We live in an era where younger, fitter, more active patients are presenting with the symptoms and signs of degenerative joint disease and require total knee and total hip arthroplasty at a young age. At the same time, this population of patients is living longer and longer and is likely to create new and more complex failure modes for their implants. The ideal solution is a biological one, whereby we can either prevent joint degradation or catch it in its early stages and avoid further deterioration. There may also be advances along the way in terms of partial arthroplasty and focal resurfacing that will help us prevent the need for total joint arthroplasty.

There are several tensions that need to be considered. Should we resurface / replace early, particularly now that we have access to navigation and robotics and can effectively customise the implants to the patient's anatomy and their gait pattern? This would allow good function at a young age. Or should we wait as long as possible and risk losing some function for the sake of preserving the first arthroplasty for the lifetime of the patient?

There are some key issues that we still do not fully understand. The lack of true follow-up data beyond 20 or 30 years is worrying. The data available tends to be from expert centers, and always has a dramatic loss to follow-up rate. We worry about bearing surfaces and how those materials will behave over time but we really do not know the effect of chronic metal exposure over several decades, nor do we really understand what happens to bone as it becomes more and more osteopenic and fragile around implants. We have largely recorded but ignored stress shielding, whereas this may become a very significant issue as our patients get older, more fragile, more sarcopaenic and more neurologically challenged. All the fixation debates that we have grappled with, may yet come back to the fore. Can ingrowth lead to failure problems later on? Will more flexible surfaces and materials be required to fit in with the elasticity of bone?

We have failed dramatically at translating the in vitro to the in vivo model. It seems that the in vitro model tells us when failure is going to occur but success in vitro does not predict success in vivo. We, therefore, cannot assume that long-term wear data from simulators will necessarily translate to the extreme situations in vivo where the loading is not always idealised, and can create adverse conditions.

We must, therefore, consider further how to improve and enhance our interventions. There is no doubt that the avoidance of arthroplasty needs to be at the heart of our thinking but, ultimately, if arthroplasty is to be performed, it needs to be performed expertly and in such a way as to minimise later failure. It also, clearly, needs to be cost-effective. The next stage will no doubt involve close cooperation between surgeons, engineers and industry partners to identify individualised surgical targets, select an appropriate prosthesis to minimise soft-tissue strain and develop a reproducible method of achieving accurate implantation. An ideal outcome can only be achieved by an appropriately trained surgeon selecting the optimal prosthesis to implant in the correct position in the well-selected patient.

In the longer term, our choice of implants and the way that they are inserted and fixed must take into account the evolving physiology of our patients, the nature of our devices and how to limit harm from them, and the long-term impact of the materials used which we sometimes still do not understand.

There are pros and cons of all bearing surface options for our young patients. I pick the bearing surface for my young patients trying to maximise durability and minimise risks.

For the ultra-young, ≤30 years of age patient, I use ceramic-on-ceramic. The pros of this are the best wear couple available and a favorable track record (with well designed implants). The risks can be minimised: fracture risk now decreased, runaway wear minimised with good surgical technique, impingement problems minimised with good technique and well designed implants, as well as squeaking is minimised with good design (majority of reported squeakers are of one designed socket).

I don't use metal-on-metal because I am not willing to subject young patients to potentially 50+ years of high metal ion exposure.

I also don't use HCLPE. This would be okay from a biologic standpoint but I still have concerns about long-term wear durability. So the marked superior wear characteristics of ceramic-ceramic win in my view.

For my middle age patients, 30–60, I use HCLPE I don't use ceramic-ceramic because at some point between 30 and 60 years of age the improved wear properties are outweighed by their potential risks (fracture, impingement, squeak). HCLPE at short F/U (<15 years) appears to be durable, reliable with good wear properties so it is a reasonable choice. Using a ceramic head versus CoCr provides minimal improvement in wear properties in the lab but no marked advantage in vivo. Concerns persist about cobalt-chrome corrosion so I use ceramic heads in the majority of patients

For patients under age 60 the wear characteristics of HCLPE appear very favorable and one doesn't assume other risks seen in with metal-on-metal and ceramic-ceramic. Little justification for a hard-on-hard bearing in this patient subgroup. I use ceramic heads in majority to avoid corrosion issues.

Ceramic-on-polyethylene (COP) bearings have traditionally been reserved for younger patients that were at high risk of polyethylene wear requiring revision. With the 1999 advent of highly crosslinked polyethylene (XLP), wear with XLP has not been a cause for revision. Simulator studies have not shown a difference in wear comparing COP to metal-on-polyethylene (MOP). Therefore, and considering the additional cost of COP, we have until recently not needed COP. However, a 2012 report of 10 cases that developed an adverse reaction to metal debris generated by head neck corrosion has resulted in COP becoming the most common bearing surface as reported by the American Joint Replacement Registry. This reactionary change has occurred despite the fact that we do not understand the cause, do not know the frequency, if it is more common in some implants than others, and we do not know the additional cost or markup of ceramic heads. One study reported a 3.2% revision prevalence caused by mechanically assisted crevice corrosion (MACC) at the head neck junction of a single manufacturer's implant. Other studies have estimated the frequency to be less than 5%. COST IS THE CONCERN in a value based health care environment. Models for and against the wholesale use of COP have been proposed and are based on variables that are unknown, including estimated frequency of the problem and the incremental cost of a ceramic head. I use COP in younger patients that I believe will use their hip for more than 15 years. This is based on my personal experience. I have prospectively followed a series of MOP patients for 5 years and not seen cobalt elevations. I have placed new metal femoral heads on corroded femoral tapers without subsequent failure. I have evaluated the taper junctions of postmortem retrievals and found them virtually free of corrosion. A query of our institutional database for MOP primary hips identified 3012 cases between 2006–2017. Eighty revisions (2.7%) were identified. Two of the 80 were for MACC representing 2.5% of revisions done on our own patients and 0.07% of our MOP cases. Further, evaluating our most recent all cause 350 revisions (7/2015-10/2017) there were 3 revisions for MACC (0.9%). Each one of us needs to EVALUATE OUR OWN PRACTICE AND MAKE AN EDUCATED, VALUE BASED DECISION whether or not to use COP in all patients.

Ceramic-on-ceramic bearings provide a solution to the osteolysis seen with traditional metal-on-polyethylene bearings. Sporadic reports of ceramic breakage and squeaking concern some surgeons and this bearing combination can show in vivo signs of edge loading wear which was not predicted from in vitro studies. Taper damage or debris in the taper between the ceramic and metal may lead to breakage of either a ceramic head or insert. Fastidious surgical technique may help to minimise the risk of ceramic breakage. Squeaking is usually a benign complication, most frequently occurring when the hip is fully flexed. Rarely, it can occur with each step of walking when it can be sufficiently troublesome to require revision surgery. The etiology of squeaking is multifactorial in origin. Taller, heavier and younger patients with higher activity levels are more prone to hips that squeak. Cup version and inclination are also relevant factors.

Osteolysis following metal-on-UHMW polyethylene Total Hip Arthroplasty (THA) is well reported. Earlier generation ceramic-on-ceramic bearings did produce some osteolysis, but in flawed implants. As third and now fourth generation ceramic THAs come into mid- and long-term service, the orthopaedic community has begun to see reports of high survival rates and very low incidence of osteolysis in these bearings. The technique used by radiologists for identifying the nature of lesions on Computed Tomography (CT) scan is the Hounsfield score which will identify the density of the tissue within the lucent area. Commonly the radiologist will have no access to previous imaging, especially pre-operative imaging if a long time has elapsed. With such a low incidence of osteolysis in this patient group, what, then, should a surgeon do on receiving a CT report on a ceramic-on-ceramic THA, which states there is osteolysis? This retrospective review aims to determine the accuracy of CT in identifying true osteolysis in a cohort of long-term third generation ceramic-on-ceramic uncemented hip arthroplasties in our department.

Pelvic CT scans were performed on the first 27 patients from a cohort of 301 patients undergoing 15-year review with third generation alumina-alumina cementless THAs. The average follow-up was 15 years (15–17). The CT scans were reviewed against pre-operative and post-operative radiographs and reviewed by a second musculoskeletal specialist radiologist.

Eleven of the CT scans were reported to show acetabular osteolysis, two reported osteolysis or a possible pre-existing cyst and one reported a definitive pre-existing cyst. After review of previous imaging including pre-operative radiographs, eleven of the thirteen patients initially reported to have osteolysis were found to have pre-existing cysts or geodes in the same size and position as the reported osteolysis, and a further patient had spot-welds with stress-shielding. One patient with evidence of true osteolysis awaits aspiration or biopsy to determine if he has evidence of ceramic wear or metallosis.

Reports of osteolysis on CT should be interpreted with care in modern ceramic-on-ceramic THA to prevent unnecessary revision. Further imaging and investigations may be necessary to exclude other conditions such as geodes, or stress shielding which are frequently confused with osteolysis on CT scans.

At the present time, there is no bearing in total hip arthroplasty that a surgeon can present to a younger and/or more active patient as being the bearing that will necessarily last them a lifetime. This is the driver to offering alternative bearings (crosslinked polyethylene with either a CoCr or ceramic head, resurfacings, and ceramic-on-ceramic) to patients. Each of these bearings has pros and cons, and none has emerged as the clear victor in the ongoing debate.

Ceramic-on-Ceramic (CoC) bearings have been available for decades. Earlier generation CoC bearings did encounter problems with rare fractures, however, with a greater understanding and improvement in the material, the fracture incidence has been significantly reduced. However, what has emerged in the past few years is an increasing reporting of significant squeaking. The incidence of squeaking, reported in the literature in various series, has varied from less than 1% to over 20%, depending on the definition used.

The primary reasons that Ceramic-on-Ceramic is not truly the articulation of choice for younger patients are:

1)

There is absolutely no evidence that this bearing has a lower revision rate. Data from the Australian joint registry actually shows that at 15 years it has a significantly increased rate of revision (7.2%) compared with using a highly crosslinked liner with either a ceramic (5.1%) or a CoCr (6.3%) head.

While Ceramic-on-Ceramic can be considered a viable alternative bearing in total hip arthroplasty, it can be in no way considered the articulation of longevity for the younger patient.

Periprosthetic joint infection (PJI) is a devastating complication of total hip arthroplasty (THA). According to registry-based studies, some bearing couples are associated with an increased risk of PJI. The recent International Consensus on Periprosthetic Joint Infection stated that metal-on-metal (MOM) bearing surface appeared to be associated with a higher incidence of PJI. Based on emerging reports, the incidence of PJI appears to be different among different bearing surfaces. We conducted a multi-institutional study attempting to study this exact issue. The purpose of the study was to determine whether there was any difference in the incidence of PJI in two commonly used bearing couples (metal- on-polyethylene versus ceramic-on-polyethylene).

Based on a retrospective multi-institutional query all patients who received primary THA with MOP or COP bearing surfaces performed during 2005–2009 in two high-volume arthroplasty centers were identified. Demographic factors, comorbidities, length of hospital stay, complications and other relevant information were extracted. PJI was defined based on the MSIS (International Consensus) criteria. Multivariate analysis was performed to determine whether bearing coupling was independently correlated with PJI.

In our data, 25/2,921 (0.9%) patients with MOP and 11/2,643 (0.4%) patients with COP developed PJI. This difference was statistically significant (p=0.01). After the multivariate analysis, controlling for potential confounders (age, body mass index and length of hospital stay, Charlson comorbidity index), MOP bearing surface was found to be an independent factor correlating with higher incidence of PJI (odds ratio: 2.6, 95% confidence interval: 1.02–6.54, p=0.04).

The finding of this study, and others from centers in Europe, suggest that the bearing surface may have an influence on the incidence of PJI. Although, we had originally thought that ceramic bearing surfaces may be used in younger and healthier patients, the multivariate analyses that controlled for all these variables confirms that use of metal femoral head is an independent risk factor for development of PJI. The finding of this study is compelling and begs for future basic science mechanistic investigations.

There is limited evidence in the literature suggesting that ceramic-on-ceramic (CoC) THA is associated with lower risk of revision for prosthetic joint infection (PJI) than other bearing combinations especially metal-on-poly (MoP) and metal-on-metal (MoM). Pitto and Sedel reported hazard ratios of 1.3 – 2.1 for other bearing surfaces versus CoC. Of interest, the PJI rate was not significantly lower in the first 6 months, when most infections occur, but only became significant in the long term. While factors such as patient age, fixation, mode, OR type, use of body exhaust suits, and surgeon volume were considered in the multivariate analysis, BMI, medical comorbidities, and ASA class were not. This is a major weakness that casts doubt on the conclusion, since those three factors are MAJOR risk factors for PJI AND all three factors are more likely to be unevenly distributed, and much more likely present in groups other than CoC. The data was also limited by the fact that it was drawn from a retrospective review of National Registry data, The New Zealand Joint Registry. While similar findings have recently been reported from the Australian Joint Registry, the danger in attributing differences in outcomes to implants alone is possibly the single greatest danger in interpreting registry results. While device design can impact implant survival, other factors such as surgical technique, surgeon, hospital, and especially patient factors have a far greater likelihood of explaining differences in observed results. A recent report from the same New Zealand joint registry reported that obesity, ASA class, surgical approach, and trainee operations all were associated with higher PJI and all would be more likely in non-CoC THAs. Accuracy of diagnosis is also a major concern. Revision for trunnionosis is more common in non-CoC THA and is frequently misdiagnosed as PJI.

Numerous non-registry studies and reviews have compared PJI in CoC vs. other bearings and none have concluded than the incidence of PJI differed significantly.

The entirety of the patient experience after contemporary total knee and total hip replacements in 2017 is markedly different from that encountered by patients just a decade ago. Ten years ago most patients were treated in a traditional sick-patient model of care and because they were assumed to require substantial hospital intervention, many cumbersome and costly interventions (e.g. indwelling urinary catheters, patient-controlled-analgesic pumps, autologous blood transfusion, continuous passive motion machines) were a routine part of the early post-operative experience. Today the paradigm has shifted to a well-patient model with a working assumption that once a patient has been medically optimised for surgery then the intervention itself, hip or knee replacement, will not typically create a sick-patient. Instead it is expected that most patients can be treated safely and more effectively with less intensive hospital intervention. While as orthopaedic surgeons we are enamored with the latest surgical techniques or interesting technologies most busy surgeons recognise that advances in peri-operative pain management, blood management, and early-mobilization therapy protocols account for the greatest share of improvements in patient experience over the past decade.

One can think pragmatically to get ahead and stay ahead of 3 predictable physiologic disturbances that adversely impact rapid recovery after knee and hip replacement: fluid/blood loss; pain; and nausea. The modern orthopaedic surgeon and his/her care team needs a simple strategy to pro-actively, not reflexively, manage each of those 3 predictable impediments to early recovery. Those surgical teams that routinely get ahead and stay ahead in each of those areas will routinely witness faster recovery, lower costs and greater patient satisfaction and that is clearly a win for patient and surgeon alike.

Effective pain management improves patient satisfaction, decreases hospital stay, and facilitates discharge to home. Today's emphasis is on a multi-modal strategy that minimises the use of opioids. Most protocols use pre-operative medications including an NSAID, acetaminophen, an oral opioid and some include gabapentin. Regional anesthesia is typically preferred over general. Both peripheral nerve blocks and periarticular local anesthetic cocktail injections have proved as effective adjuncts in decreasing early post-operative pain. Post-operative oral medications delivered on a schedule, not just as needed, often include acetaminophen, an NSAID and some include gabapentin. Oral and parenteral opioids are reserved for breakthrough pain.

Contemporary crosslinked polymers didn't just happen. The material was, has, and continues to be studied more than any other bearing surface material used in the total hip and total knee replacement construct. Historical failures and successes provided the information needed to make it the success that it is today as we approach the end of the second decade of extensive use.

Recognition that wear particles, not cement, was the major cause of osteolysis was important. Next, understanding that oxidation from free radical formation was deleterious to wear resistant polyethylene was understood and finally, that crosslinking was responsible for magnitude increases in wear resistance.

Although manufacturers have developed multiple processes to develop their crosslinked polymers (gamma and e beam radiation, melting and annealing, and most recently the addition of antioxidants) there are excellent 10-year results demonstrating head penetration rates (indicative of wear and creep) in the 0.02 to 0.04 mm/year range for many materials with minimal if any detection of osteolysis on radiographs and close to 0% revised for wear at 10+ years.

Are there any cautions? Recently, at 10- to 15-year follow up, some clinically insignificant osteolysis has been noted in one study and in that same study, 36 mm heads had twice the volumetric wear as 32 mm heads, but it was still a relatively low volume compared to the previous generation polyethylenes. We need further follow up, but at two decades of use, crosslinked polymers have dramatically reduced the osteolysis problem.

In the 1960's Sir John Charnley introduced to clinical practice his low friction arthroplasty with a highly polished cemented femoral stem. The satisfactory long term results of this and other cemented stems support the use of polymethylmethacrylate (PMMA) for fixation. The constituents of PMMA remain virtually unchanged since the 1960s. However, in the last three decades, advances in the understanding of cement fixation, mixing techniques, application, pressurization, stem materials and design provided further improvements to the clinical results.

The beneficial changes in cementing technique include femoral preparation to diminish interface bleeding, pulsatile lavage, reduced cement porosity by vacuum mixing, the use of a cement restrictor, pre-heating of the stem and polymer, retrograde canal filling and pressurization with a cement gun, stem centralization and stem geometries that increase the intramedullary pressure and penetration of PMMA into the cancellous structure of bone. Some other changes in cementing technique proved to be detrimental and were abandoned, such as the use of Boneloc cement that polymerised at a low temperature, and roughening and pre-coating of the stem surface.

In the last two decades there has been a tendency towards an increased use of cementless femoral fixation for primary hip arthroplasty. The shift in the type of fixation followed the consistent, durable fixation obtained with uncemented acetabular cups, ease of implantation and the poor results of cemented femoral fixation of rough and pre-coated stems.

Unlike cementless femoral fixation, modern cemented femoral fixation has numerous advantages: it is versatile, durable and can be used regardless of the diagnosis, proximal femoral geometry, natural neck version, and bone quality. It can be used in combination with antibiotics in patients with a history or predisposition for infection. Intra-operative femoral fractures are rare. However, the risk may be increased in collarless polished tapered stems. Post-operative thigh pain is extremely rare. Survivorship has not been surpassed by uncemented femoral fixation and it continues to be my preferred form of fixation. However, heavy, young, male patients may exhibit a slightly higher aseptic loosening rate.

The use of short femoral components in primary total hip arthroplasty (THA) represents an attractive option. Advocates tout bone preservation and ease of use in less invasive surgical approaches. In 2006 we adopted the concept and have had experience with over 5,700 short, tapered, titanium, porous plasma-sprayed stems in patients undergoing primary THA. The plasma-sprayed portion of this stem is similar to the longer, standard length TaperLoc stem, with shortening resulting from a 3 cm reduction in length of the distal portion of the implant. However, the proximal aspect maintains the same flat, tapered wedge proximal geometry as the standard stem. During insertion in some femurs it was noted that distal canal fill occurred preferentially to proximal canal fill. This required distal broaching in order to accommodate a larger stem. In an effort to avoid this clinical situation and to improve the gradual off-loading that is the goal of a tapered geometry, the design was modified in 2011 to reduce the profile of the component. Other modifications include a lower caput-collum-diaphyseal (CCD) angle to enhance horizontal offset restoration without increasing leg length, width sizing from 5–18 mm in 1 mm increments, and polished neck flats to increase range of motion. Undoubtedly, porous plasma sprayed tapered titanium stems are successful in primary THA. Short stems can better accommodate proximal-distal femoral mismatch, particularly in hips with a large metaphysis and a narrow diaphysis, hips with an excessively bowed femur, and hips with severe deformity such as that encountered with developmental dysplasia and post-traumatic arthritis. Short stems violate less femoral bone stock, allowing for more favorable conditions should revision surgery become necessary. The concept of a short stem is appealing to patients, who perceive it as less invasive. In addition, short stems facilitate shorter incision surgery and operative approaches such as the muscle-sparing anterior supine intermuscular. Increased canal fill has been associated with distal cortical hypertrophy. Reducing the distal portion of the stem has reduced the incidence of distal canal fill, and allows for placement of a slightly larger implant.

Key Points:

Historically, 22.25, 26, 28, or 32 mm metal femoral heads were used in primary total hip arthroplasty, but innovations in materials now permit head sizes 36 mm or larger.

The selection of an acetabular component for primary hip arthroplasty has narrowed significantly over the past 10 years. Although monoblock components demonstrated excellent long-term success the difficulty with insertion and failure to fully appreciate full coaptation of contact with the acetabular floor has led to almost complete elimination of its utilization. Modular acetabular components usually with titanium shells and highly crosslinked polyethylene are by far the most utilised today. This is particularly true with mid-term results demonstrating excellent wear rates and extremely low failure rates and the concern of possible mechanical failure of highly crosslinked polyethylene not being a clinical problem. Ceramic liners are also used but problems with squeaking articulations and liner chipping have made highly crosslinked polyethylene the preferred liner material. Metal-on-metal except in surface replacement arthroplasty is rarely used in primary hip arthroplasty.

With instability in total hip replacement still being a significant and the leading cause of revision hip replacement the dual mobility articulation has emerged as an increasingly used acetabular component. This is composed of either a monoblock cobalt chrome socket articulating with a large polyethylene liner into which the femoral head is constrained. The polyethylene liner becomes essentially a larger femoral head articulation and hip stability is significantly improved. A modular dual mobility can also be utilised with a titanium shell and a cobalt chrome liner inserted into the shell and then a dual mobility articulation. In a recent series of 182 dual mobility cups, all monoblock ADM, in high risk patients undergoing primary total hip replacement there was 1 interprosthetic dislocation which occurred during reduction of a dislocation. Average follow up was 4.4 years with a range of 2–6.6 years.

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: Indications for cemented and uncemented implants. Is there still a role for hip resurfacing?; 8.) Femoral material and size: Preferred head sizes and materials in different situations. 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?; 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.

Acetabular fractures can occur due to either low or high-energy trauma, and treatment can consist of non-operative management, open reduction and internal fixation (ORIF), or total hip arthroplasty in either the acute or chronic setting. These decisions are often based on the age of the patient, the fracture pattern, and the existence of pre-fracture hip debility. In the acute setting, younger patients should undergo ORIF with anatomic reduction of the fracture, while total hip arthroplasty (THA) may be considered for elderly patients with pre-existing hip arthritis. Several factors can expedite the onset of post-traumatic arthritis in the former, including difficult fracture patterns, fractures that are intra-articular in nature, or fractures involving the femoral head. A meta-analysis of seven studies with 685 patients from all age groups reported the incidence of post-traumatic arthritis following satisfactory reduction of acetabular fractures (≤2 mm) to be 13.2%. Unsatisfactory reductions (>2 mm) increased the incidence of post-traumatic arthritis to 43.5%. Factors affecting the reduction quality include fracture type, fracture characteristics (e.g. comminution, impaction), time to surgery, and experience level of the operative team. In such settings, salvage THAs can be considered. However, complications including aseptic loosening, instability, and periprosthetic infection are more common than for other indications leading to THA. In our experience, at 20 years, we found that THAs performed after operatively treated acetabular fractures still had excellent hip function, and a 70% survivorship free of aseptic acetabular revision. A more recent study of 30 primary THAs performed with highly porous acetabular components indicated excellent results as well. As such, if early complications can be avoided, patients can expect substantial pain relief and excellent durability.

Pathologic fractures about the hip are an uncommon, but increasingly prevalent, clinical scenario encountered by orthopaedic surgeons. These fractures about the hip usually necessitate operative management. Life expectancy must be taken into account in management, but if survivorship is greater than 1 month, operative intervention is indicated.

Determination must be made prior to operative management if the lesion is a solitary or metastatic lesion. Imaging of the entire femur is necessary to determine if there are other lesions present. Bone lesions that have a large size, permeative appearance, soft tissue mass, and rapid growth are all characteristics that suggest an aggressive lesion. Biopsy of the lesion in coordination with the operative surgeon should be conducted if the primary tumor is unknown. Metastatic disease is much more common than primary tumors in the adult population.

Many metastatic fractures in the intertrochanteric region, and all fractures in the femoral neck and head are an indication for hemiarthroplasty or total hip arthroplasty. Cemented femoral implants are generally indicated. This allows immediate weight bearing in a bone with compromised bone stock, thus reducing the risk of peri-operative fractures. Additionally, patients are often treated with radiation and/or chemotherapy, which may prevent proper osseointegration of an ingrowth femoral component. Highly porous ingrowth shells have been shown to provide reliable and durable fixation even in these situations.

Management of a periacetabular pathologic fracture, particularly resulting in a pelvic discontinuity is a particularly challenging situation. Use of a highly porous acetabular component combined with an acetabular cage, a custom acetabular component, a cemented Harrington technique, or a primary acetabular reconstruction cage may be utilised.

Patients with neoplastic disease are often at risk for infection and thromboembolic disease both from the disease and treatment. Pre-operative evaluation of nutrition status by measuring albumin and pre-albumin will give the surgeon insight. Additionally, dehydration is commonly seen in cancer patients, and adequate pre-operative optimization of fluids and electrolytes may reduce peri-operative complications from other organ systems.

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 press fit. The prevalence has been reported to be between 1–5% in cementless 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 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 area of 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.

Periprosthetic fractures around the femur during and after total hip arthroplasty (THA) remain a common mode of failure. It is important therefore to recognise those factors that place patients at increased risk for development of this complication. Prevention of this complication, always trumps treatment. Risk factors can be stratified into: 1. Patient related factors; 2. Host bone and anatomical considerations; 3. Procedural related factors; and 4. Implant related factors.

Total joint arthroplasty (TJA) is one of the most successful procedures in orthopaedics. Despite the excellent clinical and functional results, periprosthetic joint infection (PJI) following TJA is a feared complication. For instance, the reported PJI rate after primary total knee arthroplasty is about 0.5–1.9%. In general, prevention of periprosthetic joint and surgical site infections is of utmost importance.

This can be reduced by strict antisepsis, adequate sterilization of the surgical instruments and meticulous surgical technique. An indisputable role in prevention of SSI in TJA has been the use of peri-operative systemic antibiotic prophylaxis. The most common recommended antibiotics for prophylaxis in TJA are cefazolin or cefuroxime. In contrast, routine use of commercial antibiotic-loaded bone cement (ALBC) in primary total joint arthroplasty is still a concern of open debate. The use of antibiotic-loaded bone cement delivers a high concentration of antibiotics locally and can decrease the infection rate, which is supported by several studies in the literature. In this context, we present the pros of routine use of commercial antibiotic-loaded bone cement.

Despite the demonstrated success in revision total joint arthroplasties, the utilization of antibiotic-loaded bone cement in primary total joint arthroplasty remains controversial. Multiple studies have demonstrated several risks associated with the routine use of this technique including: allergic reactions, changing the mechanical properties of the cement, emergence of resistant bacterial strains, systemic toxicity, and the added cost. In addition, evidence shows a currently low rate of periprosthetic joint infections in primary total joint arthroplasty (around 1%) and the theoretical benefit of marginally reducing this rate by using antibiotic-cement may not necessarily justify the associated risks and the added cost. Moreover, most of the primary total hip and an increasing number of primary total knee arthroplasties are cementless, which further raises questions about the routine use of antibiotic-loaded bone cement in primary total joint arthroplasty.

The position of this surgeon is that there is no approach that provides superior outcomes for total hip replacement (THR). The direct anterior approach (DAA) has become popular with patients because of marketing by companies, misinformation given to journalists for public consumption, and yes, some surgeons. Because of patient pressure generated by this marketing there has been pressure on surgeons to convert their surgical approach for perceived protection of their practice. Unfortunately, the leaders of orthopaedic organizations have not countered this marketing with education of the public that there is NO scientific evidence to support DAA superiority. These orthopaedic organizations exist to be advocates for their members but have abdicated that responsibility. Whatever happened to the time honored belief of choosing a surgeon to do your operation? Instead we now choose an approach? Do anterior surgeons think that they are immune to the Bell Curve of talent? The fact is that there is NO outcome data of DAA with the longest follow up study being one year, and recent data from both coasts of the USA raise concerns with more failures from loosening of the femoral component. How in the world can we bamboozle patients about better results when there are no published results with the DAA except for recovery? The mini-posterior approach has data for all aspects of its use. Short term data shows rapid recovery and hospital discharge can be the same day; gait studies show A quality at six weeks (so does this mean that cut muscles recover quickly?). Dislocation rates are equal in most comparative studies, but I believe this favors the DAA, however, fractures are 3X greater with DAA. Data from the Mayo Clinic comparative studies showed posterior patients return to work faster! There are two 10 year studies of mini-posterior patients which show some of the best 10 year results in the literature. And there are superior technical surgeons who perform this operation to the benefit of their patients, and they should not need to suffer the implicit bias from DAA marketing that their care of patients is inferior.

Total hip arthroplasty (THA) has been cited as one of the most successful surgical procedures performed today. However, as hip surgeons, we desire constantly improving outcomes for THA patients with more favorable complication rates. At the same time, patients desire hip pain relief and return to function with as little interruption of life as possible. The expectation of patients has changed; they have more physical demands for strength and flexibility, and aspire to achieve more in their recreational pursuits. Additionally, health care system constraints require the THA episode of care to become more efficient as the number of procedures increases with time. These factors, over the past fifteen years, have led to a search for improved surgical approaches and peri-operative pain and rehabilitation protocols for primary THA. The orthopaedic community has seen improved pain control, length of stay, and reduction in complications with changes in practice and protocols. However, the choice of surgical approach has provided significant controversy in the orthopaedic literature. In the 2000s, the mini-posterior approach (MPA) was demonstrated as the superior tissue sparing approach. More recently, there has been a suggestion that the direct anterior approach (DAA) leads to less muscle damage, and improved functional outcomes.

A recent prospective randomised trial has shown a number of early deficits of the posterior approach when compared to the direct anterior approach. The posterior approach resulted in patients taking an additional 5 days to discontinue a walker, discontinue all gait aids, discontinue narcotics, ascend stairs with a gait aid, and to walk 6 blocks. Patients receiving the posterior approach required more morphine equivalents in the hospital, and had higher VAS pain scores in the hospital than the direct anterior approach. Interestingly, activity monitoring at two weeks post-operatively also favored DAA with posterior approach patients walking 1600 steps less per day than DAA patients. There has been little difference in the radiographic outcomes or complications between approaches in prospective randomised trials.

A number of randomised clinical trials have demonstrated that both the direct anterior and posterior approach provided excellent early post-operative recovery with a low complication rate. DAA patients have objectively faster recovery with slightly shorter times to achieve milestones of function, with similar radiographic and clinical outcomes at longer-term outcomes, with a similar complication rate.

Dislocation remains among the most common complications of, and reasons for, revision of both primary and revision total hip arthroplasties in the United States. We have advocated identifying the primary cause of instability to plan appropriate treatment (Wera, Della Valle, et al., JOA 2012). Once implant position, leg length, and offset have been optimised and sources of impingement have been removed, the surgeon can opt for a large femoral head, a dual mobility articulation or a constrained liner. Given the limitations of constrained liners, we have looked to dual mobility articulations as an alternative, including its use in patients with abductor deficiency.

We retrospectively compared a consecutive series of revision THA that were at high risk for instability and treated with either a constrained liner or a dual mobility articulation. At a minimum of two years, there were ten dislocations in the constrained group (10/43 or 23.3%) compared to three in the dual-mobility group (3/36 or 8.3%; p = 0.06). With repeat revision for instability as an endpoint, the failure rate was 23% for the constrained group and 5.5% for the dual mobility group (p = 0.03).

We have also performed a systematic review of the published literature on the use of dual mobility in revision THA. Of the 3,088 hips reviewed, the dislocation rate was 2.2%, the risk of intraprosthetic dislocation was 0.3% and overall survivorship was 96.6% at 5 years.

Dual mobility articulations offer anatomic sized femoral heads that greatly increase jump distance, without many of the negatives of a constrained liner. While dual mobility is associated with its own concerns and problems (including intraprosthetic dislocation and wear) our initial results suggest that they are a viable alternative to a constrained liner, even in the most challenging situations.

Although the incidence of total hip dislocation has decreased, it still remains a major problem particularly if recurrent. The actual incidence is around 1–2% but it has been documented as the leading cause for hip revision in the United States. In patients with recurrent hip dislocation, technical issues of leg length inequality, incorrect offset, and poor implant position should be addressed surgically and the abnormality corrected. In patients with recurrent hip dislocation, the articulation is preferably converted to a more stable articulation, with constrained sockets and dual mobility being the choices.

In my experience, dual mobility articulations remain an excellent option for recurrent hip dislocation and its use is increasing significantly. It provides improved hip stability and data have demonstrated good success with recurrent hip dislocation. However, with use of the modular variety of dual mobility which is needed for acetabular cup fixation with screw augmentation, dissimilar metals are placed in contact (titanium socket and cobalt chrome liner insert) which potentially can pose a fretting or corrosion problem in longer term outcomes. Constrained sockets of the tripolar configuration provide another option which is useful in those patients with severe abductor dysfunction or insufficiency. Constrained sockets can also be cemented into the existing shell in cases where there is a well-fixed cup and cup removal may lead to significant bone loss and need for complex acetabular reconstruction. It is important to remember that there are two types of constrained sockets, tripolar and focal constraint. Results with the tripolar constrained socket have been significantly better than the focal constraint variety which adds a polyethylene rim piece to the liner. In a mid-term follow up (2–9 years) of 116 constrained tripolar sockets, recurrent dislocation was only 3.3%. In papers reporting on focal constrained sockets, recurrent dislocation was in the 9–29% range. There continues to be a role for constrained sockets and selection of implant type has made a difference in ultimate outcome.

Obesity and the diseases linked to it such as diabetes have been associated with higher complication rates and increased medical costs following total hip arthroplasty (THA). Due to the rising prevalence of obesity and the adverse impact it has on the development of osteoarthritis, there has been a worldwide surge in the number of obese patients presenting for THA procedures, including those morbidly obese (BMI > 40) and those who are super-obese (BMI > 50).

Important issues related to total hip replacement for dysplasia are: placement of the cup and bone stock; the role of femoral osteotomy, and the choice of acetabular and femoral components.

The cup can be placed at the correct or near correct anatomical level with or without a bone graft, in a high position (high hip center) or at the right level in a protruded position. All three techniques can provide adequate coverage of the cup. In the high hip position bone graft is not usually necessary to obtain cup coverage. There is, however, a higher rate of component loosening, a higher dislocation rate, and lengthening is limited to the femoral side. Placing the cup in a protruded position to obtain coverage does not restore bone stock for future surgery, but it does place the hip at the correct level. Placing the cup in the correct anatomical position (i.e., at the right level and not protruded) may require a structural autograft which adds to the complexity of the case. However, bone stock is restored for future surgery.

Femoral osteotomy may be used as part of the exposure for diaphyseal shortening or for derotation of excessive anteversion. The osteotomy is carried out in the sub-trochanteric region and may be oblique, step-cut or transverse. Fixation of the osteotomy is achieved via the stem, a plate, or a cortical strut.

Cementless components are usually used because of the relatively young age of this patient population. Small components may be necessary. On the femoral side, the stem should be straight or modular so excessive anteversion can be neutralised.

Patients with neuromuscular disease and imbalance present a particularly challenging clinical situation for the orthopaedic hip surgeon. The cause of the neuromuscular imbalance may be intrinsic or extrinsic. Intrinsic disorders include those in which the hip is in development, such as cerebral palsy, polio, CVA, and other spinal cord injuries and disease. This can result in subluxation and dislocation of the hip in growing children, and subsequent pain, and difficulty in sitting and perineal care. Extrinsic factors involve previously stable hips and play a secondary role in the development of osteoarthritis and contractures in later life. Examples of extrinsic factors are Parkinson's disease, dyskinesis, athetosis, and multiple sclerosis.

Goals of treatment in adults with pain and dysfunction in the setting of neuromuscular imbalance are to treat contractures and to perform salvage procedures to improve function and eliminate pain. Treatment of patients with neuromuscular imbalance may include resection arthroplasty (Girdlestone), arthrodesis, or total hip arthroplasty. Resection arthroplasty is typically reserved for patients that are non-ambulatory, or hips that are felt to be so unstable that arthroplasty would definitely fail due to instability. In modern times arthrodesis has limited use as it negatively impacts function and self-care in patients with neuromuscular disorders. Total hip arthroplasty has the ability to treat pain, relieve contractures, and provide improved function.

Due to the increased risk of instability, special considerations must be made during primary total hip arthroplasty in this patient cohort. Risk of instability may be addressed by surgical approach, head size, or use of alternative bearing constructs. Posterior approach may have increased risk of posterior dislocation in this patient group, particularly if a posterior capsular repair is not possible due to the flexion contractures and sitting position in many patients. Surgeons familiar with the approaches may utilise the anterolateral or direct anterior approach judicially. Release of the adductors may be performed in conjunction with primary total hip arthroplasty to help with post-operative range of motion and to decrease risk of instability. In a standard bearing, the selected head size should be the largest that can be utilised for the particular cup size. Rigorous testing of intra-operative impingement, component rotation, and instability is required. If instability cannot be adequately addressed by a standard bearing, the next option is a dual mobility bearing. Multiple studies have shown improved stability with the use of these bearings, but they are also at risk for instability, intraprosthetic dislocation, and fretting and corrosion of the modular connections. Another option is a constrained liner. However, this results in reduced range of motion, and an increased risk for mechanical complications of the construct. The use of a constrained liner in a primary situation should be limited to the most severe instability cases, and the patient should be counseled with the associated risks. If total hip arthroplasty results in repeated instability, revision surgery or Girdlestone arthroplasty may be considered.

Down syndrome (DS), is a genetic disorder caused by a third copy of the 21st chromosome (Trisomy 21), featuring typical facial characteristics, growth delays and varying degrees of intellectual disability. Some degree of immune deficiency is variably present. Multiple orthopaedic conditions are associated, including stunted growth (90%), ligamentous laxity (90%), low muscle tone (80%), hand and foot deformities (60%), hip instability (30%), and spinal abnormalities including atlanto-axial instability (20%) and scoliosis.

Hip disease severity varies and follows a variable time course. Rarely a child presents with DDH, but during the first 2 years the hips are characteristically stable but hypermobile with well-formed acetabulae. Spontaneous subluxation or dislocation after 2 presents with painless clicking, limping or giving way. Acute dislocation is associated with moderate pain, increased limp and reduced activity following minor trauma. Hips are reducible under anesthesia, but recurrence is common. Eventually concentric reduction becomes rarer and radiographic dysplasia develops. Pathology includes: a thin, weak fibrous capsule, moderate to severe femoral neck anteversion and a posterior superior acetabular rim deficiency. A number of femoral and acetabular osteotomies have been reported to treat the dysplasia, with acetabular redirection appearing to be most successful. However, surgery can be associated with a relatively high infection rate (20%). Additionally, symptomatic femoral head avascular necrosis can occur as a result of slipped capital femoral epiphysis.

Untreated dysplasia patients can walk with a limp and little pain into the early twenties even with fixed dislocation. Pain and decreasing hip function is commonly seen as the patient enters adult life. Occasionally the hip instability begins after skeletal maturity. Total hip arthroplasty (THA) is the standard treatment when sufficient symptoms have developed. The clinical outcomes of 42 THAs in patients with Down syndrome were all successfully treated with standard components. The use of constrained liners to treat intra-operative instability occurred in eight hips and survival rates were noted between 81% and 100% at a mean follow-up of 105 months (6 – 292 months).

A more recent study of 241 patients with Down syndrome and a matched 723-patient cohort from the Nationwide Inpatient Sample compared the incidence of peri-operative medical and surgical complications in those who underwent THA. Compared to matched controls, Down syndrome patients had an increased risk of complications: peri-operative (OR, 4.33; P<.001), medical (UTI & Pneumonia OR, 4.59; P<.001) and surgical (bleeding OR, 3.51; P<.001), Mean LOS was 26% longer (P<.001).

While these patients can be challenging to treat, excellent surgical technique and selective use of acetabular constraint can reliably provide patients with excellent pain-relief and improved function. Pre-operative education of all clinical decision makers should also reinforce the increased risk of medical and surgical complications (wound hemorrhage), and lengths of stay compared to the general population.

Protrusio acetabuli can be either primary or secondary. Primary or idiopathic protrusio is a rare condition of unknown etiology. Secondary protrusio may be associated with rheumatoid arthritis, ankylosing spondylitis, osteoarthritis, osteomalacia, trauma and Paget's disease. Challenges in surgery include: lack of bone stock, deficient medial support to the cup, difficulty in dislocating the femoral head, and medialization of the hip joint center. Several surgical techniques have been described: use of cement alone without bone graft; morselised impacted autograft or allograft with a cemented cup; metal cages, reinforcement rings, and solid grafts.

We describe our technique of impaction grafting using autologous bone and a cementless porous-coated hemispherical cup without the use of acetabular rings or cages in patients with an average age of 46 years. Protrusion was graded depending on distance of medial wall from Kohler's line as mild (1–5 mm medial), moderate (6–15 mm medial) and severe if it was more than 15 mm medial to the Kohler's line. All patients were operated in the lateral position using a modified Hardinge's anterolateral approach. Adductor tenotomy may be required in cases of severely stiff hips. After careful dislocation of the femoral head, it was sectioned in situ into slivers to facilitate obtaining the graft. The periphery was reamed and care was taken to preserve the membrane lining the floor of the defect. Morselised graft was impacted with hemispherical impactors and the trial cup 1–2 mm larger than the last reamer placed in the desired position. The final socket was then inserted. Femoral preparation was performed in routine fashion.

The mean pre-operative Harris Hip Score of 52 improved to 85 points at a mean follow up of 4 years. The average acetabular inclination angle was 42 degrees. Our results have shown incorporation of the graft in all cases. There was no evidence of progression of the protrusio or cup loosening in any of the cases. Thus far, our hips have not shown osteolytic lesions. The technique described is a satisfactory biological solution of restoring bone stock particularly in young and middle-aged patients.

Successful nonarthroplasty solutions for the treatment of osteonecrosis of the femoral head continued to be sought. However, no definitive nonarthroplasty solutions have to date been found. Hence, even in the best of hands a large number of patients with osteonecrosis end up with debilitating end-stage osteoarthritis.

In the inception of total hip arthroplasty (THA), the results of treatment of femoral head osteonecrosis by THA were inferior to total hip replacement performed for osteoarthritis. Reasons for this included the young age of many osteonecrosis patients, the high numbers of comorbidities in this population (SLE, sickle cell anemia, alcoholism), and the poor bone quality at the time of surgery. Arthroplasty considerations included bipolar replacement, hemiresurfacing, resurfacing (non metal-on-metal and later metal-on-metal), cemented total hip arthroplasty and cementless total hip arthroplasty. Previous to the use of cementless arthroplasty, all of these procedures had a relatively high 5 to 10 year failure rate of 10–50%. Even our own 10-year results using contemporary cementing techniques demonstrated 10% failure compared to 1–2% failure in our nonosteonecrosis patients. For this reason, it made sense to continue exploring nonarthroplasty solutions for osteonecrosis of the hip.

The introduction of cementless fixation for total hip arthroplasty changed the entire thinking about hip osteonecrosis treatment for many of us. Although initially we were concerned about whether bone would grow into the prosthesis in the environment of relatively poor bone, the early results demonstrated that it can and does. Most recently, with the use of crosslinked polyethylene, the cementless construct gives many of us hope that with cementless fixation, the treatment of many patients including the young (especially if followed closely to exchange bearing surfaces if necessary) will last a lifetime with THA being the only and definitive procedure. Our most recent 10-year results demonstrated a femoral stem revision rate of 1.5% will all other stems (other than the stem revised) bone ingrown. Acetabular fixation was also 100% and although 6% required liner exchange, our own and others' results with crosslinked polyethylene would suggest that this problem should be markedly reduced.

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.

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage.

In situations of end-stage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement.

Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim.

Often combinations of the above are indicated.

Total hip arthroplasty (THA) is among the most successful interventions in all of medicine and has recently been termed “The Operation of the Century”. Charnley originally stated that “Objectives must be reasonable. Neither surgeons nor engineers will ever make an artificial hip joint that will last 30 years and at some time in this period enable the patient to play football.” and he defined an appropriate patient as generally being over 65 years of age. Hip rating scales developed during this time were consistent with this approach and only required relief of pain and return to normal activities of daily living to achieve a perfect score. Since this time, however, hip arthroplasty has been applied to high numbers of younger, more active individuals and patient expectations have increased. One recent study showed that in spite of a good hip score, only 43% of patients had all of their expectations completely fulfilled following THA.

The current generation metal-metal hip surface replacement arthroplasty (SRA) has been suggested as an alternative to standard THA which may offer advantages to patients including retention of more native bone, less stress shielding, less thigh pain due to absence of a stem, less limb length discrepancy, and a higher activity level. A recent technology review by the AAOS determined that currently available literature was inadequate to verify any of these suggested potential benefits. The potential complications associated with SRA have been well documented recently. The indications are narrower, the implant is more expensive, the technique is more demanding and less forgiving, and the results are both highly product and surgeon specific. Unless a clinical advantage in the level of function of SRA over THA can be demonstrated, continued enthusiasm for this technique is hard to justify.

To generate data on the level of function of younger more active arthroplasty patients, a national multicenter survey was conducted by an independent university medical interviewing center with a long track record of conducting state and federal medical surveys. All patients were under 60, high demand (pre-morbid UCLA score > 6) and had received a cementless stem with an advanced bearing surface or an SRA at one of five major total joint centers throughout the country. The detailed questionnaire quantified symptoms and function related to employment, recreation, and sexual function. Patients with SRA had a higher incidence of noises emanating from the hip than other bearing surfaces although this was transient and asymptomatic. SRA patients were much more likely to have less thigh pain than THA, less likely to limp, less likely to perceive a limb length difference, more likely to run for exercise, and more likely to run longer distances. In another study of over 400 THA and SRA patients at two major academic centers, patients completed pain drawings that revealed an equivalent incidence of groin pain between THA and SRA, but an incidence of thigh pain in THA that was three times higher than in SRA in young active patients.

While some or most of the observed advantages of SRA over THA may be attributable to some degree of selection bias, the inescapable conclusion is that SRA patients are demonstrating clinical advantages that warrants continued utilization and investigation of this procedure.

Dorr bone type is both a qualitative and quantitative classification. Qualitatively on x-rays the cortical thickness determines the ABC type. The cortical thickness is best judged on a lateral x-ray and the focus is on the posterior cortex. In Type A bone it is a thick convex structure (posterior fin of bone) that can force the tip of the tapered implant anteriorly – which then displaces the femoral head posteriorly into relative retroversion. Fractures in DAA hips have had increased fractures in Type A bone because of the metaphyseal-diaphyseal mismatch (metaphysis is bigger than diaphysis in relation to stem size). Quantitatively, Type B bone has osteoclastic erosion of the posterior fin which proceeds from proximal to distal and is characterised by flattening of the fin, and erosive cysts in it from osteoclasts. A tapered stem works well in this bone type, and the bone cells respond positively. Type C bone has loss of the entire posterior fin (stove pipe bone), and the osteoblast function at a low level with dominance of osteoclasts. Type C is also progressive and is worse when both the lateral and AP views show a stove pipe shape. If just the lateral x-ray has thin cortices, and the AP has a tapered thickness of the cortex a non-cemented stem will work, but there is a higher risk for fracture because of weak bone. At surgery Type C bone has “mushy” cancellous bone compared to the hard structure of type A. Tapered stems have high risk for loosening because the diaphysis is bigger than the metaphysis (opposite of Type A). Fully coated rod type stems fix well, but have a high incidence of stress shielding. Cemented fixation is done by surgeons for Type C bone to avoid fracture, and insure a comfortable hip. The large size stem often required to fit Type C bone causes an adverse-stem-bone ratio which can cause chronic thigh pain. I cement patients over age 70 with Type C bone which is most common in women over that age.

Tranexamic acid (TXA) is an effective medication to limit blood loss and transfusion requirements in association with contemporary total joint arthroplasty. TXA is in a class of medications termed anti-fibrinolytics due to their action to limit the breakdown of clot that has already been formed. It is useful to note that TXA does not promote the formation of clot, it simply limits the breakdown of already established clot. A recent systematic review and meta-analysis of randomised clinical trials of TXA use in total hip replacement demonstrated: 1) a substantial reduction in the proportion of patients who required transfusion and 2) no increase in DVT or PE. Similarly a recent Cochrane Database systematic review assessed Anti-fibrinolytic Use for Minimizing Perioperative Blood Transfusion and found tranexamic acid to be effective in reducing blood loss during and after surgery and to be free of serious adverse effects. In orthopaedic surgery varying doses have been used over time. A pragmatic dosing approach for Total Knee and Total Hip patients has been used at the Mayo Clinic over the past 16 years: 1 gram IV over 10 minutes prior to incision (delivered at same time as pre-op antibiotics) followed by 1 gram IV over 10 minutes at the time wound closure is initiated. Infusion rates greater than 100 mg/minute have been associated with hypotension and thus the recommendation for 1 gram over 10 minutes. A recent review of 1500 TKA patients at Mayo Clinic revealed a very low prevalence of clinically symptomatic DVT and PE when tranexamic acid was used with 3 different thromboembolic prophylaxis regimens (aspirin and foot pumps; coumadin; low molecular weight heparin). The safety of TXA for patients with coronary stents has not been fully clarified.

Thromboembolic disease (TED) remains as a major concern for orthopaedic surgeons and is a well-known complication of lower extremity joint replacement procedures. While there is voluminous literature on the topic, it is difficult for the average orthopaedic surgeon to keep up with all the advancements in this area as well as the newer pharmacological options for prophylaxis. To address this, the American Academy of Orthopaedic Surgeons (AAOS) has developed a clinical practice guideline (CPG) in this area to provide treatment recommendations based on the best available evidence. Historically, guidelines for TED prophylaxis have been based largely on randomised controlled trials whose outcome measure was venographically documented deep vein thrombosis (DVT). However, many venographically documented DVTs, particularly those distal to the popliteal vein, are of no clinical consequence. Therefore, in the AAOS CPG the systematic review of the literature was focused on those outcomes that have the most clinical relevance: all-cause mortality, symptomatic or fatal pulmonary embolism (PE), proximal DVT, major bleeding and symptomatic DVT rates.

Using these as the clinically important endpoints, it is evident that the extant literature is insufficient to provide definitive guidance in this area and to make specific recommendations about optimal pharmacological prophylaxis. Nonetheless, one strong recommendation has emerged from this systematic review: the guideline recommended against routine post-operative duplex ultrasonography screening of patients who undergo elective hip or knee arthroplasty. Only one risk factor – previous history of TED – had evidence demonstrating a higher risk beyond the risk from elective hip or knee arthroplasty itself (weak recommendation). There was not sufficient evidence that other potential risk factors increase the risk of TED, likely because of the relatively high background risk of elective hip or knee arthroplasty. In addition, there is very little evidence defining populations at increased risk for bleeding and bleeding-associated complications associated with pharmacological prophylaxis. However, the panel did come to a consensus that patients with known bleeding disorders or active liver disease are at an increased risk for post-operative bleeding. In these circumstances, it is recommended that mechanical compressive devices be the primary modality of prophylaxis as pharmacologic prophylaxis may increase the risk of bleeding.

There was a moderate strength recommendation for the superiority of neuraxial anesthesia to limit blood loss even though there is no demonstrable effect on the incidence of TED. Finally, there was a moderate grade recommendation that pharmacologic agents (including aspirin) and/or mechanical compression devices be utilised for the prevention of VTE in patients that are undergoing elective hip or knee arthroplasty who are not at elevated risk beyond that of the surgery itself for VTE or bleeding. Clearly there is great need for better evidence with appropriately powered studies that examine the most clinically relevant outcomes in TED prophylaxis.

Total hip arthroplasty (THA) is reliable and reproducible in relieving pain and improving function in patients with end-stage arthritis of the hip joint. With improvements in surgical technique and advances in implant and instrument design, there has been a shift in focus from the technical aspects of the surgical procedure to improving the overall patient experience. In addition, shifts in medico-economic trends placed a premium on early patient mobilization, early discharge, and maximizing patient satisfaction. Arguably, a single most important advance in arthroplasty over the past 2 decades has been the development of multimodal pain protocols that form the foundation of many of the rapid recovery protocols today.

The principal concept of multimodal analgesia is pain reduction through the utilization of multiple agents that synergistically act at various nodes of the pain pathway, thus, minimizing patient exposure to each individual agent and opioids in order to prevent opioid related adverse events (ORAE). Regional anesthesia has been shown to reduce post-operative pain, morphine consumption, and nausea and vomiting compared to general anesthesia but not length of stay. Additionally, general anesthesia has been shown to be associated with increased rates of post-operative adverse events, The use of peripheral nerve blocks in the form of sciatic, femoral or fascia iliaca blocks have not been shown to significantly reduce post-operative pain compared to controls.

Periarticular infiltration of local anesthetics has been shown in some settings to reduce pain during the immediate post-operative period (<24 h). However, no significant differences were noted in terms of early recovery or complications. The use of liposomal bupivacaine (LB) local infiltration decreased pain and shortened length of stay comparable to patients receiving a fascia iliaca compartment block, and has been shown in relatively few randomised trials to provide improved pain relief at 24 hours only compared to conventional bupivacaine. Continuous intra-articular infusion of bupivacaine after THA did not significantly further reduce post-operative pain compared to placebo.

In summary, the use of regional anesthesia when appropriate along with local anesthetic infiltration in the setting of a robust multimodal pain protocol minimises pain and complications while maximizing patient satisfaction following THA.

Instability is the most common reason for revision after total hip arthroplasty (THA). Since THA requires arthrotomy of the hip and replacement with a femoral head that is smaller than the normal hip, instability following THA is always a potential concern. Many factors contribute to the development of instability after THA including: restoration of normal anatomy, implant design, component position, surgical approach and technique, and numerous patient related factors. Recently, the role of spinal mobility and deformity has been shown to have a significant effect on risk of dislocation after THA. The long held guidelines for component positioning or so called “safe zone” described by Lewinnek have also been questioned since most dislocations have been shown to occur in patients whose components are positioned within this “safe” range.

In the early post-operative period, dislocation can occur prior to capsular and soft tissue healing if the patient exceeds their peri-operative range of motion limits. Closed reduction and abduction bracing for 6 weeks may allow for soft tissue healing and stabilization of the hip. It is important to try and identify the mechanism of dislocation since this can affect the technique of closed reduction, how the patient is braced following reduction and what may need to be addressed at the time of revision if dislocation recurs. Closed reduction and bracing may be effective in patients who have a previously well-functioning, stable THA who suffer a traumatic dislocation after the peri-operative period. Despite successful closed reduction, recurrent dislocation occurs in many patients and can be secondary to inadequate soft tissue healing, patient noncompliance or problems related to component positioning. Patients who incur more than 2 dislocations should be considered for revision surgery.

Prior to revision surgery, an appropriate radiographic evaluation of the hip should be performed to identify any potential mechanical/kinematic issues that need to be addressed at the time of revision. Typically this involves plain radiographs, including a cross table lateral of the involved hip to assess acetabular version, but may also involve cross-sectional imaging to assess femoral version. Patients with soft tissue pseudotumors frequently have significant soft tissue deficiencies that are not amenable to component repositioning alone and require use of constrained or dual mobility components. In general, “limited revisions” consisting of modular head and liner exchange with insertion of a lipped liner and larger, longer femoral head rarely correct the problem of recurrent instability, since component malposition that frequently contributes to the instability is not addressed. Similarly, insertion of a constrained liner in a malpositioned cup is associated with a high rate of implant failure and recurrent dislocation since impingement contributing to the instability is not addressed.

In patients who fail closed management and have a history of recurrent instability, we have found the treatment paradigm described by Wera, et al. to be very helpful in the management of the unstable THA. Several studies have shown that tripolar type constrained liners appear to perform considerably better than locking ring type constrained liners. As a result, dual mobility implants are becoming more widely utilised in patients with abductor and other soft tissue deficiencies, hip instability of uncertain etiology and patients with increased risk factors for instability undergoing primary THA. Early results with dual mobility components have been shown to have a low rate of failure in high instability risk revision THAs. These devices do have several unique potential complications and their use should be limited to patients with significantly increased risk of dislocation and instability.

Economic data, clinical outcome studies, and anatomical studies continue to support the Superior Hip Approach as a preferred approach for improved safety, maximal tissue preservation, rapid recovery, and minimised cost.

Clinical studies show exceedingly low rates of all major complications including femur fracture, dislocation, and nerve injury.

Economic data from Q1 2013 to Q2 2016 demonstrate that CMS-insured patients treated by the Superior Hip Approach have the lowest cost of all patients treated in Massachusetts by an average of more than $7,000 over 90 days. The data show that the patients treated by the Superior Hip Approach have lower cost than any other surgical technique.

Matched-pair bioskills dissections demonstrate far better preservation of the hip joint capsule and short external rotators than the anterior approach.

Design principles include: Preservation of the abductors; Preservation of the posterior capsule and short external rotators; Preparation of the femur in situ prior to femoral neck osteotomy; Excision of the femoral head, thereby avoiding surgical dislocation of the hip; In-line access to the femoral shaft axis; Ability to perform a trial reduction; Independence from intra-operative imaging; Independence from a traction table; Applicable to at least 99% of THA procedures.

Since 1997, a patented rim flared cup has been used for both primary and revision total hip arthroplasty with great success. The concept was based on a “stretched” hemispherical geometry to improve initial contact between cup and bone. This improved geometry provided a 1 mm press fit predominantly at the perimeter of the acetabulum much like the footprint of the native anatomic acetabulum. Thousands of these were implanted. A second version of this concept was introduced in August 2011. This similarly “stretched” geometry provides 1.6 mm of press fit. Building on what was learned from the original design, this updated, stretched geometry was created with a single radius for a smooth transition from the apex to the peripheral press fit. Porous coating is the key to implant durability. With this aggressive “sticky” porous coating, only 0.6 mm of press fit is required. This porous coating has 60% porosity, and 150–400 mm pore size. It has a tensile strength of 5000 psi (The FDA requires a minimum of 2900 psi) and a mean thickness of 0.8 mm. Three thousand cups have been implanted with the author contributing 400. In our own primary subgroup done in 2014–15, 142 had 2–4 year follow up with zero loosening. There was one infection and 2 dislocations. One implant was revised on a patient with psoas tendonitis from an oversized cup. At retrieval it showed excellent ingrowth into the porous coating with 38% ingrowth. This graduated rim fit concept has a proven track record spanning 2 decades and provides a stable and reproducible acetabular construct.

Hip abductor deficiency (HAD) associated with hip arthroplasty can be a chronic, painful condition that can lead to abnormalities in gait and instability of the hip. HAD is often confused with trochanteric bursitis and patients are often delayed in diagnosis after protracted courses of therapy and steroid injection. A high index of suspicion is subsequently warranted.

Risk factors for HAD include female gender, older age, and surgical approach. The Hardinge approach is most commonly associated with HAD because of failure of repair at the time of index surgery or subsequent late degenerative or traumatic rupture. Injury to the superior gluteal nerve at exposure can also result in HAD and is more commonly associated with anterolateral approaches. Multiple surgeries, chronic infection, and chronic inflammation from osteolysis or metal debris are also risk factors especially as they can result in bone stock deficiency and direct injury to muscle. Increased offset and/or leg length can also contribute to HAD, especially when both are present.

Physical exam demonstrates abductor weakness with walking and single leg stance. There is often a palpable defect over the greater trochanter and palpation in that area usually elicits significant focal pain. Note may be made of multiple incisions. Increased leg length may be seen.

Radiographs may demonstrate avulsion of the greater trochanter or significant osteolysis. Significant polyethylene wear or a metal-on-metal implant should be considered as risk factors, as well as the presence of increased offset and/or leg length. Ultrasound or MRI are helpful in confirming the diagnosis but false negatives and positive results are possible.

Treatment is difficult, especially since most patients have failed conservative management before diagnosis of HAD is made. Surgical options include allograft and mesh reconstruction as well as autologous muscle transfers. Modest to good results have been reported, but reproducibility is challenging. In the case of increased offset and leg length, revision of the components to reduce offset and leg length may be considered. In the case of significant instability, abductor repair may require constrained or multi-polar liners to augment the surgical repair.

HAD is a chronic problem that is difficult to diagnose and treat. Detailed informed consent appropriately setting patient expectations with a comprehensive surgical plan is required if surgery is to be considered. Be judicious when offering this surgery.

Fixation of cemented femoral stems is reproducible and provides excellent early recovery of hip function in patients 60–80 years old. The durability of fixation has been evaluated up to 20 years with 90% survivorship. The mode of failure of fixation of cemented total hip arthroplasty is multi-factorial; however, good cementing techniques and reduction of polyethylene wear have been shown to reduce its incidence. The importance of surface roughness for durability of fixation is controversial. This presentation will describe my personal experience with the cemented femoral stem over 30 years with 3 designs and surface roughness (RA) ranging from 30 to 150 microinches.

Hip resurfacing presents advantages and disadvantages compared to total hip arthroplasty. Dislocation and leg length discrepancy, common complaints with total hips, are unusual following resurfacing. Bone stock in the proximal femur is retained, and revision options on the femoral side of a resurfacing are much better.

Concerns persist regarding adverse tissue reactions to metal debris.

Conflicting data abounds regarding ultimate hip function, patient satisfaction, durability, etc. Yet all of these would be rendered irrelevant if resurfacing carried with it greater life expectancy. We would not speak of survivorship of the implant, but survival of the patient. Instead of quality of life, let us preserve life itself.

Beginning in 2010, the UK Registry reported improved mortality rates at 90 days and five years after hip resurfacing compared with total hip replacement. This persisted after multivariate analysis for several covariables, including age, gender, health status, type of device, provider, and country. Recently, the 2016 Australian Registry Mortality Supplement showed similar results, corrected for age and gender.

Analysis of UK data by the designing surgeons of the Birmingham device, and an independent group of Oxford statisticians confirmed the lower mortality rate in patients treated with resurfacing vs. total hip replacement. Possible reasons for these differences include greater post-operative activity, longer stride length, less fat and marrow embolism, or perhaps more internet-savvy, health-conscious patients seeking out a resurfacing procedure.

Mid-term data from the US is now starting to come in, and mortality benefits are being confirmed in a series of patients from a large, academic center. Should there be a confirmed mortality advantage of resurfacing over total hip replacement, more surgeons and patients would be interested in this procedure, and new materials and techniques may follow.

Greater trochanter fractures after total hip replacement have been reported in up to 5% of cases. The outcomes are generally poor. Treatment options include non-operative care or surgical treatment with cerclage wires or a claw plate. We present a simple tension band technique for acute fractures with a single bony fracture fragment. We have not used the technique for chronic or comminuted fractures.

Technique: 2.5mm k-wires are passed through the fragment and anterior and posterior to the femoral implant. Eighteen-gauge wire is passed through a drill hole in the femur distal to the fracture and around the k-wires in a figure eight. The patient is kept 50% weightbearing with no active abduction for 4 weeks.

In four cases the fracture has gone on to healing. Patients have had a negative Trendelenburg sign without peritrochanteric pain.

The tension band technique is familiar to surgeons and has been reliable.

We present a technique of single posterior longitudinal slot femorotomy. This technique allows the expansion of the metaphyseal-diaphyseal region of the proximal femur facilitating extraction of proximally coated uncemented femoral components while leaving the metaphysis and diaphysis intact. Since 1996 we have performed this technique in 18 revision total hip arthroplasties in 15 patients who had x-ray appearance of bony in-growth/on-growth and where found to have solidly ingrown stems at revision surgery. All were revised to a metaphyseal-fitting uncemented stem. At mean follow-up of 122.4 months, there were significant improvements in both pain and function. All revised stems achieved stable bony fixation. There were no complications due to this technique. No patient developed a limp or thigh pain post-operatively. There have been no re-revisions of the stem. With appropriate patient selection, this simple, reliable, and extensile technique is useful to assist in the extraction of uncemented proximally coated femoral components whether hydroxyapatite-coated or not.

The well-fixed femoral stem can be challenging to remove. Removal of an extensively osteointegrated cementless stem requires disruption of the entire implant-bone interface while a well-fixed cemented stem requires complete removal of all adherent cement from the underlying cortical bone in both the metaphysis and diaphysis of the femur. In these situations, access to those areas of the femur distal to the metaphyseal flare that are beyond the reach of osteotomes and high speed burrs is necessary. This typically requires use of an extended femoral osteotomy (ETO).

The ETO should be carefully planned so that it extends distal enough to allow for access to the end of the stem or cement column and still allow for stable fixation of a new implant. Too short of an ETO increases the risk of femoral perforation by straight burrs, trephines or cement removal instruments that cannot negotiate the bowed femoral canal to access the end of the cement column or end of the stem without risk of perforation. The ETO should also be long enough to allow for fixation with at least 2 cerclage cables. An ETO that is too distal makes implant and cement removal easier, but may not allow for sufficient fixation of a new revision femoral stem. After insertion of the revision stem, the osteotomy is reduced back around the stem and secured in place with cerclage cables.

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 to stimulate more controversy. This session has been very popular in the past and is fast moving, humorous and educational.

There are numerous factors that influence total hip arthroplasty (THA) stability including surgical approach, soft-tissue tensioning, impingement, abductor status, and component positioning. A long-held tenet regarding acetabular component positioning is that cup inclination and anteversion of 40 degrees ± 10 degrees and 15 degrees ± 10 degrees, respectively, represents a “safe zone” as to minimise dislocation after primary THA. However, several studies have recently challenged that notion for individual patients. A study completed by Abdel et al identified a cohort of 9784 primary THAs performed at a single institution with 206 THAs (2%) that subsequently dislocated. The authors determined that 58% of the dislocated THAs had their acetabular component within the safe zone for both acetabular inclination and anteversion. When looked at separately, 84% had their inclination within the safe zone (mean value of 44 degrees ± 8 degrees), and 69% had their anteversion within the safe zone (mean value of 15 degrees ± 9 degrees). As such, surgeons should take into account that cup positioning alone does not determine the risk of instability following THA, as there are a multitude of other factors that can contribute to dislocation. Hip stability is multifactorial and likely patient-specific, and must take into account bony and muscular anatomy, static and dynamic soft tissue balance and intra-operative tensioning, and the functional demand and rehabilitative efforts of the patient.

Acetabular implant position is important for the stability, function, and long-term wear properties of a total hip arthroplasty (THA). Prior studies of acetabular implant positioning have demonstrated a high percentage of outliers, even in experienced hip surgeons, when conventional instruments are used.

Computer navigation is an attractive tool for use in THA, as it has been shown to improve the precision of acetabular component placement and reduce the incidence of outliers. However, computer navigation with imageless, large-console systems is costly and often interrupts the surgeon's workflow, and thus, has not been widely adopted.

Another method to improve acetabular component positioning during THA is the use of fluoroscopy with the direct anterior approach. Studies have demonstrated that the supine position of the patient during surgery facilitates the use of fluoroscopic guidance, thus improving acetabular component position.

A handheld, accelerometer-based navigation unit for use in total hip replacement has recently become available to assist the surgeon in positioning the acetabular component during anterior approach THA, potentially reducing the need for intra-operative fluoroscopic studies. We sought to compare the radiographic results of direct anterior THA performed with conventional instrumentation vs. handheld navigation to determine the accuracy of the navigation unit, and to see whether or not there was a reduction in the fluoroscopic time used during surgery. Furthermore, we timed the use of the navigation unit to see whether or not it required a substantial addition to surgical time.

Our results demonstrate that a handheld navigation unit used during anterior approach THA had no difference with regard to acetabular cup positioning when compared to fluoroscopically assisted THA, but led to a reduction in the use of intra-operative fluoroscopy time.

Restoring native hip biomechanics is crucial to the success of THA. This is reflected both in terms of complications after surgery such as instability, leg length inequality, pain and limp; and in terms of patient satisfaction. The challenge that remains is that of achieving optimal implant sizing and positioning so as to restore, as closely as possible, the native hip biomechanics specific to the hip joint being replaced. This would optimise function and reduce complications, particularly, instability. (Mirza et al., 2010). Ideally, this skill should also be reproducible irrespective of the surgeon's experience, volume of surgery and learning curve.

The general consensus is that the most substantial limiting factor in a THA is the surgeon's performance and as a result, human errors and unintended complications are not completely avoidable (Tarwala and Dorr, 2011). The more challenging aspects include acetabular component version, sizing and femoral component sizing, offset and position in the femoral canal. This variability has led to interest in technologies for planning THA, and technologies that help in the execution of the procedure. Advances in surgical technology have led to the development of computer navigation and robotic systems, which assist in pre-operative planning and optimise intra-operative implant positioning.

The evolution of surgical technology in lower limb arthroplasty has led to the development of computer navigation and robotics, which are designed to minimise human error and improve implant positioning compared to pre-operative templating using plain radiographs. It is now possible to use pre-operative computerised tomography (image-based navigation) and/or anatomical landmarks (non-imaged-based navigation) to create three-dimensional images of each patient's unique anatomy. These reconstructions are then used to guide bone resection, implant positioning and lower limb alignment.

The second-generation RIO Robotic Arm Interactive Orthopaedic system (MAKO Surgical) uses pre-operative computerised tomography to build a computer-aided design (CAD) model of the patient's hip. The surgeon can then plan and execute optimal sizing and positioning of the prostheses to achieve the required bone coverage, minimise bone resection, restore joint anatomy and restore lower limb biomechanics. The MAKO robotic software processes this information to calculate the volume of bone requiring resection and creates a three-dimensional haptic window for the RIO-robotic arm to resect. The RIO-robotic arm has tactile and audio feedback to resect bone to a high degree of accuracy and preserve as much bone stock as possible.

We have used this technology in the hip to accurately reproduce the anteversion, closure and center of rotation that was planned for each hip. Whilst the precise safe target varies from patient to patient, the ability to reproduce native biomechanics, to gain fixation as planned and to get almost perfect length and offset are a great advantage. Complications such as instability and leg length inequality are thus dramatically reduced.

Two critical steps in achieving optimal results and minimizing complications (dislocation, lengthening, and intra-operative fracture) are careful pre-operative planning and more recently, the option of intra-operative imaging in order to optimise accurate and reproducible total hip replacement. The important issues to ascertain are relative limb length, offset and center of rotation. It is important to start the case knowing the patient's perception of their limb length. Patient perception is equally important, if not more important, than the radiographic assessment. On the acetabular side, the teardrop should be identified and the amount of reaming necessary to place the inferior margin of the acetabular component adjacent to the tear drop should be noted. Superiorly the amount of exposed metal that is expected to be seen during surgery should be measured in millimeters. Once the key issues of limb length, offset, center of rotation, and acetabular component position relative to the native acetabulum have been confirmed along with the expected sizing of the acetabular and femoral components, it is critical that the operative plan is reproduced at the time of surgery and this can best be consistently performed with the use of intra-operative imaging. Advances in digital imaging now make efficient, cost-effective assessment of hip replacement possible. Embedded software allows accurate confirmation of the pre-operative plan intra-operatively when correction of potential errors is easily possible. Such technology is now mature after years of clinical use and studies have confirmed its success in avoiding outliers and achieving optimal results.

A pilot study at Washington University demonstrated that intra-operative imaging was able to eliminate outliers for acetabular inclination and anteversion. In addition, the ability to achieve accurate reproduction of femoral offset and limb length within 5mm was three times better with intra-operative imaging (P <0.001).

Surface coatings have been introduced to total joint orthopaedics over the past decades to enhance osseointegration between metal implants and bone. However, complications such as aseptic loosening and infection persist. Inadequate osseointegration remains a complication associated with implants that rely on osseointegration for proper function. This is particularly challenging with implants having relatively flat and small surface areas that have high shear loading, such as noncemented uni and total condylar knee tibial trays. Faster osseointegration can enhance recovery as a result of improved load distribution and a more stable bone-implant interface. Traditionally noncemented porous bone ingrowth coatings on knee, hip and shoulder implants are typically texturised by thermal plasma spray coating, sintered metal bead coatings, or 3-D additive manufactured structures that provide porous surface features having the rough texture with pore sizes on the order of 150 to 300 micrometers. These surfaces are often further chemically enhanced with hydroxyapatite (HA) deposition. This provides macro-mechanical (millimeter scale) and micro-mechanical (micrometer scale) bone remodeling into the implant surface. However, at the nanoscale and cellular level, these surfaces appear relatively smooth. More recent studies are showing the importance of controlling the macro, micro, and the nano (nanometer scale) surface topographies to enhance cell interaction. In vitro and in vivo research shows surfaces with nanoscale features in the metal substrate result in enhanced osseointegration, greater bone-implant contact area and pullout force, and potentially bactericidal.

One surface modification treatment technique of particular promise is nano-texturing via electrochemical anodization to bio-mimicking TiO2 nanotube arrays that are superimposed onto existing porous surface microstructures to further enhance the already known bone ingrowth properties of these porous structures by superimposing onto the existing microstructure arrays of nanotubes approximately 100 nanometers in outside diameter and 300–500 nanometers in height.

In an ovine model, 3-D printed Direct Metal Laser Deposition (DMLS) additive manufactured porous Ti-6Al-4V implant with and without TiO2 nanotube array nano-texturing were compared to similar sized implants with commercially available sintered beads with HA coating and additive manufactured cobalt chrome implants. The average bond strength was significantly higher (42%) when the implants were nano-texturised and similarly stronger (53%) compared to HA coated sintered bead implants. Histology confirms over 420% more direct bonded growth of new bone from 0.5mm to 1.0mm deep into the porosity on the implants when the same implants are nano-texturised. Nano-texturing also changes the surface of the implant to repel methicillin-resistant staphylococcus aureus (MRSA) in an in vivo rabbit model limiting biofilm formation on the porous surface compared with non-treated porous surfaces.

Since nano-texturizing only modifies the nano-morphology of the surface and does not add antibiotics or other materials to the implant, these animal studies shows great promise that nano-texturizing the TiO2 coating may not only enhance osseointegration, but also repels bacteria from porous implant surfaces. As such, we believe nano-texturing of porous implants will be the next advancement in surface coating technology.

Patients with painful metal-on-metal bearings presenting to the orthopaedic surgeon are a difficult diagnostic challenge. The surgeon must go back to basic principles, perform a complete history and physical exam, obtain serial radiographs and basic blood work (ESR, CRP) to rule out common causes of pain and determine if the pain is, or is not, related to the bearing.

The Asymptomatic MoM Arthroplasty: Patients will present for either routine follow up, or because of concerns re: their bearing. It is important to emphasise that at this point the vast majority of patients with a MoM bearing are indeed asymptomatic and their bearings are performing well. The surgeon must take into account: a) which specific implant are they dealing with and what is its track record; b) what is the cup position; c) when to perform metal ion testing; d) when to perform further soft tissue imaging (MARS MRI, Ultrasound); e) when to discuss possible surgery.

Painful MoM THA causes not related to the bearing couple: These can be broken down into two broad categories. Causes that are Extrinsic to the hip include: spine, vascular, metabolic and malignancy. Causes that are Intrinsic to the hip can either be Extracapsular (iliopsoas tendonitis and trochanteric bursitis) or Intracapsular (sepsis, loosening, thigh pain, prosthetic failure)

Painful MoM THA causes related to the bearing couple: There are now described a number of possible clinical scenarios and causes of pain that relate to the metal-on-metal bearing couple itself: a) local hypersensitivity reaction without a significant soft tissue reaction; b) local hypersensitivity reaction with a significant soft tissue reaction; c) impingement and soft tissue pain secondary to large head effect.

Metal ions: obtaining serum, or whole blood, cobalt and chromium levels is recommended as a baseline test. However, there is no established cutoff level to determine with certainty if a patient is having a hypersensitivity reaction. A 7 parts per billion cutoff has been suggested. This gives high specificity, but poor sensitivity. Metal ions therefore can be used as a clue, and one more test in the workup, but cannot be relied upon in isolation to make a diagnosis.

MARS MRI: a useful tool for demonstrating soft tissue involvement, but there are many painless, well-functioning MoM implants that have soft tissue reactions, that don't require a revision. In the painful MoM hip an MRI, or ultrasound, is recommended to look for soft tissue destruction or a fluid-filled periprosthetic lesion (pseudotumor). Significant soft tissue involvement is concerning and is commonly an indication for revision in the painful MoM hip.

Treatment: management of the painful MoM hip is directly related to the etiology of the pain. Unique to MoM bearing is the issue of pain secondary to a local hypersensitivity reaction. All above tests should be utilised to help determine the best course of action in any individual patient. The painful MoM bearing, that is demonstrating significant soft tissue involvement is a concerning scenario. Earlier revision, to prevent massive abductor damage, would seem prudent for these patients. The painful MoM bearing with no significant soft tissue changes can probably be followed and reviewed at regular intervals. If the pain persists and is felt to be secondary to a hypersensitivity reaction, then revision is really the only option, although the patient must be cautioned regarding the unpredictable nature of the pain relief.

Femoral revision after cemented total hip arthroplasty (THA) might include technical difficulties, following essential cement removal, which might lead to further loss of bone and consequently inadequate fixation of the subsequent revision stem. Bone loss may occur because of implant loosening or polyethylene wear, and should be addressed at time of revision surgery. Stem revision can be performed with modular cementless reconstruction stems involving the diaphysis for fixation, or alternatively with restoration of the bone stock of the proximal femur with the use of allografts.

Impaction bone grafting (IBG) has been widely used in revision surgery for the acetabulum, and subsequently for the femur in Paprosky defects Type 1 or 2. In combination with a regular length cemented stem, impaction grafting allows for restoration of femoral bone stock through incorporation and remodeling of the proximal femur. Cavitary bone defects affecting the metaphysis and partly the diaphysis leading to a wide femoral canal are ideal indications for this technique. In case of combined segmental-cavitary defects a metal mesh is used to contain the defect which is then filled and impacted with bone grafts. Cancellous allograft bone chips of 2 to 4 mm size are used, and tapered into the canal with rods of increasing diameters. To impact the bone chips into the femoral canal a dummy of the dimensions of the definitive cemented stem is inserted and tapped into the femur to ensure that the chips are firmly impacted. Finally, a standard stem is implanted into the newly created medullary canal using bone cement. To date several studies from Europe have shown favorable results with this technique, with some excellent long-term results reported.

Advantages of IBG include the restoration of the bone stock in the proximal femur, the use of standard length cemented stems and preserving the diaphysis for re-revision. As disadvantages of the technique: longer surgical time, increased blood loss and the necessity of a bone bank can be mentioned.

The goals of revision total hip on the femoral side are to achieve long term stable fixation, improve quality of life and minimise complications such as intra-operative fracture or dislocation. Ideally these stems will preserve or restore bone stock. Modular titanium stems were first introduced in North America around 2000. They gained popularity as an option for treating Paprosky 3B and 4 defects.

Several studies at our institution have compared modular titanium stems with monoblock cobalt chromium stems. The main outcomes of interest were quality of life. We also looked at complications such as intra-operative fracture and post-operative dislocation. We also compared these 2 stems with respect to restoration or preservation of bone stock. In 2 studies we showed that modular titanium stems gave superior functional outcomes as well as decreased complications compared to a match cohort of monoblock cobalt chromium stems.

As mentioned, one of the initial reasons for introduction of these stems was to address larger femoral defects where failure rates with monoblock cobalt chromium stems were unacceptably high. We followed a group of 65 patients at 5–10 years post revision with a modular fluted titanium stem. Excellent fixation was obtained with no cases of aseptic loosening. However, there were 5 cases of fracture of the modular junction.

Due to concerns of fracture of the modular junction, more recently, at our institution, we have switched to almost 100% monoblock fluted titanium stems. We recently reviewed our first 100 cases of femoral revision with a monoblock stem. Excellent fixation was achieved with no cases of aseptic loosening. Quality of life outcomes were similar to our previous reported series on modular tapered titanium stems.

Both monoblock and modular fluted titanium stems can give excellent fixation and excellent functional outcomes. This leaves a choice for the surgeon. For the low volume revision surgeon modular tapered stems are probably the right choice.

Higher volume surgeons or surgeons very comfortable with performing femoral revision may want to consider monoblock stems. If one is making the switch it would be easiest to start with a simple case. Such a case would be one that can be done with a endofemoral approach. In this approach the greater trochanter is available as the key landmark for reaming. After the surgeon is comfortable with this stem more complex cases can easily be handled with the monoblock stem.

In summary, both modular and monoblock titanium stems are excellent options for femoral revision. As one becomes more familiar with the monoblock stem it can easily become your workhorse for femoral revision. At our institution we introduced a monoblock titanium stem in 2011. It started out at 50% of cases and now it is virtually used in almost 100% of revision cases.

The unacceptable failure rate of cemented femoral revisions led to many different cementless femoral designs employing fixation in the damaged proximal femur with biological coatings limited to this area. The results of these devices were uniformly poor and were abandoned for the most part by the mid-1990's.

Fully porous coated devices employing distal fixation in the diaphysis emerged as the gold standard for revisions with several authors reporting greater than 90% success rate 8–10 years of follow-up. Surgical techniques and ease of insertion improved with the introduction of the extended trochanteric osteotomy as well as curved, long, fully porous coated stems with diameters up to 23mm. The limits of these stems were stretched to include any stem diameter in which even 1–2cm of diaphyseal contact could be achieved. When diaphyseal fixation was not possible (Type IV), the alternatives were either impaction grafting or allograft prosthetic composite (APC).

As the results of fully porous coated stems were very carefully scrutinised, it became apparent that certain types of bone loss did not yield the most satisfactory results both clinically and radiographically.

When less than 4cm of diaphyseal press fit (Type IIIB) was achieved, the mechanical failure rate (MFR) was over 25%. It also became apparent that even when there was 4–6cm diaphyseal contact (Type IIIA), and the stem diameter was 18mm or greater, post-operative pain and function scores were significantly less than those with smaller diameter stems. This was probably due to poorer quality bone.

Many of these Type IIIA and Type IIIB femurs had severe proximal torsional remodeling leading to marked distortion of anteversion. This made judging the amount of anteversion to apply to the stem at the time of insertion very difficult, leading to higher rates of dislocation. These distortions were not present in Type I and Type II femurs.

This chain of events which was a combination of minimal diaphyseal fixation, excessively stiff stems and higher dislocation rates led to the conversion to modular type stems when these conditions existed.

For the past 13 years, low modulus taper stems of the Wagner design have been used for almost all Type IIIA and Type IIIB bone defects. The taper design with fluted splines allows for fixation when there is less than 2cm of diaphysis.

The results in these femurs even with diameters of up to 26mm have led to very low MFRs and significantly less thigh pain. Independent anteversion adjustment is also a huge advantage in these modular stems. Similar success rates, albeit with less follow-up, have been noted in Type IV femurs.

The interest in osteolysis has waned largely due to the impact of crosslinked polyethylene and the “rarity” of this phenomenon. However, the basic process still remains: particles, motion observed with unstable implants and host specific factors all play a role in bone loss around implants. There are 2 predominant patterns of lysis: Linear versus Expansile. Linear Lysis: is focal bone loss at the interface as seen in the bone cement interface in when using acrylic or at the implant-host interface with porous ingrowth/ongrowth implants. Expansile Lysis: is observed in less contained regions such as the retro- and supra-acetabular regions around the socket. These lesions can also be quite extensive yet may be subtle in appearance.

Imaging is essential in identifying the extent and magnitude of osteolysis. Available modalities include plain radiographs although they can be of limited value in that even with oblique views, they often underestimate the degree of bone loss. CT scans are useful but can be limited by artifact. Several centers have explored the role of MRI in assessing lysis. It can be useful for bone loss and provides excellent assessment for soft tissue: abductors, neurovascular structures. Metal artifact reduction sequencing is required to maximise information obtainable.

Management of osteolysis: Identification and monitoring periprosthetic osteolysis is a crucial element of patient care. Progressive bone loss leading to loss of fixation and the potential risk for periprosthetic fracture is a real possibility and early recognition and intervention is a priority. The basic Guiding Principles of management are centered around several key elements including the source of osteolysis and degree, the fixation of implant, the location of lysis, the track record of implant system, the presence of patient symptoms (if any), and finally the patient age, activity level, and general health.

Specifics of treatment of osteolysis around the acetabulum: With cemented sockets, lysis is typically seen late and frequently at the bone-cement interface. It is often associated with a loose implant and the prime indication for surgery may be pain. Treatment involves implant removal and revision with an uncemented cup and bone grafting or augmentation as needed.

With uncemented sockets in the setting of osteolysis, there are several factors to consider. These have been stratified by Rubash, Maloney, and Paprosky. The treatment of these sockets has been summarised as follows: for Type I and Type II with limited lysis, lesional treatment such as debridement and bone grafting with head and polyethylene exchange has been suggested. WATCH for impingement!!!! Graft defects via trap-doors can be performed but make the door big enough to graft. Small doors and grafting through screw holes is at best marginal. In instances of compromised locking mechanisms, consider cementing the liner into the shell.

For Type II and Type III implants, revision of the component is recommended. With the currently available cementless cup extraction tools, I rarely hesitate to remove a cup with moderate lysis and a broken locking mechanism: better access to lytic areas, better grafting achieved. CAVEAT #1: the disadvantage of implant removal is that it is clearly a bigger procedure and fixation of the new implant may be more difficult. Risks vs. rewards. CAVEAT #2: Socket revision in the setting of failed MOM implants has some unique “issues”. In the Vancouver series, almost 25% of the revision cups failed to achieve biologic fixation. As such, recommendation for using “enhanced” porous implants during revision seems prudent. Additionally, despite the use of larger diameter heads, instability rates remain high.

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 a cup with minimum diameter of 66mm in men and 62mm 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.

Uncemented acetabular component fixation remains the gold standard for managing various defects in the revision hip setting. Multiple series have demonstrated over 90% ten-year survivorship of these constructs. Modern “enhanced” metals such as trabecular tantalum and titanium continue to perform well and are growing in popularity. So called “jumbo” cups, diameters >=62mm in females and >=66mm in males have demonstrated excellent survivorship. Good bony support with viable bone and stable initial fixation is necessary for long-term success. It is unknown how much remaining bone is necessary for reliable ingrowth with modern enhanced metals. The location of the remaining bone is probably more important than the absolute amount remaining. Occasionally, the uncemented cup must be augmented with metal augments or even a so-called “cup cage” construct. Even in these situations, the uncemented cup remains the workhorse of revision THA due to its ingrowth potential and excellent track record. Augments are commercially available in various shapes and sizes to assist in the management of cavitary, segmental and combined defects while restoring the desired cup position. Trials are available to ensure good approximation of the augment to remaining bone. The constructs are typically “unitised” to the cup via bone cement. Available data show excellent survivorship of augmented constructs for these challenging reconstructions.

Uncontained acetabular defects with loss of superior iliac and posterior column support (Paprosky 3) represent a reconstructive challenge as the deficient bone will preclude the use of a conventional hemispherical cup. Such defects can be addressed with large metallic constructs like cages with and without allograft, custom tri-flange cups, and more recently with trabecular metal augments. An underutilised alternative is impaction bone grafting, after creating a contained cavitary defect with a reinforcement mesh. This reconstructive option delivers a large volume of bone while using a small-size socket fixed with acrylic cement.

Between 2005 and 2014, 21 patients with a Paprosky 3B acetabular defect were treated with cancellous, fresh frozen impaction grafting supported by a peripheral reinforcement mesh secured to the pelvis with screws. A cemented all-polyethylene cup was used. Pre-operative diagnosis was aseptic loosening (15 cemented and 6 uncemented). The femoral component was revised in 10 patients. Post-operative course consisted of 3 months of protected weight bearing. Patients were followed clinically and radiographically.

One patient had an incomplete post-operative sciatic palsy. After a mean follow up of 47 months (13 to 128) none of the patients required re-revision of the acetabular component. One asymptomatic patient presented with aseptic loosening 9 years post-operatively. Hardware failure was not observed. All patients had radiographic signs of graft incorporation and bone remodeling. There were no dislocations.

The early and mid-term results of revisions of large acetabular defects with this technique are encouraging. Reconstitution of hip center of rotation and bone stock with the use of a small-size implant makes this technique an attractive option for large defects. Longer follow-up is needed to assess survivability.

The treatment of extensive bone loss and massive acetabular defects is a challenging procedure, especially in cases with concomitant pelvic discontinuity (PD). Pelvic discontinuity describes the separation of the ilium proximally from the ischio-pubic region distally. The appropriate treatment strategy is to restore a stable continuity between the ischium and the ilium to reconstruct the anatomical hip center. Several treatment options such as antiprotrusio cages, metal augments, reconstruction cages with screw fixation, structural allograft with plating, jumbo cups, oblong cups and custom-made triflange acetabular components have been described as possible treatment options. Cage and/or ring constructs or acetabular allograft are commonly used techniques with unsatisfactory results and high failure rates. More favorable results have been presented with custom triflange acetabular components (CTAC), although the results are still unsatisfactory. Three-dimensional printing technology (3DP) has already become part of the surgical practice. In this context, preliminary clinical and radiological results using a 3D-printed custom acetabular component in the management of extensive acetabular defects are presented. The overall complication rate was 33.3 %. In one out of 15 patients (6.6 %), implant-associated complication occurred revealing an overall implant-associated survival rate of 93.3%. The 3D-printed custom acetabular component suggests a promising future, although the manufacturing process has high costs and the complication rate is still high.

Nutritional Status and Short-Term Outcomes Following THA; Initial Metal Ion Levels Predict Risk in MoM THA; THA Bearing Surface Trends in the US ‘07- ’14; Dislocation Following Two-Stage Revision THA; Timing of Primary THA Prior to or After Lumbar Spine Fusion; Failure Rate of Failed Constrained Liner Revision; ESR and CRP vs. Reinfection Risk in Two-Stage Revision?; Mechanical Complications of THA Based on Approach; Impaction Force and Taper-Trunnion Stability in THA; TKA in Patients Less Than 50 Years of Age; Post-operative Mechanical Axis and 20-year TKA Survival and Function; Return to Moderate to High-intensity Sports after UKA; “Running Two Rooms” and Patient Safety in TJA; Varus and Implant Migration and Contact Kinematics after TKA; Quadriceps Snips in 321 Revision TKAs; Tubercle Proximalization for Patella Infera in Revision TKA; Anterior Condylar Height and Flexion in TKA; Compression Bandage Following Primary TKA; Unsupervised Exercise vs. Traditional PT After Primary TKA and UKA.

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

Cup Cage Construct – in this construct there must be enough bleeding host bone to stabilise the ultraporous 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 ultraporous 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.

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.

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 3-D reconstruction using rapid prototyping technology. 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 two minor complications managed non-operatively, 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 w 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.

Until recently, research has failed to show a difference between posterior-stabilised (PS) and cruciate-retaining (CR) designs in total knee arthroplasty (TKA). This classic debate has been given pause over the past decade due to futile efforts to prove one design superior over the other. Recently, anterior-lipped and more conforming CR bearings have emerged to substitute for the PCL, if absent, damaged or resected, and obviate the need for the archaic cam-post mechanism of a traditional PS design. Advantages of avoiding a PS TKA include decreasing the risk of femoral condylar fracture that may occur via the box cut, as well as decreasing operative time by removing that step in the procedure. Avoiding a post-cam mechanism also removes the articulation that is a source of wear, post deformation, breakage, or dislocation. Patella clunk is also associated solely with PS designs.

Modern anterior lipped inserts in PCL-deficient TKAs (CS) have demonstrated similar functional outcomes compared to PS knees. A prospective randomised controlled trial of 28 patients undergoing bilateral TKAs had a PS bearing in one knee and a contralateral CS insert with the PCL excised and reported no functional outcome difference at 5-year follow up. Scott and co-authors compared 56 PS TKAs to 55 TKAs with anterior-lipped inserts in a randomised, prospective study and found no functional outcome differences at minimum two-year follow up with tourniquet times significantly longer in the PS group. In a recent report, 43 anterior-lipped compared to 39 matched PS TKAs had equivalent function scores at minimum 1-year follow-up. Ultra-congruent bearings provide inherent stability in TKA and two studies have reported identical functional outcomes compared to PS TKAs.

Equivalent functional outcomes in multiple studies comparing CR-type bearings and PS TKAs, combined with the potential deleterious outcomes associated with PS designs, preclude the need for PS TKA designs in the modern health care environment. Hence, PS TKA designs are truly “vestigial organs”, and should be relegated to historical interest.

First generation condylar knee replacements suffered from two prominent observations: 1) Difficulty in stair climbing, 2) Limited range of motion (ROM).

Improved understanding of knee kinematics, the importance of femoral rollback, and enhanced stability in flexion led to 2 differing schools of thought: Posterior Cruciate ligament retention vs. Posterior Cruciate substitution. The advantages of posterior cruciate substitution include predictable cam-post engagement leading to rollback, predictable ROM, stability during stair climbing, ease of knee balancing regardless of degree of angular deformity, and avoidance of issues such as PCL tightness / laxity at time of index procedure, as well as late ligament disruption leading to late instability.

Evolution has shown that human appendages that no longer served a purpose, slowly shrivel up. As we have seen with the appendix, the coccyx, and the erector pili muscles, these vestigial organs no longer are necessary for daily function and are destined for obsolescence. I submit: the PCL in knee arthroplasty IS THE VESTIGIAL ORGAN: not the posterior stabilizing mechanism!

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 gaps 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, 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.

Additionally, because most tibias are in varus in the native state, placement of the tibial component in a neutral position results in a valgus orientated position during weight bearing post-operatively. Placing the tibial component in a varus, kinematic aligned position negates this deleterious condition and has been linked to improved outcomes in recent studies.

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 is safe with respect to survivorship and provides better function with a more “natural” feeling knee.

Even though primary total knee arthroplasty involves resurfacing the joint with metal and plastic it is much more of a soft tissue operation than it is a bony procedure. The idea that altering the planned bony resection by a few degrees on either the tibial or femoral side of the joint might somehow eliminate the multifactorial pain complaints and reduced patient satisfaction seen in some 20% or more of cases in reported clinical series is clearly overly optimistic. Axial alignment is important, but no more so than the level of distal femoral resection, tibial and femoral rotation, tibial resection level and downslope and femoral sagittal plane alignment. The real problem is that errors in component positioning are common, rarely made one at a time, and are made more common by greater procedural complexity. No matter the resection method (let alone the resection target!) errors are commonly linked and iterative. For example: femoral malrotation on an under-resected distal femur (in a knee with minimal arthritic wear to begin with) can contribute to corresponding tibial malrotation helped by a “floated” tibial trial on an all too often overly resected and downsloped tibial surface that has been recut to allow full extension with the under-resected femur (and now also results in AP laxity in flexion). Small changes in the alignment target will not fix this!

On the other hand: Kinematic alignment individualised to the patient's anatomy as a means of reducing soft tissue imbalance and minimizing ligamentous releases is actually a reasonable objective and a laudable goal on the surface. The problem with operationalizing this widely relates to what is currently required to try and reliably achieve this goal using currently available implants and technology. In the early 1980's the proponents of “anatomic” alignment with a residual 2- to 3-degree varus tibial resection and corresponding joint obliquity were Hungerford and Krackow. This concept was widely adopted but proved to be fraught with difficulty in the hands of community based surgeons in that era due to common excessive varus tibial resection errors and resulting premature implant failures. Recent reports on kinematic alignment involve a plethora of technology combinations including pre-operative CT (or MRI) for 3D reconstruction and planning, custom jig fabrication, and navigated bony preparation or individualised bony cuts off of patient specific jigs. The goal is to allow customised resections that “estimate” original cartilage thickness and bone erosion and seek to replicate the original however native anatomy and provide better precision for bone resection. Even when successful this is often followed by placement of a standard implant not too different from those in the 80's and 90's which may well have one femoral articular “J curve” for all patents, a single patellofemoral groove design and anatomic shape for all, and that makes use of a central keel on a nonanatomic tibial design with limited sizing increments, all implanted into a patient without an ACL and not infrequently PCL deficient as well. And all of this is done with the hope of restoring the normal original knee kinematics!

The frequent combination of several of the above factors clinically in a single knee may help explain some of the variability in results of kinematic alignment reported by some authors even after excluding certain pre-operative deformities (excess valgus or varus).

For now mechanical alignment methods and instrumentation should remain the standard of care for routine TKA practice for most, and in complex primary cases for all.

The extraordinary majesty of THR, as it burst onto the scene 60 years ago, both dazzled and blinded. It dazzled patients and surgeons alike and simultaneously obstructed a clear eyed assessment of the human costs. It behooves current practitioners, who have benefited mightily by our progress, to pause and reflect thoughtfully on that progress. Look no further than the fact that the treatment of a benign disease left one patient out of every 50 dead. Dead from a pulmonary embolus and that over 25% of the patients threw pulmonary emboli.

What were the big six major disadvantages: 1) Fatal pulmonary emboli; 2) Prosthetic joint infection; 3) Failure of fixation; 4) Dislocation; 5) Periprosthetic osteolysis; 6) Prolonged hospitalization.

Start with the observation that THR in the modern era began with Charnley's experiment with Teflon articulations. Of the nearly 300 such operations done, nearly 300 failed.

Ultrahigh molecular weight polyethylene was better- much better. But still it produced wear and periprosthetic osteolysis, afflicting an estimated 1 million patients. Periprosthetic osteolysis became the most common reason for failure, the most common reason for reoperation, the most common reason for fracture, and the most common reason for extremely difficult re-operations requiring major grafting.

Reoperation rates in certain series were 20 to 30% from loosening and 20 to 40% from osteolysis. Dislocation catapulted the unsuspecting patient to the floor at a rate of one out of 20 patients and the initial rate of prosthetic joint infection was 10%. Most patients were hospitalised in the new neighborhood of 2.5 weeks, at huge expense.

Massive progress has been made but forget not that this striking progress was not obsessively linear. Recall the recent, extraordinary and continuing massive failure of metal-on-metal total hip replacements, despite 40 prior years of experience, predicting that metal-on-metal total joints should be ‘just fine’.

Over the past six decades every one of the six major disadvantages listed above has been reduced by an order of magnitude. The challenge to you is to continue that progress.

There are a number of different non-operative management options for patients with a painful knee secondary to osteoarthritis (OA). In 2013 the American Academy of Orthopaedic Surgeons developed an evidence-based clinical practice guideline addressing treatment of osteoarthritis of the knee. Strength of recommendations were designated as strong, moderate and inconclusive. Strong recommendations included: self-management program, NSAIDs or tramadol and no acupuncture, no glucosamine and chondroitin sulfate and no hyaluronic acid. The “No” recommendations for hyaluronic acid and glucosamine and chondroitin sulfate were quite controversial because orthopaedic surgeons argued that some of their patients benefited from these treatments. Moderate strength recommendations included weight loss, lateral wedge insoles and needle lavage. The evidence-based data was inconclusive with respect to valgus force unloading brace, manual physical therapy, acetaminophen, opioids and pain patches. The effectiveness of corticosteroid and platelet rich plasma (PRP) injections were also inconclusive.

Unloader braces are available to decrease pressure on the involved compartment. There is data showing that these braces can be effective for some patients. However, there are concerns with patient compliance because of poor fit and discomfort. These braces seemed to be tolerated best when used for sports activities in patients with medial compartment arthritis.

Oral anti-inflammatory agents are effective in relieving pain and are a good first line agent for patients with OA. There is significant interest in the use of PRP injections for management of patients with knee OA particularly when patients have already received a steroid and/or a hyaluronic acid injection. To date there are no appropriately powered multi-centered randomised trials demonstrating that PRP is effective in decreasing pain and function in knee OA. However, there are some studies that suggest PRP can be helpful for patients with OA. Further studies to determine the indications for PRP injections are necessary. PRP injections are not covered by insurance in the United States.

In summary, the management of patients with painful OA of the knee needs to be individualised based on patient symptoms and expectations. Non-operative management can be effective in limiting pain and enhancing function.

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

If there is an associated knee deformity, then an osteotomy was performed. 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 both femur and tibia, 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%.

Retrieval studies of 24 fresh osteochondral grafts obtained at graft revision or conversion to total knee replacement at an average of 12 years (5 – 25) revealed the following. In the areas where the graft was still intact, the cartilage was of normal thickness and architecture. Matrix staining was normal except in the superficial and upper mid-zones. Chondrocytes were mostly viable but there was chondrocyte clusters and loss of chondrocyte polarity. Host bone had extended to the calcified cartilage but variable remnants of dead bone surrounded by live bone persisted. With a stable osseous base the hyaline cartilage portion of the graft can survive for up to 25 years.

Since 2005, the author has performed nearly 1000 Oxford medial unicompartmental arthroplasties (UKA) using a mobile bearing. The indications are 1) Isolated medial compartment osteoarthritis with ‘bone-on-bone’ contact, which has failed prior conservative treatment, 2) Medial femoral condyle avascular necrosis or spontaneous osteonecrosis, which has failed prior conservative treatment.

Patients are recommended for UKA only if the following anatomic requirements are met: 1) Intact ACL, 2) Full thickness articular cartilage wear limited to the anterior half of the medial tibial plateau, 3) Unaffected lateral compartment cartilage, 4) Unaffected patellar cartilage on the lateral facet, 5) Less than 10 degrees of flexion deformity, 6) Over 100 degrees of knee flexion, and 7) Varus deformity not exceeding 15 degrees.

Exclusion criteria for surgery are BMI of more than 30, prior high tibial osteotomy, and inflammatory arthritis. All cases were performed with a tourniquet inflated using a minimally-invasive incision with a quadriceps-sparing approach. Both femoral and tibial components were cemented. Most patients were discharged home the next morning; bilaterals usually stayed a day longer.

We have previously described our results and the factors determining alignment. In a more recent study, we have compared the coronal post-operative limb alignment and knee joint line obliquity after medial UKA with a clinically and radiologically (less than Grade 2 medial OA) normal contralateral lower limb. In our series, we have had 1 revision for aseptic loosening of both components, conversion to TKRs in a patient with bilateral UKAs who developed rheumatoid arthritis 3 years later, and 9 meniscal dislocations. There have been no cases of wound infections and thromboembolism. We have reviewed our patients with a minimum 10-year follow-up which will be presented. The vast majority of our patients have been generally very satisfied with the results. Our study shows that most patients (who have no disease in the contralateral knee) regain their ‘natural’ alignment and joint line obliquity comparable to their contralateral limb.

Over the past few years our percentage of UKAs has been steadily rising to about a third of our knee cases. UKA serves as a definitive procedure in the elderly. We see it as a suitable procedure in middle-aged patients who want an operation that provides a quick recovery, full function and range of motion, and near-normal kinematics, with the understanding that they have a small chance of conversion to a total knee arthroplasty in the future.

Despite the successful, durable results, concern remains for using TKA in patients with isolated patello-femoral OA, as it requires an extensive surgical exposure and bone resection, a long recovery time, and a potentially more complex revision than that required for a patient with a failed patello-femoral arthroplasty (PFA).

PFA was introduced in the late 1970s. While PFA was successful in providing pain relief, the procedure did not gain widespread use because of initial design limitations that predisposed to PF maltracking, catching, and subluxation. The mechanical complications associated with first-generation PFA offset the potential advantages of maintaining the knee's native soft tissues and spurred efforts to improve implant design, and to refine surgical techniques and patient selection.

Over the past two decades, second generation PFAs incorporated changes in implant design and instrumentation and have shown promising results when used in the properly selected patient population. In addition, with improved instrumentation and robotics, adequate implant alignment and rotation can be achieved in the majority of patients, including those with severe patellofemoral dysplasia.

Our meta-analysis of TKA and PFA for the treatment of isolated patello-femoral OA showed that the rate of complications of patients undergoing PFA was 30% after a median follow up of 5.3 years, which is significantly higher than the 7% rate of complications in patients who underwent TKA. The most frequent type of complication associated with PFA was mechanical (including loosening and instability), which is consistent with the malalignment and maltracking-related failures previously reported. The incidence of re-operation after PFA (21%) was significantly higher than that seen after TKA (2%). The most frequent indication for re-operation after PFA was mechanical failure (7%), followed by progression of OA (6%), and persistent pain or stiffness (5%). The most common re-operations after PFA were conversion to TKA, revision of PFA components, lateral releases, open or arthroscopic debridement, manipulations under anesthesia, and bony and/or soft tissue extensor mechanism re-alignment procedures. In our study, 11% of patients treated with PFA underwent a revision arthroplasty, with 4% undergoing revision PFA and 7% undergoing conversion to TKA.

Our comparison of patients who were treated with second-generation PFA designs versus TKA showed no difference in the rate of complications, re-operation, or revision arthroplasty. Additionally, length of follow-up did not significantly influence any of these outcomes when comparing second-generation PFA and TKA.

These observations provide support for the use of current PFA designs. The mechanical complications and subsequent re-operations that affected first-generation PFA designs appear to be of less concern with proper patient selection, meticulous surgical technique, current implant designs and peri-operative care. While it is difficult to predict the survivorship of current PFA designs, it is our expectation that patient selection will continue to be a critical component in determining long-term results. The potential benefit of providing pain relief while preserving the tibiofemoral articulations makes PFA a promising treatment option.

The vast majority of fractures around the knee will heal with well-done internal fixation. TKA has a role in several scenarios. Acute TKA can be effective for fractures of the distal femur (especially periprosthetic) in very elderly patients where internal fixation attempts are likely to fail. Acute TKA for tibia plateau fractures may have a role in fractures in the elderly with pre-existing DJD and relatively simple fracture patterns. There is very little published literature regarding the outcomes of TKA for acute tibial plateau fracture and caution is advised until more data is available. TKA is commonly indicated for failed fixation and post-traumatic arthritis. Challenges include managing retained hardware, soft tissue injury and contracture, unusual ligamentous imbalances, and multiple prior incisions and/or flaps. Occasionally, a partial hardware removal may be appropriate. If extensive or multiple incisions are needed for hardware removal it may be wise to stage the reconstruction after soft tissue recovery. The available data on TKA for post-traumatic reconstructions generally demonstrate predictable functional improvement but higher complications.

It is unusual to require the use of a total knee implant with more constraint than a posterior-stabilised post in primary knee arthroplasty. The most common indication is a knee with a severe deformity, usually fixed valgus with an incompetent medial collateral ligament, and an inability to correctly balance the knee in both flexion and extension. The pre-operative deformity is usually greater than 15–20 degrees fixed valgus and may be associated with a severe flexion contracture. This is usually seen in an elderly female patient with advanced osteoarthritis. Those pre-operative diagnoses more likely to require a constrained design include advanced rheumatoid arthritis, true neuropathic joint, and the “Charcot-like” joint due to bone loss or crystalline arthritis. Rarely, patients with periarticular knee Paget's disease of bone may require more constraint following correction of a severe deformity through the knee joint. Beware those patients with a staple or screw at the medial epicondyle or those with severe heterotopic ossification at the medial joint line, as this may signify a serious prior injury to the medial collateral ligament. Finally, there is a possibility of inadvertent division of the medial collateral ligament intra-operatively. Although this situation may be treated with suture repair and bracing, my choice is to switch to more constraint and early unbraced motion.

There are over 20 designs of varus-valgus constrained components, with a variety of tibial post designs with specific rotary and angular biomechanics, and many have the option of adding modular stems. Our experience with constrained, non-linked designs has been favorable with both the use of nonmodular and modular stem extensions. Longer-term survival analysis has shown a 96% survival at 10 years with these constrained components. However, the older designs frequently required a lateral retinacular release for proper patella tracking, and there were patella complications (fracture and osteonecrosis) in 16%. With a more modern design, over the past 12 years, the need for a lateral retinacular release and patella complications have been notably decreased. Varus-valgus constrained components have a small but important role in primary total knee arthroplasty for patients with severe deformity or an incompetent medial collateral ligament.

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 independent 3-dimensional medial and lateral femoral condylar geometry, and a difference has been shown to exist between the natural flexion-extension arc and the transepicondylar axis. 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.

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.

The extent of soft-tissue release and the exact structures that need to be released to correct deformity and balance the knee has been a controversial subject in primary total knee arthroplasty. Asian patients often present late and consequently may have profound deformities due to significant bone loss and contractures on the concave side, and stretching of the collateral ligament on the convex side. Extra-articular deformities may aggravate the situation further and make correction of these deformities and restoration of ‘balance’ more arduous. These considerations do not apply if a hinged prosthesis is used, as may be warranted in an elderly, low-demand patient. However, in active, younger patients, it may be best to avoid use of excess constraint by balancing the soft-tissues and using the least constrained implant.

Releasing collateral ligaments 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, valgus, flexion and hyperextension deformities without collateral ligament release.

The steps are: 1) Determining pre-operatively whether deformity is predominantly intra-articular or extra-articular, 2) Individualizing the valgus resection angle and bony resection depth, 3) Meticulous removal of osteophytes, 4) Reduction osteotomy, posteromedial capsule resection, sliding medial or lateral condylar osteotomy, extra-articular corrective osteotomy, 5) Compensating for bone loss, 6)Only rarely deploying a more constrained device.

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

Perhaps the most significant developments in joint replacement surgery in the past decade have been in the area of multimodal peri-operative management reducing pain, nausea, and length of stay leading to outpatient joint replacement surgery with recovery at home. The surgical procedures included in the outpatient program have expanded from Partial Knee Arthroplasty to Primary TKA, Primary THA, and selected revision cases. Emerging data demonstrate safety, reduced cost, and reduced resources.

Since 2011, we helped develop and implement an outpatient program as part of 76 participating physician-owned ambulatory facilities in 19 states − 19,415 joint replacements have been performed. The cohort included 6,146 TKA, 5,102 THA, 7,227 partial knee replacements, and 940 revisions and TSA. Patients had a mean age of 58 years and 50% of the patients were female; 97% of patients were discharged same day, the deep infection rate was 0.2%, and the readmission rate was 0.3%.

The outpatient program centers on the patient needs, family engagement, essentials of home recovery, pre-operative education, efficient surgery, and a surgeon controlled environment with highly standardised care. This is a distinct shift in today's health care environment, which has seen the expansion of regulatory demands; focus on Electronic Health Records (EHR), and distractions from real discussions of demonstrated value creation. The future is bright for both ASC and hospital development of successful outpatient joint replacement program for patients and surgeons alike.

Clinical cases will be presented to a panel of experienced arthroplasty surgeons to illustrate how principles tempered by experience, are applied to challenging problems. (request pertinent additional material from kellyvince@mac.com)

Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) is a devastating complication. It is associated with high morbidity and mortality. It remains, unfortunately, one of the most common modes of failure in TKA. Much attention has been paid to the treatment of PJI once it occurs. Our attention, however, should focus on how to reduce the risk of PJI from developing in the first place. Infection prevention should focus on reducing modifiable risk factors that place patients at increasing risk for developing PJI. These areas include pre-operative patient optimization and intra-operative measures to reduce risk.

Pre-operative Modifiable Risk Factors: There are several patient related factors that have been shown to increase patient's risk of developing PJI. Many of these are modifiable risk factors can and should be optimised prior to surgery. Obesity and in particular Morbid Obesity (BMI >40) has a strong association with increased risk of PJI. Appropriate and healthy weight loss strategies should be instituted prior to elective TKA. Uncontrolled Diabetes (Hgb A1C >8) and poor glycemic control around the time of surgery increases the risk for complications, especially PJI. Malnutrition should be screened for in at-risk patients. Low Albumin levels are a risk factor for PJI and should be corrected. Patients should be required to stop smoking 6 weeks prior to surgery to lower risk. Low Vitamin D levels have been show to increase risk of PJI. Reduction of colonization of patient's nares with methicillin sensitive (MSSA) and resistant (MRSA) staphylococcus should be addressed with a screen and treat program.

Intra-operative Measures to Reduce PJI: During surgery, several steps should be taken to reduce risk of infection. Appropriate dosing and timing of antibiotics is critical and a first generation cephalosporin remains the antibiotic of choice. The use of antibiotic cement remains controversial with regards to its PJI prophylactic effectiveness. The utilization of a dilute betadine lavage has demonstrated decreased rate of PJI. Maintaining normothermia is critical to improve the body's ability to fight infection. An alcohol-based skin preparation can reduce skin flora as a cause of PJI. Appropriate selection of skin incisions and soft tissue handling can reduce wound healing problems and reduce development of PJI. Likewise, the use of occlusive dressing has been shown to promote wound healing and reduce PJI rates.

While advances in laboratory and imaging modalities facilitate the diagnosis of periprosthetic joint infection (PJI), clinical suspicion and a thorough history and physical remain the basis of evaluation. If clinical suspicion is high, the evaluation should be more vigorous, and vice versa.

The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are inexpensive as well as ubiquitous, and should be obtained as a preliminary screening tool. These tests have been found to be cost-effective and highly sensitive. If both tests are negative, there is a low risk of periprosthetic joint infection (i.e., good negative predictive value). Positive results on both tests, in contrast, are not as specific but again raise suspicion.

When either the ESR or CRP is elevated, or if the clinical suspicion for infection is high, aspiration of the knee joint is suggested. Synovial fluid should be sent for a synovial fluid white blood cell count (WBC), differential and culture. Given the ability to get three data points from one intervention, arthrocentesis, is the best single maneuver the physician can perform to rule in or out PJI. The synovial fluid WBC count has demonstrated in multiple studies excellent specificity and sensitivity in the diagnosis of infection. Based on multiple recent studies, the proceedings of the International Consensus on PJI recommend cut-offs for the synovial fluid WBC count as >3000 cells/mL and > 80% neutrophils for the differential.

Synovial fluid biomarkers represent an expanding area of clinical interests based on the unique cascade of gene expression that occurs in white blood cells in response to pathogens. Deirmegian et al. described the unique gene expression and biomarker production by neutrophils in response to bacteria that are detectable in synovial fluid. Specifically, alpha-defensin is one such antimicrobial peptide. Along with synovial CRP, alpha-defensin can be measured in a currently commercially-available immunoassays.

The diagnosis of PJI can be difficult to make in spite of the variety of tests available. That being said, the diagnosis is easily made in our experience in 90% of patients by getting an ESR and CRP followed by selective aspiration of the joint if these values are elevated or if the clinical suspicion is high. Synovial fluid obtained should be sent for a synovial fluid WBC count, differential and cultures.

The infected joint arthroplasty continues to be a very challenging problem. Its management remains expensive, and places an increasing burden on health care systems. It also leads to a long and difficult course for the patient, and frequently a suboptimal functional outcome. The choice of a particular treatment program will be influenced by a number of factors. These include the acuteness or chronicity of the infection; the infecting organism(s), its antibiotic sensitivity profile and its ability to manufacture glycocalyx; the health of the patient; the fixation of the prosthesis; the available bone stock; and the particular philosophy and training of the surgeon.

For most patients, antibiotics alone are not an acceptable method of treatment, and surgery is necessary. The standard of care for established infection is two stage revision with antibiotic loaded cement during the interval period and parental antibiotic therapy for six weeks. Single stage revision may have economic and functional advantages, however. We have devised a protocol that dictates the type of revision to be undertaken based on host, organism and local factors.

Our protocol has included single stage revision using antibiotic loaded cement in both THA and TKA. This was only undertaken when sensitive organisms were identified pre-operatively by aspiration and appropriate antibiotics were available to use in cement. Patients with immunocompromise, multiple infecting organisms or recurrent infection were excluded. Patients with extensive bone loss that required allograft reconstruction or where a cementless femoral component was necessary were also excluded.

Our algorithm was validated first in the hip and extended to infected TKA in 2004. This protocol has now been applied in over 100 TKA revisions for infection between 2004 and 2009. Our single stage revision rate is now over 25%. We continue to see a lower reinfection rate in these carefully selected patients, with high rates of infection control and satisfaction and better functional and quality of life scores than our two stage revision cases.

Whilst our indications are arbitrary and not based on specific biomarkers, we present excellent results for selective single stage exchange. A minimum three year follow-up suggests that these patients have shorter hospital stays, higher satisfaction rates and better knee scores. An ongoing evaluation is in place. One stage revision arthroplasty for infection offers potential clinical and economic advantages in selected patients.

Prevention and treatment of total joint infection is closely related to biofilm formation and concentration of antibiotics achieved in the area around the implants. Most total joint infections are caused by bacteria that enter the wound at the time of the operation. These bacteria can attach to surfaces and rapidly form biofilm that is highly resistant to antibiotics. Prophylactic antibiotics given intravenously achieve concentration of local antibiotics in the knee in response to intravenous antibiotics about 1/3 of that achieved in the serum, and the level is transient. This may be enough to treat the planktonic form of the bacteria, but far from enough to treat the biofilm. The concentration of antibiotics in the joint fluid achieved with antibiotics applied locally during surgery is 1000 times higher, and can be maintained throughout the procedure. High concentration persists in drainage fluid for 24 hours after surgery. Studies done with use of local antibiotics in spinal implant surgery indicate a major reduction in the rate of infection, and cost analysis shows remarkable monetary benefit to this effect.

Infected total joints benefit especially from direct application of antibiotics to the local area. 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 thousands of times 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.

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.

Preventing and treating infection in orthopaedic implant surgery requires achieving concentrations that are above the minimal biofilm eradication concentration. This can be achieved only with direct application.

Deep peri-prosthetic infection after partial or total knee arthroplasty is a disconcerting problem for patient and surgeon alike. The diagnosis of infection is sometimes obvious but frequently requires that the surgeon maintain a substantial index of suspicion for infection as the cause of pain or poor outcome after any joint arthroplasty. While surgical debridement with component retention is appropriate in a subgroup of patients with an acute peri-prosthetic infection, most delayed and chronic infections are best treated with component resection. With carefully selected patients and very aggressive debridement protocols some success has been demonstrated in Europe with single-stage exchange for infection. Most surgeons in North America, however, are unfamiliar with the very aggressive debridement techniques employed at European centers that promote single stage replant; and few surgeons in North America are currently comfortable in cementing a hinged total knee replacement in place for the typical infected TKA nor do they have the patience to re-prep and drape with an entirely new OR setup after debridement and prior to the insertion of the new implant − 2 steps that are often mentioned as important to the success of single stage exchange.

The pre-eminent role of two-stage exchange as the definitive treatment was established over 30 years ago. Two-stage exchange remains the gold-standard in treatment with an established track record from multiple centers and with multiple different types of infecting organisms. Some of the historical problems with two-stage exchange, such as limited mobility during the interval stage, have been mitigated with the development of effective articulating spacer techniques. Further, the emergence of drug resistant bacteria and the possibility of fungal infection make two-stage exchange the best choice for the majority of patients with deep periprosthetic joint infection in 2017.

Infection following total knee arthroplasty (TKA) can cause significant morbidity to the patient and be associated with significant costs and burdens to the health care system. Wound complications often initiate the cascade that can eventually lead to deep infection and implant failure. Galat et al. reported that wound complications following TKA requiring surgical treatment were associated with a 2-year cumulative risk of major reoperation and deep infection of 5.3% and 6.0%, respectively. Consequently, developing a systematic approach to the management of wound problems following TKA can potentially minimise subsequent complications.

Unlike the hip, the vascular supply to the soft tissue envelope to the knee is less robust and more sensitive to the trauma of surgery. Therefore, proper soft tissue handling and wound closure at the time of surgery can minimise potential wound drainage and breakdown post-operatively. Kim et al. showed, using a meta-analysis of the literature, that primary skin closure with staples demonstrated lower wound complications, decreased closure times, and lower resource utilization compared to sutures. However, a running subcuticular closure enables the most robust skin perfusion following TKA. Finally, the use of hydrofiber surgical dressings following surgery was associated with increased patient comfort and satisfaction and reduced the incidence of superficial surgical site infection.

A wound complication following TKA needs to be managed systematically and aggressively. A determination of whether the extent of the involvement is superficial or deep is critical. Antibiotics should not be started without first excluding the possibility of a deep infection. Weiss and Krackow recommended return to the operating room for wound drainage persisting beyond 7 days. While incisional negative pressure wound therapy can occasionally salvage the “at risk” draining wound following TKA, its utilization should be limited only to the time immediately following surgery and should not delay formal surgical debridement, if indicated. Finally, early wound flap coverage and co-management of wound complications with plastics surgery is associated with increased rates of prosthesis retention and limb salvage.

Prior implant designs have relied on a four-bar link theory and featured J-curve femoral components intended to recreate femoral rollback of the native knee, but this design could lead to anterior femoral sliding or paradoxical motion. Recent kinematic analyses of the native human knee have shown the medial compartment to be more stable to anteroposterior translation than the lateral, resulting in a “medial pivot” motion as the knee flexes. “Medial pivot” designs in total knee arthroplasty were introduced in the 1990s to attempt to re-create this motion. They consist of an asymmetric tibial insert with a highly congruent medial compartment and less conforming lateral compartment. The femoral component has a single radius of curvature and a high degree of conformity.

In vivo fluoroscopic studies have shown medial pivot designs to be successful in achieving its intended motion, while other cruciate-retaining designs had a higher incidence of paradoxical anterior translation and lateral condylar lift-off. Furthermore, numerous investigations have shown medial pivot designs to have excellent outcomes and survivorship at up to 10 years post-operatively. However, the contention in this debate that medial pivot designs avoid the need for ligament balancing is incorrect. Appropriate ligament balancing remains a crucial aspect of any successful total knee arthroplasty and is no less important based on the implant design utilised.

In the Methods section of all prior reports using a medial pivot design, the authors have noted that appropriate ligament balancing was obtained both in flexion and extension consistent with the recommended technique with other primary TKA implant designs. From a kinematic standpoint, this makes absolute sense. If a patient has a valgus imbalance with loose medial structures, then as the knee is brought into flexion the femur will not maintain congruency and contact with the conforming tibial surface – thus the medial pivot motion will be lost. Thus, balancing remains critical.

Lastly, although not the focal point of this debate, whether re-creation of a medial pivot motion in total knee arthroplasty actually improves patient outcomes remains an area of debate. A recent investigation by Warth and Meneghini, et al. demonstrated that re-creation of a medial-pivot pattern intra-operatively did not correlate with patient-reported outcomes at 1-year post-operatively. Thus, although the concept of a medial pivot design has merit, whether this will consistently improve outcomes and patient satisfaction remains to be seen.

Total knee arthroplasty is a successful procedure with good long-term results. Studies indicate that 15% – 25% of patients are dissatisfied with their total knee arthroplasty. In addition, return to sports activities is significantly lower than total hip arthroplasty with 34% – 42% of patients reporting decreased sports participation after their total knee arthroplasties.

Poor outcomes and failures are often associated with technical errors. These include malalignment and poor ligament balancing. Malalignment has been reported in up to 25% of all revision knee arthroplasties, and instability is responsible for over 20% of failures. Most studies show that proper alignment within 3 degrees is obtained in only 70% – 80% of cases.

Navigation has been shown in many studies to improve alignment. In 2015, Graves examined the Australian Joint Registry and found that computer navigated total knee arthroplasty was associated with a reduced revision rate in patients under 65 years of age. Navigation can improve alignment, but does not provide additional benefits of ligament balance.

Robotic-assisted surgery can assist in many of the variables that influence outcomes of total knee arthroplasty including: implant positioning, soft tissue balance, lower limb alignment, proper sizing.

The data on robotic-assisted unicompartmental arthroplasty is quite promising. Cytech showed that femoral and tibial alignment were both significantly more accurate than manual techniques with three times as many errors with the manually aligned patients. Pearle, et al. compared the cumulative revision rate at two years and showed this rate was significantly lower than data reported in most unicompartmental series, and lower revision rates than both Swedish and Australian registries. He also showed improved satisfaction scores at two years.

Pagnano has noted that optimal alignment may require some deviation from mechanically neutral alignment and individualization may be preferred. This is also likely to be a requirement of more customised or bi-cruciate retaining implant designs. The precision of robotic surgery may be necessary to obtain this individualised component alignment.

While robotic total knee arthroplasty requires further data to prove its value, more precise alignment and ligament balancing is likely to lead to improved outcomes, as Pearl, et al. and the Australian registry have shown.

While it is difficult to predict the future at this time, I believe robotic-assisted total knee arthroplasty is the future and that future begins now.

The use of robotics in total joint arthroplasty is the latest in a long list of expensive technologies that promise multiple positive outcomes, but come with an expensive price tag. In the last decade alone we've seen the same claims for navigation and patient specific instruments and implants. There are various current systems available including a robotic arm, robotic-guided cutting jigs and robotic milling systems.

For robotics to be widely adopted it will need to address the following concerns, which as of 2017 it has not.

1)

Cost - Very clearly the robotic units come with a significant price tag. Perhaps over time, like other technologies, they will reduce, but at present they are prohibitive for most institutions.

As with any new technology one must be wary of the claims superseding the results. In 2017 the jury is still out on the cost vs. benefit of robotic-assisted TKA.

Implant selection in TKA remains highly variable. Surgeons consider pre-operative deformity, patient factors such as BMI and bone quality, surgical experience, retention or substitution for the PCL, type of articulation and polyethylene, cost, and fixation with or without cement. We have most frequently implanted the same implant for the majority of patients. This is based on the fact that multiple large series of TKAs have demonstrated that the most durable TKAs have been non-modular metal-backed tibial components, retention of the PCL, with a cemented all-polyethylene patellar component. Polymer wear must be addressed for long-term durability.

One method for reducing polyethylene wear is eliminating modularity between a metal-backed tray and the articular bearing surface. This can be done with a metal-backed implant as with the IB-1, AGC, Vanguard Mono-lock, or with elimination of the metal backing via a one piece all-polyethylene tibial component. The all-polyethylene implants appear design and patient sensitive. We observed higher clinical failure rates in a flat-on-flat design. Other authors have observed improved survivorship with coronal dishing of the articular surfaces which centralises osseous stresses. All-polyethylene implants have promise in the future but require proven design and fixation design features

Stiffness after total knee replacement remains a significant factor in a suboptimal result after total knee arthroplasty. Interference with function including stair climbing, arising from a seated position, driving and return to activities of daily living and recreational sports are all compromised when stiffness results after knee replacement. The key indicator for resultant range of motion after knee replacement remains knee motion prior to surgery. A knee with limited motion prior to surgery will rarely achieve the same motion as a fully mobile knee and the patient should be counseled to this ultimate result. Patients with prior knee surgery, post-traumatic knee arthritis also tend to be stiffer after knee replacement. If a knee is stiff after replacement it is key to determine if there is a mechanical impediment to motion (e.g. implant sizing problem, overstuffing of the patellofemoral joint) and revision knee replacement to address this problem will be necessary and is best done when recognised.

When referring to a stiff knee after replacement flexion less than 90 degrees is generally accepted. Management of the knee with limited motion after knee replacement should first be treated with manipulation of the knee under anesthesia. Timing of manipulation is key to its success and if a patient is not progressing after 4–6 weeks manipulation is generally indicated. Manipulation can be performed up to 6–12 months after replacement but ultimate motion is negatively impacted by delay as scar tissue becomes more indurated and fixed.

Arthroscopic lysis of adhesions can be performed in the recalcitrant knee but in my experience will generally improve motion in the 10- to 15-degree range, if at all. In patients with persistent and disabling stiffness, open resection with radical scar excision can be performed and if there is not an implant sizing issue this may improve motion. It is important to rapidly mobilise these patients after surgery with early flexion to beyond 90 degrees with use of optimal analgesia to allow vigorous early motion. At time of open lysis of adhesions revision of components should be performed if there is any question of need to do this to improve range of motion.

Total knee arthroplasty (TKA) is one of the most common orthopaedic operations performed worldwide and it is largely successful in pain relief and functional recovery. However, when pain persists post-operatively the thorough evaluation must be instituted. Extra-articular causes of knee pain include; hip pathology, lumbar spine degenerative disease or radicular symptoms, focal neuropathy, vascular disease, and chronic regional pain syndrome. Intra-articular causes of knee pain: infection, crepitation/clunk, patella osteonecrosis, patella mal-tracking, soft tissue imbalance, malalignment, arthrofibrosis, component loosening, implant wear, ilio-tibial band irritation, and bursitis. Other causes of pain to rule out are component overhang with soft tissue irritation, recurrent hemarthrosis secondary to synovial impingement or entrapment, non-resurfaced patella, and metal sensitivity.

A careful history may reveal previous knee surgeries with delayed healing or prolonged drainage, chronology of sign and symptoms, co-morbid medical conditions, jewel or metal sensitivity.

Physical exam should help with specific signs in the operated knee. Targeted local anesthetic blocks are helpful and response to lumbar sympathetic blocks determines presence of CRPS.

Lab tests are important: ESR, CRP, WBC, aspiration with manual cell count and diff, leucocyte esterase dipstick, RA titers, metal derm patch testing, nuclear scans, CT best for rotational malalignment, and MARS MRI.

More recently patient satisfaction as an outcome measure has shown TKA results not satisfactory in 11- 18% of patients. A discordance of patient vs. surgeon satisfaction exists so the following factors may help improve this: correct patient selection, establishing and correlating surgeon-patient expectations, peri-operative optimization of patient co-morbidities to help avoid preventable complications, use of pre-operative and post-operative pathways. Satisfaction rates can best be improved by addressing the previous points with patients prior to TKA surgery.

Total Knee Arthroplasty (TKA) necessitates disruption of well vascularised tissue during exposure and soft tissue release as well as from the cutting of bone, and thus bleeding into the joint space routinely occurs to some degree following TKA. Defining a complication from bleeding is not necessarily straightforward, but includes 3 different conditions: hemarthrosis, hematoma, and bloody wound drainage. All of these conditions can be seen in the normal post-operative setting, and when mild may be simply observed. However, persistent swelling resulting in clinical symptoms should be appropriately treated.

A hemarthrosis is defined as blood being contained in the knee capsule. Although some bleeding is expected, “excessive” hemarthrosis results in increased pain limiting or difficulty regaining motion. If high levels of fluid pressure are present, rupture of the arthrotomy may occur. A hematoma occurs when intra-articular blood escapes the arthrotomy and drains into the overlying soft tissues. This may occur following performance of a large lateral release or an insufficient arthrotomy closure or simply secondary to a large hemarthrosis under tension. Symptoms include ecchymosis, soft tissue swelling, and potential skin complications. Increased pain and limited range of motion frequently accompany these symptoms. Wound drainage may present as a knee that continues to have bloody or serous drainage that continues long after the first or second dressing change. It is this continued wound drainage that is most worrisome with increased wound infection rates when prolonged drainage is allowed to persist.

The incidence of post-operative hemarthrosis as a clinical problem is not well studied, but the need for surgical treatment is uncommon. Recurrent hemarthrosis is also relatively rare after total knee arthroplasty and has been reported at rates between 0.3% and 1.6%. The etiology of this complication can be systemic or local, and initial work-up should include coagulation studies to rule out any underling systemic coagulopathy. Conservative therapy including rest, cooling, and elevation is the preferred treatment for mild cases. If conservative treatment is not successful, or the acute hemarthrosis is clinically tense, interfering with recovery, or threatening wound healing, drainage may be the preferable option. This can be done by opening the arthrotomy in the operating room or through a large bore arthroscopy cannulae. Careful attention to debridement of clotted blood must be followed by a meticulous search for potential sources of bleeding which should be managed appropriately.

Recurrent hemarthrosis may occur at any time after surgery. Repeated bleeding episodes may lead to an inflammatory cascade that propagates bleeding events more readily. If coagulation studies are normal, the most common source is the impingement of proliferative synovium or other retained soft tissue between the articulating components of the knee prosthesis. Other causes include damage to the geniculate or popliteal vessels with pseudo aneurysm formation. Mild to moderate clinical knee instability may be associated with bloody synovial effusions but limited clinical complaint specific to instability. Other causes may be multifactorial and synergistic but are not well understood, making diagnosis and treatment more difficult. If symptoms persist, and the resulting disability is sufficient, classical treatment has consisted of open or arthroscopic synovectomy. Over the past decade angiography and angiographic embolization of the source of bleeding has been shown to be successful. Radio-active synovectomy has also been successful.

The etiology of the flexion contracture is related to recurrent effusions present in a knee with end-stage degenerative joint disease secondary to the associated inflammatory process. These recurrent effusions cause increased pressure in the knee causing pain and discomfort. Patients will always seek a position of comfort, which is slight flexion. Flexion decreases the painful stimulus by reducing pressure in the knee and relaxing the posterior capsule. Unfortunately, this self-perpetuating process leads to a greater degree of contracture as the disease progresses. Furthermore, patients rarely maintain the knee in full extension. Even during the gait cycle the knee is slightly flexed. As their disease progresses, patients limit their ambulation and are more frequently in a seated position. Patients often report sleeping with a pillow under their knee or in the fetal position. All of these activities increase flexion contracture deformity. Patients with excessive deformity >40 degrees should be counseled regarding procedural complexity and that increasing constraint may be required. Patients are seen pre-operatively by a physical therapist and given a pre-arthroplasty conditioning program. Patients with excessive flexion contracture are specifically instructed on stretching techniques, as well as quadriceps rehabilitation exercises.

Avoiding Pitfalls and Complications: Treating patients with flexion contracture involves a combination of bone resection and soft tissue balance. One must make every effort to preserve both the femoral and tibial joint line. In flexion contracture the common error is to begin by resecting additional distal femur, which may result in joint line elevation and mid-flexion instability. The distal femoral resection should remove that amount of bone being replaced with metal. Attention should be directed at careful and meticulous balance of the soft tissues and release of the contracted posterior capsule with re-establishment of the posterior recess, which will correct the majority of flexion contractures.

Residual Flexion Contracture: Inability to achieve ROM after TKA represents a frustrating complication for both patient and surgeon. Non-operative treatments for the stiff TKA include shoe lift in contralateral limb, stationery bicycle with elevated seat position, extension bracing, topical application of hand-held instruments to areas of soft tissue-dysfunction by a trained physical therapist over several outpatient sessions, and use of a low load stretch device. Manipulation under anesthesia is indicated in patients after TKA having less than 90 degrees ROM after 6 weeks, with no progression or regression in ROM. Other operative treatments range from a downsizing exchange of the polyethylene bearing to revision with a constrained device and low-dose irradiation in cases of severe arthrofibrosis.

Patellofemoral complaints are the common and nagging problem after total knee arthroplasty. Crepitus occurs in 5% to over 20% of knee arthroplasty procedures depending on the type of implant chosen. It is caused by periarticular scar formation with microscopic and gross findings indicating inflammatory fibrous hyperplasia.

Crepitus if often asymptomatic and not painful, but in some cases can cause pain. Patella “Clunk Syndrome” is less common and represents when the peripatella scarring is abundant and forms a nodule which impinges and “catches” on the implant's intercondylar notch. Patella Clunk was more common with early PS designs due to short trochlear grooves with sharp transition into the intercondylar notch. Clunks are very infrequent with modern PS implants. This syndrome has been reported in CR implants as well.

Thorough debridement of the synovium and scarring at the time of arthroplasty is thought to reduce the occurrence of crepitus and clunks. Larger patella with better coverage of the cut bone may also be helpful.

The diagnosis can be made on history and physical exam. X-rays are also helpful to assess patella tracking. MRI or ultrasound can be used to identify and confirm the diagnosis, but this is not mandatory.

Painful crepitus and clunk syndrome that fail conservative management of NSAIDS and physical therapy may require surgery. Both crepitus and clunk can be treated with arthroscopic removal of the peripatella scar. Patella maltracking should also be assessed and treated. While recurrence may occur, it is uncommon.

Over the past 30 years, cemented, cementless, and hybrid fixation options have been utilised with various total knee arthroplasty (TKA) implant systems. While cemented components are widely used and considered the most reliable method of fixation, historical results may not be applicable to contemporary patients, who are increasingly younger than 65 years of age. Moreover, the literature is not definitive on which method of TKA fixation obtains the best clinical, functional, and radiographic results. A recent Cochrane meta-analysis on roentgen stereophotogrammetric analysis (RSA) included five randomised clinical trials (RCTs) in 297 participants. The authors observed that cemented fixation of tibial components demonstrated smaller displacement in relation to cementless fixation. However, the risk of future aseptic loosening with uncemented fixation was approximately half that of cemented fixation (risk ratio = 0.47, 95% CI 0.24 to 0.92) with a 16% absolute risk difference between groups. Almost all included studies recorded functional measures of Knee Society and Hospital for Special Surgery knee scores, but the authors of each study found no significant difference between the groups. Recently, highly porous metals have become an attractive fixation option in TKA due to their biomechanical properties. In a large RCT of 397 patients, Pulido et al found that uncemented highly porous metal tibias provided comparably durable fixation and reliable pain relief and restoration of function when compared with traditional cemented modular tibias. While longer term studies are needed, cementless TKAs may be a durable and reliable alternative with highly porous metals, particularly in younger patients.

Loosening is generally the most common reason for revision TKA. In the AOA NJR, the rate of revision varies depending on fixation. Cemented fixation has a lower rate of revision than cementless fixation; 6.7% vs. 8.2% at 14 years. Loosening does occur more frequently in younger patients and in males. Tibial component loosening is the most common. There is an opportunity for improvement. More durable fixation can be achieved through improved cement technique, rather than going cementless.

De-bonding of the tibial baseplate from the cement is the mechanism of failure in up to 2.9% of total knee arthroplasties. Among seven surgeons at one center, there was a 6.4 fold range (0.7%-4.5%) in the occurrence of such loosening with the same prosthesis. This surgeon-related variability in tibial component de-bonding indicates that surgical technique influences loosening. In a laboratory study, earlier application of cement to metal increases bond strength (p<0.01) while later application reduces bond strength (p<0.05). Fat contamination of the tibial tray-cement interface reduces bond strength, but application of cement to the underside of the tibial tray prior to insertion substantially mitigates this (p<0.05).

Both gap balancing and measured resection for TKA will work and these techniques are often combined in TKA. The only difference is really the workflow. The essential difference in gap balancing is that you determine femoral component rotation by cutting the distal femur and the proximal tibia, and then using a spacer to determine femoral rotation.

I prefer measured resection because I am, for most cases, a cruciate retaining surgeon. It is not ideal to determine femoral rotation based upon a gap balancing if you retain the cruciate. It is also important to maintain the joint line, especially in cruciate retention, in order to reproduce more normal kinematics and balance the knee throughout the range of flexion and extension. It is my opinion that the soft tissue balancing is easier to do with measured resection and the workflow is easier.

The sequence of cuts and soft tissue balance is different if one is a gap balancing surgeon. This is more conducive for people who are cruciate substituters, but more difficult in a varus cruciate retaining knee. In that situation, if you determine femoral rotation by gap balancing with the tibia before you have cleared the posterior medial osteophytes in the varus knee, and remove the last bit of meniscus, you could artificially over rotate the femoral component causing posteromedial laxity. The major difference is that cutting the posterior cruciate will open the flexion space and allow the surgeon easier access to the posteromedial corner of the knee before the posterior femoral cut is made. It is also important to remember that in most cases cruciate substitution surgeons will make the flexion space 2 mm smaller than the extension space to compensate for the flexion space opening when the posterior cruciate is cut. The extensor mechanism plays an important role in flexion balance and should only be tested once the patella is prepared and the patella is back in the trochlear groove. I prefer gap balancing in most revision knees as I am virtually always substituting for the posterior cruciate in that case.

My technique for measured resection is to assess the character of the knee prior to surgery. Is it varus? Is it valgus? Does it hyperextend? Does it have a flexion contracture? Would the knee be considered tight or loose? I cut the distal femur first, based upon measured resection. I use anatomic landmarks to determine femoral rotation. My most consistent landmark is the transtrochlear line, which is not always from the top of the notch to the bottom of the trochlea. I will use the medial epicondyle and the posterior reference in a varus knee, but not in a valgus knee.

The tibial cut, also by measured resection, is easier once the femur has been prepared. The patellar cut is also a measured resection. Having done a preliminary soft tissue balance based upon the deformity, I will then use trial components to finish the soft tissue balance.

In summary, both techniques can be used successfully in a cruciate substituting knee, but measured resection, in my opinion, is preferable especially in varus arthritis when the posterior cruciate is retained

The goals of total knee arthroplasty are to restore the mechanical axis of the knee and create equal and symmetric tension on the ligaments throughout an arc of motion. What surgical technique best achieves this goal remains controversial.

In gap balancing, the extension space is created (distal femur and proximal tibia) and balanced. The flexion space and femoral component rotation are then set by placing tension on the collateral ligaments. This allows the femoral component to be rotated to create an equal and symmetric flexion gap based on the tension of collateral ligaments rather than arbitrary bony landmarks. In the measured resection technique, fixed bony landmarks are utilised to set femoral component rotation. Bony landmarks are subject to variations in patient's anatomy and inconsistency of the surgeon to reliably and reproducibly locate them during surgery. Fehring et al. demonstrated that 49% of knees using bony landmarks had rotational errors of greater than 3 degrees. A recent study determined that the amount of femoral component rotation necessary to create a balanced flexion gap varied based on the amount of ligament release required, calling into question the validity of using this technique to set femoral component rotation. Additionally, a study by Dennis et al. showed that setting femoral component rotation based solely on bony landmarks leads to asymmetry in the flexion gap and excessive condylar lift-off in flexion in over 60% of knees performed with a measured resection technique.

Periprosthetic joint infection (PJI) is one of the most feared complications following total knee arthroplasty (TKA). Despite improved peri-operative antibiotic management and local antibiotic-loaded bone cement PJI is reported in about 0.5–1.9 % of primary knee replacement. In case of revision knee arthroplasty the infection rate even occurs at about 8–10 %. Depending on an acute or late PJI several surgical methods are used to treat the infection. However, suffering of a late PJI, the only surgical procedure remains the exchange of the TKA in combination with a radical debridement and removal of all foreign material.

In order to achieve complete debridement of the joint, the soft tissue must be radically excised. Frequently, the debridement of the posterior capsule causes severe difficulties, therefore it might be necessary to resect the collateral ligaments to be able to reach the posterior parts of the capsule. But this necessitates the use of a higher level of constraint such as a rotating or total hinge and fully cemented long stemmed revision implants. Furthermore, due to the cemented stems, a sufficient amount of antibiotic-loaded cement may be delivered to the bone as topical therapy.

Up to now, several studies have shown excellent functional long-term results for hinge knee prostheses after PJI and a very good infection control rate.

Advantages of the hinge knee prosthesis in cases of PJI are the opportunity for a complete debridement especially while addressing the posterior capsule after resection of the collateral ligaments and for delivering antibiotic-loaded bone cement at the stems of the prosthesis for topic therapy. Disadvantages are the need for a higher level of constraint and a possible higher blood loss due to the radical debridement.

The infected joint arthroplasty continues to be a very challenging problem. Its management remains expensive, and places an increasing burden on health care systems. It also leads to a long and difficult course for the patient, and frequently a suboptimal functional outcome. The choice of a particular treatment program will be influenced by a number of factors. These include the acuteness or chronicity of the infection; the infecting organism(s), its antibiotic sensitivity profile and its ability to manufacture glycocalyx; the health of the patient; the fixation of the prosthesis; the available bone stock; and the particular philosophy and training of the surgeon. Although there have been multiple developments to enhance our ability to effect two-stage techniques whilst limiting inpatient stay, cost and patient morbidity - these include functional spacers, the use of local as well as systemic antibiotics, and home intravenous therapy programmes – there is nevertheless still a considerable morbidity and mortality to the two-stage process, and a massive cost to the patient who has to have two operations with an unpredictable interval period in between and to the local tissues which have already been damaged and are violated on two occasions. The push for one-stage surgery has generally been from centers who are passionate about that technique and has involved a combination of knowing the organism in question prior to surgery, a very radical debridement, the use of hinge / tumor-type implants and prolonged antibiotic therapy post-surgery. The last decade has seen an evolution whereby we have recognised that treatment may be tailored to the patient. There is a big difference between a relatively healthy host and someone with multiple comorbidities, and a big difference between infection with a relatively benign organism and polymicrobial infection with multi-resistant bacteria or fungi. There has, therefore, been increased interest in the use of single-stage revision in order to decrease morbidity, potentially decrease mortality and to decrease cost to the health care system. Single stage revision may have economic and functional advantages, however. We have devised a protocol that dictates the type of revision to be undertaken based on host, organism and local factors.

Whilst we believe that there is a role for both single- and two-stage techniques in our armamentarium, we have gradually evolved to increasing use of single-stage surgery. We use antibiotic-loaded cement whenever possible but can reconstruct most cases using semiconstrained implants without resorting to a hinge.

We continue to see a lower reinfection rate in these carefully selected patients, with high rates of infection control and satisfaction and better functional and quality of life scores than our two-stage revision cases. We use hinge reconstruction in less than 20% of cases.

The most recent Australian registry has a database of 547,407 knee arthroplasties, having added over 52,000 in 2016. Total knee arthroplasties (TKA) comprise 83.8%, revisions (RevTKA) 8.1% and “partials of all types” 8.1%. Since 2003, the percent of TKA has increased from 76.7%, RevTKA has stayed stable and partial replacements have declined from 14.5%. In the last year, however, TKA declined slightly.

There is a slightly higher percentage of women (56.1%) undergoing TKA and this has remained very stable since 2003. Revision rates are slightly higher for men. Percentages of the youngest (<55) and oldest (>85) are small and stable. The 75–84 year olds have declined as 55–74 year olds have increased. This represents a gradual shift to earlier TKA surgery. More patella are resurfaced and this is a gradual trend with a cross over in 2010 when half were resurfaced. Computer navigation is progressively more popular and now accounts for almost 30% of cases. Cement fixation is also increasing and accounts for about 65% of cases. Crosslinked polyethylene is gradually replacing non crosslinked and in 2014 was used in 50% of cases.

Revisions are performed most commonly for loosening and infection. Revision rates correlate directly with age. Loosening is the most common indication for revision in both genders, but males have a distinctly higher revision rate due to infection. Revision rates are slightly higher in all forms of mobile bearing than fixed bearing.

Minimally constrained (cruciate retaining) devices are used in the majority of TKAs. Posterior stabilised implants are in slight decline, having peaked in about 2008–2010. Minimally constrained implants are in slight decline as medial pivot/medial congruent devices have been used more frequently. Revision rates are similar amongst all three implant types: PS implants are revised at a slightly higher rate. When an early Medial Pivot (MP) implant is excluded the newer version has better results. The reasons for revision are similar amongst all 3 groups with slightly higher loosening rates for PS designs. (Could this represent backside wear with older locking mechanisms, surface finish and non crosslinked poly?) The MP designs had slightly higher revision rates for “pain”, which is not recognised as a reasonable indication for revision.

Revision rates are steadily higher for TKAs without patella resurfacing over 16 years, but the questions as to whether: i. the surgeries were secondary resurfacings or full revisions or ii. if secondary resurfacings eliminated pain are unknown. The combinations at greatest risk of revision were a posterior stabilised or medial pivot arthroplasty without patellar resurfacing. Cementless fixation leads to a higher revision rate.

If age and computer navigation are evaluated in terms of revision rates, young patients with and without computer navigated arthroplasties failed at the highest rates, distinct from patients >65. However, if failure rates due only to loosening are evaluated, then computer navigation leads to a lower revision rate in the <65 group. This has been interpreted as the protective effect of better component position that only shows up in patients who use the arthroplasty more aggressively.

Patient specific instrumentation (PSI) or Individual Designed Instrumentation (IDI) were revised at marginally higher rates than conventional instrumentation. Crosslinked polyethylene appears to be superior at 12 years (CRR= 4%) versus non crosslinked polyethylene (CRR>7%). This is the result of fewer failures due to loosening with crosslinked poly. The superiority of crosslinked poly was greater in the younger, more active patient.

Pre-operative planning in revision total knee replacement is important to simplify the surgery for the implant representative, operating room personnel and the surgeon.

Revision knee arthroplasty is performed for many different reasons and of variable complexity. Many implant options can be considered including cemented and cementless primary and stemmed revision tibial and femoral components, with posterior cruciate retention or resection, and either with no constraint, varus/valgus constraint, or with rotating hinge bearings. One may also need femoral and tibial spacers, metaphyseal augments, or bulk allograft. It is important to pre-operatively determine which of these implants you may need. If you schedule a revision total knee and ask the implant representative to “bring everything you've got, just in case,” they will have to bring a truck full of instruments and implants.

The first step of pre-operative planning is to determine how much implant constraint will be needed. Survivorship of revision total knees with modern varus/valgus constrained or rotating hinge implants are not that unacceptable. Ideally to enhance longevity, the least constraint needed should be used. This requires determination of the status of the ligaments. Varus and valgus stress is applied to the knee in near full extension, mid-flexion, and ninety degrees of flexion. If instability of the knee is noted, then radiographs are reviewed to determine if component malposition or malalignment is the reason for the collateral ligament laxity. If radiographs don't show a reason, then have additional constraint available in case the knee can't be balanced with proper component position and ligament balancing. In cases other than simple revisions, the posterior cruciate ligament is usually inadequate or needs to be resected to balance the knee. Substitution for the posterior cruciate ligament is usually needed for most revisions

The second step of pre-operative planning is to review radiographs to determine the amount and location of any bone loss. Osteolysis induced bone loss is usually worse than seen on plain radiographs. If unsure, a CT scan can be of help. The presence of significant bone loss contraindicates the use of primary components and mandates the need for stemmed implants. Larger defects may warrant having metallic augments or bulk graft present. Most revision knee implants can be conservatively metaphyseal cemented with diaphyseal engaging press-fit stems.

The third step of pre-operative planning is to be familiar with what implants are present. Occasionally, one may not need to revise components that are stable and well aligned. Having compatible components available may simplify the surgery

Excellent pre-operative planning will minimise the need to bring in an excessive number of instruments and implants. It will help assure that the patient has a stable revision knee and simplify the surgery for all participants

Achievement of adequate exposure in revision total knee arthroplasty is critical as it reduces the surgical time, enhances the ability for both component removal and reconstruction, and avoids devastating complications such as extensor mechanism disruption. However, this can be challenging as prior multiple surgeries and limited mobility contribute to a loss of tissue elasticity, thickened capsular envelope, and peri-articular soft tissue adhesions. A thorough pre-operative assessment of a patient's past surgical history, comorbidities, pre-operative radiographs (i.e. the presence of severe patella baja), and physical examination including range of motion, prior incisions, and soft tissue pliability are useful in determining the appropriate surgical techniques necessary for a successful revision.

A systematic approach to the ankylosed knee is critical. Most techniques are geared towards mobilization of the extensor mechanism to safely displace the patella for component exposure. The initial exposure should consist of a long skin incision, a subperiosteal medial release, and debridement of suprapatellar, medial, and lateral adhesions to the femoral condyles. A lateral capsular release can prove helpful in further mobilization of the extensor mechanism. When performing a medial parapatellar arthrotomy it's important to keep in mind further extensile exposure techniques that may be required. For example, the arthrotomy should not extend proximally into the vastus intermedius or rectus femoris in the event that a quadriceps snip technique is to be used as this can compromise the ability to repair this exposure.

Despite a large exposure and release of adhesions, sometimes the extensor mechanism remains at risk of rupture and adequate visualization cannot be obtained. In this event, extensile exposures such as a quadriceps snip, quadriceps turndown or tibial tubercle osteotomy are considered. The location of the patella often dictates the best exposure option as severe patella baja may not be overcome with a proximally based release. The quadriceps snip is most commonly used and provides improved exposure without the necessity of modifying the patient's post-operative rehabilitation. In addition, it can be extended to a quadriceps turndown which vastly improves visualization, but at the expense of needing to immobilise the knee post-operatively. A tibial tubercle osteotomy can also be used and provides excellent exposure especially in the case of severe patella baja or when removal of a cemented tibial stem is required. It preserves the extensor muscles, but risks include increased post-operative wound drainage due to limited soft tissue coverage, failure of fixation, or fracture of the tibial tubercle fragment or tibial shaft.

Exposure in revision total knee arthroplasty is critical. Fortunately, this can be reliably achieved with a systematic approach to the knee and through the use of several extensile exposures at the surgeon's discretion.

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/loosening which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability.

Care should be given to assessing collateral ligament integrity. This can be done during physical examination by 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 retaining knees, anteroposterior instability must be assessed.

For instability, most revisions will require a posterior cruciate substituting design or a constrained condylar design that is unlinked. 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.

Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Infection should be ruled out by aspiration and off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result.

General Principles: All repairs should be repaired in full extension. Repairs should be immobilised in full extension for 6–12 weeks. Gradual resumption of motion in a hinged brace over an additional 6–8 weeks almost always yields flexion to at least 90 degrees. Marlex Mesh has been shown to be an excellent replacement as well as an augment for deficient soft tissue.

Acute tibial tuberosity avulsion: Open repair is best accomplished with a non-absorbable heavy Krackow suture, secured distally around a screw and washer followed by 6 to 8 weeks of immobilization. Augmentation with a semitendinosus graft or Marlex can provide additional support.

Acute Patella Tendon Rupture: End-to-end repair is standard, but re-rupture is not uncommon, so supplemental semitendinosus reconstruction is recommended. The tendon is harvested proximally, left attached distally and passed through a transverse hole in the inferior patella. The gracilis tendon can be harvested and sutured to semitendinosus for additional length, if needed.

Acute Quadriceps Tendon Rupture: These can be repaired end-to-end with a non-absorbable heavy Krackow suture. A superficial quadriceps fascial turndown or mesh may be a useful adjunct.

Patella Fracture: Treatment depends on the status of the patellar component and the loss of active extension. If the component remains well fixed and the patient has less than a 20-degree lag, non-operative treatment in extension. A loose component and/or > 20-degree extensor lag requires ORIF +/− component revision.

Chronic Disruptions: While standard repair techniques are possible, tissue retraction usually prevents a “tension-free” repair. If the patella remains viable and has not retracted proximally an Achilles tendon graft is appropriate. In chronic disruptions with loss of the patella, allograft extensor mechanism reconstruction may be considered. Marlex mesh repair has also been shown to be effective in reconstruction of chronic patellar and quadriceps tendon defects.

Stems are a crucial part of implant stabilization in revision total knee arthroplasty. In most cases the metaphyseal bone is deficient, and stabilization in the diaphyseal cortical bone is necessary to keep the implant tightly fixed to bone and to prevent tilt and micromotion. While sleeves and cones can be effective in revision total joint arthroplasty, they are technically difficult and may lead to major bone loss in cases of loosening or infection, especially if the stem is cemented past the cone. A much more conservative method is to ream the diaphysis to the least depth possible to achieve tight circumferential fixation, and to apply porous augments to the undersurface of the tibial tray or inner surface of the femoral component to allow them to bottom out against the bone surface and apply compressive load. If a robust, strong taper, stem and component combination is used, rim contact on only one side is necessary to achieve rigid permanent fixation.

Porous and non-porous stems are available. The non-porous stems should have a spline surface that engages the diaphyseal bone and achieves rigid initial fixation but does not provide long-term axillary support. In that way the porous rim-engaging surface can bear compressive load and finally unload the stem and taper junction.

Correctly designed stems do not stress relieve unless they are porous-coated. In situations where metaphyseal bone is not available, porous-coated stems that link to hinge prostheses are a very important part of the armamentarium in complex revision arthroplasty.

Use of stems requires experience and special technique. Slight underreaming and initial scratch fit are necessary techniques. This does not result in tight fixation every time because split of the cortex does occasionally occur. In most cases these splits do not need to be repaired, but when there is a question, an intra-operative x ray should be taken and the surgeon should be prepared to repair the fracture.

Stems are an essential part of revision total knee arthroplasty. A tightly fit stem in the diaphysis is necessary for fixation when metaphyseal bone is deficient. No amount of cement pressed into the deficient metaphyseal bone will substitute for rigid stem fixation..

Bone loss creates a challenge to achieving fixation in revision TKR. Failure to achieve metaphyseal fixation is associated with failure in revision TKR. In the absence of cancellous bone for cement fixation, metaphyseal augments placed without cement have shown promise in achieving fixation. First generation augments were modular solid titanium sleeves attached to a taper at the base of the core implant. The introduction of tantalum with its favorable mechanical qualities markedly increased the utility and utilization of metaphyseal augments, with positive reports. These are either large augments where the bone is prepared with a burr, or later small cones placed with a cannulated broaching technique. Both have solved real problems, the first being limited by the reproducibility of bone preparation, and the second with excellent reproducibility of bone preparation but limited diameters. Other highly porous titanium surfaces have broadened the choices.

Modern metaphyseal augments seek to add flexibility and options, specifically the use of offset stems. One tibial augment design features a reamed cone with a matching conical implant. Another option is based on an anatomic cone design with a single ream and a broached technique to optimise endosteal cortical bone contact. With each of these options, the augment can be placed wherever the remaining bone exists for fixation, even down to the metaphyseal-diaphyseal junction, and not limited to the area adjacent to the cut surface of bone. Once independent fixation is achieved, the intramedullary stem is cemented inside of it.

Modern femoral augments are designed to sit either in the epiphyseal region, or the metaphysis. Cannulated reaming systems allow for preparation of complex asymmetrical double cone implants at the epiphysis. Metaphyseal implants are designed anatomically to sit deeper in the femoral bone, and can manage larger bony defects. Each system has benefits and compromises, and together they comprise increasingly powerful alternatives to manage extensive bone loss.

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; (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.

Not all degenerative knees need a total knee replacement. Over the last few decades we have shifted our surgical treatment of end-stage osteoarthritis (OA) of the knee to a “compartmental approach” resulting in approximately half of end-stage OA knees receiving a partial knee replacement. Of these an emerging procedure is isolated lateral compartment replacement with the indications being isolated bone-on-bone osteoarthritis or avascular necrosis of the lateral compartment of the knee. Associated significant patellofemoral disease and inflammatory arthritis are contraindications. The purpose of this study is to present the indications, surgical technique, and early outcome of lateral partial knees from our institution.

From Aug 2011 until June 2017 we have performed 3,548 knee arthroplasties. Of these 147 were fixed bearing lateral partial knee replacements via a lateral parapatellar approach (4%), 1,481 medial partial knee replacements (42%), and 1,920 total knee replacements (54%). The average age was 66 years old and 76% were female. Average follow-up in the lateral partials was 1.3 years (range 0.5 years to 6 years). Knee Society Scores improved from 41 (pre-op) to 86 points (post-op). Range of motion improved from 6 – 113 degrees (pre-op) to 0 – 123 degrees (post-op). No knees were revised to a TKA. One knee required I&D for traumatic wound dehiscence.

This is the largest single center series of lateral partial knee replacements. We have observed this cohort to have more female patients and gain additional range of motion compared to our historic cohorts of TKA's. Longer-term follow-up is needed for determination of implant and unreplaced compartment survivorship. We believe the lateral partial knee replacement to be a viable option for isolated lateral compartment disease in approximately 4% of patients.

Each of the seven cuts required for a total knee arthroplasty has its own science, and can affect the outcome of surgery.

Adequate soft tissue balance at the time of total knee arthroplasty (TKA) prevents early failure. In cases of varus deformity, once the medial osteophytes have been resected, a progressive release of the medial soft tissue sleeve (MSS) from the proximal medial tibia is needed to achieve balance.

The “classic” medial soft tissue release technique, popularised by John Insall et al., consists of a sharp subperiosteal dissection from the proximal medial tibia that includes superficial and deep medial collateral ligament (MCL), semimembranosus tendon, posteromedial capsule, along with the pes anserinus tendons, if needed. However, this technique allows for little control over releases that selectively affect the flexion and extension gaps. When severe deformity is present, an extensive MSS release can cause iatrogenic medial instability and the need to use a constrained implant.

It has been suggested that the MSS can be elongated by performing selective releases. This algorithmic approach includes the resection of the posterior osteophytes as the initial balancing gesture. If additional MSS release is necessary in extension, a subperiosteal release of the posterior aspect of the MSS is performed with electrocautery, detaching the posterior aspect of the deep MCL, posteromedial capsule and semimembranosus tendon for the proximal and medial tibia. Dissection is rarely extended more than 1.5 cm distal to the joint line. If additional release is necessary in extension, the medial compartment is tensioned with a laminar spreader and multiple needle punctures (generally less than 8) are performed in the taut portion of the MSS using an 18G or 16G needle. If additional release is necessary to balance the flexion gap, multiple needle punctures in the anterior aspect of the MSS are performed.

This stepwise approach to releasing the MSS in a patient with a varus deformity allows the surgeon to target areas that selectively affect the flexion and extension gaps. Its use has resulted in diminished use of constrained TKA constructs and subsequent cost savings. We have not seen an increase in post-operative instability developing within the first post-operative year.

We recommend caution when implementing this technique. Unlike the traditional release method, pie-crusting is likely technique-dependent and failure can occur within the MCL itself. Due to the critical importance of the MCL in knee stability, further research and continuous follow up of patients undergoing TKA with this technique are warranted. Intra-operative sensing technology may be useful to quantitate the effect of pie-crusting on the compartmental loads and overall knee balance.

Fifteen-year survivorship studies demonstrate that total knee replacements 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 do 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 intra-operatively and post-operatively. 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 sensor 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 if compartment loading differences are greater than 15 pounds whether to perform a soft tissue balance or 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.

The development of more wear resistant biomaterials and better locking mechanisms for the polyethylene into the tibial base has significantly reduced polyethylene wear as a reason for revision TKA. Aseptic loosening is now the primary cause for revision TKA. Loosening can be caused by multifactorial operative issues: 1] patient selection, 2] implant alignment, 3] cementing technique. Furthermore, aseptic loosening occurs at a consistent rate over time. Increased cement penetration is important to counter bone resorption. Increasing penetration also improves cement mantle toughness leading to better mechanical integrity of the bone-cement interface and reduces bone-cement interface stress.

It is important to recognise that a cleaner and drier interface does improve bone-cement penetration. Techniques to improve the process include better cement formulations, drilling sclerotic bone, devices and implant features to increase pressurization, using negative pressure suction ports in the tibia. We have extensive experience with CarboJet, a method of CO2 gas jet cleaning and drying. This experience was developed during 20 years of performing TKA with NO tourniquet. Schnetler et al found that the “use of a tourniquet in TKA causes a paradoxical increase in total blood loss”. So, NO tourniquet TKA is becoming the new paradigm for knee arthroplasty in reconstructive orthopaedics. Goldstein reported that pressurised carbon dioxide jet lavage resulted in a 35% increase in cement penetration depth when used versus use of pulsatile saline lavage alone.

Another important factor in increasing the cement interdigitation is the influence of lipids which significantly weakens the bond at the interfaces. If motion is allowed during cementation there is additional loss of penetration and therefore fixation. The pressurised carbon dioxide delivered by the CarboJet system actually pushes the lipid, fatty marrow up and out of the bone allowing it to be suctioned or lap dried from the interface surface. The NO tourniquet technique and the use of carbon dioxide jet gas delivery to improve the bone-cement interface in TKA will be demonstrated.

Multiple newer wound closure techniques have been recently developed with the goals being reducing closure time, enhancing cosmesis, and decreasing wound healing problems including infections. Among these techniques are the zipper-like closure, absorbable dermal staples, scaffold devices, and others. Each of these techniques propose certain advantages. Nevertheless, this comes at an added cost and careful weighing of the cost/benefit should be considered in an evidence-based manner, in order to guide future recommendations for using these techniques.

It is a not so uncommon clinical scenario: well-fixed, well-aligned, balanced total knee arthroplasty with continued pain. However, radiographs also demonstrate an unresurfaced patella. The debate continues and the controversy remains as whether or not to routinely resurface the patella in total knee arthroplasty. In perhaps the most widely referenced article on the topic, the overall revision rates were no different between the resurfaced (9%) and the unresurfaced (12%) groups and thus their conclusion was that similar results can be obtained with and without resurfacing. However, a deeper look in to the data in this study shows that 4 times more knees in the unresurfaced group were revised for patellofemoral problems.

A more recent study concluded that selectively not resurfacing the patella provided similar results when compared to routinely resurfacing. The study does emphasise however, that this conclusion depends greatly on femoral component design and operative diagnoses. This suggests that selective resurfacing with a so-called “patella friendly” femoral component in cases of tibio-femoral osteoarthritis, is a safe and effective strategy. Finally, registry data would support routine resurfacing with a 2.3 times higher relative risk of revision seen in the unresurfaced TKA. Regardless of which side of the debate one lies, the not so uncommon clinical scenario remains; what do we do with the painful TKA with an unresurfaced patella.

Precise and accurate diagnosis of the etiology of a painful TKA can be very difficult, and there is likely a strong bias towards early revision with secondary patellar resurfacing in the painful TKA with an unresurfaced TKA. At first glance, secondary resurfacing is associated with relatively poor outcomes. Correia, et al. reported that only half the patients underwent revision TKA with secondary resurfacing had resolution of their complaints. Similarly, only 53% of patients in another series were satisfied with the procedure and pain relief. The conclusions that can be drawn from these studies and others are that either routine patellar resurfacing should be performed in all TKA or, perhaps more importantly, we need to better understand the etiology of pain in an otherwise well-aligned, well-balanced, well-fixed TKA.

It is this author's contingency that the presence of an unresurfaced patella leads surgeons to reoperate earlier, without truly identifying the etiology of pain or dissatisfaction. This strong bias; basically there is something more that can be done, therefore we should do it, is the same bias that leads to early revision of partial knee arthroplasty. While very difficult, we as knee surgeons should not revise a partial knee or secondarily resurface a patella due to pain or dissatisfaction. Doing so, unfortunately, only works about half the time.

The diagnostic algorithm for evaluating the painful, uresurfaced TKA includes routinely ruling out infection with serum markers and an aspiration. Pre-arthroplasty radiographs should be obtained to confirm suitability and severity of disease for an arthroplasty. An intra-articular diagnostic injection with Marcaine +/− corticosteroid should provide significant pain relief. MARS MRI may be beneficial to evaluate edema within the patella. Lastly, operative implant stickers to confirm implant manufacturer and type are critical as some implants perform less favorably with unresurfaced patellae. To date, no studies of secondary resurfacing describe the results of this, or similar, algorithms for defining patellofemoral problems in the unresurfaced TKA and therefore it is still difficult to conclude that poor results are not simply due to our inherent bias towards early revision and secondary resurfacing of the unresurfaced patella.

“The shortest distance between two points is a straight line.” This explains many cases of patellar maltracking, when the patellar track is visualised in three dimensions. The three-dimensional view means that rotation of the tibia and femur during flexion and extension, as well as rotational positioning of the tibial and femoral components are extremely important. As the extensor is loaded, the patella tends to “center” itself between the patellar tendon and the quadriceps muscle. The patella is most likely to track in the trochlear groove IF THE GROOVE is situated where the patella is driven by the extensor mechanism: along the shortest track from origin to insertion. Attempts to constrain the patella in the trochlear groove, if it lies outside that track, are usually unsuccessful. Physiologic mechanisms for tibial-femoral rotation that benefit patellar tracking (“screw home” and “asymmetric femoral roll-back”) are not generally reproduced.

When dealing with a flexion contracture, a surgeon first should consider all potential causes, specifically ligament contracture and osteophytes. Then consider the size of the femoral component and its position proximal to distal and also the posterior slope of the tibial component.

Most knee flexion contractures are caused by osteophytes and tight ligaments, and once these problems are corrected, no further work needs to be done on the knee. So when the bone surface cuts are made, in general, little compensation is done in terms of positioning the femoral component proximal or distal, or in terms of sloping the tibial component (beyond the normal 3–4 degrees posterior slope), before the ligaments or osteophytes are managed. If the deep medial collateral ligament (MCL) and posterior portion of the superficial MCL are tight, a flexion contracture will almost always be present after the bone surfaces are finished. Once this is corrected with proper ligament releases and removal of osteophytes, then ligament balance and flexion contracture should be reassessed. In the very few cases that still have a flexion contracture, posterior capsule release should be done. Once this is finished, releasing the capsule from both the femur and the medial aspect of the tibia, then ligament balance is reassessed again. If flexion contracture still remains (<10% of cases), then the distal surface of the femur is resected another 4–6 mm, trial components are inserted, and flexion contracture is evaluated. If more bony resection is needed, then changing tibial slope from 4 degrees posterior slope to 0 degrees slope is another step that can be done to remove bone from extension space of the knee finally to achieve full extension. Virtually all flexion contractures, except those with severe contracture resulting from hamstring tightness, can be corrected with this method.

In the valgus knee with flexion contracture, similar management is used. Knees that will not extend and remain tight on the lateral side usually are corrected with release of the posterior capsule and posterior portion of the iliotibial band. Just as on the lateral side, bone resection from the distal femur can be performed as a final effort to achieve full extension of the knee.

It is worth reiterating that almost all flexion contractures are caused by ligament imbalance, and that over-resection of the distal femur at the start of these cases can easily result in hyperextension that is difficult to manage once ligaments have been balanced.

Metaphyseal bone loss, due to loosening, osteolysis or infection, is common with revision total knee arthroplasty (TKA). Small defects can be treated with screws and cement, bone graft, and non-porous metal wedges or blocks. Large defects can be treated with bulk structural allograft, impaction grafting, or highly porous metal cones. The AORI classification of bone loss in revision TKA is very helpful with pre-operative planning. Type 1 defects do not require augments or graft—use revision components with stems. Type 2A defects should be treated with non-porous metal wedges or blocks. Type 2B and 3 defects require a bulk structural allograft or porous metal cone. Highly-porous metal metaphyseal cones are a unique solution for large bone defects. Both femoral (full or partial) and tibial (full, stepped, or cone+plate) cones are available. These cones substitute for bone loss, improve metaphyseal fixation, help correct malalignment, restore joint line, and permit use of a short cemented stem. The technique for these cones involve preparing the remaining bone with a high speed burr and rasp, followed by press-fit of the cone into the remaining metaphysis. The interface is sealed with bone graft and putty. The fixation and osteoconductive properties of the outer surface allow ingrowth and biologic fixation. The revision knee component is then implanted, with antibiotic-cement, into the porous cone inner surface, which provides superior fixation compared to cementing into deficient metaphyseal bone. There are several manufacturers that provide porous cones for knee revision, but the tantalum-“trabecular metal” cones have the largest and longest clinical follow-up. The advantages of the trabecular metal cone compared to allograft include: technically easier; biologic fixation; no resorption; and lower risk of infection. The disadvantages include: difficult extraction and intermediate-term follow-up. The author has reported the results of 33 trabecular metal cones (9 femoral, 24 tibial) implanted in 27 revision cases at 2–5.7 years follow-up. One knee (2 cones) was removed for infection. All but one cone showed osseointegration. Multiple other studies have confirmed these results. Trabecular metal cones are now the author's preferred method for the reconstruction of large bone defects in revision TKA.

Historical perspective: Irrigation and debridement (I&D) with modular exchange has historically been the recommended treatment for acute post-operative periprosthetic joint infection (PJI), and acute hematogenous PJI. The theory supporting this practice was that because the bacterial glycocalyx had not yet formed by these early time points, by simply debriding the intra-articular bacterial load and exchanging the modular parts, one could potentially eradicate the infection, retain the prior components, and minimise morbidity to the patient. More recently, literature is coming out suggesting that this may not necessarily be the case.

The vast majority of published research on the outcomes following I&D for treatment of PJI has focused on either cohorts of total knee arthroplasty patients or combined cohorts of total hip and knee patients. For this reason, it is difficult to tease out the differential success rate of periprosthetic hip vs. knee infections. Sherrell et al. performed a systematic review of the existing literature and created a table detailing the failure rates for various published articles on I&D for periprosthetic TKA infection.

Since it is the glycocalyx that has been thought to be the reason for treatment failure of many cases of PJI treated with I&D, many authors have implicated staphylococcal species as a predictor of a negative outcome with failure rates ranging from 30–35%. Methicillin resistant organisms have been shown to be particularly difficult to eradicate with an isolated I&D, with a 72–84% failure rate at 2 year follow-up. Interestingly, a recent study by Odum et al. suggests that neither the infecting microbe, nor the antibiotic resistance profile of the organism, as has been classically thought, actually predicts success of I&D.

Previous reports have indicated that the ability of I&D to control infection is related to the duration of symptoms and its timing relative to the index surgery. However, more recent literature is coming out to support the contrary. Koyonos et al. reviewed the outcomes of a series of 138 cases of PJI treated with I&D based on acuity of infection and concluded that an I&D has a limited role in controlling PJI regardless of acuity.

Intuitively, the physical health of the host/patient should influence the success of I&D for treatment of PJI. Several authors have shown that an immunocompromised state is a predictor of treatment failure. Furthermore, Azzam et al. reported that patients with a higher American Society of Anesthesia (ASA) score, a proxy of severity of medical comorbidities, had a significantly higher failure rate.

Although potentially appealing due to relative ease of execution and minimal surgical morbidity, the ability to successfully eradicate infection with an arthroscopic procedure may be compromised. Given the inability to perform a radical surgical debridement, nor exchange modular components, arthroscopic debridement should be used with extreme reservation in any case of PJI, regardless of the host, nature of the infecting organism, or acuity of infection.

I&D as a conservative, less morbid alternative to two-stage exchange - There is a growing body of literature to suggest that an I&D with modular component exchange may not be the benign, less morbid alternative to the ‘gold standard’ two-stage exchange arthroplasty. In fact, Fehring et al. has reported that the success of a two-stage antibiotic spacer exchange arthroplasty may be compromised by an initial I&D. They found that patients who were initially treated with an I&D only had a 66% chance of eradicating infection following a two-stage exchange arthroplasty, in contrast to historical reports of 80–90% success.

Success in knee revision begins in the office. The initial evaluations determine the implant design and pre-operative diagnosis. The physical examination identifies the presence of instability, stiffness, extensor mechanism malfunction and previous incisions all of which influence the planned procedure. Prior to surgery arrangements are made to have all manner of revision implants, removal tools, and allograft material available.

Removal of implants must be done with a focus on preserving bone stock and the extensor mechanism. Initial exposure involves release of the gutters, lateral subluxation of the patella and removal of the polyethylene insert. These maneuvers combined with a quadriceps snip provide exposure for implant removal in 80–90% of cases. More extensive exposure options include quadriceps turndown, tibial tubercle osteotomy, medial epicondylar osteotomy and a femoral peel.

Tools needed for implant removal include thin osteotomes, offset osteotomes, thin saws and a high-speed bur. After polyethylene removal the femur followed by the tibia are removed. In many cases the existing well-fixed patellar component can remain. The implant cement or implant bone interface is approached for cemented and cementless implants, respectively. Tools are always directed parallel to the fixation surface. Offset osteotomes are helpful gaining access to the femoral notch when femoral pegs prevent access from the sides. Central keels or peripheral pegs can complicate tibial removal. Working completely around the keel from medial and lateral disrupts the peripheral tibial interface leaving just the central posterior metaphysis. Stacked osteotomes or a slap hammer can be used to lift the baseplate from the tibia.