a constrained acetabular liner may be needed to prevent instability.

Type C) Fractures Distal to the Stem: These usually accompany a stable stem and many fixation devices are available. Locking plates have become most popular and should be secured with cerclage wires proximally around the component with screws distally. Retrograde nails may be employed if there is adequate bone distal to the stem tip and above the fracture.

It's easy to say that hip resurfacing is a failed technology. Journals and lay press are replete with negative reports concerning metal-on-metal bearing failures, destructive pseudotumors, withdrawals and recalls. Reviews of national joint registries show revision risks with hip resurfacing exceeding those of traditional total hip replacement, and metal bearings fare worst among all bearing couples. Yet, that misses the point. Modern hip resurfacing was never meant to replace total hip replacement (THR). It was intended to preserve bone in young patients who would be expected to need multiple revisions due to their youth and high-demand activities. The stated goal of the developers of the Birmingham Hip Resurfacing (BHR) was to delay THR by 10 years. In the two decades that followed the release of BHR, this goal has been met and exceeded. Much has been learned about indications, patient selection, and surgical technique. We now know that this highly specialised, challenging procedure is best indicated in the young, active male with osteoarthritis, as a complementary, not competitive procedure, to THR.

Resurfacing has many advantages. First and foremost, it saves bone, on the day of surgery, and over the next several years by preventing stress shielding. Dislocations are very rare. Leg length discrepancy and changes in offset are avoided. Post-operative activity, including heavy manual labor and contact sports, is unrestricted. More normal loading of the femur and joint stability has allowed professional athletes to regain their careers. Femoral side revisions, if necessary, are simple total hips, and dual mobility constructs allow one to keep the socket.

Adverse reactions to metal debris (ARMD), including pseudotumors, have generated great concern. Initially described only in women, it was unclear whether the etiology was allergy, toxicity, or inflammation. A better understanding of the wear properties of the bearing, and its relation to size, anteversion, hip dysplasia and metallurgy, along with retrieval analysis, allow us to conclude that it is excessive wear due to edge loading which is the fundamental mechanism for the vast majority of ARMD. Thus, patient selection, implant selection and surgical technique, the orthopaedic triad, are paramount.

What has been most impressive are the truly exceptional results in young, active men. The worst candidates for THR turn out to be the best candidates for resurfacing. The ability to return to full, unrestricted activity is just as important to these patients as the spectacular survivorship in centers specializing in resurfacing. If they are unlucky and face a revision, they are not facing the life-changing outcomes of a long revision femoral stem. So if the best indication for hip resurfacing is the young, active male, let's look at the results of resurfacing these patients in centers with high volumes, using devices with a good track record, such as BHR. Several centers around the world report 10–18 year success rates of BHR in males under 50 at 98–100%. Return to athletics is routinely achieved, and even professional athletes have regained their careers.

Hip resurfacing doesn't have to be better than THR to be popular among patients. Just the idea of saving all that bone makes it attractive. In the young active male, however, the results exceed those of THR, while leaving better revision options for the future. This justifies its continued use in this challenging patient population.

Metal-on-metal hip resurfacing enjoyed a period of increased global clinical application beginning in the early to mid-2000's. This tapered off quickly, to the point that it is now a niche surgery. One naturally asks the question, why?

The answers are quite simple: 1) There are no clinical benefits when compared with total hip replacements (THA). While many authors have tried valiantly to demonstrate a benefit clinically to performing a resurfacing over a THA, they have simply been unable to convincingly do so. The procedures produce equivalent clinical results. Many claims, such as allowing a patient greater activity levels and return to sports are clearly heavily biased depending on patient selection. The only credible claim to an advantage over THA that can be made regarding resurfacing implants is indeed there is preservation of host bone of the femoral head and neck. However, this retained bone also reduces the femoral head-to-neck ratio compared to a THA and leads to the potential for bone-on-bone impingement that would not be seen if the neck was resected. Additionally the clinician needs to carefully question the true clinical relevance of this preserved bone. One need only think of all of the isolated acetabular component revisions, or polyethylene liner exchanges, that are performed while retaining solidly ingrown femoral components with good preservation of calcar bone years following the index procedure.

2) Resurfacing implants are much more costly than conventional THA implants. In an era of increased cost constraints, parties are willing to pay more only when there is a proven benefit. Resurfacing implants offer no such benefit.

3) There is a well-documented higher revision rate with resurfacing implants over THA.

While the previous claim was that this wasn't seen in younger males, that too has been disproven. The latest data from the Australian Joint Replacement Registry demonstrates the 15-year cumulative percentage revision rates for conventional total hip at 9.7% and resurfacing at 13.3%.

4) There is the significant risk of metal ions and local hypersensitivity secondary to the metal-on-metal bearing. Again, this risk is significantly limited with the use of a THA with a polyethylene insert.

5) There is a significant incidence of femoral neck fractures.

6) The overall femoral component loosening rates are higher than for total hip replacements.

7) There is a clear learning curve with resurfacing implants with most series showing increased complications in the first fifty cases, and depending on a surgeons overall clinical practice, it may be quite a challenge to ever really overcome this learning curve issue.

8) There is difficulty restoring offset and leg length discrepancies in certain cases when trying to utilise a resurfacing implant.

Cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sexes and level of activity. However, a number of issues related to cementless stem fixation could be further improved: Optimization of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially for Anterior and MIS exposures; Facilitation of revision with implants capable of providing durable fixation for active patients.

The potential benefits of short stem femoral THA implants include: Ease of insertion; Reproducibility of insertion; Avoidance of issues related to proximal-distal anatomic mismatch or variations in proximal femoral diaphyseal anatomy (e.g. femoral bowing); Facilitation of MIS surgical approaches, especially anterior exposures; Optimization of proximal femoral load transfer with consequent maximization of proximal bone preservation.

The purpose of this presentation is to describe the design rationale and characteristics of short (< 120 mm) uncemented primary THA femoral stems and to evaluate the clinical and radiographic results of short stems.

Outcome results extending beyond 10 years support the proposition that short stems of appropriate design provide dependable long-term fixation and equivalent clinical results to those currently achievable with cementless stems of conventional length in patients of all ages, sexes and level of activity.

Short stems are an option for primary THR, but these are the technical challenges. Stem anteversion is increased with short stems usually above 20 degrees so cup anteversion must be adjusted lower. Offset is better if increased up to 5 mm more because more bony neck is retained and with increased stem anteversion the greater trochanter is more posterior, and both of these increase the risk of bony impingement. Short stems are best in A bone, okay in B bone, not recommended yet in C bone. With standard stems performing so well use caution for conversion to short stems.

Total hip arthroplasty (THA) performed in patients aged 60 years and younger requires several decades of implant use under increased activity demands. Implant longevity and stable fixation are necessary for 30 or more years. The search for the optimal bearing combination for use in younger, high demand patients presents a challenge for orthopaedic surgeons as they consider the pros and cons of each material and interaction. A recent U.S. study of implant utilization trends that included 174 hospitals and 105,000 THA between 2001 and 2012 found that in 2012 93% of THA were cementless and 35% of THA bearings were ceramic-on-highly crosslinked polyethylene (HXLPE). Another recent article used the Nationwide Inpatient Sample from 2009 to 2012 to study bearing usage trends in 9265 primary THA in patients 30 years old or younger. The researchers observed ceramic-on-polyethylene as the most commonly bearing surface, used in 36% of patients, and which represented an increase from an earlier study of extremely young patients undergoing primary THA between 2006 to 2009, use of so-called hard-on-hard bearings decreased. Benefits of ceramic-on-HXLPE bearings are that unlike metal-on-polyethylene and metal-on-metal combinations, taperosis and adverse reactions to metal debris are non-existent. Ceramic-on-polyethylene is forgiving, it is an extremely low wear couple, it is the current presenter's bearing of choice in high demand patients, and it is a good option in the scenario of revision of failed metal-on-metal or for taperosis. Advantages to bulk ceramics are: extremely hard and scratch resistant to third body wear, not damaged by instruments and repositioning, excellent wettability, extreme low wear against itself with no known pathogenic reaction to ceramic particles, inherently stable with no oxidation or aging effect, no corrosion, safe in terms of metal ion release, no known risk of hypersensitivity or allergy, and no concerns about biological reaction. Biolox® (Ceramtec AG; Plochingen, Germany) ceramics have been available since 1974, with fourth generation Biolox® Delta introduced in 2003. Extensive clinical experience includes over 1630 published studies with over 12 million Biolox® components implanted with almost every available hip system. Two recent meta-analyses studies of randomised controlled trials comparing ceramic-on-ceramic to ceramic-on-polyethylene found significantly higher linear wear in ceramic-on-polyethylene but higher incidences of noise and fracture in ceramic-on-ceramic THA. There were no differences in revision, function, dislocation, osteolysis or loosening. A recent meta-analysis review of randomised controlled trials reporting survivorship of ceramic-on-ceramic, ceramic-on-HXLPE, and metal-on-HXLPE found no difference among bearing surfaces in risk of revision after primary THA in patients younger than 65. Risk ratio for revision was 0.65 (p=0.50) between ceramic-on-ceramic and ceramic-on-HXLPE, and 0.40 (p=0.34) between ceramic-on-ceramic and metal-on-HXLPE. A recent study of ceramic-on-HXLPE bearings for 130 cementless THA in 119 patients younger than 50 years at mean follow-up of 8.3 years (range, 7–9) reported a mean post-operative Harris hip score of 94, UCLA activity score of 8.1, no acetabular revisions, no osteolysis, no head or liner fracture, and 0.022 ± 0.003 mean annual penetration rate of the femoral head. While longer follow-up is necessary, ceramic-on-HXLPE bearings are an attractive option in younger, high demand patients undergoing primary THA.

Age is often used as a surrogate for activity. However, it has been demonstrated that BMI has a stronger correlation to post-operative activity than age. The fundamental exercise in choosing a bearing is maximizing the benefit-to-risk ratio. The following question should be addressed on a patient by patient basis: what available bearing is most likely to meet the needs of this patient, with an acceptable risk of revision surgery during their lifetime, is accepted in my community, and with a justifiable cost?

The risk of ceramic fracture is very low with Biolox® Delta, and that risk decreases with increasing head size. However, concerns of taper corrosion, not wear and osteolysis, have driven the increase in utilization of ceramic heads. More research is needed into the etiology of taper corrosion, especially surgeon variability in taper assembly.

Crosslinked polyethylene has substantially reduced wear, osteolysis, and revision rates compared to non-crosslinked polyethylene, regardless of the countersurface. In the AOA National Joint Replacement Registry, ceramic/ceramic, metal/XLPE, ceramic/XLPE, and ceramicised metal/XLPE are the most commonly used bearing surfaces. With 12–15 year follow-up, there is no difference in the cumulative percent revision of these four bearings in patients aged <55.

Ceramic heads are variably more expensive. The ability to recoup the increased cost of ceramic heads through a diminished lifetime revision cost is dependent on the price premium for ceramic and the age of the patient. A wholesale switch to ceramic bearings regardless of age or cost differential could result in an economic burden to the health system.

One measure of “standard” is simply “the most frequently used”. In this regard, market data alone makes the determination of “standard” without regard to clinical or economic outcomes. However, longer follow-up, including financial data, is necessary to better assess the relative value (benefit-to- risk ratio) of all the available bearing couples.

Background: Metal sensitivity following total joint arthroplasty (TJA) has been of increased concern, but the impact of a patient-reported metal allergy on clinical outcomes has not been investigated. The purpose of this study was to report the incidence and impact of patient-reported metal allergy following total knee (TKA) and total hip arthroplasty (THA).

Methods: This was a retrospective, IRB-approved investigation of patients undergoing a primary, elective TJA between 2009 and 2011. All patients completed a pre-operative questionnaire asking about drug and environmental allergies. In January of 2010, a specific question was added regarding the presence of a metal allergy. UCLA Activity, SF-12, Modified Harris Hip (MHHS), and Knee Society (KSS) scores were collected pre-operatively and at most recent follow-up. Overall cohorts of metal allergy and non-metal allergy patients were compared and a 1:2 matching analysis was also performed.

Results: 906 primary THAs and 589 primary TKAs were included. The incidence of patient-reported metal allergy was 1.7% before January 2010 and 4.0% after (overall 2.3% of THAs and 4.1% of TKAs). 97.8% of metal allergy patients were female. Following TKA, post-operative KSS function, symptoms, satisfaction, and expectation scores were all decreased in the metal allergy cohort (p<0.001 to 0.002). Following THA, metal allergy patients had a decreased post-operative SF-12 MCS score and less incremental improvement in their SF-12 MCS score versus the non-metal allergy cohort (p<0.0001 and p<0.001).

Conclusion: Patient-reported metal allergy is associated with decreased functional outcomes following TKA and decreased mental health scores following THA.

As the American population ages and a trend toward performing total hip arthroplasty (THA) in younger patients continues, the number of Americans undergoing THA is projected to increase over time. The advent of the bundled payment system combined with the current medical utilization climate has placed considerable pressure on surgeons to produce excellent results with early functional recovery and short hospital stays. The US obesity epidemic has transcended into the arthroplasty patient population and surgeons must assess whether obesity is a risk factor for poor outcomes in THA and determine how it should be managed. We performed a recent literature review to determine how obesity impacts outcomes in total hip arthroplasty and what must be done to improve outcomes in the obese arthroplasty patient. Our goal is to answer 3 questions: does obesity increase the complication rate in THA, if obesity matters how obese is too obese, and what must be done to improve outcomes in the obese patient?

Ultimately, obesity has been shown to correlate with increased post-operative complications in THA. The arthroplasty surgeon must optimise the obese patient prior to surgery by identifying associated comorbidities and consider malnutrition screening with counseling. Notice should be taken of the degree of obesity as patients with BMI > 40 have demonstrated much higher complication rates. Strong consideration should be given to avoiding direct anterior approach in the obese patient. Healthy weight loss must be encouraged with appropriate patient counseling and treatment in order to achieve success with THA in obese patients.

Developmental dysplasia of the hip (DDH) represents a heterogeneous group of deformities that are commonly associated with secondary osteoarthritis. Affected hips may require total hip arthroplasty (THA) for endstage disease and these cases can present unique challenges for the reconstructive surgeon. While the severity of deformity varies greatly, optimizing THA can be challenging even in the “mildly” dysplastic hip. These disorders are commonly characterised by acetabular deficiency with inadequate coverage of the anterolateral femoral head and proximal femoral abnormalities including excessive femoral antetorsion, coxa valga and femoral stenosis. In more severe cases, major femoral head subluxation or dislocation can add additional complexity to the procedure. In addition to the primary deformities of DDH, secondary deformities from previous acetabular or proximal femoral osteotomies may also impact the primary THA. Primary THA in the DDH hip can be optimised by detailed understanding of the bony anatomy, careful pre-operative planning, and an appropriate spectrum of techniques and implants for the given case. This presentation will review the abnormal hip morphologies encountered in the dysplastic hip and will focus on the more challenging aspects of THA. These include acetabular reconstruction of the severely deficient socket and in the setting of total dislocation, femoral implant procedures combined with corrective osteotomy or shortening, and issues related to arthroplasty in the setting of previous pelvic osteotomy. Despite the complexity of reconstruction for various dysplastic variants the clinical outcomes and survivorship of these procedures are good to excellent for most patients. Nevertheless, more complex procedures are associated with an increased complication rate and this should be considered in the surgical decision-making process.

Acetabular protrusio occurs from migration of the femoral head medial to Kohler's line. This occurs in inflammatory arthritis, osteoarthritis with coxa vara deformities, previous acetabular fracture, and in metabolic bone diseases such as osteomalacia, Paget's disease, Marfan's syndrome, and osteogenesis imperfecta. Total hip replacement in this situation is difficult due to the requirement to place the acetabular component opening at the level of the normal rim or the patient will be at risk for component-on-component or bone-on-bone impingement, resulting in dislocation or component loosening. The deficient medial wall doesn't resist cup subsidence and the deficient peripheral rim may provide poor initial cup stability.

Many management options have been described including using cement, bulk bone graft, and particulate graft to support the cup medially, and use of a reinforcement ring cage to provide better rim support. Gates reported on a series of 36 primary total hip replacements with acetabular protrusio treated with cemented cups and medial particulate autograft with a mean follow-up of 12.8 years with 6 definitively loose, 3 probably loose, and 22 possibly loose. The technique that provides initial porous cup stability and potential for long-term biological fixation is preferred. Mullaji and Shetty reported 90% good and excellent results and no loosening or migration at a mean 4.2 years in 30 primary total hips with acetabular protrusio treated with oversized porous cups for rim support and medial particulate bone grafting. Forty percent of their cases had protrusio greater than 15 mm medial to Kohler's line. Hansen and Ries also reported no revisions using this same technique in 19 revision total hips with an average follow-up of 2.8 years. However, they emphasised that this technique should only be used if the peripheral rim is intact, and if inadequate, to use a reconstruction cage. In revision total hips with large medial acetabular defects this is more likely to be the case. However, use of a reconstruction cage doesn't provide biological fixation. Ilyas reported a 15.1% loosening rate using cages for revisions with medial defects at a follow-up of 6 years.

I have alternatively used a porous protrusio shell when rim support is poor and the medial defect is greater than 10 mm. The technique is to perform a cylindrical peripheral ream and a medial hemispherical ream. This provides greater host bone to shell contact for stability and greater biological fixation, and fills much of the medial defect. I used this technique in 43 cases with an average follow-up of 3.7 years. There were no revisions, no apparent cup migrations, and no progressive component bone radiolucencies. For primary total hips with protrusio, when good rim support can be achieved with a few millimeters of peripheral over-ream, a standard porous cup and medial particulate autografting is preferred. However, in many primary cases with greater than 10 mm of protrusio, the peripheral rim may be significantly stress shielded and thus, may have poor rim support unless the rim is significantly over-reamed. Because of my excellent results using protrusio shells in revision cases, I will consider also using a protrusio shell in primary total hips in elderly patients with >10 mm of protrusio. I have experience in 10 primary cases with an average follow-up of 4.1 years. One failed for infection. The other 9 have been successful with no apparent cup migration and no progressive component bone radiolucencies.

Significant hip osteoarthritis has been reported in 8–28% of patients with Down Syndrome. The prolonged life expectancy of these patients has allowed many of them to become disabled by their hip arthritis with the need for hip replacement.

We have been able to perform a multi-center study evaluating total hip replacement in patients with Down Syndrome. Twenty patients (25 hips) with Down Syndrome underwent primary THA at a mean age of 35 years old with a mean 105-month follow-up. Cementless acetabular fixation with screws were used in all cases and all but one femoral component was cementless. Constrained liners were used in 8 cases to enhance stability. Five hips required revision surgery: two femoral components (one for periprosthetic fracture and one for aseptic loosening), two acetabular components (one for recurrent dislocation and one for wear with metallosis), and one hip required a two-stage revision for infection. Other than the hip revised for loosening, no other hip had radiographic evidence of loosening. The mean Harris Hip score improved from 42 points pre-operatively to 83 points at final follow-up.

THA is a reliable surgical intervention in patients with Down Syndrome and symptomatic coxarthrosis. These patients and their families have been tremendously satisfied with this procedure. Strategies to prevent dislocation post THA are appropriate and need continued evaluation.

There has been a reluctance, until relatively recently, to consider replacement of the hip in patients with substantial neuromuscular imbalance. This relates to many factors, including the young age of many (such as cerebral palsy in the older teen and young adult), developmental anatomic abnormality, oft-present poor bone health, neuromuscular imbalance, and the risk of complication; especially dislocation. Mental retardation also introduces challenges with rehabilitation and an increased burden on the family and societal support systems if the outcome is to be maximised. With the development of newer techniques and technology, and the emergence of encouraging outcome studies, these patients can be more easily offered predictable relief of pain, a reasonable chance of improved function, longevity of the reconstruction, and an acceptable risk of complication.

A large number of background neurological diagnoses can lead to hip degeneration, or can introduce increased complexity during management of hip degeneration unrelated to that background. Be that as it may, a short list of fundamental questions is common to all and will help guide management:

Important questions to be addressed include:

1. Did the NV imbalance precede skeletal development? This relates to the dependence of skeletal shape and size on the loads being placed upon it: hence “Form Follows Function”. The shape and size of the hip, and location of the femoral head, will be much different in the young adult with spastic dislocation due to cerebral palsy, when compared with the elderly adult with a late onset CVA-related spasticity superimposed on hip degeneration.

2. Is the muscle tone which will support the hip arthroplasty predominantly spastic or flaccid? In each there is a risk of dislocation, which needs to be addressed at the index procedure, but in spasticity there is the added question as to what tissues need to be released or de-functioned so as to alter the magnitude and direction of the joint reaction forces.

3. Is pain the main reason for consultation? Because pain relief is the most predictable outcome that we can offer, it should guide the indications and timing of intervention. Replacement of the NM hip to improve function, in the absence of pain, should be approached with great caution.

Osteonecrosis of the femoral head (ONFH) is a debilitating, painful, progressive, and refractory disease that has multiple etiologic risk factors. It is caused by bone cell death, which itself has various causes, leading to femoral head collapse and subsequent osteoarthritis. ONFH primarily influences patients aged from 20 to 50 years; in addition, bilateral hip joints are involved in 75% of patients. Causes include use of corticosteroids, alcohol abuse, previous trauma, hemoglobinopathy, Gaucher disease, coagulopathies, and other diseases. No pharmacologic treatment has been shown to be effective for early ONFH. Outcomes of total hip arthroplasty (THA) for these young and active patients have some drawbacks, primarily due to the young age of these patients, limited lifetime and durability of the implants and their fixation, and the skeletal manifestations of osteonecrosis.

As a result of these concerns, there has been an increased focus on early interventions for ONFH aimed at preservation of the native articulation. Core decompression is currently the most widely accepted surgical treatment at the early stage of avascular osteonecrosis (AVN); however, due to limited efficacy, its use has been debated. There is currently no standardised protocol for evaluating and treating osteonecrosis of the femoral head in adults in the United States.

Although total hip replacement is the most frequent intervention for treatment of post-collapse (Steinberg stage-IIIB, IVB, V, and VI) osteonecrosis; core decompression is the most commonly offered intervention for symptomatic, pre-collapse (Steinberg stage-IB and IIB) osteonecrosis. Less frequently offered treatments include non-operative, pharmacologic or modality management, osteotomy, vascularised and non-vascularised bone-grafting, hemiarthroplasty, resurfacing and arthrodesis.

A promising, minimally invasive, core decompression procedure combined with a mesenchymal stem cell grafting technique which restores vascularity and heals osteonecrotic lesions has become popularised. This procedure is called a bone marrow aspirate concentrate (BMAC) procedure. During a BMAC, mesenchymal stem cells (in the form of concentrated iliac crest bone marrow) are injected through a core decompression tract into the area of necrosis in the femoral head. Most patients with early (pre-collapse) disease have excellent results at 2 to 5 years of clinical follow-up. Patients are weight bearing as tolerated on crutches after the procedure for 6 weeks, and are able to go home on the same day or next day after surgery with minimal pain. We can report on the early, promising results of 300 patients with ONFH treated with BMAC in the United States by two expert hip surgeons with at least 75%-80% survivorship.

The care of adults with osteonecrosis of the femoral head is highly variable. This paper will discuss the various non-operative and operative treatment algorithms for ONFH available today. We will also report on a promising, new technique (BMAC), which improves the efficacy of traditional core decompression for early ONFH. The goal of treatment of early ONFH is to avoid THA in young, active patients and this talk will discuss those interventions and treatments which help accomplish that goal.

This session will present a series of challenging and complex primary and revision cases to a panel of internationally respected hip arthroplasty experts. The primary cases will include challenges such as hip dysplasia, altered bony anatomy and fixation challenges. In the revision hip arthroplasty scenarios issues such as bone stock loss, leg length discrepancy, instability and infection will be discussed. This will be an interactive case-based session that at its conclusion should leave the attendee with a more thorough approach to these challenging issues.

Over the past fifteen years hip preservation surgery has rapidly evolved. Improved understanding of the pathomechanics and associated intra-articular degeneration of both hip instability and femoroacetabular impingement have led to improved surgical indications, refined surgical techniques and more effective joint preservation surgical procedures. The periacetabular osteotomy (PAO) was initially introduced by Ganz and colleagues and has become the preferred treatment in North America for pre-arthritic, symptomatic acetabular dysplasia. Both hip arthroscopy and safe surgical dislocation of the hip have been popularised for the treatment of symptomatic femoroacetabular impingement disorders. Hip arthroscopy is effective for focal and\or accessible impingement lesions while the surgical dislocation approach is reserved for nonfocal disease patterns as seen in complex FAI, and residual Perthes and SCFE deformities. Femoroacetabular impingement from major acetabular retroversion can be managed with the PAO if there is coexistent posterosuperior acetabular insufficiency. Short- to mid-term results of these procedures are generally good to excellent for most patients and the complication rates associated with these procedures are very acceptable. Long-term outcomes are best known for the PAO. Several recent studies have documented survivorship rates of 65–90% at 10–20-year follow-up. Certain factors are associated with long-term success including minimal pre-operative radiographic OA, early symptoms, accurate acetabular correction, and younger age. These data strongly suggest that the PAO can defer THA to an older age for most patients while completely avoiding arthroplasty may only be possible in select patients with excellent congruency, no secondary OA and an ideal surgical correction.

Introduction: Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup.

Technique: The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increase or decrease of lumbar lordosis and combined anteversion.

Methods: Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using EBRA software.

Results: There were no malalignment or dislocation. The mean cup inclination angle and anteversion were 41 ± 5.1 degrees (range 37.1 – 48.4) and 22.1 ± 4.8 degrees (range 16.6 – 29.3), respectively.

Conclusion: This is a reproducible method of cup positioning and with proper femoral component position, restores leg length, offset, combined anteversion, and balances soft tissue around the hip. These factors affect the incidence of dislocation, infection, reduced wear, and durability.

Longevity of total hip arthroplasty (THA) is dependent upon avoiding both short- and long-term problems. One of the most common short-term / early complications of THA is instability while longer term issues of wear remain a concern. Both of these concerns appear to be related to implant position: either static or functional. While achieving “ideal” implant position in primary THA for osteoarthritis is only successful in 50% of cases (Callanan et al.), it is even more difficult in complex primary disorders such as dysplasia and post-traumatic arthritis.

Many theories exist as to why implant position and short-term complications appear to be higher in this “complex primary” cohort but certainly the ability to achieve desired implant position appears to be more challenging. The loss of usual anatomic landmarks, the presence of soft tissue contractures, and the recognition of both pelvic and femoral deformities play a role.

Enabling technologies have emerged to help in achieving improved implant position. These technologies include both navigation (both imageless and image guided) as well as the newly adopted technology of robotic assistance. Robot-assisted THA is based upon a CT scan protocol. Three-dimensional pre-operative planning on both the femoral and acetabular side can be performed. Precision guided bone preparation and exacting implant delivery is achievable using robotic technology.

Examples of use of this technology in complex primary THA will be demonstrated including planning, preparation and implantation.

Acute peri-operative blood loss warranting transfusion is a frequent consequence of major joint replacement (TJR) surgery. Significant peri-operative anemia can contribute to hypotension, dyspnea, coronary ischemia and other peri-operative medical events that can result in increased risk of peri-operative complications, readmissions and impair the patient's ability to mobilise after surgery resulting in a longer length of stay (LOS) and increase skilled nursing facility (SNF) utilization. The risks associated with allogeneic blood transfusions (ABT) administered to treat symptomatic peri-operative anemia are numerous and extend beyond the concerns of transmission of communicable disease (HIV, hepatitis, other). Patients receiving ABTs have been shown to have a longer hospital LOS, higher risk of infection, and higher mortality after TJR than those who do not require transfusion after surgery. As a result, many different pre-operative, peri-operative and post-operative strategies have been utilised to minimise peri-operative blood loss and transfusion need for patients undergoing TJR. Several studies have shown that the strongest predictor of the need for ABT in the TJR patient is the pre-operative hematocrit (Hct). As a result, all patients with unexplained pre-operative anemia should be evaluated for an underlying cause prior to elective TJR surgery.

In recent years, focus has shifted towards peri-operative reduction of blood loss with the use of pharmacologic agents like tranexamic acid (TXA). These agents work by inhibiting fibrinolysis and activating plasminogen. Numerous studies have shown that TXA given IV, applied topically into the surgical wound or given orally have been shown to reduce peri-operative bleeding and ABT after both THA and TKR. Regardless of route of administration, all appear to be more efficacious and considerably more cost-effective in reducing the need for ABT than other methods discussed previously. Despite concerns about the potential increased thromboembolic risk in patients undergoing TJR, there does not appear to be any conclusive evidence suggesting an increased risk of venous thromboembolic disease (VTED) in TJR patients who receive peri-operative TXA. Although it may be unnecessary, many TJR surgeons still, however, avoid use of TXA in patients with a past history of VTED, stroke, coronary artery disease (including coronary stents), renal insufficiency, hypercoagulable state and seizure disorder. The use of topical TXA may be safer in some of these high risk patients since systemic absorption is minimal when administered via this route. Although the optimal method of administration (IV, topical, oral or combined) has not yet been determined based on safety, cost and reduction of need for ABT, incorporation of tranexamic acid into a blood conservation program is clearly the standard of care for all TJR programs that should nearly eliminate the need for ABT for patients undergoing TJR.

Traditional risk factors for post-operative neuropathy include learning curve of surgical approach, DDH, and significant leg lengthening (>1 inch). Despite these risk factors, the most common scenario of a neuropathy is in a routine THA, by an experienced surgeon, for osteoarthritis, with no leg lengthening.

Post-operative hematoma can lead to nerve compression, albeit rarely. The usual clinical presentation is of an acute event, with a previously intact nerve, sometime within the first days of surgery. Once diagnosed, immediate surgical decompression should be performed.

Sciatic neuropathy is the most common, regardless of surgical approach, but the posterior approach poses the highest risk. Routine gluteus maximus tendon release may help to reduce the risk. When seen in the PACU, our approach is to immediately perform CT imaging to evaluate nerve integrity or to check on acetabular screw position. If no underlying cause is identified, the patient will be managed conservatively with foot orthotics and monitored for recovery.

Femoral nerve palsy (FNP) can result in significant initial disability. Fortunately most patients recover function (although it can take over 18 months). In the early post-operative period it is often diagnosed after a patient complains of the leg giving away while attempting to walk. A knee brace will assist the patient with mobilization while the nerve recovers. The highest incidence of FNP is described for the direct lateral approach.

Superior gluteal nerve (SGN) palsy is related to the direct lateral approach and may be avoided if the gluteus medius split is made within the safe zone (<5 centimeters from the tip of the greater trochanter). While early post-operative limp is common after the direct lateral approach, the true reported incidence of SGN palsy is low. Few studies showed that the persistent positive Trendelenburg test and limp is not exclusively related to the SGN damage and therefore the clinical effect of the SGN damage remains controversial.

Lateral femoral cutaneous nerve can be affected during the direct anterior hip approach. One study suggests the presence of peri-incisional numbness in over 80% of patients. This is akin to numbness seen lateral to the incision after TKA. The incidence of meralgia paresthetica is extremely low (<1%).

Venous thromboembolism (VTE) prophylaxis following total joint arthroplasty (TJA) should be individualised in order to maximise the efficacy of prophylactic measures while avoiding the adverse events associated with the use of anticoagulants. At our institution, we have developed a scoring model using the Nationwide Inpatient Sample (NIS) database, which is validated against our institutional data, to stratify patients into low- and high-risk groups for VTE. Low-risk patients are placed on aspirin 81 mg twice daily for four weeks post-operatively, and high-risk patients are placed on either a Vitamin K antagonist (warfarin), low molecular weight heparin, or other oral anticoagulants for four weeks post-operatively. All patients receive sequential pneumatic compression devices post-operatively, and patients are mobilised with physical therapy on the day of surgery. Patients who have a history of peptic ulcer disease or allergy to aspirin are also considered for other types of anticoagulation following surgery.

Risk Stratification Criteria

Major comorbid risk factors utilised in our risk stratification model include history of hypercoagulability or previous VTE, active cancer or history of non-cutaneous malignancy, history of stroke, and pulmonary hypertension. We consider patients with any of these risk factors at elevated risk of VTE and therefore candidates for formal anticoagulation.

Other minor risk factors include older age, bilateral surgery compared with unilateral, inflammatory bowel disease, varicose veins, obstructive sleep apnea, and history of myocardial infarction, myeloproliferative disorders, and congestive heart failure. Each minor criterion is associated with a score. The cumulative score is compared with a defined threshold and the score that surpasses the threshold indicates that the patient should receive post-operative anticoagulation. To facilitate the use of this scoring system, an iOS mobile application (VTEstimator) has been developed and can be downloaded from the app store.

Metal-on-metal bearing surfaces were reintroduced to take advantage of the reduction in volumetric wear afforded by these bearings and reduce the complications of osteolysis and aseptic loosening. In addition, metal-on-metal hip resurfacing and many metal-on-metal total hip replacement systems employed large diameter femoral heads, thereby reducing the risk of dislocations. Unfortunately, many metal-on-metal systems demonstrated poor survivorship and were associated with adverse local tissue reactions (ALTRs) related to metal debris generated from the bearings and/or modular connections.

Careful clinical surveillance of patients with metal-on-metal bearings is warranted to identify patients with ALTR at an early stage in order to intervene prior to the development of extensive peri-articular soft tissue damage. Monitoring may include serum or whole blood metal levels and metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) depending on the patient's signs and symptoms and the track record of the implanted device. While there currently is a lack of high quality evidence-based guidelines on the management of patients with either symptomatic or asymptomatic metal-on-metal total hip replacements, professional organizations have issued consensus-based algorithms to guide the practitioner in management. Ultimately, the decision for revision surgery should not be based on a single diagnostic test but on the entire clinical scenario.

Recurrent dislocation following total hip arthroplasty (THA) is a complex, multifactorial problem that has been shown to be the most common indication for revision THA. At our center, we have tried to approach the unstable hip by identifying the primary cause of instability and correcting that at the time of revision surgery.

Type 1: Malposition of the acetabular component treated with revision of the acetabular component and upsizing the femoral head.

Type 2: Malposition of the femoral component treated with revision of the femur and upsizing the femoral head.

Type 3: Abductor deficiency treated with a constrained liner or dual mobility bearing.

Type 4: Soft tissue or bony impingement treated with removal of impingement sources and upsizing the femoral head.

Type 5: Late wear of the bearing treated with bearing surface exchange and upsizing the femoral head.

Type 6: Unclear etiology treated with a constrained liner or dual mobility articulation.

The most common etiologies of instability in our experience include cup malposition (Type 1) and abductor deficiency (Type 3).

We reviewed 75 hips revised for instability and at a mean 35.3 months, 11 re-dislocations occurred (14.6%). Acetabular revisions were protective against re-dislocation (p<0.02). The number of previous operations (p=0.04) and previously failed constrained liners (p<0.02) were risk factors for failure. The highest risk of failure was in patients with abductor insufficiency with revisions for other etiologies having a success rate of 90%.

Although instability can be multifactorial, by identifying the primary cause of instability, a rational approach to treatment can be formulated. In general, the poorest results were seen in patients with abductor deficiency. Given the high rate of failure of constrained liners (9 of the 11 failures were constrained), we currently are exploring alternatives such as dual mobility articulations. Our early experience with dual mobility suggests improved results when compared to constrained liners.

The number one reason to consider large heads in total hip arthroplasty (THA) is for increased stability. Large diameter femoral heads substantially increase stability by virtue of increased range of motion and increased jump distance, which is the amount of displacement required to sublux the head out of the socket. Prevention is the best means for reducing dislocation, with requisites for stability being appropriate component position, restoration of leg length, and restoration of offset.

In a review from our center studying the frequency of dislocation with small diameter femoral heads (≤32 mm) in 1262 patients (1518 hips) who underwent primary THA performed via a direct lateral approach, we observed a dislocation rate of 0.8% (12 of 1518). In a subsequent study of 1748 patients (2020 hips) who underwent primary THA at our center with large diameter heads (mean 43 mm, range 36–60 mm), we observed a substantially lower 0.04% frequency of dislocation (one of 2010) at a mean followup of 2.6 years.

Our findings have been echoed in studies from several other centers. Howie et al. reported a prospective controlled trial of 644 low risk patients undergoing primary or revision THA randomised to receive either a 36 mm or 28 mm metal head articulated on highly crosslinked polyethylene. They observed significantly lower frequency of frequency of dislocation with 36 mm heads both overall (1.3%, 4 of 299 versus 5.4%, 17 of 216 with 28 mm heads, p=0.012) and in primary use (0.8%, 2 of 258 versus 4.4%, 12 of 275 with 28 mm heads, p=0.024), and a similar trend in their smaller groups of revision patients (5%, 2 of 41, versus 12%, 5 of 41 with 28 mm heads, p=0.273).

Lachiewicz and Soileau reported on early and late dislocation with 36- and 40 mm heads in 112 patients (122 hips) at presumed high risk for dislocation who underwent primary THA. Risk factors were age >75 for 80 hips, proximal femur fracture for 18, history of contralateral dislocation for 2, history of alcohol abuse in 2, large acetabulum (>60 mm) in 6, and other reasons in 14. Early dislocation (<1 year) occurred in 4% (5 of 122), all with 36 mm heads. Late dislocation (>5 years) did not occur in any of the 74 patients with followup beyond 5 years.

Stroh et al. compared 225 patients (248 hips) treated with THA using small diameter heads (<36 mm) to 501 patients (559 hips) treated with THA using large diameter heads (≥36 mm). There were no dislocations with large diameter heads compared with 1.8% (10 of 559) with small diameter heads.

Allen et al. studied whether or not large femoral heads improve functional outcome after primary THA via the posterior approach in 726 patients. There were 399 done with small heads (<36 mm), 254 with medium heads (36 mm), and 73 with large heads (>36 mm), analyzed pre-operatively, at 6 months, and at 12 months. The authors could not find a correlation between increasing head size and improved function at one year, but observed that dislocation was reduced with large diameter heads.

Optimization of hip biomechanics via proper surgical technique, component position, and restoration of leg length and offset are mandatory in total hip arthroplasty. Large heads enhance stability by increasing range of motion prior to impingement and enhancing jump stability.

Instability after total hip arthroplasty is the most common indication for revision arthroplasty and can be difficult to treat. The purpose of this study is to evaluate the outcomes associated with the use of a constrained acetabular component as a treatment for instability after hip arthroplasty. We reviewed the clinical and radiographic outcomes of 149 arthroplasties, that had been performed with use of a single design of constrained acetabular component between 2007 and 2012 at a single institution. Patient demographics and case specific data were collected The Mann-Whitney U test was used to assess continuous variables. Categorical variables were examined using the Chi-square test and Fisher's exact test when appropriate. Survival probability was calculated using the Kaplan-Meier method.

The mean age at time of index surgery was 70 years, 65% were female, and mean BMI was 26.3. The average number of previous surgeries was 3.6. The constrained liner was cemented into a well-fixed cup in 40 hips (20%). In eighty-two (55%) hips the constrained component was implanted for the treatment of recurrent instability, and in sixty-seven (45%) hips it was implanted because the hips demonstrate instability during revision surgery. At an average duration of follow-up of 4.2 (2–7) years the overall revision rate was 10.6 % The constrained acetabular device eliminated or prevented hip instability in all patients except five; 3.3% had a new dislocation and six (4.0%) had failure of the retentive ring. Three revisions (2%) were performed for deep infection, and 2 (1.3%) for acetabular component loosening. Radiographic analysis revealed a non-progressive radiolucent line around the cup in 19 hips (12.7%). When stratified by patient age, survivorship for patients less than 65 years of age versus those greater than 65 years was similar.

This study correlates with results of other papers in the literature looking at outcome of constrained tripolar type sockets. The focal constraint socket with a metal ring type design has a much greater failure rate (9–29%). Constrained liners remain an excellent option for hip instability in early to mid- term follow up.

Treatment of recurrent dislocation: approximately: 1/3 of failures (probably higher in the absence of a clear curable cause).

In the US: most popular treatment option: constrained liners with high redislocation and loosening rates in most reports. Several interfaces leading to various modes of failures.

In Europe: dual mobility cups (or tripolar unconstrained): first design Gilles Bousquet 1976 (Saint Etienne, France), consisting of a metal shell with a highly polished inner surface articulating with a mobile polyethylene insert (large articulation). The femoral head is captured into the polyethylene (small articulation) using a snap fit type mechanism leading to a large effective unconstrained head inside the metal cup. With dual mobility, most of the movements occur in the small articulation therefore limiting wear from the large polyethylene on metal articulation.

Contemporary designs include: CoCr metal cup for improved friction, outer shell coated with titanium and hydroxyapatite, possible use of screws to enhance primary stability (revision), cemented version in case of major bone defect requiring bone reconstruction.

Increased stability obtained through an ultra-large diameter effective femoral head increasing the jumping distance.

Dual mobility in revision for recurrent dislocation provided hip stability in more than 94% of the cases with less than 3% presenting redislocation up to 13-year follow-up. A series from the UK concerning 115 revisions including 29 revisions for recurrent dislocation reported 2% dislocation in the global series and 7% re-dislocation in patients revised for instability. A recent report of the Swedish hip arthroplasty register including 228 patients revised for recurrent dislocation showed 99% survival with revision for dislocation as the endpoint and 93% with revision for any reason as the endpoint.

One specific complication of dual mobility sockets: intra-prosthetic dislocation (ie: dislocation at the small articulation): often asymptomatic or slight discomfort, eccentration of the neck on AP radiograph, related to wear and fatigue of the polyethylene rim at the capturing are through aggressive stem neck to mobile polyethylene insert contact (3rd articulation). Risk factors include: large and aggressive femoral neck design implants, small head/neck ratio, skirted heads, major fibrosis and periprosthetic ossifications.

Current (over ?) use in France: 30% of primary THA, 60% in revision THA.

Proposed (reasonable) indications: primary THA at high risk for dislocation, revision THA for instability and/or in case of abductors deficiency, Undisputed indication: recurrent dislocation.

Total hip replacement is among the most successful interventions in medicine and has been termed “The Operation of the Century”. Most major problems have been solved including femoral fixation, acetabular fixation, and wear. With a success rate of over 95% at 10 years in both hip and knee arthroplasty in a number of studies, the question remains as to whether the current status quo is optimal or acceptable. The literature, however, reports are from centers that represent optimised results and registry data, including the Medicare database, indicates that substantial short-term problems persist. The major issue is the variability in the performance of the procedure. The inability to consistently position components, particularly the acetabular component, results in major problems including instability and limb length discrepancy. A report by Malchau, et al. reveals that even among the best surgeons, optimal acetabular component positioning is only achieved 50% of the time. The penalty for missing the target is increased incidence of instability, increased wear rate, and diminished function due to restricted motion. Complications are related to position and a major potential explanation is the impact of patient position. Traditional imaging presents a two-dimensional rather than three-dimensional view of the patient and the patient is in a supine, non-functional position at the time that imaging is performed. Adverse events attributed to malposition, however, occur in functional positions and there is evidence that the orientation of the pelvis changes from the supine position at which imaging is performed. This topic has been studied extensively on three continents and the consensus is that the pelvis shifts on the order of 30–40 degrees from the supine to standing and sitting and furthermore, the acetabular component position changes proportionally with the rotation of the pelvis that occurs. How do we incorporate this information into imaging arthroplasty patients? This would require imaging the entire body, acquiring AP and lateral images simultaneously so that 3D imaging can be performed, performing imaging in a functional position (standing or sitting) and optimally at a lower radiation dose since these patients have repeated images and therefore a cumulative radiation dose over their lifetime. This technology was FDA approved for use in the hip and knee in 2011 and pilot studies have been performed at Washington University School of Medicine in St. Louis to validate the number of the hip and knee arthroplasty applications.

In conclusion, weightbearing and rotation have substantial impact on the standard measurements obtained before and after hip and knee arthroplasty. These differences in measurements between supine, sitting, and standing as well as correction for rotation may explain the lack of a stronger correlation between component position and a variety of complications that are observed such as variability in wear rates as well as instability. In knee arthroplasty, the change in mechanical axis that occurs from restoring all of patients to a neutral mechanical axis may explain some of the persistent pain and dissatisfaction that has been recently been reported at a relatively high percentage of knee arthroplasty patients. Because of the numerous potential clinical implications of three-dimensional weightbearing imaging, it is likely that the future of arthroplasty imaging will focus on functional three-dimensional imaging of the patient.

Avulsion of the abductor muscles of the hip may cause severe limp and pain. Limited literature is available on treatment approaches for this problem, and each has shortcomings. This study describes a muscle transfer technique to treat complete irreparable avulsion of the hip abductor muscles and tendons.

Ten adult cadaver specimens were dissected to determine nerve and blood supply point of entry in the gluteus maximus and tensor fascia lata (TFL) and evaluate the feasibility and safety of transferring these muscles to substitute for the gluteus medius and minimus. In this technique, the anterior portion of the gluteus maximus and the entire TFL are mobilised and transferred to the greater trochanter such that the muscle fiber direction of the transferred muscles closely matches that of the gluteus medius and minimus. Five patients (five hips) were treated for primary irreparable disruption of the hip abductor muscles using this technique between January 2008 and April 2011. All patients had severe or moderate pain, severe abductor limp, and positive Trendelenburg sign. Patients were evaluated for pain and function at a mean of 28 months (range, 18–60 months) after surgery.

All patients could actively abduct 3 months post-operatively. At 1 year post-operatively, three patients had no hip pain, two had mild pain that did not limit their activity, three had no limp, and one had mild limp. One patient fell, fractured his greater trochanter, and has persistent limp and abduction weakness.

The anterior portion of the gluteus maximus and the TFL can be transferred to the greater trochanter to substitute for abductor deficiency. In this small series, the surgical procedure was reproducible and effective; further studies with more patients and longer follow-up are needed to confirm this.

An expert panel of orthopaedic surgeons is going to be evaluating primary and revision total hip and total knee replacements submitted by the audience. Participants will present the x-rays and clinical findings of difficult cases for which they are seeking an expert opinion from the panel. The panel will probably have conflicting opinions which will lead to an entertaining and educational session. The moderator will also provide some extremely challenging cases once again, to stimulate more controversy. This session has been very popular in the past and is fast moving, humorous and educational.

As the number of patients who have undergone total hip arthroplasty rises, the number of patients who require surgery for a failed total hip arthroplasty is also increasing. Reconstruction of the failed femoral component in revision total hip arthroplasty can be challenging from both a technical perspective and in pre-operative planning. With multiple reconstructive options available, it is helpful to have a classification system which guides the surgeon in selecting the appropriate method of reconstruction.

Type I: Minimal loss of metaphyseal cancellous bone with an intact diaphysis. Often seen when conversion of a cementless femoral component without biological ingrowth surface requires revision. Type II: Extensive loss of metaphyseal cancellous bone with an intact diaphysis. Often encountered after the removal of a cemented femoral component. Type IIIA: The metaphysis is severely damaged and non-supportive with more than 4 cm of intact diaphyseal bone for distal fixation. This type of defect is commonly seen after removal of grossly loose femoral components inserted with first generation cementing techniques. Type IIIB: The metaphysis is severely damaged and non-supportive with less than 4 cm of diaphyseal bone available for distal fixation. This type of defect is often seen following failure of a cemented femoral component that was inserted with a cement restrictor and cementless femoral components associated with significant distal osteolysis. Type IV: Extensive meta-diaphyseal damage in conjunction with a widened femoral canal. The isthmus is non-supportive.

Based on our results, the following reconstructive algorithm is recommended for femoral reconstruction in revision total hip arthroplasty. An extensively coated, diaphyseal filling component reliably achieves successful fixation in the majority of revision femurs and the surgical technique is straightforward. However, in the severely damaged femur (Type IIIB and Type IV), other reconstructive options may provide improved results. Type I: Cemented or cementless fixation can be utilised. If cemented fixation is selected, great care must be taken in removing the neo-cortex often encountered to allow for appropriate cement intrusion into the remaining cancellous bone. Type II: In this cohort of patients, successful fixation was achieved using a diaphyseal fitting, extensively porous coated implant. However, as the metaphysis is supportive, a cementless implant that achieves primary fixation in the metaphysis can be utilised. Type IIIA: An extensively coated stem of adequate length is utilised to ensure that more than 4 cm of scratch fit is obtained in the diaphysis. Type IIIB: Our present preference is a modular, cementless, tapered stem with flutes for obtaining rotational stability. Type IV: Cementless fixation cannot be reliably used in our experience, as it is difficult to obtain adequate initial implant stability that is required for osseointegration. Reconstruction can be performed with impaction grafting if the cortical tube of the proximal femur is intact. However, this technique can be technically difficult to perform, time consuming and costly given the amount of bone graft that is often required. Although implant subsidence and peri-prosthetic fractures (both intra-operatively and post-operatively) have been associated with this technique, it can provide an excellent solution for the difficult revision femur where cementless fixation cannot be utilised. Alternatively, an allograft-prosthesis composite can be utilised for younger patients in an attempt to reconstitute bone stock and a proximal femoral replacing endoprosthesis used for more elderly patients.

Femoral revision in cemented THA might include some technical difficulties, based on loss of bone stock and cement removal, which might lead to further loss of bone stock, inadequate fixation, cortical perforation or consequent fractures. Femoral impaction grafting, in combination with a primary cemented stem, allows for femoral bone restoration due to incorporation and remodelling of the allograft bone by the host skeleton. Historically it has been first performed and described in Exeter in 1987, utilizing a cemented tapered polished stem in combination with morselised fresh frozen bone grafts. The technique was refined by the development of designated instruments, which have been implemented by the Nijmegen group from Holland. Indications might include all femoral revisions with bone stock loss, while the Endo-Clinic experience is mainly based on revision of cemented stems. Cavitary bone defects affecting meta- and diaphysis leading to a wide or so called “drain pipe” femora, are optimal indications for this technique, especially in young patients. Contraindications are mainly: septical revisions, extensive circumferential cortical bone loss and noncompliance of the patient.

Generally, the technique creates a new endosteal surface to host the cemented stem by reconstruction of the cavitary defects with impacted morselised bone graft. This achieves primary stability and restoration of the bone stock. It has been shown, that fresh frozen allograft shows superior mechanical stability than freeze-dried allografts. Incorporation of these grafts has been described in 89%. Technical steps include: removal of failed stem and all cement, reconstruction of segmental bone defects with metal mesh (if necessary), preparation of fresh frozen femoral head allografts with bone mill, optimal bone chip diameter 2–5 mm, larger chips for the calcar area (6–8 mm), insertion of an intramedullary plug including central wire, 2 cm distal the stem tip, introduction of bone chips from proximal to distal, impaction started by distal impactors over central wire, then progressive larger impactors proximal, insertion of a stem “dummy” as proximal impactor and space filler, removal of central wire, retrograde insertion of low viscosity cement (0.5 Gentamycin) with small nozzle syringe, including pressurization, and insertion of standard cemented stem. The cement mantle is of importance, as it acts as the distributor of force between the stem and bone graft and seals the stem. A cement mantle of at least 2 mm has shown favorable results. Post-operative care includes usually touch down weightbearing for 6–8 weeks, followed by 4–6 weeks of gradually increased weightbearing with a total of 12 weeks on crutches.

Relevant complications include mainly femoral fractures due to the hardly impacted allograft bone. Subsidence of tapered polished implants might be related to cold flow within the cement mantle, however, could also be related to micro cement mantle fractures, leading to early failure. Subsidence should be less than 5 mm. Survivorship with a defined endpoint as any femoral revision after 10-year follow up has been reported by the Exeter group being over 90%, while survivorship for revision as aseptic loosening being above 98%. Within the last years various other authors and institutions reported about similar excellent survivorships, above 90%. In addition, a long-term follow up by the Swedish arthroplasty registry in more than 1180 patients reported a cumulative survival rate of 94% after 15 years.

Impaction grafting might technically be more challenging and more time consuming than cement-free distal fixation techniques. It, however, enables a reliable restoration of bone stock which might especially become important in further revision scenarios in younger patients.

The femur begins to bow anteriorly at the 200 mm level, but may bow earlier in smaller people. If the stem to be used is less than 200 mm, a straight stem can be used. If the stem is longer than 200 mm, it will perforate the anterior femoral cortex. I know this because I did this on a few occasions more than 20 years ago.

To use a long straight stem, there are two techniques. One can either do a diaphyseal osteotomy or one can do a Wagner split (extended trochanteric osteotomy). Both of these will put the knee in some degree of hyperextension, probably insignificant in the elderly, but it may be of significance in the young. In very young people, therefore, it may be preferable to use a bowed stem to avoid this degree of recurvatum.

There are two different concepts of loading. Diaphyseal osteotomy implies a proximal loading has been sought. The Wagner split ignores the proximal femur and seeks conical fixation in the diaphysis. There will be very little bone-bone contact between what remains of the attached femur and the detached anterior cortex so that it is important to ensure that the blood supply to the anterior cortex remains intact, preferably by using Wagner's technique, using a quarter-inch osteotome inserted through the vastus to crack the medial cortex. Current modularity is of two types. Distal modularity was attempted many years ago and was never successful.

Proximal modularity, as for example, the S-ROM stem, implies various sizes of sleeves fit onto the stem to get a proximal canal fill. In mid-stem modularity, the distal stem wedges into the cone. It has to be driven into where it jams and this can be somewhat unpredictable. For this reason, the solid Wagner stem has been replaced by the mid-stem modular. Once the distal femur is solidly embedded, the proximal body is then selected for height and version. The proximal body is unsupported in the mid-stem modular and initially, few fractures were noted at the taper junction. Cold rolling, shot peening and taper strengthening seem to have solved these problems.

There are a variety of types of osteotomy, which can be used for different deformities. With a mid-stem modular system, generally, all that needs to be done is a Wagner-type split and fixation is sought in the mid-diaphysis by conical reaming. No matter what stem is used, distal stability is necessary. This is achieved by flutes, which engage the endosteal cortex. The flutes alone must have sufficient rotational stability to overcome the service loads on the hip of 22 Nm.

I divide revision into three categories. In type one, the isthmus is intact, i.e. the bone below the lesser trochanter so that a primary stem can be used. In type two, the isthmus is damaged, i.e. the bone below the lesser trochanter, so a long revision stem is required. In a type three, there is more than 70 mm of missing proximal femur. The Wagner stem may be able to handle this on its own, but most other stems are better supported with a structural allograft cemented to the stem.

The reported long term results of mid-stem modular revision implants are good as in most, over 90% survivorship. The introduction of modularity appears to have overcome initial disadvantage of the Wagner stem, i.e. its unpredictability in terms of leg length.

Modern modular revision stems employ tapered conical (TCR) distal stems designed for immediate axial and rotational stability with subsequent osseo-integration of the stem. Modular proximal segments allow the surgeon to achieve bone contact proximally with eventual ingrowth that protects the modular junction. The independent sizing of the proximal body and distal stem allows for each portion to obtain intimate bony contact and gives the surgeon the ability precisely control the femoral head center of rotation, offset, version, leg length, and overall stability.

The most important advantage of modular revision stems is versatility - the ability to manage ALL levels of femoral bone loss (present before revision or created during revision). Used routinely, this allows the surgeon to quickly gain familiarity with the techniques and instruments for preparation and implantation and subsequently master the use for all variety of situations. This also allows the operating room staff to become comfortable with the instrumentation and components. Additionally, the ability to use the stem in all bone loss situations eliminates intra-operative shuffle (changes in the surgical plan resulting in more instruments being opened), as bone loss can be significantly under-estimated pre-operatively or may change intra-operatively. Furthermore, distal fixation can be obtained simply and reliably. Paprosky 1 femoral defects can be treated with a primary-type stem for the most part. All other femoral defects can be treated with a TCR stem. Fully porous coated stems also work for many revisions but why have two different revision stem choices available when the TCR stems work for ALL defects?

The most critical advantage is the ability to separate completely the critical task of fixation from other important tasks of restoring offset, leg length, and stability. Once fixation is secured, the surgeon can concentrate on hip stability and on optimization of hip mechanics (leg length and offset). The ability to do this allows the surgeon to maximise patient functionality post-operatively. Modular tapered stems have TWO specific advantages over monolithic stems in this important surgical task. The proximal body size and length can be adjusted AFTER stem insertion if the stem goes deeper than the trial. Further, proximal/distal bone size mismatch can be accommodated. The surgeon can control the diameter of the proximal body to ensure proper bony apposition independent of distal fitting needs. If the surgeon believes that proximal bone ingrowth is important to facilitate proximal bone remodeling, modular TCR stems can more easily accomplish this.

The most under-appreciated advantage is the straightforward instrumentation system that makes the operation easier for the staff and the surgeon, while enhancing the operating room efficiency and reducing cost. Also, although the implant itself may result in more cost, most modular systems allow for a decrease in inventory requirements, which make up the cost differential.

One theoretical disadvantage of modular revision stems is modular junction fracture, which can happen if the junction itself is not protected by bone. Ensuring proximal bone support can minimise this problem. Once porous ingrowth occurs proximally, the risk of junction fracture is eliminated. Even NON-modular stems fracture when proximal bone support is missing. Another theoretical issue is modular junction corrosion but this not a clinical one, since both components are titanium. One can also fail to connect properly the two parts during surgery.

Modularity in femoral revision evolved to address the specific weaknesses in the execution and results of the early Wagner SL stem, namely dislocations and subsidence. With modularity, distal canal fit can be achieved independently, and the proximal geometry can be created to re-establish the leg length and offset. The benefits of modularity relate specifically to being able to modify a plan intra-operatively based on the conditions that are encountered in mid battle. Inherent in this concept is the principle of predictability. The extent to which the conditions of operation may change requires alternatives to manage those changes. More importantly we need to be able to predict how an implant will sit in the bone.

At the inception and with subsequent manifestations of modular fluted stems, our ability to predict where the final implant will seat based on the trial options that existed was poor. For this reason, some modular stem designs offered no trial. This was part of the imperative for modularity, so that if the implant set too high it could be easily removed with reaming a little deeper and put back in. If the stem sat more deeply than had been anticipated, the change could be compensated by an alteration in the proximal modular segment. Reproducible mid- to long-term results have been published with this type of stem. Potential negatives of the modular junction include stem breakage, fretting and corrosion, cost, and the need to accommodate a large sized proximal segment within the proximal femur. The most important feature in modern non-modular implants will be predictability. We need to be able to predict that the final reamer will sit at a particular level in the femoral bone, and the trial will reproduce this level, and the final implant will reproduce this level. More importantly, we need to be able to predict that implants will remain where they are put, and not subside.

Subsidence has been causally associated with implant under-sizing, which is an error in surgical execution. As such, design features that optimise the ability to achieve intimate and broad endosteal contact between the implant and the bone can help reduce subsidence. These include precise, sharp reamers, implants in 1 mm increments, and trials that reproduce the position of the final implant. A larger implant is less likely to break, and we recommend preparation for the largest implant that the diaphysis can accommodate, often evident in the tactile feedback from the reamer, and the quality of the reamed bone being removed. Reaming is performed eccentrically in the proximal femur, so as to engage the diaphysis optimally.

The need for a kink in the stem is important for modular stems, which have bulky proximal segments that can create conflict with the peritrochanteric bone in smaller patients. Non-modular stems can have a smaller proximal diameter, such that a straight stem can be accommodated in most revision cases.

Early follow-up of a modern non-modular stem has shown excellent clinical improvement and reproducible ingrowth. Subsidence of > 10 mm occurred in 6 hips (6%), which is a notable improvement in historical values for this stem type, but remain short of some reports with modular stems. Improvements in goals and techniques of reaming and implantation are surely part of the improvements that have been documented, as well as those yet to be realised. Predictability will lead to simplicity and intuitiveness.

Cementless stem fixation is a widely used method of stem revision in North America and elsewhere in the world. There is abundant literature in its support. Most of the reports from 1985 to 2005 related to proximally or extensively porocoated designs, the former falling into disfavor with time because of unpredictable outcomes. With few exceptions (e.g. S-ROM) the modularity of these designs was limited to the head/neck junction. But this generation of designs was associated with some issues such as insertional fractures, limited control of anteversion (and risk of dislocation), limited applicability in the setting of severe bone loss (Paprosky Type 4 osteolysis or Vancouver Type B3 periprosthetic fracture), as well as ongoing concern relating to severe proximal stress shielding.

In the past decade we have seen the mounting use of a new design concept: tapered fluted titanium stems (TFTS), which incorporate the advantages of titanium (for less flexural rigidity), conical taper (for vertical taper-lock stability), longitudinal ribs or flutes (for rotational stability), and surface preparation which attracts bone ongrowth for long term fixation.

Four consecutive reports from our center have documented the superiority of the TFTS in our hands, with encouraging outcomes even when dealing with severe bone loss or periprosthetic fractures. There is an increasing body of other literature which reports a similar experience.

Furthermore, with increasing experience and confidence in this design concept, we now use a monoblock or non-modular design in the majority of cases in which a TFTS is indicated. This circumvents the potential drawbacks of stem modularity, including taper corrosion and taper junction fracture. Our recent report of this concept in 104 cases with a 2-year minimum follow-up supports the use of this concept in many if not most stem revisions.

The question remains as to which should be favored? Because of equipoise in the outcomes of the two fundamental stem designs, at least in our hands, clearly the surgeon needs to ask other, more practical questions:

Am I familiar enough with the TFTS technique so as to bypass the potential versatility of the modular stem for the simplicity and potential cost savings of the non-modular?

Is this a case in which modularity will offer me distinct advantages (periprosthetic fracture, and severe bone loss as examples)

Should I introduce the nonmodular TFTS to my practice, choosing straightforward cases first; ones in which I would comfortably and with confidence use an extensively porocoated stem?

Bone is a dynamic organ with remarkable regenerative properties seen only otherwise in the liver. However, bone healing requires vascularity, stability, growth factors, a matrix for growth, and viable cells to obtain effective osteosynthesis. We rely on these principles not only to heal fractures, but also achieve healing of benign bone defects. Unfortunately, we are regularly confronted with situations where the local environment and tissue is insufficient and we must rely on our “biologic tool box.” When the process of bone repair requires additional assistance, we often look to bone grafting to provide an osteoconductive, osteoinductive, and/or osteogenic environment to promote bone healing and repair.

The primary workhorses of bone grafting includes autogenous bone, cadaver allograft, and bone graft substitutes. Among the first types of bone graft used and still used in large quantities today include autogenous and cadaver allograft bone. Allografts are useful because it is present in multiple forms that conform to the desired situation. But autogenous bone graft is considered the gold standard because it possesses all the fundamental properties to heal bone. However, it has been associated with high rates of donor site morbidity and typically requires an inpatient hospitalization following the procedure only adding to the associated costs.

The first bone graft substitute use was calcium sulfate in 1892, and over the past 122 years advancements have achieved improved material properties of calcium sulfate and helped usher in additional bioceramics for bone grafting. Today there are predominantly 4 types of bioceramics available, which include calcium sulfate, calcium phosphate, tricalcium phosphate, and coralline hydroxyapatite. They come in multiple forms ranging from pellets and solid blocks to injectable and moldable putty. In comparison to autogenous bone graft, the primary limitation of bioceramics are the lack of osteogenic and osteoinductive properties. Bioceramics work by creating an osteoconductive scaffold to promote osteosynthesis. The options of bone graft substitutes don't end with these four types of bioceramics. Composite bioceramics take advantage of the differing biomechanical properties of these four basis types of bioceramics to develop improved materials. To overcome the lack of osteoinductive and osteogenic properties growth factors or bone marrow aspirate can be added to the bioceramic. As a result, the list of combinations available in our “biologic tool box” continues to expand. More than 20 BMPs have been identified, but only BMP-2 and BMP-7 have FDA approval.

As we look forward to areas of future research and need within orthobiologics, some will likely come in the near future while others are much further in the future. We will continue to strive for the ideal bone graft substitute, which will have similar osteoinductive properties as autograft. The ultimate bone graft substitute will likely involve stem cells because it will allow an alternative to autogenous bone with the same osteogenic potential.

Porous-coated acetabular hemispherical components have proven successful in all but the most severe revision acetabular defects. A revision jumbo porous coated component has been defined as cup with minimum diameter of 66 mm in men and 62 mm in women. In published studies this size cup is used in 14–39% of acetabular revisions. The advantages of this technique are ease of use, most deficiencies can be treated without structural graft, host bone contact with the porous surface is maximised, and the hip center is generally normal. Jumbo cups are typically used in Paprosky type 2, 3A, and many 3B defects. Requirements for success include circumferential acetabular exposure, an intact posterior column, and much of the posterior wall. The cup should be stable with a press-fit between the ischium and anterior superior acetabulum with the addition of some superior lateral support. Additional support is provided with multiple dome or rim screws. Survivorship of the metal shell with revision for any reason has been reported to be 80%-96% at time frames from 15–20 years. The most common post-operative complication is dislocation.

Major bone loss involving the acetabulum can be seen during revision THA due to component loosening, migration or osteolysis and can also occur as a sequela of infected THA. Uncemented porous ingrowth components can be used for reconstruction of the vast majority of revision cases, where smaller segmental or cavitary defects are typically present. But when stable structural support on host bone is lacking, highly porous metal acetabular augments have been described as an alternative to large structural allograft, avoiding the potential for later graft resorption and the resulting loss of mechanical support that can follow. The fundamental concept behind these acetabular augments is the provision of critical additional fixation, structural support and increased contact area against host bone over the weeks following surgery while the desired ingrowth into porous implant surfaces is occurring.

Technique: Three separate patterns of augment placement have been utilised in our practice since the development of these implants: Type 1 - augment screwed onto the superolateral acetabular rim in a “flying buttress” configuration for treatment of a segmental rim defect, Type 2 – augment placed superiorly against host and then fixed (with cement) to the acetabular component adjacent to the cup to fill a mainly elliptical cavitary defect, and Type 3 – augment(s) placed medial to the cup to fill a protrusio type cavitary or combined cavitary segmental defect of the superomedial or medial wall, and allow peripheral cup placement against the still intact acetabular rim. In all cases the acetabular component and augment interface is fixed together with cement, with care to prevent any cement extrusion between any implant and the bone. When possible, we now prefer to place the acetabular component first and fix it provisionally with 2 or more screws, and then place the augments second as this is technically quicker and easier. This order of insertion is only possible though in type 1 and a few select type 2 cases. Type 3 cases always require placement of one or more augments first, before cup insertion. Supplemental cancellous bone graft is used routinely.

Results: From 2000 through 2007, porous tantalum acetabular augments were used very selectively in 85 revision THA procedures out of total of 1,789 revision hip cases performed at our institution in that time frame. All cases had associated massive acetabular deficiency precluding stable mechanical support for a cup alone. Fifty-eight hips had complete radiographic as well as clinical follow at minimum 5 years. The majority of patients had either Paprosky type 3A defects (28/58, 48%) or 3B defects (22/58, 38%). Ten out of 58 had pre-operative pelvic discontinuities. At 5 years, 2/58 (3%) were revised for aseptic loosening and another 6/58 demonstrated incomplete radiolucencies between the acetabular shell and zone 3. One of the revised cups and 5 of 6 of the cups with radiolucencies had an associated pelvic discontinuity.

Summary: Highly porous metal acetabular augments are an infrequently needed, but extremely valuable, versatile and reliable adjunctive fixation method for use with uncemented acetabular components during complex revision THA associated with major bone deficiency. Intermediate term durability and apparent radiographic incorporation has been very good despite the complex reconstructions originally required. This technique can allow the avoidance of structural bone grafting for even the most massive of bone defect problems, but additional followup is needed to see how durable these encouraging results are over the longer term.

Revision of total hip arthroplasty (THA) is being performed with increasing frequency. However, outcomes of repeated revisions have been rarely reported in the literature, especially for severe defects. Cup revision can be a highly complex operation depending on the bone defect. In acetabular defects like Paprosky types 1 and 2 porous cementless cups maybe fixed with screws give good results. Modern trabecular metal designs improve these good results. Allografts are useful for filling cavitary defects. In acetabular defects Paprosky types 3A and 3B, impacted morselised allografts with a cemented cup technique produce good results. Difficult cases with pelvic discontinuity require reconstruction of the acetabulum with acetabular plates or large cup-cages to solve these difficult problems. However, there is still no consensus regarding the best option for reconstructing hips with bone loss. Although the introduction of ultraporous metals has significantly increased the surgeon's ability to reconstruct severely compromised hips, there remain some that cannot be managed readily using cups, augments, or cages. In such situations custom acetabular components may be required. Individual implants represent yet another tool for the reconstructive surgeon. These devices can be helpful in situations of catastrophic bone loss. Ensuring long-term outcome mechanical stability has a greater impact than restoring an ideal center of rotation.

We have done so far 15 3D Printed Individual Implants. All of them where Paprosky Type 3B defects, 10 with a additional pelvis discontinuity. The mean follow-up is 18 months. All implanted devices are still in place, no infection, no loosening.

However, despite our consecutive case series, there are no mid- to long-term results available so far. Re-revision for failed revision THA acetabular components is a technically very challenging condition.

The 3D Printed Individual Implants have a lot of advantages, like excellent surgical planning and a very simple technique (operative time, blood loss, instruments). They are a very stable construct for extensive acetabular defects and pelvic discontinuity.

Although the introduction of ultraporous metals in the forms of acetabular components and augments has substantially improved the orthopaedic surgeon's ability to reconstruct severely compromised acetabuli, there remain some revision THAs that are beyond the scope of cups, augments, and cages. In situations involving catastrophic bone loss, allograft-prosthetic composites or custom acetabular components may be considered. Custom components offer the potential advantages of immediate, rigid fixation with a superior fit individualised to each patient. These custom triflange components require a pre-operative CT scan with three-dimensional (3-D) reconstruction using rapid prototyping technology, which has evolved substantially during the past decade. The surgeon can fine-tune exact component positioning, determine location and length of screws, modify the fixation surface with, for example, the addition of hydroxyapatite, and dictate which screws will be locked to enhance fixation. The general indications for using custom triflange components include: (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. The general indications for using custom triflange components include: (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means.

We previously reported on our center's experience with 23 patients (24 hips) treated with custom triflange components with minimum 2-year follow-up. This method of reconstruction was used in a cohort of patients with Paprosky Type 3B acetabular defects, which represented 3% (30 of 955) of the acetabular revisions we performed during the study period of 2003 to 2012. At a mean follow-up of 4.8 years (range, 2.3–9 years) there were 4 subsequent surgical interventions: 2 failures secondary to sepsis, and 1 stem revision and 1 open reduction internal fixation for periprosthetic femoral fracture. There were 2 minor complications managed nonoperatively, but all of the components were noted to be well-fixed with no obvious migration or loosening observed on the most recent radiographs. Harris hip scores improved from a mean of 42 (SD ± 16) before surgery to 65 (SD ± 18) at latest follow-up (p<0.001). More recently, we participated in a multi-center study of 95 patients treated with reconstruction using custom triflange components who had a mean follow-up of 3.5 years. Pelvic defects included Paprosky Type 2C, 3A, 3B and pelvic discontinuity. Concomitant femoral revision was performed in 21 hips. Implants used a mean of 12 screws with 3 locking screws. Twenty of 95 patients (21%) experienced at least one complication, including 6% dislocation, 6% infection, and 2% femoral-related issues. Implants were ultimately removed in 11% of hips. One hip was revised for possible component loosening. Survivorship with aseptic loosening as the endpoint was 99%,

Custom acetabular triflange components represent yet another tool in the reconstructive surgeon's armamentarium. These devices can be helpful in situations of catastrophic bone loss, achieving reliable fixation. Clinical results are inferior to both primary THA and more routine revision THA. Patients and surgeons should be aware of the increased complications associated with these complex hip revisions.

Acetabular distraction for the treatment of chronic pelvic discontinuity was first described by Sporer and Paprosky. The authors advocate the posterolateral approach for exposure of the posterior ilium and posterior column, The patient is secured in the lateral decubitus position. Following a systematic approach to surgical exposure, acetabular component removal should be performed with “cup out” osteotomes resulting in minimal iatrogenic bone loss.

Following component removal and confirmation of a chronic discontinuity determine the integrity of the remaining AS and PI columns. If porous metal augments are needed for primary stabilization, the augments are placed prior to cup insertion for reconstruction of the AS and/or PI column. Next, Kirschner (K) wires (size 2.4) are placed in the remaining AS and PI bone so that the distractor can be secured in an extra-acetabular position. The distractor is placed over the K-wires allowing for lateral or peripheral acetabular distraction and resultant medial or central compression at the discontinuity.

With the distractor in an extra-acetabular position, hemispherical reamers are used until an interference fit is achieved between the native or augmented AS and PI columns. The acetabulum should be reamed on reverse to avoid excessive removal of host bone. When the proper acetabular component size has been reached, the reamer will disengage from the reamer handle and the reamer can be used as a surrogate acetabular shell; when the acetabulum is maximally distracted, the entire construct will move as a unit.

Crushed cancellous allograft is used to bone graft the discontinuity and reamed on reverse. A revision tantalum cup is inserted with continual distraction using the distractor. Cement is applied to the augment surface prior to cup insertion in order to utilise the construct. Following cup insertion, the distractor and K-wires are removed. Adjuvant screw fixation is performed, with a minimum of 4 screws, and placing at least one of the screws inferiorly for fixation in the superior public ramus or ischium to prevent abduction failure of the construct.

In the setting of severely osteoporotic bone and inadequate screw fixation, an augment placed posterosuperiorly can be used for supplemental fixation. This augment is also unitised to the cup with cement at the same time as the liner is cemented into the cup. Bone wax is placed over the exposed tantalum surface of the posterosuperior augment to minimise soft-tissue ingrowth into the augment.

Acetabular cages are necessary when an uncemented or cemented cup cannot be stabilised at the correct anatomic level. Impaction grafting with mesh for containment of bone graft is an alternative for some cases in centers that specialise in this technique.

At our center we use three types of cage constructs –

(A) Conventional cage ± structural or morselised bone grafting. This construct is used where there is no significant bleeding host bone. This construct is susceptible to cage fatigue and fracture. This reconstruction is used in young patients where restoration of bone stock is important.

(B) Conventional cage in combination with a porous augment where contact with bleeding host bone can be with the ilium and then by the use of cement that construct can be unified. The augment provides contact with bleeding host bone and if and when ingrowth occurs, the stress is taken off the cage.

(C) Cup Cage Construct – in this construct there must be enough bleeding host bone to stabilise the ultra-porous cup which functions like a structural allograft supporting and eventually taking the stress off the cage. This construct is ideal for pelvic discontinuity with the ultra-porous cup, i.e., bridging and to some degree distracting the discontinuity. If, however, the ultra-porous cup cannot be stabilised against some bleeding host bone, then a conventional stand-alone cage must be used.

In our center the cup cage reconstruction is our most common technique where a cage is used, especially if there is a pelvic discontinuity.

Acetabular bone loss and presence of pelvic discontinuity were assessed according to the Gross classification. Sixty-seven cup-cage procedures with an average follow-up of 74 months (range, 24–135 months; SD, 34.3) months were identified; 26 of 67 (39%) were Gross Type IV and 41 of 67 (61%) were Gross Type V (pelvic discontinuity). Failure was defined as revision surgery for any cause, including infection.

The 5-year Kaplan-Meier survival rate with revision for any cause representing failure was 93% (95% confidence interval, 83.1–97.4), and the 10-year survival rate was 85% (95% CI, 67.2–93.8). The Merle d'Aubigné-Postel score improved significantly from a mean of 6 pre-operatively to 13 post-operatively (p < 0.001). Four cup-cage constructs had non-progressive radiological migration of the ischial flange and they remain stable.

Effectiveness of Liposomal Bupivacaine for Post-Operative Pain Control in Total Knee Arthroplasty: A Prospective, Randomised, Double Blind, Controlled Study

Pericapsular Injection with Free Ropivacaine Provides Equivalent Post-Operative Analgesia as Liposomal Bupivacaine following Unicompartmental Knee Arthroplasty

Total Knee Arthroplasty in the 21st Century: Why Do They Fail? A Fifteen-Year Analysis of 11,135 Knees

Cryoneurolysis for Temporary Relief of Pain in Knee Osteoarthritis: A Multi-Center, Prospective, Double-Blind, Randomised, Controlled Trial

Pre-Operative Freezing of Sensory Nerves for Post-TKA Pain: Preliminary Results from a Prospective, Randomised, Double-Blind Controlled Trial

Proximalization of the Tibial Tubercle Osteotomy: A Solution for Patella Infera during Revision Total Knee Arthroplasty

Treatment of Periprosthetic Joint Infection Based on Species of Infecting Organism: A Decision Analysis

Alpha-Defensin Test for Diagnosis of PJI in the Setting of Failed Metal-on-Metal Bearings or Corrosion

Risk of Reinfection after Irrigation and Debridement for Treatment of Acute Periprosthetic Joint Infection following TKA

Serum Metal Levels for the Diagnosis of Adverse Local Tissue Reaction Secondary to Corrosion in Metal-on-Polyethylene Bearing Total Hip Arthroplasty

Intra-Articular Injection for Painful Hip OA - A Randomised, Double-Blinded Study

Six-Year Follow-up of Hip Decompression with Concentrated Bone Marrow Aspirate to Treat Femoral Head Osteonecrosis

No Benefit of Computer-Assisted TKA: 10-Year Results of a Prospective Randomised Study

Total hip arthroplasty (THA) represents one of the most safe and effective medical procedures. However, with an unchanged rate of 3% in primary and 10% in revision THAs, despite alleged surgical technique and implant design improvements, dislocation continues to be a matter of concerns with important functional and financial consequences. A number of parameters influence the risk for dislocation including patient specific factors, surgeon experience, femoral head size, implant orientation, and surgical approach. The latter has been less investigated during the past 15 years, as it was supposed that large femoral heads or specifically designed implants such as dual mobility sockets would notably decrease the risk for dislocation. Also, minimally invasive approach including the anterior approach, and rapid recovery have been aggressively marketed, making the transtrochanteric approach rarely if ever used by most surgeons. Also, this surgical technique is demanding and time consuming, not exactly what is expected in the 21st century. However, there are some clear advantages to the transtrochanteric approach both in primary and revision THAs: it gives a large view on the acetabulum allowing for anatomic reconstruction of the artificial joint and correct implants orientation; it allows for preservation of the entire periarticular muscles and tendons including the external rotators (external obturator+++); and it permits to balance the abductors tension by lowering and/or translating the greater trochanter. These advantages can notably reduce the rate of dislocation in both primary and revision THAs. Data from our institution including senior and junior surgeons have showed rates of dislocation ranging from 0.1 to 1.7% in primary THAs and from 1.5 to 2.3% in revision THAs. Our rate of nonunion is less than 2% even in revision using a specifically designed trochanteric claw plate almost systematically used in revision THAs to allow for a more rigid fixation. Finally, the transtrochanteric approach can be extended to the femur to cope with specific situations. The surgical tips and tricks of this approach will be discussed in the presentation.

Larger diameter femoral heads and improved operative approaches and soft tissue repair/closure have somewhat reduced the incidence of recurrent instability after total hip arthroplasty (THA). Nevertheless, hip instability remains one of the most common reasons for reoperation after THA, and accounts for roughly a quarter of hip revisions in the United States in Medicare patients. The prevalence of instability after THA varies widely, from 0.3% to 15%. Surgeons have come to understand that hip instability can be caused by implant malposition, impingement, and inadequate soft tissue tension or integrity. While the cumulative risk of instability is acceptable at approximately 2.8% with transtrochanteric approaches, this is based upon the trochanter actually healing (and often being advanced). On the other hand, trochanteric nonunion and proximal migration have been noted by many, and this frequently results in catastrophic instability. Moreover, and importantly, abductor insufficiency is one the most difficult causes of hip instability to solve. Woo and Morrey reported a 17.6% instability rate when trochanteric nonunion occurred with 1 cm proximal trochanteric migration. Alternatively, the contemporary incidence of instability with the posterolateral or anterolateral approaches, and an adequate soft tissue repair, is approximately 1–2%.

Introduction: I always aim for neutral mechanical axis alignment. My principles of a successful TKA are proper alignment in all 3 planes, soft tissue balance in extension first, flexion gap balancing by parallel to tibial cut technique, maintenance of joint line, correct sizing of femoral component, and proper cement fixation.

Long-term Survivorship: There is long-term data that supports the efficacy and durability of the neutral position of the proximal tibial cut. Over a 20-year follow-up there was a 92.6% success rate in my study. Other authors have found similarly successful survivorship for mechanical failure.

Balance Technique in TKR: My technique to balance the knee is a balance extension gap first, which requires medial soft tissue balancing. Next, I balance the flexion gap parallel to the tibial cut.

Our Results: In one study, I examined the clinical and radiographic data of 68 varus knees. Average post-operative mechanical alignment was 0 ± 3 degrees. There were no outliers which displays the reproducibility of the technique. This is the method of choice in the hands of most surgeons.

Conventional total knee arthroplasty aims to place the joint line perpendicular to the mechanical axis resulting in an overall neutral mechanical alignment. This objective is promulgated despite the fact healthy adult populations are on average in varus with few proximal tibias being neutral to the mechanical axis. The goal of a neutral mechanical axis is based largely on historical studies and the fact that it is easier to make a neutral tibial cut with conventional jigs and the eye. In order to balance the flexion and extension gap to accommodate a neutral tibial cut, in most patients, asymmetrical distal and posterior femoral cuts are required. The resulting position of the femoral component could be considered to be “mal-rotated” with respect to the patient's soft tissue envelope. Soft tissue releases are often required to “balance” the knee. Planning and execution of the surgery are largely based off 2-dimensional radiographs which grossly oversimplifies the concept of alignment to the coronal plane, largely ignoring what happens to the knee in 3 dimensions through range of motion and 4 dimensions with respect to gait, stair climbing, etc. Subsequently, sticking with neutral mechanical for all engenders the “looks' good, feels bad” phenomenon seen in many patients that may in part drive the higher dissatisfaction rates seen in knee arthroplasty globally compared to hip arthroplasty.

New imaging and surgical techniques allow for the identification of patient specific alignment targets and the ability to more precisely execute the surgical plan with respect to 3-dimensional placement of the components. Long-term outcomes studies as well as more recent studies on “kinematic” positioning suggest that deviation away from a neutral mechanical target may in fact be safe with respect to survivorship and provide better function with a more “natural” feeling knee.

Critical review of the literature fails to make a convincing case for use of cement in TKA. Many studies demonstrate clinical, mechanical, and biological failure when cement is used for fixation. Work by Ryd et al. has shown that initial migration within the first few months diminished rapidly after the first 6 months with virtually no additional movement for years after. They also suggested that cemented components do not remain rigidly fixed to bone long-term, but loosen enough to move 0.2 to 1 mm at the bone-cement interface with provocative testing. Although bone-ingrowth tibial components migrate slightly more initially than cemented ones do, they stabilise and do not sink progressively. Screw fixation adds rigidity, but does not seem to improve results. Rigidity of initial fixation is the most important feature after alignment to ensure pain-free function after arthroplasty, and can be achieved with press-fit techniques in TKA. Several early reports of bone-ingrowth TKA had inferior results because the tibial component had no stem, peg, or screw fixation, leading to implant migration and loosening. An effective stem has been shown to greatly improve tibial component fixation. The cut upper surface of the prepared tibia has areas that are too weak to withstand the forces that are applied to the surface, and failure in compression is likely unless fixation is augmented. An effective stem also reduces the shear and tensile loads at the bone-prosthesis interface. The effectiveness of compression or compaction of the tibial cancellous bone with an appropriately sized tibial metaphyseal stem has been shown, and probably was a major factor in the long-term success of fixation in our series.

Clinical results of TKA with osteointegration techniques for fixation of the femoral and tibial components in our series are comparable with the best series reported with cemented fixation. Many recent studies show significant advantages of osteointegration over cement fixation in TKA. Fixation of implants with PMMA pressed into cancellous bone eventually loosens, and fixation of a metal component to bone cement also is tenuous in most cases. Cement is disappearing rapidly from use in total hip, ankle, and shoulder arthroplasty, and soon will be replaced with osteointegration technique in the knee.

Perhaps the most appealing aspect of bone-ingrowth TKA is bone preservation. The ease of revisability because of good bone was encouraging in the components that wore, loosened, or became infected in the current series of TKA. These knees are functioning as well as knees with primary TKA. Should these knees develop additional problems, progressive destruction of bone is unlikely to occur, even if repeated revision is necessary.

Total knee arthroplasty has been demonstrated to provide durable results with excellent pain relief and improvement in function. Our institution has studied and published the longest follow-up of mobile bearing TKR, fixed bearing modular TKR, and unicompartmental replacement. Indeed these studies support the durability of the operation and the improvement in function and relief of pain. They, however, are not perfect. In tricompartmental replacement, up to 5 or 6% are revised for loosening and or wear and in unicompartmental replacement, up to 25% are revised for loosening. There are also one or two percent of cases revised for periprosthetic fracture and one or two percent for hematogenous infection. One must remember these cases were performed in patients of average age 71.

When one looks at our results in more active patients with osteoarthritis who are less than 55, the results are less spectacular with 15% revised at 10 to 15 years for loosening. We all hope that better polyethylene and better tibial tray locking mechanisms (in fixed bearing modular designs) will improve these results, but to predict there will be no failures is a “leap of faith”. Long-term follow-up of cemented TKA in patients under 55 where monolithic tibial trays were utilised have demonstrated better results at 20 years (92.3%) survivorship versus those where modular tibial trays (68%) were utilised. Long-term studies of cementless total knee replacement, especially in younger patients are needed to see if this approach provides better results.

In 1983 we underscored the importance of understanding the cause or mechanism of failure following total knee arthroplasty. In this article we reported that revision total knee replacement was generally unsuccessful unless the surgeon new the mechanism of failure. In the ensuing years we have collectively made improvements in instrumentation, component design and material properties such that the mechanisms of failure are now different and less common than in the earlier years.

Early failure following total knee arthroplasty is generally related to technical issues. There are a myriad of such issues but many of them relate to component positioning and soft tissue balance. Post-operative wound complications are concerning as they cause an increased incidence of deep infection. Hematoma from over anticoagulation is a particular problem that leads to stiffness and increased risk for infection. Most knee systems now have multiple sizing options and instrument systems that can improve reproducibility of component implantation. Midterm failure is often due to flexion instability which has been reported in cruciate substitution and cruciate retention knees. The instability can be global, mid flexion, flexion or a combination of all 3. Issues with extension and mid flexion instability but no flexion instability are generally those with tight extensor mechanisms. Pain and stiffness are frequently due to component malalignment. One common problem is abnormal internal rotation of the tibial component.

Late failure in our institution is generally seen due to wear and loosening from earlier designs with inferior polyethylene. Late hematogenous infection occurs in people with immunocompromise, severe diabetes and diagnoses that alter the patient's ability to mount an immune response. The newest epidemic in total knee failure has been that of periprosthetic fracture. As these patients are becoming older and with worse proprioception, they are at greater risk. Generalised osteopenia and increased activity also increase the risk of fracture. Total knee arthroplasty represents a remarkable improvement in the care of the patient with knee arthritis. It is only by focusing upon and decreasing the causes of failure that we will advance use of this procedure in patient care.

The parameters to be considered in the selection of a cartilage repair strategy are: the diameter of the chondral defect; the depth of the bone defect; the location of the defect (weight bearing); alignment.

A chondral defect less than 3 cm in diameter can be managed by surface treatment such as microfracture, autologous chondrocyte transplantation, mosaicplasty, or periosteal grafting.

An osteochondral defect less than 3 cm in diameter and less than 1 cm in depth can be managed by autologous chondrocyte transplantation, mosaicplasty or periosteal grafting.

An osteochondral defect greater than 3 cm in diameter and 1 cm in depth is best managed by an osteochondral allograft.

If there is an associated knee deformity, then an osteotomy should also be performed with all of the aforementioned procedures. In our series of osteochondral allografts for large post-traumatic knee defects realignment osteotomy is performed about 60% of the time in order to off load the transplant. To correct varus we realign the proximal tibia with an opening wedge osteotomy. To correct valgus, we realign the distal femur with a closing wedge osteotomy.

Our results with osteochondral allografts for the large osteochondral defects of the knee have been excellent in 85% of patients at an average follow-up of 10 years. The Kaplan-Meier survivorship at 15 years is 72%. At an average follow-up of 22 years in 58 patients with distal femoral osteochondral allograft, 13 have been revised (22%). The 15-year survivorship was 84%.

The results for the hip are early. To date we have performed this procedure on 16 patients. Surgical dislocation of the hip is carried out via a trochanteric osteotomy and the defect defined and trephined out. A press-fit fresh osteochondral allograft is inserted using the trephine technique. We have published our early results on a series of 8 patients with 5 good to excellent results, 1 fair result and 2 failures.

The prevalence of knee osteoarthritis (OA) in The United States is approximately 40 million cases, and this number is expected to rise to 60 million by the year 2020. Multiple non-operative treatment options are available for patients, including bracing. Braces can also be used for “pre-habitation” prior to total knee arthroplasty (TKA), after TKA, after traumatic sports injuries, and in neurologic patients. Although, the AAOS recommendations for brace use for treatment of knee osteoarthritis (OA) are “inconclusive”, recent studies have shown improved functional outcomes with the use of off-loader braces for the treatment of uni-compartmental knee OA. In addition, supplemental modalities such as transcutaneous electrical nerve stimulation (TENS) and neuromuscular electrical stimulation (NMES) have demonstrated improved subjective and functional outcomes. These off-loader braces and supplemental modalities are easy to use, may decrease pain, delay TKA, and improve clinical outcomes following surgery. In addition, they may decrease the use of other costly knee OA treatment options such as pain medications and intra-articular injections.

Distal femoral varus osteotomy is a procedure intended to relieve pain, correct valgus deformity, and delay or possibly prevent the progression of lateral compartment osteoarthritis in the knee. It is indicated in patients who are considered too young or are too active to be considered candidates for total knee arthroplasty. It also allows protection of the lateral compartment in cases of meniscal or cartilage allograft. In patients who are a good candidate for total knee replacement, TKR is the procedure of choice.

A sloping joint line requires that the correction be performed above the knee. Several methods of distal femoral varus osteotomy have been proposed. These include a medial closing wedge, a lateral opening wedge, and a dome osteotomy. In the author's experience, the medial closing wedge has proven reliable. This technique uses a 90-degree blade plate, and does not require any angle measurements during surgery. Fixation is secure, allowing early motion. Healing proceeds rapidly in the metaphyseal bone, and non-unions have not occurred. The desired final alignment was zero degrees, which was reliably achieved using this method.

Medium to long-term results are generally satisfactory. When conversion to total knee replacement is required, standard components may generally be used, and function was not compromised by the prior osteotomy.

Distal femoral varus osteotomy is a successful procedure for lateral compartment osteoarthritis in a valgus knee. It is indicated in patients who are too young or active for total knee arthroplasty, and provides an excellent functional and cosmetic result.

The biomechanical rationale for osteotomy and the pathogenesis of degenerative arthrosis accompanying malalignment has been delineated well. Malalignment of the limb results in added stress on damaged articular cartilage and causes further loss of articular cartilage that subsequently exacerbates the limb malalignment. A downward spiral of progressive deformity and additional loss of articular cartilage occurs over time. Osteotomy can be used to realign the limb, reduce stress on the articular cartilage at risk and share the load with the opposite compartment of the knee. In appropriately selected patients osteotomy is a reliable operation to improve pain and function. Over the past two decades osteotomy has been viewed largely as a temporizing measure to buy time for patients before they ultimately have a total knee arthroplasty. In this role, osteotomy has largely been accepted as successful. Substantial improvements in pain and function have been documented and seem to hold up well over a 7- to 10-year period after the osteotomy. Medial opening wedge osteotomy has recently gained in popularity in the United States after a long period of use in Europe. Potential advantages of the medial opening wedge technique include the ability to easily adjust the degree of correction intra-operatively, the ability to correct deformities in the sagittal plane as well as the coronal plane, the need to make only one bone cut, and avoiding the tibiofibular joint. The downsides of the opening wedge technique include the need for bone graft to fill the created defect, a potentially higher rate of non-union or delayed union, and a longer period of restricted weight bearing after the procedure.

Unicompartmental knee arthroplasty (UKA) has a long history that extends back nearly as far as the first tricompartmental designs. While initial results were erratic, with a greater understanding of patient selection and surgical techniques, more consistent and favorable results have been reported. While there has been somewhat of a resurgence in interest in UKA, the percentage of primary knee arthroplasties that are unicompartmental hovers around 6–8%. It is my belief that you should be doing more!

Several peer review studies suggest that with both fixed and mobile bearing designs, survivorship exceeds 90% at ten year. In our own initial series of 62 fixed bearing medial UKA, survivorship was 90% at 20 years.

UKA is an outstanding option for younger patients, who are amongst the most challenging to satisfy with a TKA. In a cohort of patients < 55 years old, Biswas et al. reported a mean KSS of just over 95 points and a mean UCLA activity score of 7.5. This is opposed to the report by Parvizi et al. who suggested 1/3 of young, active patients reported residual symptoms and limitations following modern TKA.

Most data suggests that UKA is a less morbid procedure than TKA. In a retrospective review of 605 UKA compared to 2235 TKA, Brown et al. found the risk of complications was 11% vs. 4.3% favoring UKA with a shorter length of stay and risk of discharge to an extended care facility, which also translates into lower costs for our health care system.

Finally, in the only randomised study that I am aware of that has compared UKA and TKA, UKA was associated with significantly better survivorship (90% vs. 79%). Further, UKA was associated with better ROM and functional scores at 5 and 15 years. Finally, recovery with UKA was faster and the risk of peri-operative complications was lower.

Isolated patellofemoral arthritis is not an uncommon problem, with no clear consensus on treatment. Nonoperative and many forms of operative treatments have failed to demonstrate long-term effectiveness in the setting of advanced arthritis. Total knee arthroplasty (TKA) has produced excellent results, but many surgeons are hesitant to perform TKA in younger patients with isolated patellofemoral arthritis. In properly selected patients, patellofemoral arthroplasty (PFA) is an effective procedure with good long-term results. Contemporary PFA prostheses have eliminated many of the patellar maltracking problems associated with older designs, and short-term results, as described here, are encouraging. Long-term outcome and prospective trials comparing TKA to PFA are needed.

While no one would argue the necessary role for the medical management of patients with early knee arthritis, significant controversy remains regarding the ideal treatment for a patient with bone-on-bone osteoarthritis who could equally be treated with a high tibial osteotomy, a uni-compartmental total knee, potentially a patello-femoral replacement if dealing with isolated patello-femoral disease or lastly, a complete total knee replacement. While clearly to date there has not been consensus on this issue, a review of the arguments, both pro and con, should be used as a guide to the surgeon in making this clinical judgment.

1. Patient Satisfaction.- Many ardent supporters of uni-compartmental knee replacements espouse one of the principle benefits of the uni knee as much greater patient satisfaction. Unfortunately, what is never taken into account is the pre-selection bias that occurs in this patient population. Patients with the most minimal amount of arthritis and those with the greatest range of motion are pre-selected to undergo a uni-compartmental knee replacement compared to the more advanced arthritic knee with mal-alignment and more significant pre-operative disability that will undergo a total knee replacement. Additionally the sources of data to draw the conclusions must be carefully analyzed. We must avoid using data from small series with unblinded patients performed by surgeons expert in the technique. Instead registry data, with its broad based applicability, is a much more logical source of information. Of significance, when over 27,000 patients were assessed regarding satisfaction following knee surgery; there was no difference in proportions of satisfied patients whether they had a total knee or a uni-compartmental knee.

2. Implant Longevity - Once again large prospective cohort data in the form of arthroplasty registries strongly favors total knee arthroplasty over uni-compartmental knee arthroplasty. The Swedish Knee Arthroplasty Registry demonstrated higher revision rates with uni's as compared with total knee replacements. In the Australian Joint Replacement Registry the cumulative 13-year percent revision rate for primary total knee replacements is 6.8% and for uni-compartmental knee replacements is 15.5%. Higher failure rates in uni-compartmental knee replacements seen in Australia has correlated to a significant decrease in the number of uni's being performed, which peaked at 15.1% in 2003 and in 2014 has reduced to 4.7%. There is a direct correlation to age, with younger patients having a significantly higher percentage of revision following uni-compartmental knee replacements (25% failure rate at 11 years if less than 55 years old). There is also tremendous variability in the success rate of the uni in the Australian Registry depending on the implant design (5 year cumulative revision rate range 5.0% to 18.9%), which is simply not seen in the total knee replacement population (5 year cumulative revision rate range 1.6% to 7.7%).

While one can perform the philosophical exercise of debating the merits of a total knee versus uni-compartmental knee, the evidence is overwhelming that in the hands of the masses a total knee replacement patient will have equal satisfaction to a uni-compartmental patient, and will enjoy a much lower probability of revision in the short term and in the long term.

Knee replacement is a proven and reproducible procedure to alleviate pain, re-establish alignment and restore function. However, the quality and completeness to which these goals are achieved is variable. The idea of restoring function by reproducing condylar anatomy and asymmetry has been gaining favor. As knee replacements have evolved, surgeons have created a set of principles for reconstruction, such as using the femoral transepicondylar axis (TEA) in order to place the joint line of the symmetric femoral component parallel to the TEA, and this has been shown to improve kinematics. However, this bony landmark is really a single plane surrogate for 3-dimensional medial and lateral femoral condylar geometry, and a difference has been shown to exist between the natural flexion-extension arc and the TEA. The TEA works well as a surrogate, but the idea of potentially replicating normal motion by reproducing the actual condylar geometry and its involved, individual asymmetry has great appeal.

Great variability in knee anatomy can be found among various populations, sizes, and genders. Each implant company creates their specific condylar geometry, or “so called” J curves, based on a set of averages measured in a given population. These condylar geometries have traditionally been symmetric, with the individualised spatial placement of the (symmetric) curves achieved through femoral component sizing, angulation, and rotation performed at the time of surgery. There is an inherent compromise in trying to achieve accurate, individual medial and lateral condylar geometry reproduction, while also replicating size and avoiding component overhang with a set implant geometry and limited implant sizes. Even with patient-specific instrumentation using standard over-the-counter implants, the surgeon must input his/her desired endpoints for bone resection, femoral rotation, and sizing as guidelines for compromise. When all is done, and soft tissue imbalance exists, soft tissue release is the final, common compromise.

The custom, individually made knee design goals include reproducible mechanical alignment, patient-specific fit and positioning, restoration of articular condylar geometry, and thereby, more normal kinematics. A CT scan allows capture of three-dimensional anatomical bony details of the knee. The individual J curves are first noted and corrected for deformity, after which they are anatomically reproduced using a Computer-Aided Design (CAD) file of the bones in order to maximally cover the bony surfaces and concomitantly avoid implant overhang. No options for modifications are offered to the surgeon, as the goal is anatomic restoration.

Given these ideals, to what extent are patients improved? The concept of reproducing bony anatomy is based on the pretext that form will dictate function, such that normal-leaning anatomy will tend towards normal-leaning kinematics. Therefore, we seek to evaluate knee function based on objective assessments of movement or kinematics.

In summary, the use of custom knee technology to more closely reproduce an individual patient's anatomy holds great promise in improving the quality and reproducibility of post-operative function. Compromises of fit and rotation are minimised, and implant overhang is potentially eliminated as a source of pain. Early results have shown objective improvements in clinical outcomes. Admittedly, this technology is limited to those patients with mild to moderate deformity at this time, since options like constraint and stems are not available. Yet these are the patients who can most clearly benefit from a higher functional state after reconstruction. Time will reveal if this potential can become a reproducible reality.

Soft-tissue release plays an integral part in primary total knee arthroplasty by ‘balancing’ the knee. Asian patients often present late and consequently may have large deformities due to significant bone loss and contractures medially, and stretching of the lateral collateral ligament. Extra-articular deformities may aggravate the situation further and make correction of these deformities more arduous.

Several techniques have been described for correction of deformity by soft-tissue releases. However, releasing the collateral ligament during TKA has unintended consequences such as the creation of significant mediolateral instability and a flexion gap which exceeds the extension gap; both of these may require a constrained prosthesis to achieve stability. We will show that soft-tissue balance can be achieved even in cases of severe varus deformity without performing a superficial medial collateral ligament release.

The steps are: Determining pre-operatively whether deformity is predominantly intra-articular or extra-articular; Individualizing the valgus resection angle and bony resection depth; Reduction osteotomy, posteromedial capsule resection, sliding medial condylar osteotomy, extra-articular corrective osteotomy; Compensating for bone loss; Only rarely deploying a more constrained device.

Case examples will be presented to illustrate the entire spectrum of varus deformities.

Deformity correction is a fundamental goal in total knee arthroplasty. Severe valgus deformities often present the surgeon with a complex challenge. These deformities are associated with abnormal bone anatomy, ligament laxity and soft tissue contractures. Distorted bone anatomy is due to bone loss on the lateral femoral condyle, especially posteriorly. To a lesser extent bone loss occurs from the lateral tibia plateau. The AP axis (Whiteside's Line) or epicondylar axis must be used as a rotational landmark in the severely valgus knee. Gap balancing techniques can be helpful in the severely valgus knee, but good extension balance must be obtained before setting femoral rotation with this technique. Coronal alignment is generally corrected to neutral or 2- to 3-degree overcorrection to mild mechanical varus to unload the attenuated medial ligaments.

The goal of soft tissue releases is to obtain rectangular flexion and extension gaps. Soft tissue releases involve the IT band, posterolateral corner/arcuate complex, posterior capsule, LCL, and popliteus tendon. Assessment of which structures is made and then releases are performed. In general, pie crust release of the IT band is sufficient for mild deformity. More severe deformities require release of the posterolateral corner / arcuate and posterior capsule. I prefer a pie crust technique, while Ranawat has described the use of electrocautery to perform these posterior/ posterolateral releases. In most cases the LCL is not released, however, this can be released from the lateral epicondyle, if necessary.

Good ligament balance can be obtained in most cases, however, some cases with severe medial ligament attenuation require additional ligament constraint such as a constrained condylar implant.

Fifteen-year survivorship studies demonstrate that total knee replacement have excellent survivorship, with reports of 85 to 97%. However, excellent survivorship does not equate to excellent patient reported outcomes. Noble et al. reported that 14% of their patients were dissatisfied with their outcome with more than half expressing problems with routine activities of daily living. There is also a difference in the patient's subjective assessment of outcome and the surgeon's objective assessment. Dickstein et al. reported that a third of total knee patients were dissatisfied, even though the surgeons felt that their results were excellent. Most of the patients who report lower outcome scores due so because their expectations are not being fulfilled by the total knee replacement surgery.

Perhaps this dissatisfaction is a result of subtle soft tissue imbalance that we have difficulty in assessing intraoperatively and postoperatively. Soft tissue balancing techniques still rely on subjective feel for appropriate ligamentous tension by the surgeon. Surgical experience and case volume play a major role in each surgeon's relative skill in balancing the knee properly.

New technology of “smart trials” with embedded microelectronics and accelerometers, used in the knee with the medial retinaculum closed, can provide dynamic, intra-operative feedback regarding knee quantitative compartment pressures and component tracking. After all bone cuts are made using the surgeon's preferred techniques, trial components with the sensored tibial trial are inserted and the knee is taken through a passive range of motion. After visualizing the resultant compartment pressures and tracking data on a graphical interface, the surgeon can decide whether to perform a soft tissue balance or a minor bone recuts. If soft tissue balancing is chosen, pressure data can indicate where to perform the release and allow the surgeon to assess the pressure changes as titrated soft tissue releases are performed.

A multi-center study using smart trials has demonstrated dramatically better outcomes out to three years.

Pain control is critical in the management of TKA patients and is crucial to allow for early ambulation and accelerated physical therapy. Currently data suggests that 19% of patients are not satisfied with their results following TKA, and failure to control pain may result in prolonged hospitalization, worse outcomes, and increased patient dissatisfaction. Studies suggest that local analgesics coupled with both pre- and post-operative multimodal pain management may result in improved pain control and increased patient satisfaction. Minimization of opioid use is helpful in decreasing complications, accelerating physical therapy milestones, minimizing length of stay and increasing discharge to home.

Femoral nerve blocks (FNB) can reduce pain scores for up to 48 hours post-operatively, but may delay ambulation and result in an increased rate of falls. Periarticular injection (PAI) with local analgesics can provide significant short term relief comparable to FNB and can also facilitate decreased opioid consumption. One commonly used local anesthetic is bupivacaine, but the average half-life of this drug is only 2.7 hours. An alternative to this for PAI during TKA is liposomal bupivacaine (LB). LB is a multivesicular drug designed for rapid absorption, prolonged release of bupivacaine, and analgesia that is maintained for up to 72 hours with a single injection. LB exhibits a bimodal peak of distribution, one immediate associated with extra-liposomal bupivacaine, and a second 10–36 hours later associated with the release of liposomal encapsulated bupivacaine. The safety profile of LB has been investigated and adverse events are similar to standard bupivacaine and demonstrate acceptable tolerability. Multiple studies have demonstrated efficacy of this drug compared to other pain control modalities. LB is highly technique dependent and only one piece of a multimodal pain management protocol.

Our study consisted of 1808 consecutive primary TKA patients from Sept 2013 to Sept 2015. Three patient cohorts were compiled by date, from Sept 2013 to May 2014 was cohort 1, consisting of FNB and PCA. Department wide adoption of LB began in May 2014 and became routinely used in all patients undergoing total joint arthroplasty at our institution. Cohort 2 entailed a PCA along with LB injection from May 2014 through Feb 2015. Cohort 3 consisted of LB injection only and was from Feb 2015 through Sept 2015. All patients undergoing TKA were eligible and there were no exclusion criteria as long as the protocols were followed.

The standard multi-modal analgesia protocol was provided to all patients in all three cohorts. Prior to entering the operating room, patients received preemptive oral analgesics, consisting of: 200 mg celecoxib, 1000 mg acetaminophen, and 50 mg pregabalin. Intra-operative analgesia was chosen at the discretion of the anesthesiologist and preferentially consisted of spinal anesthesia with general anesthesia as an alternate. For all three cohorts, a peri-incisional analgesic cocktail was injected prior to closure consisting of: 40 cc 0.25% Marcaine, 5 cc of (1 mg/cc) morphine, and 1 cc of (30 mg/cc) ketorolac. Cohorts 1 and 2 received PCA post-operatively for pain control post-operatively with prn oral narcotic administration as well. Cohort 3 did not receive a PCA.

The cohort treated without FNB and without a PCA using a multimodal pain management protocol including a short acting periarticular injection and a longer acting periarticular injection with LB, had equivalent pain control, less narcotic use, faster achievement of physical therapy milestones, earlier and more frequent discharge home, less complications and a lower cost of the episode of care.

Bilateral one stage total knee replacement has a number of advantages. There is one operative procedure and anesthetic and overall recovery time is significantly reduced. It is a more cost effective procedure in that acute hospital stay is less and although rehabilitation time is greater in the short term overall it is less. Additionally if there is a bilateral flexion contracture present there is an inevitable loss of extension if a single knee is operated upon as this knee will assume the position of the unoperated knee. Patients greatly prefer having both knees corrected at one operative setting rather than having to have the inconvenience and pain associated with a second operative procedure at three to six months after the first one.

There are potential disadvantages to a one stage procedure. One concern has been that there is more peri-operative morbidity associated with one stage bilateral total knee replacement. In a review of 501 patients undergoing bilateral one stage total knee replacement at the Hospital for Special Surgery there were no peri-operative deaths, myocardial infarctions or cerebrovascular accidents. There were arrhythmias present in 5% of patients. Fat emboli were present in 3% and 2 patients (0.4%) had pulmonary emboli. The average transfusion requirement was 2.6 units and allogeneic blood was required in 42%. There were 2 deep infections, 3 hematomas and 5 patients with delayed wound healing. There was an increased incidence of major complications in patients with ASA classification 3 and with increasing age over 70 years.

New data indicates peri-operative administration of hydrocortisone my mitigate lung injury as demonstrated by reduction in cytokine and desmosine levels in a randomised trial. There was also a trend toward less need for narcotic medication and better range of motion in the steroid treated group

Patient selection is important and all patients are screened pre-operatively by an internist and anesthesiologist. In over 3000 bilateral TKR at HSS infection rate and mortality were lower than in the unilateral total knee replacement patients. Much of this has is due to patient selection criteria. All patients underwent the procedure with epidural anesthesia with post-operative epidural PCA for 48 hours. All patients are discharged on warfarin and spend the operative night in the recovery room. The procedure has acceptable morbidity and great advantage in properly selected patients.

Not all knee surgery cases are created equal is a maxim that holds true for both primary and revision scenarios. Complex cases involve patients presenting with compromised bone and/or soft tissue. For primary knees, these include cases with bony deformity or deficiency, severe malalignment, arthrofibrosis, ligamentous instability or contracture, prior fracture or trauma with or without failed fixation, prior hardware complicating component placement, or compromised extensor mechanism. In revision surgery, complex scenarios include cases compromised by bone loss, deterioration of the soft tissues and resulting instability, periprosthetic fracture, leg length discrepancy, infection, and more recently, hypersensitivity reactions. In this interactive session, a moderator and team of experts will discuss strategies for evaluation and management of a variety of challenging knee case scenarios.

Background: Total knee arthroplasty (TKA) overall is a very reliable, durable procedure. Biomechanical studies have suggested superior stress distribution in metal-backed tibial trays, however, these results have not been universally observed clinically. Currently, there is a paucity of information examining the survival and outcomes of all-polyethylene tibial components.

Methods: We reviewed 31,939 patients undergoing a primary TKA over a 43-year period (1970–2013). There were 28,224 (88%) metal-backed and 3,715 (12%) all-polyethylene tibial components. The metal-backed and all-polyethylene groups had comparable demographics with respect to sex distribution (57% female for both) mean age (67 vs. 71 years), and mean BMI (31.6 vs. 31.1). Mean follow-up was 7 years (maximum 40 years).

Results: The purpose of this investigation was to analyze the outcomes of all-polyethylene compared to metal backed components in TKA and to determine (1) is there a difference in overall survival? All-polyethylene tibial components had improved survivorship (P<0.0001) and metal backed tibias were at increased risk of revision (HR 3.41, P<0.0001). (2) Does body mass index (BMI) or age have an affect on survival of all-polyethylene compared to metal-backed tibial components? All-polyethylene tibias had improved survival (P<0.01) in all ages groups except in patients 85 years or greater, where there was no difference (P=0.16). All-polyethylene tibial components had improved survival (P<0.005) for all BMI's except in the morbidly obese (BMI ≥40) where there was no difference (P=0.20). (3) Is there an increased risk of post-operative infection? Metal-backed tibial components were found to have an increased risk of infection (HR 1.60, P=0.003). (4) Is there a difference in the rate of reoperation and post-operative complications? Metal-backed tibial components were found to have an increased risk of reoperation (HR 1.84, P<0.0001).

Conclusions: The use of all-polyethylene tibias should be considered for the majority of patients, regardless of age and BMI.

Two big problems exist with the all-polyethylene cemented tibial component; the polyethylene and the cement. The polyethylene is too weak and flexible to bear high tibial load, so it deforms and loosens. The interface stresses are too high when two flexible structures are poorly bonded and heavily loaded.

Modularity between the polyethylene tibial component and the metal-backed tray was introduced in the mid-80's for versatility and to facilitate screw fixation for cementless implants. These designs allow exchange of various polyethylene thicknesses, and aids the addition of stems and wedges. Other advantages include the reduction of inventory, and the potential for isolated tibial polyethylene exchanges as a simpler revision procedure. Several studies have documented the high failure rate of isolated polyethylene exchange procedures, because technical problems related to the original components are left uncorrected. However, revision for wear is the simplest revision ever!

Since the late 1980's the phenomena of polyethylene wear and osteolysis has been observed much more frequently when compared with earlier eras. The reasons for this increased prevalence of synovitis, progressive osteolysis, and severe polyethylene wear remain unclear. There is some association with the widespread use of both cementless and cemented modular tibial designs. Improved polyethylene attachment is the answer even if a screw, a wire, or a pin is needed. Do not abandon the module tibia.

Multiple contemporary TKA designs that sacrifice the anterior cruciate ligament and then either retain or substitute for the posterior cruciate ligament have demonstrated-records of good durability and good function across joint registries worldwide. In recent years there has been an emphasis on improving function in TKA and to that end various strategies including changes in surgical alignment targets (kinematic alignment), the addition of advanced technologies such as computer navigation and sensors in trial components, the expansion of indications for unicompartmental knee arthroplasty and the re-introduction of total knee implants that preserve both the ACL and PCL have been championed. Early ACL/PCL retaining total knee implants had mixed results with some designs failing while others championed by Cloutier and by Pritchett have had some success in regard to reasonable durability. Unfortunately those early designs, despite decent durability, did not conclusively demonstrate better function.

More recently a new bi-cruciate retaining TKA was introduced with some substantial fanfare. Unfortunately, the widely touted theoretical or potential benefits of bi-cruciate preservation (in regard to better function) have failed to materialise or have been offset by a higher than expected re-operation rate. Even some of the initial proponents of the bi-cruciate implants have noted that the short-term findings are not very encouraging. The largest report to date shows 5% vs. 1.6% all-cause revision at 1 year (BCR vs. CR, respectively) and no improvement in standardised patient reported outcome measures. Some have placed their hopes for BCR TKA on the introduction of robotic technologies or advanced sensor devices but whether those prove to be meaningful enabling technologies remains to be determined. In 2017 it appears that while bi-cruciate retaining TKA is intellectually intriguing it does require the practicing surgeon to cross “a bridge too far.”

Bi-cruciate-retaining (BCR) total knee arthroplasty (TKA), which retains both the anterior (ACL) and posterior cruciate (PCL) ligaments, serves as an alternative to the traditional TKA procedure. Despite the difficulty of ensuring the structural integrity of the prosthesis, the BCR TKA can yield improved patient outcomes such as range of motion, kinematics, and even the survivorship of the implant. When possible, BCR TKA can and should be considered as a viable option to treat end-stage arthritis of the knee. Reconsidering the frequency of the BCR TKA is necessary for several reasons. Patient outcomes following BCR TKA are similar to outcomes for mobile-bearing UKA. Patients with an intact ACL do better with preservation (UKA or BCR TKA) of the ACL. The corollary is also true that removing an intact ACL at the time of arthroplasty has worse outcomes than traditional TKA in patients with an absent ACL. Reported outcomes of BCR TKA include more normal knee function, excellent prosthetic survivorship, and greater patient satisfaction. The BCR TKA may provide a missing link in the continuum of constraint for primary knee arthroplasty.

Many early BCR designs fell out of favor because of high rates of prosthetic loosening, and because the procedure was more technically demanding than that of highly successful ACL-sacrificing TKA devices. Recently there has been a reemergence of the BCR arthroplasty concept with improvements in design. By retaining both the ACL and PCL, BCR TKA patients show more normal knee function and flexibility due to anterior stability and replication of the physiological tension in the ACL. Modern BCR TKA models have improved upon early designs but are limited in use mainly due to the lack of an optimal prosthesis design and the relative difficulty of the surgical procedure.

Bi-cruciate-retaining TKA is a viable procedure if an appropriate femorotibial gap can be created to mimic physiological tension of the ACL and PCL. In terms of the surgical technique, the procedure begins with femoral preparation to facilitate tibial preparation. Distal femoral resection is performed first taking care to avoid damage to the ACL. Femoral preparation is then completed with a four-in-one guide that incorporates a protector to ensure the ACL is not resected. Good exposure is essential to tibial preparation, which is the critical part of the procedure and involves several steps of setting the depth of resection, and making accurate cuts to protect the tibial eminence island of bone and set tibial component rotation. The medial and lateral tibial cuts must be absolutely parallel. Precise cement technique is required for the tibial baseplate, and care must be taken when trialing the dual bearings.

Normal kinematics are preserved when both the ACL and PCL remain intact. Bi-cruciate-retaining TKA knees have been shown to restore more normal kinematics and have better “feel” than traditional ACL-sacrificing TKA knees. Bilateral TKA patients with designs of both types prefer their BCR TKA to their ACL-sacrificing TKA more often than not. An intact ACL has been shown to be present in 60–80% of arthritic knees, further justifying the consideration to retain both cruciate ligaments during TKA. New materials and refined instrumentation and techniques have helped improve the viability of BCR TKA, which may represent an additional option in the continuum of constraint for knee arthroplasty.

Resurfacing the patella is performed the majority of the time in the United States and in many regions it is considered standard practice. In many countries, however, the patella is left un-resurfaced an equal amount of the time or even rarely ever resurfaced. Patella resurfacing is not a simple or benign procedure. There are numerous negative sequelae of resurfacing including loosening, fragmentation, avascular necrosis, lateral facet pain, stress fracture, acute fracture, late fracture, and restricted motion. In a study by Berend, Ritter, et al, failures of the patella component were reported 4.2% of the time at an average of only 2.6 years. A study was undertaken at Washington University in recent years to determine rather more clinical problems were observed following total knee replacement with or without patella resurfacing. Records were maintained on all problem total knees cases with well localised anterior knee pain. The referral area for this clinic is St. Louis which is among the largest American cities, with the highest percentage of total knees that are performed without patella resurfacing. During 4 years of referrals of total knee patients with anterior knee pain, 47 cases were identified of which 36 had a resurfaced patella and 11 had a non-resurfaced patella. Eight of 36 resurfaced patellae underwent surgery while only 2 of 11 non-resurfaced patellae underwent subsequent surgery. More than 3 times as many painful total knees that were referred for evaluation had already had their patella resurfaced. In spite of the fact that approximately equal number of total knees were performed in this area without patella resurfacing, far more patients presented to clinic with painful total knee in which the patella had been resurfaced. The numerous pathologies requiring a treatment following patella resurfacing included patella loosening, fragmentation of the patella, avascular necrosis patella, late stress fracture, lateral facet pain, oblique resurfacing, and too thick of a patellar composite. In a large multi-center randomised clinical trial at 5 years from the United Kingdom in over 1700 knees from 34 centers and 116 surgeons, there was no difference in the Oxford Score, SF-12, EQ-5D, or need for further surgery or complications. The authors concluded, “We see no difference in any score, if there is a difference, it is too small to be of any clinical significance”. In a prospective of randomised clinical trial performed at Tulane University over 20 years ago, no differences were observed in knee score, a functional patella questionnaire, or the incidence of anterior knee pain between resurfaced and un-resurfaced patellae at time intervals of 2–4 years, 5–7 years, or greater than 10 years. Beyond 10 years the knee scores of total knee patients with a resurfaced patella had declined significantly greater than those with a non-resurfaced patella. There are numerous advantages of not resurfacing the patella including less surgical time, less expense, a lower risk of “major” complications (especially late complications), and if symptoms develop in an un-resurfaced patella, it is an easier salvage situation with more options available. A small percentage of total knee patients will be symptomatic whether or not their patella is resurfaced. Not resurfacing the patella retains more options and has fewer complications. The major determinant of clinical result and the presence of anterior knee pain after knee replacement is surgical technique and component design not whether or not the patella is resurfaced. Patella resurfacing is occasionally necessary for patients with inflammatory arthritis, a deformed or maltracking patella, or symptoms and pathology that are virtually restricted to the patellofemoral joint. For the vast majority of patients, however, patella resurfacing is not necessary.

The decision to resurface the patella has been well studied. While regional differences exist, the overwhelming choice by most Surgeons in the United States is to resurface the patella. Data supports that this is the correct choice.

Articular cartilage on metal has not been shown to be a good long term bearing surface. Cushner et al. has also shown that cartilage in the arthritic knee has significant pathologic abnormalities. Patella surfacing has excellent long-term results with a low complication rate. Anterior knee pain is a common complaint after knee replacement and is even more common in TKA with un-resurfaced patella. Pakos et al. had more reoperations and greater anterior knee pain when the patella was NOT resurfaced. Parvizi et al. also found less patient satisfaction with un-resurfaced patellas. Meta-analysis results indicate higher revision rates with un-resurfaced patellas. Bilateral knee studies also favor resurfaced patella. Higher revision rates were also confirmed in the Swedish Registry with a 140% higher revision rate in TKA with un-resurfaced patellas In addition, second operations to resurface the patella often are unsuccessful at alleviating pain.

Surgeons who choose not to resurface the patella must accept that their patients will have the same or greater degree of anterior knee pain and a significantly greater risk for reoperation.

Infection following primary total knee arthroplasty (TKA) is fortunately a relatively uncommon complication with an incidence of approximately 1%. However, because the morbidity and cost of treatment of deep prosthetic TKA infections is so high, effective prevention strategies are key quality improvement initiatives. The cause of post-operative infections are multifactorial and complex but can generally be categorised into 1) host, 2) surgical, and 3) environmental factors. The purpose of this abstract to provide an outline of these factors and their influences on the infection risk following TKA.

Patient factors and optimization of modifiable risk factors have been shown to decrease the risk for infection. While the individual contributions of factors such as body mass index (BMI), diabetes, nutritional status, Charlson Comorbidity Index (CCI), and renal disease are unknown, together, they have been shown to influence infection risk. Additionally, Tayton et al. analyzed 64,566 primary TKAs in the New Zealand Joint Registry and found that male gender and prior knee surgery were also independent risk factors of development of PJI 12 months following TKA. Finally, Crowe and colleagues also identified tobacco use and Staphylococcus aureus colonization as modifiable risk factors for minimizing PJI following primary TKA.

Timely administration of prophylactic antibiotics prior and after surgery has been shown to be the most effective strategy to reduce infection risk. The optimal prophylaxis regimen for all patients is unknown and in certain situations, administration of Vancomycin in additional to a conventional cephalosporin may be beneficial. However, universal administration of Vancomycin has not been shown to decrease the incidence of surgical site infections and could actually increase the risk for renal failure. Conversely, addition of antibiotics to cement during primary TKA has not been shown to reduce long term infection risk. The use of dilute betadine lavage has been shown by some authors to be beneficial. Finally, good surgical technique, proper soft tissue handling, and meticulous wound closure are all critical factors influencing the risk for infectious complications following TKA.

Environmental factors have also been shown to affect infection rates following TKA. While the use of laminar flow and body exhaust suits have not been shown to significantly influence the risk for infection, minimizing operating room traffic has been shown effective in reducing the risk for contamination. Some authors have shown ultraviolet light systems to decrease airborne contaminants.

In summary, factors influencing infection risk following TKA are complex and multifactorial. Patient selection, optimization of modifiable risk factors, appropriate use of antibiotics, and minimization of OR traffic are among the most common strategies to minimizing infection.

The infected joint arthroplasty continues to be a very challenging problem. No test has 100% diagnostic accuracy for PPI and the treating surgeon must correlate the clinical and radiographic presentation with a combination of blood tests, synovial fluid analysis, microbiological and histopathological evaluation of periprosthetic tissue and intra-operative inspection to reach a definitive diagnosis. Diagnosis should begin with a high index of suspicion for new onset of pain or symptoms in well-functioning joints. Plain radiographs may identify osteolysis or early signs of implant failure and should be promptly investigated further for PPI.

Peripheral blood ESR and CRP remain the most widely used next step for the diagnosis of PPI. Both these tests are widely available, inexpensive, and have a rapid turnaround time in laboratories. The results should be interpreted with caution due to their relative lack of specificity. The sensitivity and specificity values for CRP are approximately 88 and 74%, respectively; while that of ESR is slightly lower at 75 and 70%, respectively. The combined ESR and CRP tests are 96% sensitive for ruling out PPI but the specificity of this combination is as low as 56%. Advanced imaging modalities may be used as a part of the diagnostic algorithm. However, they require expert interpretation and are limited by availability and high costs. When available they have high sensitivity and specificity but their routine use is not recommended and indications have to be individualised in the light of clinical presentation.

In the presence of high clinical suspicion, the clinician should plan synovial fluid analysis. This provides a synovial fluid white cell count with differential cell count, specimen for culture and possibility of analyzing other synovial fluid markers. It is important to note that failed metal-on-metal hip arthroplasties can give a falsely elevated synovial fluid cell count when using automated cell counters. This can be overcome by manually counting cell numbers. Synovial fluid should be directly into blood culture bottles, and antibiotics should be withheld at least 2 weeks prior to aspiration, whenever possible. Cultures also help establish the organism, virulence and sensitivities that help plan subsequent treatment algorithm.

Periprosthetic tissue biopsy provides valuable information in microbiological diagnosis and workup of PPI. Routine use of gram staining is not recommended due to poor sensitivity. However, frozen section may have some role especially when performed by a skilled pathologist. Tissue culture remains the gold standard for diagnosis despite false-positive and false-negative results. Whenever possible multiple samples should be obtained to aid interpretation. A threshold of 2 to 3 positive specimens yielding indistinguishable microorganisms has been recommended to improve sensitivity. Acute inflammation, evidenced by neutrophilic infiltrate on fixed or frozen tissue, is suggestive of PPI and is defined as the presence of at least 5 neutrophils per high-powered field, in at least 5 separate microscopic fields.

Sonication of removed prosthetic components is used to dislodge the biofilm and the associated bacteria from the surface of the implant. The fluid surrounding the implant can be used for culture or analysis.

PCR testing: Synovial fluid aspirate, periprosthetic tissue or sonicate fluid may be subject to molecular diagnosis to amplify genetic material and improve microbiological diagnosis of PPI. This technique has shown increased sensitivity in patients who had received antibiotics within 14 days before implant removal. Results have to carefully interpreted with due consideration for possibility of false positive results.

Infection is one of the most devastating complications following total joint arthroplasty. Treatment is difficult, often requiring multiple surgical procedures, prolonged hospitalization, and long-term intravenous (IV) antibiotic therapy. Failure rates are high for resistant organisms and mixed-flora infections, and antibiotic-loaded cement spacers deliver antibiotics for only a few days and can harbor resistant bacteria on the surface. We have adopted a direct-exchange method with antibiotics infused directly into the joint using Hickman catheters to achieve extremely high levels of intraarticular (IA) antibiotics for six weeks. Hickman catheters have a fibrous cuff that allows soft-tissue ingrowth and seals the surface of the tube to prevent contamination of the joint by tracking along the catheter. Two catheters are inserted to ensure that at least one will be functional for six weeks.

The safety and efficacy of this protocol was evaluated in patients undergoing primary or revision TKA by measuring joint and serum levels of vancomycin following IV administration (as a prophylactic) and IA administration (as a treatment for infected TKA), and comparing the levels with each method. Therapeutic levels of vancomycin were present in the knee following IV or IA administration, but much higher levels were possible with IA administration (avg. of 6.8 and 9,242 µg/mL). Vancomycin achieved therapeutic levels in the synovial fluid of the knee with IV administration, but clearance from the knee was rapid, suggesting that the synovial fluid concentration may be sub-therapeutic for hours before the next IV dose is given. In contrast, IA delivery of vancomycin resulted in peak levels that were many orders of magnitude higher, and trough levels remained therapeutic for 24 hours in both the joint space and in the serum (minimum trough levels of 8.4 and 4.2 µg/mL, respectively). The elimination constant (half-life) of IA-administered vancomycin was 3.1 hours.

This protocol was used in 18 knees (18 patients) with methicillin-resistant Staphylococcus aureus treated between January 2001 and January 2007 with one-stage revision that included débridement, uncemented revision of total knee components, and IA infusion of 500 mg vancomycin via Hickman catheter once or twice daily for 6 weeks. No IV antibiotics were used after the first 24 hours. Serum vancomycin levels were monitored to maintain levels between 3 and 10 µg/mL. Mean serum vancomycin peak concentration was 6 ± 2 µg/mL and the mean serum vancomycin trough concentration was 3 ± 1 µg/mL at 2 weeks post-operative. Knee synovial fluid peak and trough vancomycin levels were measured in two knees. Synovial fluid peak concentrations were 10,233 µg/mL and 20,167 µg/mL and trough concentrations were 724 µg/mL and 543 µg/mL, respectively. Minimum follow-up was 27 months (range, 27–75 months). Mean followup was 62 months, (range, 27–96 months). At 2-year follow-up, mean Knee Society score was 83 ± 9. No radiographic evidence of implant migration has occurred. One knee reinfected with MRSA and was reoperated at 5 months. A necrotic bone segment was found, the knee was debrided and revised, and the antibiotic infusion protocol was readministered. The knee remained free of infection at 42 months post-operatively.

Directly infusing antibiotics into the infected area maintains a high local concentration level while minimizing systemic toxicity. This method avoids the use of antibiotic-loaded cement and the potential for growth of antibiotic-resistant strains of bacteria. These findings support single-stage revision in cases treated with cementless revision and IA antibiotics.

Two stage exchange has been the gold standard in north America for the treatment of infected knee replacements. The choice of static versus articulated spacers has been debated for a number of years.

At our institution our choice of spacer for 2 stage exchanges is an articulated spacer. This allows motion between stages which facilitates recovery, and makes the second stage technically easier. In a study from our institution we followed 115 infected TKAs treated with the PROSTALAC articulated spacer for 5–9 years. Success for eradication of infection was 88%. With a repeat two stage overall infection control was 98%. In addition we compared functional outcomes to a group of aseptic knee revisions and found no difference in functional outcomes with standard quality of life outcome scores.

While the articulated spacers was our treatment of choice in 2 stage exchange around 2012 the company that manufactured the PROSTALAC knee components ceased to manufacture them. At that time based on the work of 2 previous studies (Hofmann, Lee), at our institution we continued to use articulated spacers. However, this was now the so called Hofmann technique with a new standard femoral component with an all polyethylene tibia. The only difference from a standard knee revision was no stems and the utilization of high dose antibiotics. We also followed the principles from Europe of one stage exchange, such as wide debridement and soaking in dilute betadine for 15 minutes.

More recently as of Sept 2015 we have used an all-polyethylene tibia with a keel. The hope being that this will give a more stable tibia than previous and perhaps make a second stage unnecessary. Our first case was September 2015. The intention was not to do a second stage if the infection was eradicated and the patient had good pain relief and function. To date we have implanted 12 of these and in all cases we have not had to do a second stage revision. Further study will reveal where this inadvertent one stage fits in our practice.

Two-stage treatment of chronically infected TKA is the most common form of management in North America and most parts of the world. One-stage management has pros and cons which will not be discussed in this lecture.

There is great variation of techniques and timing and little data to definitively support one technique or timing approach vs. another. Most methods are based on empirical success and logic. At the time of surgery, the first step is removal of infected implants. All metallic implants and cement should be removed. The most common places to leave cement behind inadvertently include patellar lug holes, femoral lug holes, and the anterior proximal tibia behind the tibial tubercle. Formal synovectomy should be performed. The next step is typically antibiotic-impregnated spacer placement. There are pros and cons of dynamic and static spacers with no clear evidence of superiority of one vs. another. Dynamic spacers work satisfactorily with mild to moderate bone loss, but more severe bone loss is usually better treated with static spacers and a cast. Most antibiotic spacers are made of methyl methacrylate cement with addition of high-dose antibiotics. In most cases, doses of 4–8 gm of antibiotics per pack of cement are preferred. The type of dosing depends on the specific antibiotic and the type of cement used. The most common antibiotics used are vancomycin and gentamycin. When the femoral canals have been instrumented, antibiotic-impregnated cement wands are usually placed in the medullary canal, as the medullary canals have been shown to have high risk of residual bacteria being present.

The resection interval may vary and there is no clear evidence of a “best” resection interval. Practically speaking, most surgeons use a resection period of 8–16 weeks depending on the type of spacer utilised. During the resection interval, serum markers (ESR and CRP) are followed periodically. One anticipates a decline or normalization of these parameters prior to second stage reimplantation procedure. There has not been a demonstrated advantage to reaspiration of the knee before reimplantation in most circumstances.

At the time of reimplantation, the spacers are removed and the knee is redebrided. The key at the time of reimplantation is to obtain good implant fixation but to also balance this with the potential for manageable extraction of the implants at some later date. Good implant fixation is important because failure rates due to mechanical failure are approximately equal to those of failure due to reinfection by 10 years. It is important to remember that reinfection risk is at least 10% by ten years, and therefore extractability of implants is also important. Post-operative management typically includes IV antibiotics, followed by oral antibiotics until final intra-operative cultures are available.

The results of two-stage reimplantation are reported in many series. Most show approximately 85–95% rate of successful eradication of infection in the first five years. Reinfections, often with different organisms, may occur even late after reimplantation. By ten years after surgery survival free of mechanical failure and infection in most series drops to 80% or less due to recurrent infections and mechanical failures.

Drainage from the knee wound after TKA is an obvious concern for the arthroplasty surgeon. One of the inherent problems with a total knee arthroplasty is there is a focus on obtaining maximum range of motion but at the same time the wound needs to heal in a timely fashion. Consistent knee drainage after a TKA is a source of concern. The quantity and quality of drainage needs to be assessed and there are certain questions that need to be answered including: 1) Is there bloody drainage which suggests fascial dehiscence?; 2) Is the patient too active?; 3) Is the drainage in some way related to DVT prophylaxis?; 4) Is the patient obese and could the drainage be secondary to fat necrosis or seroma? and 5) Is the drainage suggestive of an infection? The work up can include C-reactive protein and sed rate, and possibly a knee aspiration. In general, C-reactive protein >100 mg/L within the first six weeks after surgery suggests the presence of an infection. The sed rate is generally not useful in the early post-operative period. In the first six weeks after surgery if the number of white cells in the aspiration is >10,000 this suggests infection especially if there are 80–90% polymorphonuclear cells.

Each day of prolonged wound drainage is noted to increase the risk of infection by 29%. Morbid obesity has been shown to be an independent risk factor for infection. Some anticoagulants (i.e. low molecular weight heparin) have been associated with increased wound drainage. In a retrospective review of 11,785 total joint arthroplasties, 2.9% of joints developed wound drainage, and of these patients, 28% required further surgery. It was noted that patients that were malnourished had a 35% failure rate with respect to controlling the drainage and preventing infection versus 5% in patients that were healthy.

The International Consensus Conference on Infection concluded that a wound that has been persistently draining for greater than 5–7 days requires surgical intervention. The available literature provides little guidance regarding the specifics of this procedure. In general, if the wound is draining or is red, rest the leg for a day or two. In some instances a bulky Jones dressing can be helpful. If there is persistent drainage or cellulitis, then operative intervention is probably necessary. Evaluation of CRP and a knee joint aspiration can be helpful. The decision to return to the OR should be made within the first 7 days after the surgery. At the time of the procedure one will need to decide to perform either a superficial washout versus a washout and polyethylene exchange.

The high and ever increasing cost of medical care worldwide has driven a trend toward new payment models. Event based models (such as bundled payment for surgical events) have shown a greater potential for care and cost improvement than population-based models (such as accountable care organizations). Since joint replacement is among the most frequent and costly surgical events in medicine, bundled payments for joint replacement episodes have been at the forefront of evolution from fee-for-service to value-based care models and episode-based healthcare reform in general.

Our education as surgeons in medical school, residency, fellowship, and in continuing education has been almost entirely non-economic in focus. Yet, we surgeons are now evolving from being primarily responsive for our patients' medical care to being also responsible for all expenditures associated with our patients' care. Similarly, while the cost of our patients' care was not even available to us, every dollar of expenditure for a patient's episode of care is now available to us in some circumstances. For example, a typical primary joint replacement episode may cost $30,000 for a patient insured by Medicare in the US. A surgeon performing 400 joint replacements per year is therefore authorizing upwards of $12M a year in health care spending by making the decisions to perform reconstructive procedures on those patients.

The risk for value-based surgical episodes of care can be born by various entities including hospital systems or the surgeons themselves. Recent evidence demonstrates that quality improves and cost decreases more rapidly when surgeons take primary responsibility and risk for episodes of care as compared to when a hospital system or third party takes primary responsibility and risk. Yet, as surgeons, our education in the field of medical economics, value-based episodes of care, and payment reform is only just beginning. The more we understand about the cost and value of the services that we order for our patients, the more leadership can provide as healthcare evolves. The current presentation will describe the specific cost of care for the primary joint replacement patient preliminary experience with accepting risk and responsibility for these patients. It is likely that our patients will be best served if we surgeons provide as much leadership as possible in their care, both medically and economically.

The United States is in the midst of an opioid epidemic, with the World Health Organization reporting that American's consume 99% of the world's supply of hydrocodone and 83% of the world's oxycodone. Additionally, pre-operative opioid use has been associated with worse clinical outcomes and higher rates of complications following TKA. This is especially important in the TKA population given that approximately 15% of patients are either dissatisfied or very dissatisfied at least one year after their TKA procedure. Given the concerning rise is opioid use the American Academy of Orthopaedic Surgeons (AAOS) has recently released an information statement with practice recommendations for combating this excessive and inappropriate opiate use. However, little is known regarding peri-operative opioid use for TKA patients. Therefore, the purpose of this study was to: 1) identify rates of opioid use prior to primary TKA, 2) evaluate post-operative trends in opioid use throughout the year following TKA and 3) identify risk factors for prolonged opioid use following TKA.

Overall, 31% of TKA patients are prescribed opioids within 3-months prior to TKA; this percentage has increased over 9% during the years included in this study. Pre-operative opioid use was most predictive of increased refills of opioids following TKA, however, other intrinsic patient characteristics were also predictive of prolonged opioid use. These characteristics remained predictive after controlling for opioid user status. The increasing rates of opioid prescribing prior to TKA are concerning, especially given literature concluding opioids have minimal effect on pain or function in patients with osteoarthritis and pre-operative opioid use is associated with poor outcomes and more complications following TKA. This data provides an important baseline for opioid use trends following TKA that can be used for future comparison and identifies risk factors for prolonged use that will be helpful to prescribers as the AAOS works to decreased opioid use, misuse and abuse within the United States. Our data on THA and unicompartmental arthroplasty is similar with an increase in pre-THA use of 9% with 38% receiving narcotics within 3 months of surgery and continued use in opioid users (9 times non-opioid users at 12 months).

The true results of revision total knee arthroplasty (TKA) are not fully understood, for a variety of understandable reasons. But it is has been clear for decades that revision without a diagnosis is likely to fail. The evaluation of the problem TKA should be systematic (follow the same scheme every time) and comprehensive (all possibilities should be considered even if one diagnosis seems obvious).

Evaluation begins, as with all of medicine with a list of possible causes: the mechanisms of failure. John Moreland was the first to describe a coherent system which needed only one simple addition to be complete: 1.) Prosthetic joint infection; 2.) Extensor disruption; 3.) Patella and malrotation; 4.) Loose; 5.) Component breakage; 6.) PP fracture; 7.) Poor motion; and 8.) Tibial femoral instability.

Evaluation begins with the history, where 10 questions in particular are useful: 1.) What seems to be the problem? 2.) Was the “knee” ever successful after surgery? If there was never pain relief, is the current pain, the same or different? 3.) Standard pain quality questions - Location, duration, frequency, quality, exacerbating, ameliorating. 4.) Swelling? 5.) Stiffness? 6.) Giving way? 7.) Weakness? 8.) Things “just don't feel right”? 9.) Possible sepsis questions - Fever, chills, sources, primary TKA healing. 10.) Mood, social situation?

The physical exam should cover these ten points: 1.) Active extension; 2.) Rising from chair; 3.) Gait: hip, knee alignment, knee instability; 4.) Hip (internal rotation); 5.) Inspection; 6.) Tenderness; 7.) ROM; 8.) Stability (extension and 30–45 degrees flexion; 9.) Sitting on edge of exam table (knee at 90 degrees); and 10.) Step up on low stool (stair).

Investigations include: 1.) ESR + CRP; 2.) CBC; 3.) HGB- anemia; 4.) Lymphocytes- nutrition; 5.) GGT- alcohol abuse; 6.) Albumen- nutrition; 7.) HbA1c- diabetic control.

Imaging includes: 1.) Single leg weightbearing AP; 2.) Lateral; 3.) Merchant; 4.) Full length (hip-knee-ankle); 5.) AP pelvis; 6.) CT scan; and 7.) (Technitium bone scan).

Stiffness after TKR is a frustrating complication that has many possible causes. Though the definition of stiffness has changed over the years, most would agree that flexion > 75 degrees and a 15-degree lack of extension constitutes stiffness. This presentation will focus upon the potential causes of a stiff TKR, intra-operative tips, the post-operative evaluation and management, and the results of revision for a stiff TKR.

The management of this potentially unsatisfying situation begins pre-operatively with guidance of the patient's expectations; it is well-known that pre-operative stiffness is strongly correlated with post-operative lack of motion. At the time of surgery, osteophytes must be removed and the components properly sised and aligned and rotated. Soft-tissue balancing must be attained in both the flexion/extension and varus/valgus planes. One must avoid overstuffing the tibio-femoral and/or patello-femoral compartments with an inadequate bone resection.

Despite these surgical measures and adequate pain control and rehabilitation, certain patients will continue to frustrate our best efforts. These patients likely have a biological predisposition for formation of scar tissue. Other potential causes for the stiff TKR include complex regional pain syndrome or joint infection.

Close followup of a patient's progress is crucial for the success in return of ROM. Should motion plateau early in the recovery phase, the patient should be evaluated for manipulation under anesthesia. At our institution, most manipulations are performed within 3 months post-operative under an epidural anesthetic; patients will stay overnight for continuous epidural pain relief and immediate aggressive PT.

The results of re-operations for a stiff TKR are variable due to the multiple etiologies. A clear cause of stiffness such as component malposition, malrotation or overstuffing of the joint has a greater chance of regaining motion than arthrofibrosis without a clear cause. Although surgical treatment with open arthrolysis, isolated component or complete revision can be used to improve TKR motion, results have been variable and additional procedures are often necessary.

Peri-prosthetic fractures above a TKA are becoming increasingly more common, and typically occur at the junction of the anterior flange of the femoral component and the osteopenic metaphyseal distal femur. In the vast majority of cases the TKA is well fixed and has been functioning well prior to fracture. For loose components, revision is typically indicated. Typically a megaprosthesis is required. Well-fixed components, internal fixation is preferred. Fixation options include retrograde nailing or lateral plating. Nails are typically considered in arthroplasties that allow intercondylar access (“open box PS” or CR implants) and have sufficient length of the distal fragment to allow multiple locking screws to be used. This situation is rare, as most distal fragments are quite short. If a nail is chosen, use of a long nail is preferred, since it allows the additional fixation and alignment that diaphyseal fill affords. Short nails should be discouraged since they can “toggle” in the meta-diaphysis and do not engage the diaphysis to improve coronal alignment. Plates can be used with any implant type and any length of distal fragment. The challenge with either fixation strategy is obtaining stable fixation of the distal fragment while maintaining length, alignment, and rotation. Fixation opportunities in the distal fragment can be limited due to obstacles caused by femoral component lugs, boxes, stems, cement mantles, and areas of stress shielding or osteolysis. Modern lateral locked plates can be inserted in a biologically friendly submuscular extra-periosteal fashion. More recent developments with polyaxial locked screws (that allow angulation prior to end-point locking) may offer even more versatility when distal fragment fixation is challenging. The goal of fixation is to obtain as many long locked screws in the distal fragment as possible. High union rates have been reported with modern locked plating techniques, however, biplanar fluoroscopic vigilance is required to prevent malalignments, typically valgus, distraction, and distal fragment hyperextension.

Extensor mechanism complications after or during total knee arthroplasty are problematic. The prevalence ranges from 1–12% in TKR patients. Treatment results for these problems are inferior to the results of similar problems in non-TKR patients. Furthermore, the treatment algorithm is fundamentally different from that of non-TKR patients. The surgeon's first question does not focus on primary fixation; rather the surgeon must ask if the patient needs surgery and if so am I prepared to augment the repair? Quadriceps tendon rupture, periprosthetic patellar fracture, and patellar tendon rupture have similar treatment algorithms. Patients who are able to perform a straight leg raise and have less than a 20-degree extensor lag are generally treated non-operatively with extension bracing. The remaining patients will need surgical reconstruction of the extensor mechanism. Loose patellar components are removed. Primary repair alone is associated with poor results. Whole extensor mechanism allograft, Achilles tendon allograft, and synthetic mesh reconstruction are the current techniques for augmentation. In the acute setting if these are not available hamstring tendon harvest and augmentation is an option. Achilles tendons and synthetic mesh are easier to obtain than and entire extensor mechanism but are limited to patients that have an intact patella and the patella that can be mobilised to within 2–3 cm of the joint line. No matter which technique is used the principles are: rigid distal/tubercle fixation, coverage of allograft/mesh with host tissue to decrease infection, tensioning the augment material in extension, no flexion testing of reconstruction and post-operative extension bracing.

It has become clear that computer navigation in total joint replacement provides more reliable obtaining of a neutral mechanical axis during total knee surgery. The real issue is when one attains a more reliable mechanical axis, is that going to change the clinical outcome both in terms of function and durability? To date, we really haven't been able to answer that question definitively. Is there really a one simple target value for alignment in all patients undergoing total knee replacement?

The constraints on accuracy imposed by our standard total knee instruments and the constraints on assessment imposed by 2-dimensional radiographs made broad, simple targets like a mechanical axis ± 3 degrees reasonable starting points; yet we have not further worked to verify if we can do better. It is naïve to think that the complex motion at the knee occurring in 6 dimensions over time can be reduced to a single static target value like a neutral mechanical axis and have strong predictive value in regard to the success or failure of an individual TKA. We assessed 399 knees of 3 different modern cemented designs at 15 years and found that factors other than alignment were more important than alignment in determining the 15-year survival. That work does not mean that alignment is not important, instead it suggests that either the way we traditionally define malalignment (outside 0 ± 3 degrees) is too imprecise or that the other causes of failure overwhelm malalignment in determine TKA durability.

There is enough evidence to show that navigation improves precision of component placement and consistent and accurate restoration of limb alignment, allowing the surgeon to achieve the desired neutral or kinematic alignment. Computer-assisted TKA provides excellent information regarding gap equality and symmetry throughout the knee range of motion. Accurate soft-tissue balancing is facilitated by CAS. It allows precise, quantitative soft tissue release for deformities, especially in knees with severe flexion contractures and severe rigid varus and valgus deformities. It allows accurate restoration of joint line, and posterior femoral offset. Knee arthritis with complex extra-articular deformities and in-situ hardware can be tackled appropriately using computer navigation where conventional techniques may be inadequate. It also allows intra-articular correction for extra-articular deformities due to malunions and facilitates extra-articular correction in cases with severe extra-articular tibial deformities. In obese patients, where the alignment of the limb is difficult to assess, computer navigation improves accuracy and reduces the number of outliers. The ability to quantify the precise amount of bone cuts and soft tissue releases needed to equalise gaps and restore alignment, reduced blood loss, and reduced incidence of systemic emboli improves the safety of the procedure and hastens functional recovery of the patient. Recent evidence shows that the rate of revision especially in younger patients is reduced with navigation.

Total knee arthroplasty (TKA) is widely accepted as a successful treatment option for the pain and limitation of function associated with severe joint disease. The ideal knee arthroplasty implant should provide reliable pain relief and normal levels of functional strength and range of motion. However, there are still a number of implant-specific problems following knee arthroplasty, such as irregular kinematics, polyethylene wear and poor range of motion.

MRI and cadaveric studies have highlighted important kinematics during movement of the native knee. In particular, flexion of the joint results in a phenomenon referred to as “roll back and slide”. This essentially describes posterior translation of the femur on the tibia which in turn has a two-fold biomechanical function: to increase the lever arm of the quadriceps and allow clearance of the femur from the tibia in deep flexion. During extension of the joint, the femur rolls forward increasing the lever arm of the hamstrings to act as a brake on hyperextension.

Additional rotation of the joint arises in the axial plane. This is attributed to the concave tibial plateau and relatively fixed meniscus on the medial compartment of the joint in comparison to a lateral convex plateau with a mobile meniscus. This asymmetry allows axial rotation of the lateral compartment over the medial compartment by up to 30 degrees. Subsequently, from extension to full flexion the tibia rotates internally on the femur and vice versa. The external rotation of the tibia on the femur that occurs during the terminal degrees of knee extension is often referred to as the “screw home mechanism” and results in tightening of both the cruciate ligaments locking the knee such that the tibia is in a position of maximum stability on the femur.

Numerous studies over the past two decades have characterised the in-vivo motions of knee replacements. Major conclusions from these studies are that the motion after knee arthroplasty generally does not replicate normal knee motions. In particular, many kinematic studies of unconstrained devices have demonstrated the femur sliding forwards rather than backwards with flexion. This paradoxical movement is also seen in many posterior cruciate retaining knees. This in turn has a negative outcome in range of movement, particularly in light of fluoroscopic studies highlighting strong positive correlations in weight-bearing flexion with femoral roll back. In contrast knee arthroplasties that retain both cruciate ligaments come closest to replicating normal knee motion and furthermore, provide greater stair climbing stability. It may therefore be presumed that this excessive AP motion in a well-designed prosthesis is attributed to a loss in the natural intrinsic stabilizing structures.

A number of studies to date have also highlighted close correlation between knee kinematics and functional strength. Generally, patients with knee replacement exhibit a significant loss of strength compared to normal. The common experimental findings is that knees with the highest intrinsic stability, whether provided by retained ligaments, conforming articular surfaces or post-cam substitution, exhibit the greatest functional strength in high-demand activities in TKA patients.

On the basis of this knowledge, it would be intuitive to choose a TKA design that attempts to restore natural knee joint stability. The medially conforming ‘ball and socket’ articulation of the medial tibio-femoral compartment is a design concept thought to provide stability through the complete arc of knee flexion. Clinical and biomechanical data from a number of centers suggests that this has been a successful evolution in TKA that will continue to benefit patients.

Introduction: Although volumetric wear reduction has been demonstrated in knee simulator studies, there is no long-term in-vivo evidence supporting wear reduction and durability with uni-directional rotating platform PS design. This design was introduced to reduced spin-out and provide greater range of motion. This is the first long-term report of this implant, a prospective study investigating clinical and radiographic survivorship with 10 years follow-up.

Material and Methods: Between January 2000 to March 2001, 118 consecutive patients (141 knees) received cemented RP TKRs. All patients were followed prospectively using clinical and radiographic criteria as defined by the Knee Society. At minimum nine years follow-up 20 patients were deceased, 11 were lost to follow-up and two refused to participate in the study, leaving 85 patients (100 knees) for final analysis.

Results: Good to excellent results were achieved in 95% of patients. There were no cases of malalignment, spinout, aseptic loosening or osteolysis. The mean ROM improved from 111.2 ± 15.2 degrees to 119 ± 3.8 degrees. The mean WOMAC score was 30 ± 14, KSS scores improved from an average of 48 to 96. Sporting activities such as golf, tennis and walking was 29%, 12% and 32%, respectively.

Anterior knee pain was present in 15% of cases. The incidence of asymptomatic crepitation and painful crepitation requiring scar excision was 10% and 4% respectively. During this period we had one case of infection and one revision for fracture. Kaplan-Meier survivorship at 10 years for mechanical failure and failure for all failures was 100% and 95.7%, respectively.

Discussion and Conclusion: Ten-year follow-up of RP-PS design demonstrates excellent clinical and radiographic results with no failures for mechanical reasons. There were no spin-out and average ROM was 119 ± 3.8 degrees.

Tourniquet use in total knee arthroplasty is convenient for the surgeon and provides a bloodless field for expeditious surgery and a dry field for cementation, but can best be described as an orthopaedic tradition. It is logical for complex anatomy of ligament, nerve, and vessel surgery but it may not be necessary for total knee replacement. In one recent randomised trial, the absence of the tourniquet was not found to affect the quality of cement fixation. There are numerous potential downsides to the use of a tourniquet including decrease range of motion, delayed recovery, increased pain, wound complications, micro-emboli, neuropathy, and increased VTE. There are also a number of complications associated with the use of a tourniquet including arterial thrombosis, skin irritation below the tourniquet, post-operative hyperemia, blood loss, less accurate intra-operative assessment, and it complicates intravenous drug administration. Studies of range of motion have shown that when there is a difference noted, the range of motion is consistently better without tourniquet use. When a tourniquet is utilised it has been found to be advantageous to only use of tourniquet for a minimal amount of the case, typically when cementing is performed. Functional strength has also been found to be improved without the use of a tourniquet. This was attributed to muscle damage, tourniquet-induced ischemia, and compressive injury. Increased peri-operative pain has also been reported in randomised trials associated with the use of a tourniquet. Edema, swelling, and limb girth issues have also been noted to be associated with tourniquet use. Exsanguinating a limb will result in swelling approximately 10% of the original volume half due to a return of blood, and half due to reactive hyperemia. Longer tourniquet times are also associated with increased wound drainage and more wound hypoxia. Tourniquet use has also been associated with embolic phenomenon with several times greater risk of large emboli associated with tourniquet use.

A number of complications have been associated with tourniquet use including thromboembolic complications. In one study where quantitative MRI was utilised on both thighs after unilateral total knee replacement with and without a tourniquet, the tourniquet group showed more atrophy with a loss of 20% of the volume compared to the normal side in total knees performed with a tourniquet which also performed clinically worse. There is a small but substantial risk of arterial thrombosis particularly in patients that have atherosclerotic plaque. Ironically there is a risk of increased post-operative blood loss due to the post-tourniquet “blush” as the blood pressure and pain increase hours after a surgical procedure is completed. There is also difficulty in identifying and coagulating posterior and lateral geniculate vessels with the components in place. Utilizing a tourniquet also interferes with intra-operative assessment of patella tracking, range of motion, ligament stability, and gap balancing. Randomised clinical trials have concluded that there is less pain and quicker recovery without the use of a tourniquet. There have also been reports of less swelling, increased range of motion, less analgesic use and better clinical outcome when a tourniquet is not utilised. A meta-analysis of systematic reviews favored not utilizing a tourniquet due to the decrease in complication rate and the improvement in clinical results. While it is standard practice in the US to utilise a tourniquet, the strong consensus of the literature on the subject favors either not using a tourniquet or minimizing the use of a tourniquet for the period of time necessary for a very dry field for cement fixation.

The use of a tourniquet when performing total knee arthroplasty (TKA) is subject to different methodologies. Some surgeons see no need to use a tourniquet, others use the tourniquet only during cementation, some utilise the tourniquet from prior to incision to after cementation, while others maintain throughout and release after closure. At our center, use of the tourniquet is part of the TKA routine: position the patient, administer antibiotics, inflate the tourniquet, note pressure and time, complete preparation and draping, set time-out, and cut. We release the tourniquet after cementation of components, prior to assessment of patellofemoral tracking and closure. Advantages of using a tourniquet are enhanced TKA durability, less blood during cementation, and reduced intra-operative blood loss and need for transfusion. Adequately preparing the bone surfaces and cleaning away blood and fat are essential to good cement technique, providing better interdigitation and penetration and resulting in fewer radiolucencies and longer survivorship. Lateral retinacular release, performed to alleviate patellar maltracking, is not a benign procedure and is associated with increased patellar complications including loosening, fracture, and avascular necrosis. Several articles, including one from our center, have studied the effect of tourniquet deflation and patellar tracking, observing 31% to 86% reduction in maltracking and indication for lateral release when assessing after deflation. A prospective study of 28 patients undergoing same day bilateral TKA using a tourniquet inflated prior to incision and released after cementation on one side and either no tourniquet or tourniquet only during cementation of the contralateral side found slightly lowered quadriceps strength in the tourniquet group that persisted for up to 3 months. However, another recent prospective study of 120 patients assessing wound closure in 90 degrees flexion versus full extension, with the combination of an inflated versus deflated tourniquet, found that closure of the knee in flexion after tourniquet deflation significantly decreased post-operative pain and promoted early recovery of ROM. Safe use of the tourniquet is essential to avoid neurologic injury, and includes pneumatic, wider, contoured cuffs, moderate maximum applied pressure, and monitoring during release for emboli and metabolite return. Operative efficiency minimises overall operative and tourniquet time, thereby reducing risk of complications. Several meta-analysis reviews have compared TKA performed with versus without use of a tourniquet. All found using a tourniquet resulted in a significant decrease in operative time and intra-operative blood loss, but a trend for increase in deep vein thrombosis and wound complications. Other meta-analysis articles have studied time of tourniquet release comparing early versus late. These studies unanimously found late release to be associated with substantial increase in post-operative complications. Some studies found early release before wound closure to be associated with increased total blood loss and greater drop in hemoglobin while the other studies reported no differences in these measures. Our practice is to deflate the tourniquet prior to wound closure and to achieve hemostatis. The use of a tourniquet to perform TKA facilitates efficient operative technique, improves visualization of anatomical structures, facilitates the surgeon's focus on proper component positioning, and facilitates good cement technique.

Understand the nature of the problem. Revision TKR is a major undertaking and should be focused on problem solving. Know the problem!- Pain is not a diagnosis. Review history of problem. Think of possibilities: Infection, loosening, instability, stiffness, malalignment, poor kinematics.

Ensure an adequate workup - History, Exam; Imaging: Radiographs: consider long alignment films, MR for soft tissue issues: Clunk, recurrent hemarthroses; CT scan: Remains gold standard for rotational alignment. Labs: CBC, ESR, C-reactive protein. Aspiration: Cell count, Culture.

Assessment of where the patient is currently!

Synthesise a working diagnosis and formulate a provisional plan. Revise “part of knee”: you better know what's in there! Revise “all of knee”.

How will you get there? Think old incisions

How will get the parts out? What tools do you need? High speed burrs / diamond tip wheel /long thin saw blades; Osteotomes; Implant specific tools.

Once everything is out: What do you have left? Soft tissue defects, Bone defects.

How to “rebuild”: Constraint for soft tissue defects, Stems for mechanical stability, Cones / augments / bone graft for osseous defects; Fixation: Cement, Cementless.

Like all surgery, if you can see it, you can usually get the job done. This is especially true for extracting well-fixed components, as iatrogenic bone loss is a serious consideration regarding the reconstruction challenge. While reasons for revision are varied, several general principles are useful to consider during the pre and peri-operative course.

Pre-operatively, forewarned is forearmed. Certain factors pre-operatively can suggest the degree of operative difficulty regarding exposure. Revisions for stiffness obviously would suggest difficulty with exposure. Revisions in knees with patellar baja are almost always challenging as the patella is difficult to evert. When revising infected knees, an exuberant synovial response can result in beefy, friable synovium that has a volume effect with decreased tissue compliance. Further, the hyperemic friable tissue bleeds easily, even with tourniquet, and is difficult to anticoagulate.

Peri-operatively, the general principles to consider are as follows: 1) Don't rush exposure. Good exposure is the result of a series of deliberate and sequential steps that safely reduce tissue volume and improvement in tissue compliance. These steps include in almost all cases: a. Extend the incision as necessary, there is no call for minimally invasive revision knee surgery; b. Tenolysis of the patellar tendon; c. Clearing of the medial and lateral gutter; d. Clearing of the flexion space; e. Clearing of quadriceps adhesions.

2) Protect the extensor mechanism, above all else. Carefully monitor the insertion of the patellar tendon when beginning to flex the knee. If an avulsion begins, back off flexion and spend more time on clearing of scar tissue, as above. If still unsuccessful, then extensile exposure should be considered, such as a quadriceps snip. Be especially careful when osteolysis is present around the tibial tubercle.

3) The most difficult area to of the knee to expose in revision surgery is the posterior lateral corner, resulting in difficulty in exposing the posterior lateral femur and the posterior corner of the tibial component. Extensile exposures do not necessarily result in complete exposure of these regions. Redoubling efforts to remove scar tissue is often more successful. Bovie dissection of soft tissue on the proximal medial tibia can assist, with extension back to the semimembranosus insertion sometimes being necessary. While adequate exposure can result because of the increased ability to externally rotate the tibia, this exposure can also destabilise the medial side of the knee, sometimes resulting in the need to add constraint. The pros and cons need to be considered on a case-by-case basis.

4) Be judicious in the utilization of extensile exposures, and choose the exposure technique best suited for the situation. If the patellar tendon is normal, consider a simple quadriceps snip. If the knee is particularly stiff or the tibial tubercle or patellar tendon insertion is in jeopardy, then the snip can be extended into a V-Y turndown. If the patellar tendon is contracted resulting in patellar baja, then a tibial tubercle osteotomy (TTO) can be considered. Careful removal of tissue in scar tissue, as above, allows for relative external rotation of the tibia on the femur that translates the patella laterally, reducing the need for TTO. TTO can also be effective when approaching a cemented tibial stem.

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment secondary to loosening and settling of the implants which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability. Also, collateral ligament integrity may change following total knee replacement slightly after complete correction of a severe deformity that presents rarely as instability after several months.

Care should be given to assessing collateral ligament integrity. This can be done during physical examination by manual or radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate ligament retaining knees, anteroposterior instability must be assessed.

For instability, most revisions will require a posterior cruciate substituting design or a constrained unlinked condylar design. Occasionally, a posterior cruciate ligament preserving design can be used in situations where the bone-stock is well preserved and the posterior cruciate ligament shows excellent structural integrity. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time. Revision can range from simple polyethylene insert exchange to a thicker dimension, isolated component revision or complete revision of both femoral and tibial devices.

During revision surgery, laminar spreaders may be utilised to assess the flexion and extension spaces after the tibial platform is restored. If a symmetric flexion and extension space is achieved, then the collateral ligaments are intact. Depending on the remaining existing bone stock, a posterior stabilised or constrained condylar unlinked prosthesis may be used for implantation. In cases with considerable asymmetry or a large flexion/extension mismatch, a rotating hinge design should be utilised.

Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Currently, stems should be placed cementless to permit easier future revision. Cementing the stems is only recommended if there is lack of intramedullary isthmic support or there is a hip prosthetic stem that prohibits a stem from engaging the isthmic cortex. However, it should be realised that later revision of the fully cemented revision implant may be quite difficult.

Infection should be ruled out by aspiration off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability early. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result.

As with any revision knee arthroplasty, the first rule of revision is to ensure that the reason for failure has been identified, as revision for pain alone is associated with poor results. This is particularly important when considering revision of a UKA, as surgeons may have a lower threshold for revision than following TKA given the perception that the revision is “easy” and that the pain is “probably from the unresurfaced compartments”.

In a multi-center study, we found that many patients undergoing revision of a failed UKA do not have an appropriate evaluation for infection. Evaluation should include a screening ESR and CRP and if abnormal, an aspiration of the knee joint for synovial fluid WBC count, differential and culture.

To revise a UKA to a TKA, we perform the revision as we would a primary TKA, ignoring the implanted femoral component and using it to assist with reference of femoral component rotation and for the distal femoral cut; the component is not removed until it must for the final preparation. After finishing the femoral component cuts, the tibia is completely exposed prior to carefully removing the tibial component and re-cutting the tibia. In our experience of 45 consecutive both component revisions of UKA to TKA at Rush, 44 used primary implants (98%), including cruciate retaining implants in 36 of these 44 knees (82%; the balance were PS implants) and tibial stems were utilised in 6 of 44 knees (14%).

In order to better understand the outcomes of revision of failed UKA we studied 49 patients revised from UKA to TKA and 43 revised from HTO to TKA and matched them to 43 aseptic, both component revision TKA and 97 primary TKA. At a mean of 4.8 years, the KSS and Function Scores in the UKA to TKA, HTO to TKA and primary TKA cohorts were similar. Total operative times were significantly higher in the HTO to TKA and revision TKA groups. Length of hospital stay was shorter in the primary TKA cohort. The rate of complications and reoperations were higher in the HTO to TKA and revision TKA groups compared to the UKA to TKA and primary TKA groups. Based on these results, we believe that revising an HTO and UKA to a TKA both had functional outcomes more similar to a primary than a revision TKA, however, the complication rate of revising an HTO was more similar to a revision than a primary TKA.

The amount of bone loss due to implant failure, loosening, or osteolysis can vary greatly and can have a major impact on reconstructive options during revision total knee arthroplasty (TKA). Massive bone loss can threaten ligamentous attachments in the vicinity of the knee and may require use of components with additional constraint to compensate for associated ligamentous instability. Classification of bone defects can be helpful in predicting the complexity of the reconstruction required and in facilitating pre-operative planning and implant selection. One very helpful classification of bone loss associated with TKA is the Anderson Orthopaedic Research Institute (AORI) Bone Defect Classification System as it provides the means to compare the location and extent of femoral and tibial bone loss encountered during revision surgery. In general, the higher grade defects (Type IIb or III) on both the femoral and tibial sides are more likely to require stemmed components, and may require the use of either structural graft or large augments to restore support for currently available modular revision components. Custom prostheses were previously utilised for massive defects of this sort, but more recently have been supplanted by revision TKA component systems with or without special metal augments or structural allograft.

Options for bone defect management are: 1) Fill with cement; 2) Fill with cement supplemented by screws or K-wires; 3) Morselised bone grafting (for smaller, especially contained cavitary defects); 4) Small segment structural bone graft; 5) Impaction grafting; 6) Large prosthetic augments (cones); 7) Massive structural allograft-prosthetic composites (APC); 8) Custom implants. Maximizing support on intact host bone is a fundamental principle to successful reconstruction and frequently requires extending fixation to the adjacent diaphysis. Pre-operative planning is facilitated by good quality radiographs, supplemented on occasion by additional imaging such as CT. Fluoroscopically controlled x-ray views may assist in diagnosing the loose implant by better revealing the interface between the implant and bone and can facilitate accurate delineation of the extent of bone deficiency present. Part of the pre-operative plan is to ensure adequate range and variety of implant choices and bone graft resources for the planned reconstruction allowing for the potential for unexpected intra-operative findings such as occult fracture through deficient periprosthetic bone.

Reconstruction of bone deficiency following removal of the failed implant is largely dictated by the location and extent of bone loss and the quality of bone that remains. While massive bone loss may compromise ligamentous attachment to bone, in the majority of reconstructions the degree of implant constraint needed for proper balancing and restoration of stability is independent of the bone defect. Thus some knees with minimal bone deficiency may require increased constraint due to the status of the soft tissues while others involving very large bone defects especially of the cavitary sort may be well managed with minimal constraint.

There are many challenges facing the revision knee surgeon. Bony defects, ligamentous imbalance, and difficult gap balancing scenarios are common and require practical management strategies. Typically, am implant with the least amount of constraint necessary to provide a well-aligned, well-balanced arc of motion is preferred. Constraint in implants increases the stresses on both the bearing surfaces and the bony interfaces and may result in earlier mechanical failure of the implant. Despite this fact, there are situations where one cannot rely on a simple larger polyethylene post (such as found in CCK type devices) to balance gaps. The author prefers to choose hinge type devices in situations that demonstrate massive gap imbalance (typically huge flexion gaps), situations with deficient extensor mechanisms that can result in recurvatum stresses, or in situations of global ligamentous instability. Techniques of supporting the bony interfaces with stems and sleeves may improve the longevity of these constructs. Complications are common, including extensor mechanism problems. Multiple studies have demonstrated reasonable results of hinged implants for these challenging revision scenarios, and the hinge should remain in the armamentarium of the revision surgeon.

The moderator will lead a structured panel discussion that explores how to manage challenges commonly found in the multiply revised knee. Topics covered will include: (1) Exposure in the multiply operated knee (when to use quad snip, tibial tubercle osteotomy, other techniques); (2) Implant removal: Tips for removing stemmed implants; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (4) Level of constraint (when to use posterior stabilised, constrained condylar, and hinge) and management of instability in multiply operated knees; (3) Management of bone loss in multiply operated knees (metal cones/sleeves vs. structural allograft vs. particulate graft); (5) Preferred management of infection in the multiply operated knee; (6) The extensor mechanism: Preferred deficient patellar bone management; Preferred extensor mechanism deficiency management; (7) When is it time to convert to a salvage procedure (i.e. fusion, resection arthroplasty, amputation)?; (8) Post-operative management: wound management; knee range of motion.

Titanium (Ti) alloy is the material of choice for the porous bone ingrowth materials for non-cemented total Joint arthroplasty. Recent studies have shown the importance of controlling the macro, micro, and nano surface topographies on the bone apposition surfaces of these implants. Historically, much attention has been given to the designs of macro fixation features (millimeter scale), and the design of micro fixation porosity (micrometer scale). More recently, the importance of the nano-surface texture (nanometer scale) is being recognised as an integral component of the design. Nano-textures are being enhanced during implant processes to optimise the bond between implant and bone.

The ultra-hydrophilic nano-texture of an implant interacts with the corresponding nano-texture of the outer cell membranes to increase cell adhesion and differentiation. This speeds the osseointegration rate between Ti alloys, and the surrounding osteoblast tissues. Living cells sense and respond to surface texturing on the nanoscale which in turn direct stem cell and osteoblast differentiation. This has been recognised to improve the speed at which the implant interface bonds to bone with the end goal of ultimately allowing patients to weight bear on non-cemented arthroplasty implants sooner.

One surface modification treatment technique of particular promise is nano-texturing via. electrochemical anodization to form arrays of vertically aligned, laterally spaced titanium dioxide (TiO2) nanotubes on titanium implant surfaces in areas where enhanced implant-to-bone fixation is desired. Bio-mimicking TiO2 nanotube arrays are superimposed onto existing porous surface micro-structures to further enhance the already known bone ingrowth properties of these porous structures. These nanotube arrays show an accelerated osseointegration. Foundational work has demonstrated that the TiO2 nanotube surface architecture significantly accelerates osteoblast cell growth, improves bone-forming functionality, and even directs mesenchymal stem cell fate. Current generation nano-surface modification technologies show improved osseointegration response between implant materials and surrounding tissue and also provide surfaces that resist microbial adhesion.

Implant surfaces treated with and without TiO2 nanotubes were compared to grit blasted Ti controls in-vitro and in-vivo. The samples we evaluated after exposure to human mesenchymal stem cell (hMSC). Additionally, implants have been evaluated in multiple animal models with and without TiO2 nanotubes. The bones with implants were retrieved for mechanical testing and histology analysis. The average bond strength was significantly higher (150% to 600%, depending on the in-vivo animal model) for TiO2 nanotube implants compared to the non-treated Ti control implants. The histology confirms direct bonded growth of new bone onto the nanotubes with a significantly less trapped amorphous tissue at the implant-bone interface compared to the controls. Both in-vitro and in-vivo analysis indicates that TiO2 nano-texturing enhances the speed and proliferation of osseointegration. This surface treatment technique can be applied to non-porous or porous surfaces on TJA implants where improved bone fixation is desired.

The number of Americans over the age of 80 is increasing at a faster rate than that of the 65–80 population. The cohort age 85–94 years had the fastest rate of growth from 2000–2010. The number of Americans older than 95 years grew at approximately 26% during the same period. This rapid growth has been associated with an increasing incidence of osteoarthritis of the hip and knee in this population. This surge in the growth rate of the elderly population has coincided with an increasing demand for primary and revision total joint arthroplasty. Surgeons need to be prepared to perform safely and appropriately these procedures in this rapidly growing segment of the population. Surgeons need to be aware of the 1) clinical outcomes that can be expected when total joint procedures are performed in this group of patients; 2) the morbidity and mortality associated with the performance of these procedures; and 3) the relative cost effectiveness of these interventions.

Clinical outcomes of TJA in this population are generally good. Pain and satisfaction scores are similar to those of younger patients. Although pre-operative pain and functional impairment scores are higher pre-operatively in elderly patients, these improve significantly following TJA. However, functional outcome scores decline noticeably after 5 years, reflecting the impact of coexistent comorbidities. The continued need for assistive devices is greater in this age group than in younger total joint patients. The risk of falls, a particular issue of concern in this age group, is reduced after total hip and knee surgery.

The rate of complications, including mortality, following TJA in this age group is greater than in the 65–79-year-old group. The use of hospitalists to co-manage peri-operative care is particularly important in this age group. The increased rate of complications is associated with longer lengths of stay. However, the length of stay for this age group after primary total joint replacement is decreasing significantly; reflecting the widespread streamlining of peri-operative care that is being incentivised and implemented nationwide. The use of extended care facilities is also greater in this age group.

The performance of revision TJA in this age group is particularly challenging. The rates of revision in elderly patients are anticipated to rise significantly in coming years. Although revision TJA is associated with significant pain relief and patient satisfaction, it is accompanied by mortality and complication rates that are substantially greater than those in younger age groups.

Functional restoration of patella kinematics is an essential component of TKA, whether the patella is replaced or not. This goal is accomplished by a multifactorial approach: establish proper component position and alignment, especially rotation; avoid IR of the femoral and ER of the tibial components; maintain correct joint line position; achieve symmetrical soft tissue balance.

Most modern TKA designs have an anatomic trochlear groove shape to enable midline tracking. Patella implants are better designed as well with three equilateral lugs for fixation and either dome or anatomic shape. The apex of the patella component should be aligned with the apex of the patella raphe which is more medial than lateral. This method leaves an island of exposed lateral patella facet which is managed with the “lateral slat technique” to be described. It is essentially an intraosseous lateral release. The early mobilization of modern TKA patients demands watertight closure to prevent soft tissue attenuation and late tracking issues.

When confronted with a patient with a laterally dislocated patella, implementation of the “lateral slat technique” should be done at the approach to obtain midline tracking. Such patients require a median parapatellar (MPP) approach and may need distal-lateral vastus medialis advancement (Insall procedure).

Adherence to the principles iterated herein will produce a happy patient with good patello-femoral kinematics and function.

In general, “alignment” refers to the position of all components in three dimensions. This discussion is limited to “varus-valgus” (v-v) alignment, or angulation in the frontal plane. This is largely determined by rotational position of the tibial and femoral components about the “z” (antero-posterior) axis. The earliest paper to note the importance of alignment, described only “valgus” on short x-rays.

It is difficult to argue that knee alignment is irrelevant, as angulation increases, so does the lever arm at the knee. (Biomechanics) Alignment is relevant to the development of osteoarthritis, most likely as the result of load on the medial compartment with varus alignment. (Natural History of OA) The first knee arthroplasties were an attempt to resurface worn cartilage with biological tissue and then non-biological material. Alignment and biomechanics were not considered. (History)

Frontal plane alignment can be depicted as “anatomic” (the angle between the femoral and tibial canals) on short radiographs or “mechanical” on full-length radiographs. Mechanical alignment may be reported in degrees or distance. Degrees describes the angle between a line from center of femoral head to center of knee (MA of the femur) with the line from center of knee to center of ankle (MA of tibia.) Alternately if a line is drawn form the center of the femoral head to the center of the ankle, MA may be described as the distance from the center of the knee to this axis along the joint line. Sometimes this is depicted by sectors in the knee. “Mechanical alignment” is a method of describing the angulation of the knee, not strictly a surgical technique.

Long radiographs: Short radiographs, though perhaps cost effective in most clinical settings, are unreliable images for studies of alignment. Physiologists and astute surgeons have always considered the entire limb. When clinicians applied full-length radiographs to clinical practice, along with navigation technology, assumptions evolved about the most desirable alignment of an arthroplasty. Arbitrarily, a neutral mechanical axis, or a straight line from the centers of the hip, knee and ankle was promoted. This also means that a line from hip to ankle would pass through the center of the knee. Many surgeons have entertained the erroneous concept that a “neutral mechanical axis” represents “normal human alignment: it does not. Others contend that a neutral mechanical axis necessarily means that there will be equal load on medial and lateral compartments: it will not.

Received wisdom about the necessity of a neutral mechanical axis has been questioned and yet malalignment and pre-operative deformity both appear to contribute to failure.

Stability is clearly important, because it limits deviations in alignment, and a range of alignments are probably highly functional, just as the knee may be loaded in a variety of directions. Dynamic features of patient activity are undoubtedly important, as is pre-operative deformity.

Lavage and preparation of the cancellous bony surface can facilitate adequate fixation of components in cemented total knee arthroplasty (TKA). Commonly used techniques for bone preparation such as pulse lavage, apart from adding to the cost, may cause local loss of loose cancellous bone and may even drive contaminants deeper into the tissue when used during TKA. We describe a simple, inexpensive and effective tool of using a sterilised toothbrush for preparing bone surface during cemented TKA. This must be followed by adequate pressurization of cement at the right time to achieve close interdigitation of cement with trabecular bone.

Complications involving the knee extensor mechanism occur in 1% to 12% of patients following total knee arthroplasty (TKA), and have negative effects on patient outcomes. While multiple reconstruction options have been described, the results in patients with a prior TKA are inferior to those in patients without a TKA. However, optimistic results have been reported by Browne and Hanssen with the use of a synthetic mesh (knitted monofilament polypropylene)3. In this technique, a synthetic graft is created by folding a 10 × 14 inch sheet of mesh and securing it with nonabsorbable sutures. A burr is then used to create a trough in the anterior aspect of the tibia to accept the mesh graft. The graft is inserted into the trough and secured with cement. After the cement cures, a transfixion screw with a washer is placed. A portal is subsequently created in the lateral soft tissues to allow delivery of the graft from deep to superficial. The patella and quadriceps tendon are mobilised, and the graft is secured with sutures to the lateral retinaculum, vastus lateralis, and quadriceps tendon. The vastus medialis is then mobilised in a pants-over-vest manner over the mesh graft, and secured with sutures. Finally, the distal arthrotomy is closed tightly to completely cover the mesh graft with host tissue. In their series, Browne and Hanssen noted that 9 of 13 patients achieved an extensor lag of > 10 degrees with preserved knee flexion and significant improvements in the mean Knee Society scores for pain and function.

Removing well-fixed components can be difficult. It can be required in instances of infection, malalignment, instability and polyethylene wear. Success requires patience, skill and the use of correct instruments. Using too much force or haste will result is excessive bone loss and a more difficult reconstruction. One's goal should be to save bone and save time. The surgeon must be familiar with the implants to know if any special techniques will be required to deal with modularity of the tibial polyethylene, surface coatings and geometry of pegs and stems. The usual steps are to remove the tibial liner if modular, followed by removal of the femoral component, then tibial component. Thin osteotomes are used to loosen the cement prosthesis or bone prosthesis interfaces to be able to remove the implants and not lose bone in the process. Removal of cement mantles around long-stemmed femoral and tibial components can be facilitated by femoral cortical window osteotomies and tibial crest osteotomies.

Heterotopic ossification (HO) is a relatively common complication of total hip arthroplasty (THA), but is rather rare after total knee arthroplasty (TKA). In both cases, it is usually asymptomatic and is most commonly identified as an incidental finding on post-operative radiographs. However, in severe cases it can result in decreased range of motion and pain. There are several risk factors that have been shown to be associated with development of HO. These include male gender, ceramic-on-ceramic bearings, prior stroke, and hypertrophic osteoarthritis.

Heterotopic ossification can be treated with physical therapy during the maturation phase (12 to 24 weeks), but surgical intervention is required if the stiffness persists. All heterotopic bone should be excised with careful attention to neurovascular structures. Patients should begin prophylaxis following HO excision and prior to any subsequent surgeries. Heterotopic ossification prophylaxis consists of NSAIDs, radiotherapy, or a combination of both modalities. These therapies are not without complications, therefore, routine administration of prophylaxis for all patients is not indicated. Several new pathways of inhibiting extra-skeletal bone formation in HO are under investigation (retinoid acid receptor agonists, apyrase, and LDN-193189). Future studies should focus on identification of patients at risk for HO as well as better therapeutic options with less side effects.

Hip fusion is an uncommon procedure. Hip fusion takedown, therefore, is equally an uncommon procedure. What is of considerable interest is that the results, which I achieved in 20 cases in a paper published in 1987 are considerably superior to the results, which I am achieving today. This suggests that no simple case is now fused. It also equally suggests that there is little sense in looking at literature more than 10 or 15 years old on fusion takedowns as the two conditions are likely completely different.

Most patients do not like a hip fusion. There are long-term problems with low back pain, ipsilateral global instability and contralateral patellofemoral osteoarthritis. A stiff hip produces a poor quality of life, especially in a tall person. The main problem in doing a hip fusion takedown is the condition of the abductors muscles. If fused before growth was complete, there may be pelvic hypoplasia. If the pelvis is small, the glutei will also be small. Sometimes, the glutei may have undergone fatty degeneration. This can be assessed by means of an MRI. If the abductors were damaged during fusion, a limp may persist. Other problems are that leg lengthening is difficult to achieve any longstanding hip fusion. Lengthening of 1–2 cm is usually about all that can safely be achieved. If the hip was fused in childhood, there is likely to be femoral hypoplasia. There is also likely absence of proximal cancellous bone and the proximal femur is a thin brittle cortical tube. The greater trochanter should not be detached as it is difficult to obtain union under such circumstances. The approach, which I prefer for a fusion takedown is an anterior Smith Peterson. The glutei are slid off the pelvis sidewall and then the upper part of the fusion can be exposed, blunt Hohmans can then be passed around the femoral neck prior to transection. Obviously, if any AO cobra plate has been used for a fusion, a trochanteric osteotomy may be required to preserve any glutei left. Old hardware can be removed either concurrently or as an interval procedure. In 1986, I published the results of 20 cases with a five to 40-year fusion time (mean 19). I used a variety of implants. Flexion was achieved to 90 degrees at 12 months in about 88% of people. Seventy-five percent ceased to limp by year one, although the elderly limp when tired. One patient was dissatisfied with the procedure. One was revised for pain.

I have reviewed the cases done in the last 20 years. These were 28 cases, two bilateral. Seven were spontaneous fusions. Twenty-one were formal hip fusions. One was an AO fusion with a cobra plate. There were various intra-operative complications including two calcar cracks, which were wired, three femoral shaft fractures, which necessitated the use of long stems. There was one drop foot, which recovered. At review, a limp was absent in 20%, mild in 12% and severe, i.e. Trendelenburg positive in 68%. Harris hip scores were excellent in 28%, good in 32%, fair in 16% and poor in 24%. Four patients only, however, continued to use canes. The eventual range of movement was good. In 80%, more than 90 degrees of flexion was obtained, but it took up to two years to obtain maximum flexion. In 12%, the range of motion was poor at being 50 degrees to 85 degrees. The range of motion was poor, i.e. less than 45 degrees in one bilateral case of athrogryposis. This was a stiff arthrogrypotic. Further surgery is required in several cases. An ipsilateral total knee replacement and one a supracondylar femoral osteotomy. One cup loosened and was revised at seven years and one liner was exchanged at ten years.

Wear and osteolysis are the major problems limiting the longevity of total hip arthroplasty. There is general agreement that if left untreated osteolysis will eventually lead to loosening of the acetabular component. In many cases polyethylene liner exchange may be preferable to revision of a well-fixed acetabular component. If there is osteolysis present the question is when should the polyethylene liner exchange be performed? The answer to that question has not been definitively defined at the present time.

There are few studies available that evaluate the timing of surgical intervention when acetabular osteolysis is present. Indications for surgical intervention include prevention of complete wear of the head through the polyethylene liner (liner thickness < 1.5 mm) and when the osteolysis involves 50% or more of the shell circumference on AP or lateral x-rays. Of course persistent pain with wear or osteolysis is another indication for surgery. Contraindications to cup retention and liner exchange include: 1) Malpositioned component; 2) Non-modular component; 3) Unable to obtain hip stability; 4) Thin polyethylene liner (relative); 5) Severe damage to acetabular shell; and 6) Poor track record of the acetabular component.

If one decides to retain the component the following steps are generally involved in operative management. Remove the liner and assess component stability. Assess the locking mechanism for the polyethylene. If the locking mechanism is not intact one can consider cementing the liner in place. In general, it is recommended to debride and bone graft the osteolytic lesion. The author prefers to use an access hole at the periphery of the component or at times a trapdoor can be made in the ilium. It is essential not to de-stabilise the acetabular component. At the present time there is no optimal graft material to use. Potential graft options include demineralised bone matrix or cancellous bone chips. Since dislocation is the number one complication after polyethylene liner exchange, it is a good idea to use a larger femoral head whenever possible. In some cases it is also worthwhile to consider bracing the patient after the surgery.

It is essential to be ready to perform a complete revision. Therefore, when planning to perform a polyethylene liner exchange one needs to have the appropriate components available to completely revise the acetabular component.

The well-fixed cemented femoral stem and surrounding cement can be challenging to remove. Success requires evaluation of the quality of the cement mantle (interface lucency), position of the stem, extent of cement below the tip of the stem and skill with the specialised instruments and techniques needed to remove the stem and cement without perforating the femur. Smooth surfaced stems can usually be easily removed from the surrounding cement mantle with a variety of stem extractors that attach to the trunnion or an extraction hole on the implant. Roughened stems can be freed from the surrounding cement mantle with osteotomes or a narrow high speed burr and then extracted with the above instruments. Following this, the well-fixed cement mantle needs to be removed.

Adequate exposure and visualization of the cement column is essential to remove the well-fixed cement without damage to the bone in the femur. This is important since fixation of a revision femoral component typically requires at least 4 cm of contact with supportive cortical bone, which can be difficult to obtain if the femur is perforated or if the isthmus damaged. Proximally, cement in the metaphyseal region can be thinned with a high speed burr, then split radially and removed piecemeal. It is essential to remember that both osteotomes and high speed burrs will cut thru bone easier than cement and use of these instruments poses a substantial risk of unintended bone removal and perforation of the femur if done improperly. These instruments should, as a result, be used under direct vision.

Removal of more distal cement in the femur typically requires use of an extended femoral osteotomy (ETO) to allow for adequate access to the well-fixed cement in the bowed femoral canal. An ETO also facilitates more efficient removal of cement in the proximal femur. The ETO should be carefully planned so that it is distal enough to allow for access to the end of the cement column and still allow for stable fixation of a new implant. Too short of an ETO increases the risk of femoral perforation since the straight cement removal instruments cannot negotiate the bowed femoral canal to access the end of the cement column without risk of perforation. An ETO that is too distal makes cement removal easier, but may not allow for sufficient fixation of a new revision femoral stem. Cement below the level of the ETO cannot be directly visualised and specialised instruments are necessary to safely remove this distal cement. Radiofrequency cement removal devices use high frequency (ultrasonic) radio waves to melt the cement within the canal. Although cement removal with these devices is time consuming and tedious, they do substantially reduce the chances of femoral perforation. These devices can, however, generate considerable heat locally and can result in thermal injury to the bone and surrounding tissues. Once the distal end of the cement mantle is penetrated, backbiting or hooked curettes can be use to remove any remaining cement from within the canal. It is important that all cement be removed from the femur since reamers used for preparation of the distal canal will be deflected by any retained cement, which could result in eccentric reaming and inadvertent perforation of the femur and make fixation of a new implant very challenging. An intra-operative x-ray can be very helpful to insure that all cement has been removed before reaming is initiated.

One should always plan for a possible femoral perforation and have cortical strut grafts and a stem available that will safely bypass the end of the cement column and the previous cement restrictor.

The burden of periprosthetic joint infection (PJI) continues to rise and the management of this dreaded complication continues to pose challenges to the orthopaedic community. Dr Buchholz from the Endo Klinik has been credited for reporting the initial observation that addition of antibiotic to polymethylmethacrylate (PMMA) cement lead to better ability to deliver higher concentrations of antibiotic to the joint milieu and avoid administration of high doses of systemic antibiotics with potential for systemic toxicity.

Addition of antibiotics to PMMA cement has continued to be an important aspect of managing patients with chronic PJI. The rationale for this practice is that higher doses of local antibiotics can be reached without placing the patients at risk of systemic toxicity. Whether a one-stage or a two-stage exchange arthroplasty is being performed, antibiotics that can withstand the exothermic reaction of PMMA and are able to elude from cement are added at various doses to the PMMA for later delivery. Although this practice continues to be almost universal, there are a few unknowns. First of all, a recent study raised a valid question regarding this practice. Though intuitively logical, addition of antibiotics to PMMA spacers has not been scrutinised by any level 1 study and hence one is not able to prove that this practice does indeed accomplish its intended objectives of reducing recurrence or persistence of infection. Orthopaedic community is advised to seek avenues to generate this much-needed evidence. The other main unknown is how much, and in some instances which antibiotic, needs to be added to the PMMA cement. Some authorities have declared that antibiotics can be added at high doses, with an average total dose of 10.5 g of vancomycin (range, 3–16 g) and 12.5 g of gentamicin (range, 3.6–19.2 g) in one study, to PMMA cement without the fear of systemic toxicity.

In recent years, renal toxicity and other systemic adverse effects have been attributed to addition of high doses of antibiotics to cement. I have personally witnessed such adverse reactions in a few patients. Although initially I was inclined to “blame” the concurrent administration of systemic antibiotics for the renal toxicity that patients developed following insertion of spacer, selective nephrotoxicity (i.e. reaction to aminoglycoside that was only present in the spacer and not systemically administered) and resolution of the nephrotoxicity upon removal of antibiotic spacer, convinced me that our nephrology colleagues have a valid reason to be concerned about addition of high doses of antibiotics to PMMA spacers.

What has become clear is that high viscosity cements containing MA-MMA copolymers have been shown to have better antibiotic elution profiles than other PMMA formulations. So when fashioning a spacer in the operating room the surgeon needs to be aware of the differences in elution profile of antibiotics from PMMA and individualise the dose of antibiotics being added to spacer based on the type and viscosity of cement being used and the renal status of the patient. Thus, systemic toxicity caused by addition of antibiotics to cement spacer appears to be a real issue in some circumstances and this needs to be born in mind when managing patients with PJI.

There are numerous other issues related to the use of antibiotic cement spacers. In the hip, the lack of adequate offset and limited portfolio of products result in laxity in the soft tissue and subsequent dislocation of the hip. In addition, the dose and type of antibiotic in the premanufactured spacers, at least in the US, are inadequate to lead to a substantial delivery of antibiotics in the local tissues. Because of these issues, I prefer to fabricate “customised” spacers for each patient that I operate on.

The indications for cementless acetabular fixation have been broadened because our data supports the use of trabecular metal cups even when there's limited bleeding host bone contact. Trabecular metal augments have allowed us to use cementless cups when there is segmental loss of bone.

Surgical Technique: The acetabular bed is prepared. If there is less medial bone stock than 2 mm, then morselised allograft is impacted by reverse reaming. When reaming is complete and less than 50% bleeding host bone is available for cup stabilization, then a trabecular metal cup is indicated.

Trabecular augments are used if the trabecular cup trial is not stable, or if it is uncovered by 40% or more. The conventional augments come in different sizes to accommodate the diameter of the cup and the size of the defect. Larger defects are addressed with anterior and posterior column augments, and superior defects with figure of seven augments. Augments are fixed with at least two screws. The interface between the cup and the augments should be stable, but some surgeons place a very thin layer of cement between the augment and cup so micromotion does not occur while ingrowth is occurring.

We have used trabecular metal augments in 46 acetabular revisions in conjunction with a trabecular metal cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There has been 4 cup loosenings with 3 re-revisions. Our most up to date data is 101 cases with an average follow-up of 3 years. There has been one infection that underwent a two stage revision. There are 4 loose cups – 3 revised.