No, not my mother, but metal-on-metal (MoM) hips! My involvement in the DEFENSE side of MoM hips has allowed me the luxury of reflection and continued study on the basic and clinical science of this particular wear couple. Much of what I have learned is relevant to other articular couples, and might help you in your next THR.

No amount of in vitro laboratory testing can replicate or predict in vivo behavior of a particular wear couple. (Mother Nature always has something new to teach us!) Although MoM implants went through complete pre-market evaluation and approval in both the US and EU, the process is inadequate and does not assure safety or success of new designs and materials. Two year results obtained in pre-market (IDE) studies are of insufficient follow-up for accurate evaluation of new materials or designs. Be conservative! Be neither the first, nor the last, to embrace new technology!

Clinical experience and retrieval analysis of MoM devices has revealed factors that are not as apparent for other wear couples such as metal-on-polyethylene (MoP), or ceramic-on-ceramic (CoC). For instance:

All THR's are at risk of micro-lateralization, or displacement of the femoral head from the acetabular wear couple during swing phase, resulting in edge loading. In addition, impingement or displacement related to component malposition or failure to balance the soft tissues about the hip can produce subluxation, producing edge loading and accelerated wear. In the case of MoM implants, the tribology and wear properties of MoM produce identifiable wear scars; all MoM designs appear to be subject to these phenomena. However, evidence now exists that both MoP and CoC wear couples are at similar risk for accelerated wear, although at different rates than MoM.

Hard-on-hard wear couples (ceramic, metal) are less tolerant of edge loading than hard-on-soft (e.g., MoP or CoP) wear couples, and therefore require a higher degree of surgical precision in implant placement and reconstruction of the soft tissue balance of the hip.

One of the previously unrecognised factors that can change relative implant position (and therefore, the risk of subluxation or edge loading) is the effect of the lumbar spine on apparent acetabular component position (e.g., changes between sitting, standing, or lying prone). This is largely due to the effect of lumbar spine flexibility, as shown in both orthogonal x-ray (“EOSr”) studies, and dynamic CAT scan studies. There is currently no validated algorithm or technique to assess these factors; however, surgeon awareness and at least clinical assessment preoperatively may result in better positioning of implants. Femoral component position can also have a major effect of the risk of impingement or subluxation of the femoral head; the combined anteversion concept of Dorr et al. should be rigorously adhered during THR.

Other issues such as fretting corrosion associated with large diameter femoral heads and tissue response to wear debris may not be anticipated until a very large cohort population is available for examination and analysis.

No matter how extensive in vitro testing may be, only clinical experience and retrieval analysis can provide the ultimate reassurance as to the success of a new design or material.

Only a little over a decade ago the vast majority of primary total hip replacements performed in North America, and indeed globally, employed a conventional polyethylene insert, either in a modular version or in a cemented application. Beginning in the early 2000's there was an explosion in technology and options available for the bearing choice in total hip arthroplasty.

Highly cross-linked polyethylene was introduced in 1998, and within a few short years the vast majority of polyethylene inserts performed in North America were manufactured from this material. Globally there was a mixed picture with variable market penetration. Surgeons had seen historically poor results with attempts at “improving” polyethylene in the past and many were hesitant to use this new technology. Many randomised clinical trials have been performed and all have shown to a greater or lesser degree, that indeed the highly cross-linked polyethylene insert has undergone less linear and volumetric wear than its more conventional counterpart. This replicates well the hip simulator data. The challenge, however, is as we approached mid-term results, orthopaedic manufacturers began altering the polyethylene to improve wear and improve mechanical strength. Therefore while ten-year and greater data will ultimately be published, the actual polyethylene in use at that time will be a different material. Additionally while wear rates are undoubtedly lower, we are still waiting for long-term results of actual osteolytic lesion development and the effect that highly cross-linked polyethylene will have on this clinical scenario. That being said, with over a decade of clinical experience, unquestionably highly cross-linked polyethylene has truly been a revolution in design, essentially eliminating polyethylene wear as an early failure mode.

The question still remains as to the best material for the femoral ball. Essentially two options exist – cobalt chrome (CoCr) and ceramic. There are theoretically advantages to ceramic heads; however, they come at a cost premium:

To date there have been no published reports that demonstrate any improved clinical outcomes with the use of ceramic heads. In fact, the Australian registry demonstrates that the cumulative revision rate is lowest with CoCr heads (at 10 years, 4.3% with CoCr on XLPE and 4.6% with ceramic on XLPE).

Costs continue to be significantly higher for ceramic heads. A price premium of 2–4x higher cost for ceramic over CoCr heads exists in most global markets.

Trunnion issues. An emerging concern is corrosion at the head neck junction in THA. Ceramic heads should theoretically have a lower incidence of taper corrosion. To date this is unproven, as is the actual incidence of this as a significant clinical problem.

A multitude of different bearing combinations exist to recreate the artificial hip joint. To date, there is no particular ‘gold-standard’ total hip arthroplasty (THA) couple since none is faultless. Strategies to improve performance are aimed either at modifying the shape and design of components or their material properties. Wear particle generation is now well recognised as a cause of aseptic loosening which consistently features amongst the most common indication for revision THA and thus minimising wear lies at the cornerstone of developing bearing couples. However, history has shown the use of supposed newer and improved materials have not been without occasional catastrophic failure. Hard-on-hard bearings are theoretically more resistant to wear but component fracture and squeaking has been witnessed with ceramic-on-ceramic articulations whilst metal-on-metal articulations have been plagued by reports of pseudotumor and ALVAL formation. This has all led to resurgence in the hard-on-soft couple.

More recently, corrosion at taper junctions has been identified as a significant factor in hip arthroplasty failure. Femoral head materials, surface changes or coatings may therefore have an increasing role to play.

In 2005, a multi-center, prospective, assessor and patient-blinded, randomised control trial was initiated. This was designed as a three armed study with either cobalt-chrome or oxidized zirconium femoral heads articulating against highly cross-linked polyethylene (XLPE) liners and oxidized zirconium articulating against ultra-high molecular weight polyethylene (UHMWPE). Early reports that XLPE was significantly superior to UHMWPE when coupled with cobalt-chrome meant no patient involved in the study was approved to receive a couple of cobalt-chrome and UHMWPE since it was deemed to be a high wear group.

We hypothesised that oxidized zirconium femoral heads would produce less linear wear than cobalt- chrome femoral heads at mid-term evaluation, whilst maintain similar outcomes when recording WOMAC, SF-36 and pain scores, and complication rates. All three groups were statistically comparable preoperatively and at five years when measuring normalised WOMAC, SF-36 and pain scale scores; all groups showed a statistically significant improvement in scores from baseline compared to at five years (p<0.001).

There was no significant difference in mean femoral head penetration when either oxidized zirconium or cobalt-chrome where articulated with XLPE (p=0.1533) but a significant difference in mean femoral head penetration was observed between the group that had used UHMWPE and both the other groups which had used XLPE (p<0.001). There were no hips in which either acetabular or femoral osteolysis was observed.

We have demonstrated that oxidized zirconium femoral heads are safe with low rates of wear when coupled with XLPE. However at five year follow-up, it appears that the choice of material of the acetabular bearing is more important than the choice of femoral head bearing. Further follow-up is needed in order to see if femoral head choice leads to a difference in outcome beyond 5 years as laboratory data suggests. Moreover the potential reduction of corrosion with ceramic or oxidized zirconium heads may yet also prove to be significant.

It is likely that current and future data will lead us away from the use cobalt chrome heads towards alternatives that are less likely to be associated with corrosion or wear and osteolysis.

Dual mobility components for total hip arthroplasty provide for an additional articular surface, with the goals of improving range of motion, jump distance, and overall stability of the prosthetic hip joint. A large polyethylene head articulates with a polished metal acetabular component, and an additional smaller metal head is snap-fit into the large polyethylene. New components have been released for use in North America over the past four years. In some European centers, these components are routinely used for primary total hip arthroplasty. Some surgeons in USA suggest routine use in primary hip arthroplasty. However, their greatest utility is to manage recurrent dislocation in the setting of revision total hip arthroplasty.

Recent biomechanical data suggests that, in a 3D CT scan-cadaver hip model, there is no difference in range of motion between a 36mm head and an ADM dual mobility component sizes 50–56mm. There is little wear data on dual mobility components, except from one implant manufacturer. It is feared that there is a “3rd articulation” in dual mobility components—the routine impingement of the femoral neck against the polyethylene femoral head. Several retrospective series have shown satisfactory results for these dual mobility components at short- to medium-term follow-up times. There are important concerns with polyethylene wear, late intra-prosthetic dislocation, and the lack of long-term follow-up data.

Big femoral heads (36mm and 40mm) articulating with highly cross-linked, e-beam, remelted, polyethylene are a better choice in primary total hip arthroplasty, to decrease the frequency of dislocation in “high risk” patients. Although the risk of early dislocation was 4% in “high risk” patients, there was no recurrence, no revision, and no late first dislocation. Until further long-term results are available, caution is advised in the routine use of dual mobility components in primary total hip arthroplasty.

Dislocation is a particular problem after total hip replacement in femoral neck fractures and elderly especially female patients. The increased rate of dislocation in this population is probably due to significant ligamentous laxity in these patients and poor coordination and proprioception. Another population of patients with increased propensity for dislocation is the revision hip replacement patient. Current dislocation rates in these patients can approach 10% with conventional implant systems.

The Dual Mobility total hip system is composed of a cobalt chrome acetabular shell with a grit blasted, beaded and/or hydroxyapatite coating to improve bone ingrowth. The polyethylene liner is highly cross-linked polyethylene and fits congruently into the cobalt chrome shell and acts like a large femoral head (usually >40mm). The femoral head attached to the trunnion is usually 28mm or 32mm. The femoral head snaps into the polyethylene liner to acts as a second protection against dislocation.

Indications for the Dual Mobility socket are in the high risk for dislocation patient and particularly in elderly female patients. One hundred fifty-six patients with an average age of 79 have been performed to date with a maximum follow up to 4.2 years. To date there have been no mechanical or septic failures and no dislocations. Pain relief has been no different than conventional hip replacement and range of motion is unchanged as well. There have been reported cases of intraprosthetic dislocation but these have not occurred to date.

The leading cause for total hip arthroplasty (THA) revision remains aseptic loosening due to bearing wear. The younger and more active patients currently undergoing arthroplasty present unprecedented demands on THA-bearings. Ceramic-on-ceramic (CoC) bearings have consistently shown the lowest wear rates. The recent advances, especially in alumina CoC bearings, have solved many past problems and produced preferable results in vitro.

Alumina ceramics are extremely hard, scratch resistant, biocompatible, offer a low coefficient of friction, superior lubrication and lower wear rates in comparison to other bearings in THA. The major disadvantage of ceramics used to be fracture. The new generation of alumina ceramics, has reduced the risk of ball fracture to 0.03–0.05%. The risk for liner fracture is even lower.

Assuming an impingement-free component implantation, CoC bearings have major advantages over other bearing combinations. Due to the superior hardness, CoC bearings produce less third body wear and are virtually impervious to damage from instruments during the implantation process.

A complication specific to CoC bearings is squeaking. Squeaking occurs if the friction in the joint articulation is sufficient to excite vibrations to audible magnitudes (due to loss of lubrication). The high range of reported squeaking (0.45% to 10.7%) highlights the importance of correct implant position. If a correct implant position can be guaranteed, then squeaking is rare and without clinical significance.

The improved tribology and presumable resulting implant longevity make CoC the bearing of choice for young and active patients. Especially the alumina matrix (Biolox delta) offers increased burst strength and greater fracture toughness.

The use of hard-on-hard bearings, including ceramics peaked in the mid 2000's and has seen rapid decline since that time. Ceramics are not new to the market place but have had a 40 year history outside the U.S. The basis for renewed enthusiasm for ceramics included improved manufacturing, improved taper tolerances, higher strength, and lower wear. In spite of the major improvements concerns have been expressed with new generation ceramics by the experts and thought leaders in the field. The major concerns included complications related to modularity, continued problems with fracture and consequences of fracture, limited surgical options, and squeaking and impingement. The conclusion of one review article was that “although ceramics show promise as a lower wear articulation, manufacturing and design modifications and improvements will continue in an attempt to address the substantial concerns that persist”. Modifications have indeed occurred. The question is rather all of these concerns have been addressed and the answer is no. One proposed solution was a hybrid material of Alumina and Zirconia (Delta Ceramic). The advantages included higher strength, lower wear, more options and possibly less squeaking. Unfortunately the modest material improvements did not begin to overcome the obstacles to adopting this technology. High on this list is the problem with cost with the current health care environment unwilling to pay for expensive new technology that does not have proven value. A 2nd major issue is new technology must account for variability in surgeon performance in maximising margin for error. The medical legal environment is unforgiving of failure of new unproven options. Most of the old issues with ceramics have not been completely resolved. Delta Ceramic in particular, has increased cost with no demonstrated benefit.

A major problem is there is no known problem with metal or ceramic against cross-linked polyethylene bearing in terms of wear or osteolysis in the 10–15 year time frame. Among all the bearing articulations, metal-on-cross-linked performs the best. The persistent vexing problems with ceramics include impingement, liner breakage, and squeaking. Ceramic components do not tolerate component malposition which increases wear and squeaking. The problem is that a substantial percentage of hip replacements are put in outside of the ideal radiographic zone even at specialty centers. Breakage continues to be a problem especially with liners. There is also a need for complete rim exposure for concentric placement with impaction of liners which makes ceramics less compatible with small incision surgery. The problem of squeaking has not been solved by Delta Ceramic. Originally a case report appeared in the literature of squeaking with Delta Ceramic. Since that time a large scale study has showed that only 69% of Delta Ceramic hips were silent with up to 13% being associated with reproducible squeaking.

While a new generation of ceramics are better than the earlier generation and have lowered the fracture risk and increased intraoperative options, the current generation ceramics still provide far fewer options than a standard metal-on-cross-linked total hip. The current generation metal-on-cross-linked total hips have 10–15 year results that cannot be improved upon in terms of wear and osteolysis. Other unsolved problems include breaking, chipping and squeaking. Ceramic-on-ceramic is less tolerant of suboptimal position which leads to impingement, edge loading, and an increased incidence of squeaking. Until all of these problems are successfully addressed, ceramic-on-ceramic cannot be advocated for widespread use.

As a generic technology, intentionally cross-linked polyethylene has improved the durability of total hip replacement. Regardless of the manufacturing method, the wear rates have been reduced on the order of 90% compared to historical materials, with a substantial reduction in the occurrence of osteolysis. Most of the data is with 28mm and 32mm bearings. Larger diameter bearings have been shown to reduce the occurrence of dislocation. However, there is clinical evidence that volumetric wear is increased with larger diameter cross-linked polyethylene bearings, and this may increase the occurrence of osteolysis. Further, modular liner fracture is more likely with larger diameter bearings (thinner liners), which is generally associated with increased cup abduction angle and/or increased anteversion. Contemporary polymers are better than their predecessors, but there is always opportunity for improvement.

Cemented total hip arthroplasty (THA) has become an extremely successful operation with excellent long-term results. Although showing decreasing popularity in North America, it always remained a popular choice for the elderly patients in Europe and other parts of the world. Various older and recent studies presented excellent long-term results, for cemented fixation of the cup as well as the stem.

Besides optimal component orientation, a proper cementing technique is of major importance to assure longevity of implant fixation. Consequently a meticulous bone bed preparation assures the mechanical interlock between the implant component, cement and the final bone bed.

Preoperative steps as proper implant sizing/ templating, ensuring an adequate cement mantle thickness, and hypotensive anesthesia, minimising bleeding at the bone cement interface, are of major importance.

First the fossa pyriformis should be clearly identified, including the posterolateral entry point of the prosthesis. The femoral neck cut is usually 1.5cm to 2cm above the minor trochanter, based on the preoperative planning and implant type. Opening of the canal is done with an awl or osteotome, followed by any blunt tipped instrument, to follow the intramedullary direction. A box osteotome opens the lateral portion of the femoral neck, gently to preserve as much cancellous bone as possible. Sequential broaching follows carefully and according to the planning, to ensure preservation of 2mm to 3mm cancellous bone for interdigitation. Some systems might require over-broaching by one size. Trialing is done with the broach. Following, irrigation using a long nozzle pulsatile lavage, reduces the chance for fat embolism. A cement restrictor is then placed 1.5cm to 2cm distal to the tip of the stem, to ensure an adequate cement mantle distally. A second complete pulsatile irrigation of the canal follows, to minimise bleeding, followed by a dry sponge. Cement mixing is vacuum based in the meantime, usually 60–80g. We prefer the use of low dose antibiotic laden cement in our set up. Two to three minutes after mixing, the cement is applied rapidly in a retrograde technique, with a cement gun placing the nozzle tip against the cement restrictor. The gun is “pushed” out during the application, rather than being withdrawn from the canal. Proximal pressurization is first done by thumb, then with a proximal seal for 1 minute. The stem is inserted slowly using steady manual pressure, in the center of the cement mantle, however should never be impacted. The stem is aligned with the previously defined lateral entry point and is held in position until the cement hardens. The desired outcome is a cement interdigitation into cancellous bone for 2mm to 3mm and an additional mantle of 2mm pure cement.

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

As an increasing number of young, active, large patients are becoming candidates for total hip replacements, there is an increasingly urgent need to identify arthroplasties that will be durable, highly functional and amenable to possible future successful revision. In an era when cemented femoral stems were the primary implant option, the concept of a surface replacement was attractive and, perhaps, appropriate. However, cementless femoral stems of many designs now provide dependable long-term fixation and excellent, near normal function in patients of all ages, sex and level of activity.

However, a number of issues related to cementless stem fixation could be further improved: Optimization of load transfer to proximal femur to minimise fracture risk and maximise bone preservation; Elimination of proximal-distal mismatch concerns, including bowed femurs; Facilitation of femoral stem insertion, especially with MIS THA exposures; Facilitation of revision with implants capable of providing durable fixation for active patients.

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

The purpose of this presentation is to describe the design rationale and characteristics of short (<115mm) uncemented primary THA femoral stem, to evaluate the clinical and radiographic results of short stems and to discuss the possible drawbacks specific to the use of short stems.

Hip resurfacing, like other orthopaedic procedures, depends for its success upon the confluence of three factors: a well-designed device, implanted using good technique, in a properly selected patient.

Cleveland Clinic has had good mid-term results in more than 2,200 patients using the Birmingham device since its FDA approval in 2006. These results are quite similar to other reported series from many centers around the world.

All surgery was performed using an anterolateral approach. Males accounted for 72% of the patients, and the average age was 53 years (12‐84). More than 90% of the patients had a diagnosis of osteoarthritis, and femoroacetabular impingement was the predominant pathology. The average component head size in males was 51mm, and in females 45mm.

Complications were few, with no dislocations, no femoral loosening, one socket loosening, one head collapse, 2 femoral neck fractures, and 2 deep infections. There were two patients with metallosis, one due to component malposition, and one in a small, dysplastic female. There were no destructive pseudotumors.

Overall survivorship at up to 8 years was more than 99%. Survivorship in young males, under age 50 with OA was 100%.

New mushroom templates for head size are described. Additional imaging recommendations including a standing lateral of the pelvis, and a CT scan for femoral anteversion may be helpful in patient selection.

There are many types of articulating surfaces in uncemented acetabular cups. Most of the designs currently available are modular, with the shell snapping into a locking mechanism of some type. An Elliptical Monoblock design has been available for 15 years and was originally made of titanium with a factory assembled compression molded polyethylene liner. Porous tantalum (trabecular metal) was used as the shell material in a subsequent more recent design and in this design the polyethylene is actually molded directly into the tantalum framework.

Monoblock acetabular components do not allow particulate access to the ilium via screw holes and require no surgeon assembled locking mechanism which may increase backside wear and metallic debris. There are no holes in the socket because of the monoblock construct. Because of this absence of screw holes there is an inability to visualise the floor of the acetabulum and perfect coaptation between the shell and the acetabular floor may not occur. The presence of dome gaps of greater than 1.5mm have been noted in 5% of these components but these have not compromised implant stability and in a review of over 600 cups there has been no change in implant position. The Elliptical shape of the cup makes the mouth of the acetabular component 2mm greater than the dome so that an exceptionally strong acetabular rim fit results.

Results will be reported from two major institutional series with a minimum 10-year follow-up (range 10–15 years). No pelvic osteolysis was not seen in any patient in either series. In the HSS series of 250 cases with minimum 10 year follow up there were 4 revisions for instability but none for mechanical failure. There were three femoral revisions for loosening but the cup was intact and not revised in these patients. Utilising the Livermore measurement method polyethylene wear averages 0.8mm per year (0.6mm-1.3mm) and there have been no revisions for wear. Radiographic evaluation demonstrates stable bony interface in all patients. In a Mayo series of prospectively randomised patients also at minimum 10 years there was no lysis and only one case of aseptic loosening in a beaded titanium cup. At minimum 10-year follow up two similar elliptical monoblock cementless acetabular component designs with compression molded polyethylene have confirmed the theoretical advantages of this design concept and demonstrate long term results that have been excellent to date.

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.

Perioperative antibiotics/blood management/preferred anesthetics; Surgical approach for primary total hip arthroplasty: indications or preferences for direct anterior, anterolateral, posterior; Acetabular fixation; Tips for optimising acetabular component orientation; Femoral fixation: indications for cemented and uncemented implants, role of hip resurfacing; Femoral head size: preferred head sizes in different situations; Bearing surface: present role of different bearings; Tips for optimising intraoperative hip stability; Tips for optimising leg length; Postoperative venous thromboembolism prophylaxis; Heterotopic bone prophylaxis; Postoperative pain management; Postoperative rehabilitation protocol: weight bearing, role of physical therapy; Postoperative activity restrictions; Postoperative antibiotic prophylaxis for procedures

Prevention: Many periprosthetic femur fractures may be prevented by: good patient follow-up; timely reoperation of lytic lesions if radiographs suggest fracture risk; prophylactic use of longer stemmed implants or strut grafts to bypass cortical defects at revision surgery.

Treatment: Periprosthetic fractures can be treated using an algorithmic approach based on the Vancouver classification system.

Fractures of greater or lesser trochanter (Type A): nonoperative treatment if displacement acceptable and if not associated with lysis; operative treatment if displacement unacceptable or associated with progressive lysis.

Fractures of distal femur well distal to implant (Type C): treat as any other femur fracture, usually operatively; fixation options: plate/retrograde nails.

Fractures around the implant or at its tip (Type B): these fractures almost always require surgery. Nonoperative treatment is associated with high rate of malunion, nonunion, poor results. Treatment is according to fixation status of implant and bone quality.

Well-fixed stem (Type B1): ORIF with cable plate and/or strut grafts; or with locking plate and minimally invasive biologic technique.

Loose stem (Type B2 and Type B3): revise implant to long stem; usually use uncemented distally-fixed implant; occasionally long cemented stem (avoid cement extrusion). In most cases we favor use of a modular fluted tapered stem which provides axial and rotational stability by fixation distal to the fracture.

Principles: obtain fracture stability, implant stability, and optimise conditions for bone healing (use bone grafts, don't strip periosteum)

Over the past decade there has been a shift in the approach to management of many femoral neck fractures. As noted by Miller et al. those trends are reflected in the practice patterns of surgeons applying for board certification through the American Board of Orthopaedic Surgeons. From 1999 to 2011 there was a trend toward total hip arthroplasty and corresponding small decreases in the use of hemi-arthroplasty and internal fixation for treatment of femoral neck fractures. For many years the treatment approach has been a simple diagnosis-related algorithm predicated upon classification of the fracture as displaced (historically treated with hemi-arthroplasty) or non-displaced (historically treated with internal fixation). More recently, however, the focus has shifted to a patient-centered approach. In the patient-centered approach factors such as age, functional demands, pre-existent hip disease and bone quality should all be considered. In the contemporary setting it is still important to distinguish between displaced and non-displaced fracture patterns. Non-displaced femoral neck fractures, regardless of patient age or activity, are well-suited to closed reduction and internal fixation, most commonly with three cannulated screws. The union rate is high in non-displaced fractures treated with internal fixation and the benefits of preserving the native hip joint are substantial. Displaced femoral neck fractures in younger active patients, particularly those without pre-existent hip arthritis, are best treated with early anatomic reduction and internal fixation. While a subgroup of young, active patients who undergo ORIF may fail, the benefits of native hip preservation in that group are again substantial. Displaced femoral neck fractures in older patients or those with substantial pre-existing hip arthritis are best treated with arthroplasty. The biggest practice change has been the trend to total hip arthroplasty as opposed to hemi-arthroplasty for a subgroup of patients. Total hip arthroplasty is now favored in almost all active, cognitively well-functioning patients as the degree of pain relief is better and the risk of reoperation is lower in the current era (32mm and 36mm femoral heads). Hemi-arthroplasty, either uni-polar or bi-polar, remains an appropriate treatment for cognitively impaired patients who also have limited functional demands in whom the risk of dislocation is particularly high.

Although the vast majority of fractures of the proximal femur will heal with well-done internal fixation, occasionally failure of fixation will occur. Having effective salvage options is important to restore function and minimise complications. In general, it is logical to separate salvage options into those for fractures of the femoral neck, and those for fractures of the intertrochanteric region. Additionally, patient age and remaining bone stock should be considered.

Femoral neck fracture fixation failure salvage, young patients: All efforts are focused on preserving the native femoral neck. Valgus producing osteotomy is typically indicated, and can be successful even with small patches of AVN.

Femoral neck fracture fixation failure salvage, older patients: Total hip arthroplasty is generally most predictable. Be prepared for very poor bone quality. Supplement uncemented acetabular component with multiple screws. Be prepared to cement femoral component, if necessary.

Intertrochanteric fracture fixation failure salvage, young patients: Repeat internal fixation attempts with fixed angle devices (such as a 95-degree blade plate) and bone grafting generally preferred. Avoid varus of proximal fragment and target inferior femoral head bone.

Intertrochanteric fracture fixation failure salvage, older patients: Total hip arthroplasty preferred. Long stems to bypass femoral shaft stress risers and “calcar replacement” stems may be necessary due to proximal bone defects. Trochanteric fixation must be stable. Results are generally good but trochanteric complaints are common.

Fracture of the acetabulum can result in damage to the articular surface that ranges from minimal to catastrophic. Hip arthroplasty may be required for more severe injuries due to marked articular surface damage, post traumatic degenerative changes, persistent malunion or nonunion, or occasionally avascular necrosis and destruction of the femoral head. These problems may be seen following both closed and open fracture treatment, but prior open reduction and internal fixation often makes subsequent THA more difficult due to soft tissue scarring and retained hardware. In select acute acetabular fracture cases with severe initial comminution of the joint, open reduction and fixation can be technically impossible or so clearly destined to early failure that initial fracture treatment with combined limited fixation and simultaneous THA is the best option, especially in osteoporotic elderly fracture patients.

Problems which may be encountered during any THA in a patient with a prior acetabular fracture include: difficult exposure due to soft tissue defects and scarring, presence of heterotopic ossification, and nerve palsy from the original fracture or subsequent osteosynthesis. Retained hardware can present significant challenges and frequently is left in place or removed in part or completely, when intraarticular in location or blocking preparation of the acetabular cavity and placement of the cup. Additional potential problems include residual deformity and malunion, persistent pelvic dissociation or nonunion of fracture fragments, cavitary or segmental bone loss from displaced or resorbed bone fragments, and occasionally occult deep infection.

Preoperative assessment and planning should include careful consideration of the most appropriate surgical approach, which may be impacted by the need for hardware removal. Screening laboratory studies and aspiration of the hip may prove helpful in excluding associated deep infection. Intraoperative sciatic nerve monitoring may be of assistance in patients with partial residual nerve deficits or where extensive posterior exposure and mobilization of the sciatic nerve is needed for hardware removal or excision of heterotopic ossification. Metal cutting tools to allow partial removal of long plates and adjunctive equipment for removal of broken or stripped screws should be routinely available during these cases. Careful preoperative planning regarding implant and reconstructive options can also ensure availability of proper components and equipment. Often implants and techniques developed for revision surgery for management of major bone deficiencies are needed.

Reported results suggest that surgery is frequently prolonged, can be associated with greater blood loss and may result in increased risk of post-arthroplasty heterotopic ossification when compared to routine primary procedures. Bone stock and fracture union may be better in patients with prior internal fixation than in those with nonoperative treatment of major displaced acetabular fractures. Available long-term results document more durable results with lower rates of aseptic loosening with uncemented acetabular fixation compared to cemented acetabular components. These patients are at higher risk of revision and failure than patients undergoing THA for simple osteoarthritis, though initial short-term results are comparable to conventional hip arthroplasty patients, as long as early wound healing problems and deep infection can be avoided, which is a greater risk for acute THA for initial fracture care. The application of newer implant designs, highly porous ingrowth materials, and methods for management of acetabular bone deficiency developed for revision THA have helped improve results in this challenging subset of primary THA patients.

Perioperative fracture during routine THA represents one of the “not so fresh” feelings that occur for both patients and surgeons. With the increase in the use of uncemented implants and MIS techniques this truly is a problem on the rise. We have examined and quantified the risk factors associated with proximal femoral fracture during THA. Risk factors (risk ratios) identified were: uncemented stems (8.9), anterolateral approach (7.4) and female gender (2.2). Fortunately, treatment with cerclage wiring for uncemented stems has facilitated excellent stem stability and acceptable survivorship with many different femoral component designs. Reduced proximal geometry stems that better match the endosteal osseous anatomy have reduced fracture rates at our institution and maintained excellent stem survivorship. New data examining this design will be presented.

In our series, cemented stems, however, had decreased survivorship in the presence of a proximal femoral fracture. MIS techniques may accelerate rehabilitation but they certainly permit limited visibility of the proximal femoral and acetabular anatomy and may result in less accurate component position. Relatively high fracture rates in series of MIS-THA have been reported. A bigger concern, however, is the unrecognised fracture that displaces postoperatively and requires a return to surgery for treatment with or without revision and mandates that we “see it before it sees us!” Cerclage wiring with looped Luque wires has been our treatment of choice for many years. Wires are significantly less expensive than cables and have proven to be durable in our series. This technique allows intraoperative repositioning and variable tightening in multiple locations. Cable fretting and breakage have been common in our experience with braided cable devices. Acetabular fracture during uncemented THA is most likely an under-reported occurrence and has been associated with elliptical component designs and under-reaming. In the presence of a stable cup, long-term performance has been acceptable.

The orthopaedist may need to act as an important adjunct to the oncologist in management of the cancer patient with hip disease. Management of the cancer patient with routine hip pathology may be relatively straightforward but the surgeon should note that the cancer patient may be on treatment protocols which affect wound healing, the immune system and the risk of DVT. The principles of managing metastatic disease include recognising the presence of lesions in bone about the hip, the occasional need for biopsy, the use of radiation in sensitive tumors and finally surgical stabilization or replacement when needed. In some cases percutaneous cementation of metastatic disease or radiofrequency ablation may be appropriate. Factors which can complicate management of patients who have completed treatment of peri-pelvic cancer, may include radiation therapy which can lead to osteonecrosis of the acetabulum. Greater than 500Cgy of radiation has been associated with high rates of acetabular fixation failure regardless of fixation type in several series. Decision making in these patients can be aided by consultation with previous radiation therapy providers to estimate the dose sustained by the local tissues under consideration. Increased rates of infection and wound healing have also been noted secondary to long term lymphatic obliteration caused by radiation. These concerns also affect the surgeon who must manage patients with acute metastatic disease where radiation and immune-compromise secondary to chemotherapy are often present.

Several design principles were considered paramount when the surgical technique of performing total hip arthroplasty through an incision in the superior capsule without dislocation of the hip joint was developed. These design principles include: Preservation of the abductors; Preservation of the posterior capsule and short external rotators; Preparation of the femur in situ without dislocation of the hip; In-line access to the femoral shaft axis; Ability to perform a trial reduction; Independence from intraoperative imaging; Independence from a traction table; Applicable to at least 99% of THA procedures

Personal experience with more than 1950 THA using the superior capsulotomy technique over a 12-year period has demonstrated several observations: Dislocation rate of 0.15% (3 in 1950); Acute deep infection rate of 0% (0 in 1950); Universal applicability: used in 99.7% of primary THA; Lateral femoral cutaneous nerve palsy incidence: 0/1950; Femoral nerve palsy incidence: 0/1950; Transient peroneal palsy incidence: 2/1950; Length of stay (since 2010): 1.55 days; Discharge to home: 98%; 90-day cost (2/13 to 2/14) compared to other exposures in CMS patients in the same institution: $24,200 vs $30,100; Readmission costs (CMS 2/13 to 2/14) at 90 days: $0.

Conclusion: Performing total hip arthroplasty without dislocation and with preservation of the abductors, posterior capsule and short external rotations has proven to have a low dislocation rate, a low infection rate, and wide applicability. CMS 12-month expenditure data documenting ZERO dollars spent on readmission for any reason within 90 days of surgery demonstrates the potential for simultaneously improving incomes and reducing cost, with particular benefit within the CMS BPCI and private bundled payment programs.

Merriam Webster - ide•al adjective \ī-′dē(−ə)l, ′ī\: exactly right for a particular purpose, situation, or person

Dictionary.com - 1: conceived as constituting a standard of perfection or excellence; 2: regarded as perfect of its kind; 3: existing only in the imagination; not real or actual

Concepts: Tissue Preserving - anterior and posterior capsule maintained: YES; No dislocation; Minimal leg manipulation; Rapid Rehabilitation: YES; Half the average LOS at NE Baptist; Safe: YES; Fewer complications than standard approach; Transferable and Reproducible ???; Limited adoption; Optimally executed with navigation; Leg length assessment less accessible; Neck cut measured from GT; “Funny looking” impactors/reamers - different “feel”.

IDEAL: For some… but not for most.

The proximal modular neck in total hip arthroplasty is not a new concept, but there has been resurgence in interest with multiple companies offering proximal modularity.

The proposed advantages of proximal modularity are 1) reduced impingement and subsequent reduced risk of ceramic liners, 2) reduced risk of dislocation and 3) fine tuning of leg length and offset. All of these surgical goals can be accomplished with careful surgical planning and technique, without introducing the risks associated with new technologies. Further, according to the Australian Orthopaedic Association 2014 Joint Replacement Registry annual report, the dislocation rate for components with femoral neck modularity is actually higher than fixed necks. As such, there are no advantages to modular necks.

Modular necks introduce new problems and risks. Modular necks introduce an additional source of corrosion and fretting, and specific systems have been recalled over such concerns. There are numerous case reports of dissociation and fracture at the junction. Fracture appears to be a significant issue in some systems. Retroversion of the neck to reduce the chance of dislocation is not necessarily benign with respect to implant fixation and stability, with RSA and registry data suggesting caution in the application of retroverted necks. Modular necks are difficult to dissociate when in vivo, negating the long-term benefit of modular conversion. Finally, proximal neck modularity significantly increases the cost of the implant, without any documented improvement in long-term outcome.

Modular necks offer limited advantages with significant potential downside. On balance of the evidence, the routine use of modular necks in primary total hip arthroplasty is difficult to justify.

The advantages of modularity in both primary and revision hip surgery are well documented, and have been at the heart of innovation in hip implant design over the last two decades. There have been significant developments in modularity proximally at the head-neck junction, more distally with modular necks and at mid-stem level, notable for complex revisions. Modularity allows us to address version, length and offset issues and to restore optimal hip biomechanics. There are, however, increasing clinical concerns associated with the failure of taper junctions. The use of large femoral heads and modular stems are now considered major risk factors for taper corrosion. Recent studies have shown an 8–9% early revision rate of one modular neck design due to pain and adverse local tissue reaction. I will summarise our laboratory and retrieval data on taper design and tribology in order to put in perspective the clinical use of modularity in hip arthroplasty.

Modular junctions rely on a frictional interlock. The engagement obtained and resulting micromotion is strongly influenced by taper size, taper length/engagement, material, surface finish, neck length and offset. In our quest for thinner femoral necks, greater offsets and bigger femoral heads, we have inadvertently created an environment that can generate fretting corrosion at modular junctions and leads to premature implant failure.

Our work demonstrates that increasing torque and bending moment leads to increased susceptibility to fretting corrosion at the modular taper interface of total hip replacements. This is particularly relevant with the increasing use of larger diameter femoral heads that produce higher torques. It also identifies surface area and surface finish as important factors in wear and corrosion at the modular interface of total hip replacements. Critically, the combination of these factors can lead to extensive corrosion at the interface.

Surgical technique is also important. Higher impaction loads on clean, dry surfaces result in greater contact length and extraction forces, which may influence micromotion.

It is critical in future that all innovation is introduced in a systematic gradual fashion so that we do not fall into similar traps again. The unintended consequences of minor changes in design may have a massive effect on outcomes. Our findings suggest that it may be possible to continue to employ the advantages of modularity in hip surgery whilst avoiding some of the pitfalls that have led to the failure of some modular systems.

Understanding the key design and surgical factors that drive the performance of taper junctions is vital for the surgical community. There is a body of knowledge that supports appropriate taper use / modularity to help surgeons deal with complex situations. We must be careful not throw the baby out with the bathwater.

Cemented total hip arthroplasty (THA) has become an extremely successful operation with excellent long-term results. Although it always remained a popular choice for the elderly patients in many countries, recent trends show an increased use of non-cemented stems in all age populations in many national registries. So far, there has been no clear age associated recommendation, when a cemented stem should be used. Described major complications such as periprosthetic fractures are usually associated at age >75 years, in many registries. Uncemented stems perform better than cemented stems in recent registries; however, unrecognised intraoperative femoral fractures may be an important reason for early failure of uncemented stems. Experimental studies have indicated that intraoperative fractures do affect implant survival, in addition it has been shown that intraoperative and direct postoperative fractures increase the relative risk of revision during the first 6 postoperative months significantly. Furthermore it has been clearly shown, that uncemented stems were more frequently revised due to periprosthetic fracture during the first 2 postoperative years than cemented stems.

Although often associated reduction of femoral bone quality in especially female patients >60 years, uncemented fixation has become the standard in most scenarios worldwide. Based on the implant fixation type: metaphyseal vs. diaphyseal of various uncemented stems, major attention should be, however, drawn to the intraoperative bone quality during the broaching process, especially for metaphyseal fixation stem types. Although cementless distal fixation can be achieved in thick cortices still in many patients, the incidence of associated thigh pain needs to be considered for some implant types. Furthermore small femoral canals might generate certain implant-bone size mismatch in relation to the proximal femur, thus nonoptimal fixation could be achieved. Consequently proper implant planning is mandatory preoperatively.

In any cemented THA, a proper cementing technique is of major importance to assure longevity of implant fixation. This also includes proper implant sizing/ templating, ensuring an adequate cement mantle thickness, which might be restricted in a small diameter femur. The desired outcome is a cement interdigitation into cancellous bone for 2–3mm and an additional mantle of 2mm pure cement. Consequently proper planning in small diameter patients, prevents sizing problems, while in few cases special/individualised stem sizes might be considered.

In summary attention needs to be drawn on small diameter stems, to prevent fractures and achieve proper implant fixation, in both uncemented and cemented fixation types. Proper implant planning preoperatively might be more important than in usual cases, while sometimes individual /small implant types might become necessary.

Small canals are usually in small people, but occasionally some normal-sized people have huge cortical thickness with a corresponding small canal.

To give adequate strength to the cement mantle, either pure cement or cement/cancellous bone, it must be at least 2mm thick. If the medullary canal is 9mm or less, then the thickest stem, which can be used with cement will be 5mm. This stem is so small that under load, it may deform repetitively, i.e. cycle. If it does cycle, it will break up the cement mantle. In order to get in a stem large enough to prevent cycling, hard reaming will be required, thus, removing most of the cancellous bone so the cement interlock is poor.

Small stems are also usually fairly short stems. With a follow-up of more than 15 years, inevitably, some lucency between the cement and bone occurs in zones one and seven. If the stem is long enough, that is of no significance. If the stem is short, i.e. 120mm or less, then the area of distal fixation becomes precariously small.

For these reasons, if the canal is small, it is preferable to use a non-cemented stem. The reaming technique for a non-cemented stem is to reach endosteal cortical contact either circumferentially with a canal-filling stem or at the point of wedge for a wedge-shape stem. The metaphyseal bone may be poor quality in the elderly, but it is going to be removed anyway to load the endosteal cortex.

This means that a large stem can be used, which is, therefore, stronger and less likely to undergo mechanical failure and fixation failure.

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity always leads to arthrosis if uncorrected. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Preoperative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces.

Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Cam impingement can be treated by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of preoperative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis preop whereas dysplastic hips can become symptomic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctible problems prior to the development of significant secondary arthrosis.

Obesity is clearly a worldwide epidemic with significant social, healthcare and economic implications.

A clear association between obesity and the need for both hip and knee replacement surgery has been demonstrated. Specifically the presence of class 3 obesity (BMI > 40) increases the incidence of THA by 8.5 times, and the incidence of TKA by 32.7 times, compared with patients of normal weight.

Issues related to TJA in the morbidly obese include: Outcomes - There is a growing body of evidence to support the premise that patients undergoing either THA or TKA who are morbidly obese derive significant benefit from the surgical intervention. Specifically patient and disease specific outcome measures (WOMAC, SF-12, KSCRS, HSS) demonstrate equal change between preoperative and postoperative scores in those patients of normal weight compared to the morbidly obese cohort; Complications - It would appear that the rate of deep infection is increased in the morbidly obese, and that the greater the BMI, the greater the risk of infection. This is important to understand and appreciate preoperatively as the surgeon discusses the risk/benefit ratio of the operative intervention.

There is little debate that performing total joint arthroplasty in the morbidly obese is technically challenging and that the potential for increased perioperative morbidity, particularly in the form of infection is present. That being said, the realised benefit to the patient of the surgical intervention is significant, and denying surgery on the basis of obesity alone is not justified.

The endoprosthetic treatment of secondary osteoarthritis resulting from congenital hip dysplasia is difficult due to the small diameter of the acetabulum and the hypoplastic anterolateral bone stock. On the femoral side the increased femoral anteversion, insufficient femoral offset and proximal femoral deformities (mostly valgus deformities) as well as the small diameter and straight form of the intramedullary canal pose challenges. Careful preoperative planning is mandatory. The Crowe classification is usually used to describe these pathologies. In severe cases (Crowe 3 and especially Crowe 4) a shortening and derotating femoral osteotomy should be taken into account. Small acetabular components, acetabular augments, and modular femoral components must be available at all times.

For acetabular fixation press-fit cups are preferred today, but excellent results were also described for threaded cups. The advantage of press-fit cups is the extensively documented and superior track record, but threaded cups allow for an easier reconstruction of the original hip center as well as slight medialization. As a result of medialization a reduction in polyethylene wear together with a low rate of loosening lead to very good long-term results in a younger patient population.

Cementless straight stems are documented to be preferable for the small femoral diameter and the straight anatomic shape of the proximal femur. Nevertheless, the higher complication rate, especially the increased rate of nerve palsies, should be preoperatively discussed with the patient. The ideal bearing surface is currently unclear, ceramic-on-ceramic seems to be promising, although the longest data available support the use of metal-on-polyethylene.

Protrusio acetabuli (arthrokatadysis or Otto pelvis) is a relatively rare condition associated with secondary osteoarthritis of the hip. Radiographically, protrusio acetabuli is present when the medial aspect of the femoral head projects medial to Kohler's (ilioischial) line. This results in medialization of the center of rotation (COR) of the hip. Protrusio acetabuli is typically associated with metabolic bone disease (osteoporosis, osteomalacia, Paget's disease) or inflammatory arthritis (RA or ankylosing spondylitis). Idiopathic acetabular protrusio can occur without the above associated factors however. Patients with protrusio acetabuli typically present with significant restriction of range of motion (ROM) of the hip due to femoral neck and trochanteric impingement in the deep acetabular socket and pain associated with secondary osteoarthritis (OA).

Total hip arthroplasty (THA) in patients with protrusion acetabuli is more challenging than THA in patients with a normal hip COR. ROM is typically quite restricted which can compromise surgical exposure. Dislocation of the hip in the patient with a deep socket and medialised COR can be extremely difficult and associated with fracture of the femur if not carefully performed. Restoration of the hip COR to the normal more lateralised position is a principle goal of surgery. This restores more normal mechanics of the hip and has been associated with improved durability. A variety of techniques to accomplish this have been described including medial acetabular bone grafting with cemented cups, protrusio rings or porous coated cementless cups fixed with multiple screws. The latter technique has been shown to be more durable and associated with better outcomes.

THA in protrusio acetabuli starts with templating of the preoperative x-rays to determine the optimal acetabular implant size and final position of the acetabular component that restores the hip COR to the normal position. Patients with protrusio acetabuli often have varus oriented femoral necks and the femur needs to be carefully templated as well to insure that an appropriate femoral component is available that will allow for restoration of the patient's anatomy. Cartilage covering the thinned medial wall needs to be carefully removed without disruption of the medial acetabular wall. The acetabulum is then carefully reamed with the goal of obtaining stable peripheral rim support of a cementless socket and at least 50% contact of the implant on good quality host bone. Unlike acetabular preparation in the normal hip, preventing the reamer from “bottoming out” is essential in order to obtain desired rim support and return of the hip COR to the normal lateralised position. When good rim support of the reamer is obtained, a trial component is placed and intraoperative x-ray obtained to confirm fit, position and restoration of hip COR. Limited addition reaming can be performed to obtain desired degree of press fit (1‐2mm) and contact with host bone. Morselised autograft from the femoral head and neck is then packed into the medial defect and reverse reamed. The cementless acetabular component is then impacted into position and fixed with screws. Weight bearing is determined by bone quality, size and containment of the medial defect, amount of contact of the cementless cup with host bone and stability of the acetabular construct. Incorporation of autograft bone in the acetabulum and stable long term fixation occurs reliably if stable initial press-fit fixation of the cementless cup is obtained. Restoration of hip COR to within 7mm of its normal location is associated with better implant survival.

There is an increased incidence of dislocation, dysplasia, slipped epiphysis, Perthes’ disease, and avascular necrosis leading to degenerative arthritis which occurs in up to 28% of Down's syndrome patients. As the life expectancy for patients with Down's syndrome has increased, so has the presence of hip disease. Hip replacement has been shown to have good results in this population. Special considerations include a high risk of postoperative dislocation and leg length inequality which often require large head THR or dual mobility type reconstruction to reduce these risks. Numerous spine deformities including scoliosis and C1-2 subluxation need to be taken into account-anesthesia consult.

The mean age of patients with osteonecrosis reported in series in our literature is 38 to 53. Thus, performing a total hip replacement on a patient who would need a procedure to last 40–45 years is a concern. Patients with osteonecrosis of the hip require some type of surgical treatment. Without treatment, a large majority of femoral heads in patients even with Ficat stage I osteonecrosis will collapse or become symptomatic. A common scenario is a patient who first presents to the orthopaedic surgeon with severe arthritis secondary to osteonecrosis in one hip and a normal appearing radiograph on the asymptomatic contralateral side. Performing a total hip on the severe arthritic hip is usually not debated. A MRI will commonly show Ficat stage I osteonecrosis on the asymptomatic contralateral hip. Some method of core decompression is a reasonable choice if it is non-steroid induced, small more medially positioned lesion, but not for other Ficat stage 1 lesions or those with more advanced stages. The problem is convincing the patient to have anything done when they are asymptomatic. Because results with total hip replacement for patients with osteonecrosis of the hip have significantly improved, most patients with a symptomatic hip prefer arthroplasty as treatment. Arthroplasty has become the predominant surgical treatment for osteonecrosis of the hip in the United States. 88% of procedures performed on 6,400 patients with osteonecrosis in 2008 reported in the Nationwide Inpatient Sample Database of the hip were total hip replacements. From 16 years earlier, the number of procedures performed had almost doubled and the percentage use of arthroplasty as the performed treatment had increased by 13%. I expect both numbers will continue to increase.

Not all total hip arthroplasty cases are created equal is a maxim that holds true for both primary and revision scenarios. Complex cases involve patients presenting with compromised bone and/or soft tissue. For primary cases, these include hips with dysplasia, ankylosis, deformed proximal femora, protrusio acetabuli, prior hip fracture with or without failed fixation, previous bony procedures, or neuromuscular conditions. In revision surgery, complex scenarios include cases compromised by bone loss, deterioration of the soft tissues and resulting instability, periprosthetic fracture, leg length discrepancy, infection, and more recently, hypersensitivity reactions. In this interactive session, a moderator and team of experts will discuss strategies for evaluation and management of a variety of challenging hip case scenarios.

The practice at most centers in North America for the investigation and management of non-acute infection after hip replacement has been relatively standard for some time. Diagnosis has depended on a thorough history, physical examination, plain radiographs, straightforward laboratory inflammatory markers, joint aspiration for bacteriologic study, intraoperative frozen section in selected cases, and intraoperative synovial biopsies for confirmatory bacteriologic evaluation. The cornerstone of treatment on this continent has revolved around two-stage revision hip replacement, with increasing popularity for the use of interval articulating antibiotic loaded spacers, and increasing use of cementless fixation at the second stage. But this standard approach has been under increasing scrutiny in recent years, for good reason.

The use of more precise “best evidence” paradigms on which to base the diagnosis have been developed. There is encouraging work on the application of more specific synovial and serum markers. The need to remove all implant material in all cases has been challenged. And there is evidence that the two stage approach is associated with greater morbidity, mortality and cost. The latter has led to a re-examination of the role and results of single-stage exchange revision, at least in selected cases, where the patient is immune competent, the soft tissue and bone anatomy is not badly deficient, the organism is known, and the antibiotic sensitivity is favorable.

The most encouraging of the recent developments is the increasing consensus that multicenter collaborative study is required if we are to make genuine progress in the one-stage/two-stage debate. At least one multicenter prospective randomised study is scheduled to commence in 2015.

Preoperative planning is important – an ounce of prevention is worth a pound of cure. It is perhaps useful to consider the process of preoperative planning in three areas: 1) the patient, 2) the hip, and 3) the operative environment.

The Patient - The patient must first be an appropriate candidate for surgery. By this, they should have confirmed arthritis of the hip by radiograph and physical exam and should have failed conservative management. They should have pain and/or physical disability that impair their activities of daily living. They should be fit and willing to undergo surgery. Their expectations of surgical outcome should be reasonable and the anticipated net clinical benefit of the procedure should outweigh the risks.

There are several patient variables that should be optimised prior to surgery. Blood glucose control in diabetics should be tightly controlled prior to surgery as failure to do so results in an increased risk of infection. Anemia should be ascertained in the history and diagnosed with a CBC if suspected. Reasons for anemia should be addressed and hemoglobin should be optimised preoperatively. Nutrition is important to reduce the risk of infection. Be aware of paradoxical malnutrition in the obese. Understand if the patient has an allergy to penicillin and what specifically the reaction is. Patients with a history that is not characteristic of an IgE mediated response should be offered a cephalosporin. The patient's risk of bleeding or clot as well as their tolerance of specific anticoagulants should be understood and planned for regarding the postoperative anticoagulant. Assess the patient for risk of dislocation.

The Hip - Assessment of the hip is important. An AP of the pelvis and lateral of the hip should be obtained in all cases. Any pelvic obliquity should be assessed in relation to leg length discrepancy, and, if necessary, a 3-foot standing x-ray should be obtained. Leg length and offset should be assessed carefully. Beware of the patient with the operative hip presenting as the longer leg as it is difficult to shorten a hip via THA and the net effect of the intervention is most often lengthening. Patients with low offset should be planned for carefully so that low offset components are available. Patients with high offset need corresponding high offset implants in order to avoid leg lengthening. The acetabulum should be assessed for true center of rotation and orientation, as well as for dysplasia or deficiency. The femur should be assessed for shape, offset and neck angle, as well as for any proximal or distal mismatch. Be prepared to remove hardware that will be in the way.

Template all your cases. The most experienced surgeons still template for THA. Have a Plan A and a Plan B for every case

The Operative Environment - The surgeon is ultimately in control of the operative environment. Make sure that the implants anticipated and sizes are available. I personally put them in the room before the case. Ensure that qualified assistants and nurses are available. Know in advance and communicate when high BMI patients are involved. Display the radiographs and anticipated plan and make sure the team is aware of it. Ensure that antibiotics and tranexamic acid (if not contra-indicated) are administered at a timely fashion. Tell the staff in the time out that traffic flow is important and should be reduced to a minimum. Plan to close one of the doors during the case. Make sure protective covering is available and worn, such as protective eyewear and hair covers.

Increasing demand for total hip and total knee arthroplasty in an era of economic uncertainty and shrinking budgets has put pressure on surgeons to deliver excellent results and early functional recovery with shorter hospital stays. Patients receiving these operative interventions tend to be younger and more active. Their ultimate source of information is the Internet, which may be compromised by low quality, non-peer reviewed information, or information not at an appropriate reading level for comprehension by lower literacy individuals. Unfortunately, not all patients undergoing total hip and total knee arthroplasty are satisfied with their operative intervention. The most significant etiology of this dissatisfaction is reported to be lack of clarification and alignment of expectations between the surgeon and the patient, which may result from misinformation or lack of understanding by the patient. Furthermore, in the era of rapid recovery, length of stay has significantly decreased from 3–5 days a decade ago, now down to 1–2 days, and in some cases same day surgery. In an effort to mitigate this compromise in communication, we have developed a set of frequently asked questions and responses. These are divided into preoperative questions, perioperative questions, and postoperative questions. These are part of our patient educational materials and provide both office and hospital staff with structured responses to avoid miscommunication and misinformation. We have found it to be imperative that all information provided by the office and hospital have a consistent message.

Ideal cup positioning remains elusive both in terms of defining and achieving target.

Our aim is to restore original anatomy by using the Transverse Acetabular Ligament (TAL). In the normal hip TAL and labrum come beyond the equator of the femoral head therefore if the definitive cup is positioned such that: It is cradled by the TAL; Is ideally no more than 4mm greater in diameter than the original femoral head; Sits just deep to the plane of TAL and labrum (this means that normally we leave the fat pad intact and do not ream down to the true floor).

That should restore joint center in terms of height and offset. If the face of the cup is then positioned parallel and just deep to the TAL and psoas groove that should restore original version. We still use TAL for version in dysplasia because we believe the TAL and labrum compensate for any underlying bony abnormality. However in dysplasia the TAL and labrum fall short of original femoral head equator and therefore in such cases we ream down to the true floor if necessary and use a cup which is often smaller than the original head.

Inclination represents a greater challenge and TAL should not be used as an aid to inclination. Our research has shown that errors in postoperative x-ray inclination above 50 degrees are generally caused by errors in patient positioning when in lateral decubitus. Consequently great care needs to be taken when positioning the patient.

Venous thromboembolic events, either deep vein thromboses or pulmonary emboli, are important complications in patients undergoing knee or hip arthroplasty. The purpose of this study was to evaluate the effectiveness of a mobile compression device (ActiveCare+S.F.T.®; Medical Compression Systems, Inc., Or Akiva, Israel) with or without aspirin compared with current pharmacology protocols for venous thromboembolism prophylaxis in patients undergoing elective primary unilateral lower extremity joint arthroplasty.

A multicenter registry was established to capture the rate of symptomatic venous thromboemboli following primary lower extremity joint arthroplasty in 3,060 patients from ten sites including knee arthroplasty (1,551) or hip arthroplasty (1,509). All patients were eighteen years of age or older with no known history of venous thromboembolism, coagulation disorder, or solid tumor. Use of the compression device began perioperatively and continued for a minimum of ten days. Patients with symptoms of deep venous thrombosis or pulmonary embolism underwent duplex ultrasonography and/or spiral computed tomography. All patients were evaluated at three months postoperatively to document any evidence of deep venous thrombosis or pulmonary embolism.

Of 3,060 patients, 28 (0.92%) had venous thromboembolism (20 distal deep venous thromboses, 3 proximal deep venous thromboses, and 5 pulmonary emboli). One death occurred with no autopsy performed. Symptomatic venous thromboembolic rates observed in lower extremity joint arthroplasty patients using the mobile compression device were non-inferior (not worse than) at a margin of 1.0% to rates reported for pharmacological prophylaxis, including warfarin, enoxaparin, rivaroxaban, and dabigatran except in the knee arthroplasty group where the mobile compression device fell short of rivaroxaban by 0.06%.

Use of the mobile compression device with or without aspirin for patients undergoing lower extremity joint arthroplasty provide a non-inferior risk for developing venous thromboembolism compared with current pharmacological protocols reported in the literature.

Revision of M-O-M articulation:

Indications

Loose cup either radiographically or clinically. Clinical symptoms are persistent startup pain; straightening from the bent position; inability to do single limb stance; limp.

Unrelenting pain with any activity, even turning over in bed.

Soft tissue mass in groin or anterior hip (more common anterior to greater trochanter than posterior.

Elevated ion levels, especially cobalt. Elevated is 10µg/L but dangerous levels not defined (my definition is 40µg/L. Danger is cobalt poisoning. Also elevated ions almost always mean increased wear so local osteolysis and bone destruction is a risk with increased follow up.

Cobalt poisoning: objective findings are cardiopulmonary with increasing shortness if breath; second most common is cognitive change. (Memory loss, psychomotor retardation). Subjective finding is psychological effect of a poison in their body.

The purpose of this study is to evaluate the indications and technique of hip arthroscopy for problems associated with total joint replacement.

Anterior supine intermuscular total hip arthroplasty (ASI-THA) has emerged as a muscle sparing, less-invasive procedure. The anterior interval is both intermuscular and internervous, providing the advantages of little or no muscle dissection, and a true minimally invasive alternative. It is versatile, with reported use expanding beyond the primary realm to revision and resurfacing THA as well as treatment of acute fracture in elderly patients, who due to their diminished regenerative capacity may benefit more from the muscle-sparing nature of the anterior approach. The ASI approach involves the use of a standard radiolucent operative table with the table extender at the foot of the bed and the patient supine. Fluoroscopy is used in every case. A table-mounted femur elevator is utilised to facilitate femoral preparation.

A retrospective review identified 824 patients undergoing 934 consecutive primary ASI-THA performed between January 2007 and December 2010. Age averaged 63.2 years (27‐92), BMI averaged 29.9 kg/m2 (16.9–59.2). Gender was 49% males and 51% females. Stem types were short in 82% and standard length in 18%. Follow-up averaged 23.1 months (1‐73). Operative time averaged 63.1 minutes (29‐143). Blood loss averaged 145.3 mL (25‐1000). Transfusion rate was 3.3% (30 of 914) in single procedures and 80% (8 of 10) in simultaneous bilateral procedures. Length of stay averaged 1.7 days (1‐12). Intraoperatively there were 3 calcar cracks and 1 canal perforation treated with cerclage cables. There were 6 wound complications requiring debridement. Four hips had significant lateral femoral cutaneous nerve parathesias not resolved at 12 months. One femoral nerve palsy occurred. At up to 73 months follow-up there have been 21 revisions (2.2%): 2 infection, 1 malpositioned cup corrected same day, 5 metal complications, 2 dislocations, 2 loose cups with one requiring concomitant stem revision secondary to inability to disarticulate trunnion, 1 femoral subsidence and 8 periprosthetic femoral fractures.

Primary THA can be safely performed utilising this muscle-sparing approach. We did not see an alarmingly high rate of complications. Instead, rapid recovery and quick return to function were observed. ASI-THA appears to be safe. The recovery advantage utilising this surgical approach is irrefutable. There are complications, most notably periprosthetic femur fracture. The rate, however, appears to be low and decreases with increased experience. There is no need for a special operative or fracture table to perform the procedure. Whether the complication rate is higher with the use of these expensive devices is unknown, but our results demonstrate a 2.2% reoperation rate with the use of the ASI approach performed on a standard OR table. Continued refinement of the technical aspects of ASI-THA may lessen the complication rate.

Mini-posterior technique advantages: Familiar anatomy; Widely applicable; Predictable (and thus preventable) sources of errors; Demonstrated functional advantages over the 2-incision THA in recent prospective randomised trials and in direct comparison studies

Familiar anatomy: A substantial number of surgeons routinely use the posterior approach; With careful attention to skin incision placement and leg positioning intraoperatively it is relatively easy for most surgeons to shorten the skin incision; With the addition of specialised retractors, offset reamers and offset cup and stem inserters many THA can be done with a skin incision of 10cm or less; Easily converted to standard posterior approach if intraoperative concerns arise; Formal posterior capsular repair substantially lowers historical risk of dislocation.

Widely applicable: With relatively little variation this approach can be used for a broad range of THA patients; Several variations of the mini-posterior technique exist (Sculco, Dorr, Swanson, Goldstein); Dorr technique has been used in my practice and we have studied it extensively in direct comparison studies against the 2-incision technique.

Acetabular component malalignment remains the single greatest root cause for revision THA with malposition of at least ½ of all acetabular components placed using conventional methods. The use of local anatomical landmarks has repeatedly proven to be unreliable due to individual variation of these structures. As a result, the use of such landmarks without knowledge of their three-dimensional orientation may actually be a major cause of component malpositioning. Traditional navigation and robotics can potentially lead to improved component placement but these technologies have not gained widespread use due to the increase in time of use, complexity, and cost of these systems. The alternative of placing the cup in the supine position, even with the use of arthroscopy, has been proven to have an incidence of inaccuracy equal or greater than that in the lateral position.

A smart mechanical instrument system was developed to quickly and easily achieve accurate cup alignment (HipXpert System, Surgical Planning Associates, Boston, MA). The system is based on a low dose, low cost CT study and a customised patient-specific surgery plan. The laterally-based system docks on a patient-specific basis with 3 legs: one through the incision behind the posterior rim, one percutaneously on the lateral side of the ASIS, and a third percutaneously on the surface of the ilium. A direction indicator on the top of the instrument points in the desired cup orientation. The anteriorly-based system also docks on a patient-specific basis with one leg on the anterior ischium and one leg on each ASIS, either to skin or to bone.

The lateral system has been proven to be robust, with repeated studies showing accurate cup placement in 100% of cases and an independent study showing accurate cup placement in 98% of cases. The newer anterior system has the potential for even greater accuracy.

Smart mechanical navigation of cup placement offers the optimum combination of accuracy, speed, and simplicity for solving the ubiquitous problem of acetabular component malorientation.

The inability to consistently position components is associated with the major complications of hip replacement including instability, wear, liner breakage, limb length discrepancy, and limited function. This was a major catalyst for the demise of hard-on-hard bearings. The greatest challenge is accurate, reproducible positioning of acetabular component which is obtained in a surprisingly low percentage of cases. Other major issues include consistently obtaining proper limb length, offset, component sizing, and complete seating without fracture of either the acetabulum or the femur. There are two approaches to this issue; to either use virtual reality which applies technology that provides surrogates to direct visualization of components. The major issues with computer assisted techniques include questions of accuracy and increased time and cost. The other approach is to utilise intraoperative imaging which has been the gold standard traditionally, however, previously it has been a challenge to utilise intraoperative imaging without adding substantial time and cost. Historically intraoperative imaging has not been adopted because it disrupts work flow, the quality of images has been inadequate, and it has added too much additional time to allow for a series of repeat radiographs to be obtained.

Modifications of existing portable imaging that utilise direct radiography (DR plate technology) allow for intraoperative images that display within seconds. Imbedded software allows measurement of all parameters of interest. Three or 4 systems are currently in use, and this is not virtual reality but it is the gold standard. Advantages include higher quality images, faster service speed, minimal impact on OR work flow, eventual reduction in operating costs, elimination of processing of chemicals and film room/storage room, and most importantly the elimination of outliers and return to the operating room due to unexpected findings on recovery room radiographs.

Intraoperative imaging has been utilised at a number of centers in recent years and has led to numerous intraoperative changes to optimise component implantation in a surprisingly high percentage of cases. Advances in technology have made intraoperative digital imaging a practical feasible strategy to avoid outliers that increase complications and compromise results. The rapidly evolving technology makes this a very attractive option for optimising total hip component placement. In addition it is an excellent teaching tool that is rapidly embraced by residents and fellows and is an extremely effective in eliminating outliers.

A) Mastering the Art of Cemented Femoral Stem Fixation

During the development and early use of the First Generation of Universal Total Knee Replacement Instruments, those instruments supplied with the PCA knee and also available for use with the Kinematic and Total Condylar knees, David Hungerford and I noticed our imperfection in balancing some varus and valgus deformed total knee patients.

We decided to start ligament tightening procedures to address this problem.

I became impressed with the potential difficulty of simply grasping the medial capsular ligamentous sleeve and pulling it distally on the proximal tibia so that it could be stapled in place. I thought that use of a suture and then incorporation of that suture with a staple or screw could enhance the fixation.

The tissue we were working with and are now talking about is rather thin, 1mm to 2mm, flat and broad with longitudinal fibers running in a caudad-cephalad direction.

I wanted some way to grab these longitudinal fibers and exert a distal pull without having the suture material pull through. This suggested the use of a locking loop, analogous to what I had seen in my training when locking stitches were commonly used on different layers of wound closure. I developed in my head the picture of a row of locking loops and then saw the cross-over to the other side which revealed the entire structure with trailing tails.

At this writing, I am uncertain of the year, but I am thinking it was 1982.

Soon after that I illustrated it with OR suture thru paper and then began using it in surgery.

I felt that publication would require studies of relative pull-out strength, and we added an injection study to look at possible influence of the tissue vascularity.

For tensile strength we used #5 Ethibond in bovine xenograft material, stapled and sewn to wood. In summary, different from individual stitches or stapling without stitching, The K-stitch fails at the suture material and not by pulling the tissue. This statement is true when the suture reasonably matches the heft or thickness and strength of the soft tissue. Otherwise one is dealing with suture that is overpoweringly stronger than the tissues being fixed or held.

Clearly this stitch has found common application in Achilles tendon repair and a wide variety of other applications. My own most common use is with re-attachment of the gluteus minimus tendon after an anterolateral total hip exposure.

I imagine that this suture is used or at least known by all orthopaedic surgeons with one exception, spine surgeons. I just do not see an application in their surgery. However, some of the younger ones will know it from their general orthopaedic training.

A video is shown of the technique and it is emphasised that the suture need not be used so that it loops the edge of a tendon. It may just as easily and helpfully be used on a broader surface as shown.

Infection is a devastating complication following total hip arthroplasty. For chronically infected total hip arthroplasty; we utilise a 2-stage articulating antibiotic hip spacer technique. Our success rate with the technique is 90% with patients clinically free of infection at an average of five years postoperatively. 80% of the patients had a positive identification of the infecting organism. The other 20% had a positive frozen section and clinically infected joints. All patients receive a minimum of 6 weeks of intravenous antibiotics. Postoperative hip scores average 90 points. Some patients elected to keep their antibiotic spacers for up to 2 years before the 2nd stage. Advantages of this technique include improved patient function, maintenance of bone stock and soft tissue tension, thus simplifying reimplantation.

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

Surgical Technique:

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

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

We have used trabecular metal augments in 46 acetabular revisions in conjunction with a TM cup. Thirty-four cases have at least 2 years follow-up with an average of 64.5 months. There has been 4 cup loosenings with 3 re-revisions.

The technique for removal of bone ingrown extensively coated devices involves cutting the stem below the metaphyseal portion of the stem, followed by removal of the proximal stem and trephine removal of the cylindrical distal portion of the stem. This can be done with or without an extended trochanteric osteotomy (ETO). When the proximal portion of the stem is not bone ingrown (extensive proximal osteolysis, or the stem is broken) or the metaphyseal bone is easily accessed (there is no collar) the stem can be cut through a bone window. In all other cases an ETO at the level where the stem becomes a cylinder is required to disrupt the metaphyseal bone prosthesis interface, cut the stem and extract the proximal portion of the stem.

Glassman described the techniques for removal of cementless stems in 1992. 42 loose stems were easily removed, 11 fibrous stable implants were removed with thin osteotomes, and 11 bone ingrown, canal filling, extensively coated stems were removed with trephines. In no cases was reconstruction precluded by stem removal. The critical tools required included manufacturer specific removal tools, high speed burs, thin osteotomes, universal extraction device for connection to the neck, and multiple trephines.

More recently, Kancherla reported the use of trephines to remove 36 porous coated stems. 86% of cases were bone ingrown after removal, however, complications included an extruded trephine causing a femoral fracture and two periprosthetic fractures thought to be secondary to trephine induced osteonecrosis. The authors recommend bypassing the most distally trephined bone by a minimum of 4cm.

Trephines are very helpful for removing distally fixed stems. Multiple trephines need to be irrigated and changed frequently to avoid dull cutting teeth which can lead to bone necrosis.

The well-fixed cemented femoral stem and surrounding cement can be challenging to remove. Success requires evaluation of the quality of the cement mantle (interface lucency), position of the stem, extent of cement below the tip of the stem and skill with the specialised instruments and techniques needed to remove the stem and cement without perforating the femur.

Smooth surfaced stems can usually be easily removed from the surrounding cement mantle with a variety of stem extractors that attach to the trunnion or an extraction hole on the implant. Roughened stems can be freed from the surrounding cement mantle with osteotomes or a narrow high speed burr and then extracted with the above instruments. Following this, the well fixed cement mantle needs to be removed.

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

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

Revision of the total hip femoral component in the presence of significant bone loss requires a variety of implants as well as fixation devices and bone substitute materials.

Rule 1: Fix the implant into the best remaining bone.

A variety of stem shapes and sizes are needed to fill the bone cylinder. Stem modularity is helpful to fashion a good fit, but every taper junction is a liability as a potential source of metal debris and a weak spot in the stem. Rather, fully porous-coated titanium femoral components with a tapered stem design are safe, convenient, and reasonably inexpensive.

Rule 2: Reconstruct the bone to accept a rigidly fixed intramedullary stem.

Cables, strut allograft, plates, and screws are needed to support the remaining bone.

Rule 3: Manage the bone so that it is still viable after the implant is inserted.

As much intraosseous and extraosseous blood supply as possible should be maintained, so broaching rather than extensive reaming is the best choice for maintaining bone viability.

Rarely more exotic procedures such as reduction osteotomy must be done to achieve rigid fixation of implants.

Revision of the failed femoral component of a total hip arthroplasty can be challenging. Multiple reconstructive options are available and the operation itself can be particularly difficult and thus meticulous preoperative planning is required to pick the right “tool” for the case at hand. The Paprosky Femoral Classification is useful as it helps the surgeon determine what bone stock is available for fixation and hence, which type of femoral reconstruction is most appropriate.

Monoblock, fully porous coated diaphyseal engaging femoral components are the “work-horse” of femoral revision. This type of a stem is used in my practice for Type 1–3a femoral defects. These stems are not used, however, in the following situations: The canal diameter is greater than 18mm; There is less than 4cm available for distal fixation in the isthmus; There is proximal femoral remodeling into retroversion.

While many surgeons often believe that revision femoral components need to be “long”, they really only need to be long enough to engage 4cm of intact femoral isthmus, which is oftentimes the shortest, “primary length” fully porous coated stem. Advantages of using a shorter revision stem include: Easier surgical technique as you avoid the femoral bow, with a lower risk of fracture and under-sizing; Preserves bone stock for future revisions if required; Easier to remove if required.

I prefer monolithic, cylindrical, fully porous coated femoral components for most femoral revisions. Our institutional database holds information on 1000 femoral revisions using extensively porous-coated stems. To date, 27 stems have been rerevised (14 for loosening, 4 for infection, 7 for stem fracture, 2 at time of periprosthetic femoral fracture). Using femoral rerevision for any reason as an end point, the survivorship is 99 ± 0.8% (95% confidence interval) at 2 years, 97 ± 1.3% at 5 years, 95.6 ± 1.8% at 10 years, and 94.5 ± 2.2% at 15 years.

Similar to Moreland and Paprosky, we have identified prerevision bone stock as a factor affecting femoral fixation. Among the 777 femoral revisions graded for femoral bone loss, 59% of the femurs were graded as having no cortical damage before the revision, 29% had cortical damage extending no more than 10cm below the lesser trochanter, and 12% had cortical damage that extended more than 10cm below the lesser trochanter. When the cortical damage involved bone more than 10cm below the lesser trochanter, the survivorship, using femoral rerevision for any reason or definite radiographic loosening as an end point, was reduced significantly, as compared with femoral revisions with less cortical damage.

In addition to patients with Paprosky type 3B and 4 femoral defects there are rare patients with femoral canals smaller than 13.5mm or larger than 26mm that are not well suited to this technique. Eight and 10-inch stems 13.5 or smaller should be used with caution if there is no proximal bone support for fear of breaking. Patients with canals larger than 18mm may be better suited for a titanium tapered stem with flutes. While a monolithic stem is slightly more difficult for a surgeon to insert than a modular femoral stem there is little worry about taper junction failure.

The most important advantage of modular revision stems is versatility - managing ALL levels of femoral bone loss (present before revision or created during revision). The surgeon quickly gains familiarity with the techniques and instruments for preparation and implantation and subsequently masters its use for all variety of situations. This allows the operating room staff to become comfortable with the instrumentation and components. This ability to use the stem in a variety of bone loss situations eliminates intraoperative shuffle (changes in the surgical plan resulting in more instruments being opened), as bone loss can be significantly under-estimated preoperatively or may change intraoperatively. Furthermore, distal fixation can be obtained simply and reliably.

The most critical advantage is the ability to separate completely the critical task of fixation from other important tasks of restoring offset, leg length, and stability. Once fixation is secured, the surgeon can concentrate on hip stability and on optimization of hip mechanics (leg length and offset). This allows the surgeon to maximise patient functionality postoperatively. Additionally, the surgeon can control the diameter of the proximal body to ensure proper bony apposition, especially if an extended trochanteric osteotomy was made to obtain femoral exposure.

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

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

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

Four consecutive reports from our center have documented the superiority of the TFTS in our hands, with encouraging outcomes even when dealing with severe bone loss or periprosthetic fractures. There is an increasing body of other literature which reports a similar experience. Furthermore, with increasing experience and confidence in this design, we now use a monoblock or non-modular design in greater than 95% of cases in which a TFTS is indicated at our center. This circumvents the potential drawbacks of stem modularity, including taper corrosion and taper junction fracture.

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

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

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

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

Dual mobility (DM) cups have 2 points of articulation – between the shell and the polyethylene (external bearing) and between the polyethylene and the femoral head (internal bearing). Primary motion occurs at the inner bearing while the outer bearing moves only in cases of extreme range of motion.

Dislocation is a top reason for revision surgery and a major cost burden on society. Instability is also a significant problem after revision THA. While a variety of factors are important in hip stability, DM cups provide the safety of larger femoral heads in virtually all patients. These larger heads increase jump distance (the distance the femoral must travel before dislocation occurs) and they also increase ROM before impingement occurs.

ROM and impingement are competing with each in primary THA. Especially in the flexible female with small bone structure, their increased ROM significantly increases the risk of impingement during physiologic activities. While not necessarily leading to dislocation, subluxation can occur resulting in pain. Further, ongoing impingement reduces the longevity of the PE. The ability to increase head size and head-neck ration with the DM cups in these patients is both an immediate and long-term advantage.

PE thickness still can compromise the integrity of the liner. DM cups have thicker PE, especially in the smaller size cups than standard PE inserts. Even with the dual articulation, PE wear in DM cups are less, or at worst, equivalent to standard cups while at the same time providing adequate PE thickness for PE integrity and longevity.

Reoperation on the acetabular side of the total hip arthroplasty construct because of acetabular liner wear with or without extensive osteolysis is the most common reoperation performed in revision hip surgery today. The options of revision of the component or component retention, liner exchange (cemented or direct reinsertion) and bone grafting represent a classic surgeon dilemma of choices and compromises.

CT scanning is helpful in determining the size and location of osteolytic lesions. My preference is to retain the existing shell when possible especially when there are large osteolytic lesions but where structural support is maintained.

The advantages of complete revision are easy access to lytic lesions, ability to change component position and the ability to use contemporary designs with optimal bearing surfaces (for wear and dislocation prevention).

The disadvantage is bone disruption including pelvic discontinuity with component removal (less so with Explant Systems) and difficult reconstructions due to excessive bone loss from the osteolytic defects (sometimes requiring cup cages).

The advantage of component retention is that structural integrity of the pelvis is maintained and in general, a higher quality polyethylene is utilised. For large lesions I use windows to debride and bone graft the lesions. If the locking mechanism is inadequate, cementing a liner, including a constrained liner in some cases, that has been scored in a spider web configuration provides durable results at 5-year follow-up. The downside to liner exchange is potential instability. We immobilise all liner exchange patients postoperatively.

Using the Mayo Clinic definition (>62mm in women and >66mm in men), the “jumbo acetabular component” is the most commonly used method for acetabular revisions now. There are numerous advantages: surface contact is maximised; weight-bearing is distributed over a large area of the pelvis; the need for bone grafting is reduced; and usually, hip center of rotation is restored. The possible disadvantages, or caveats, of jumbo cups include: may not restore bone stock; may ream away posterior column or wall; screw fixation required; the possibility of limited bone ingrowth and late failure; and a high rate of dislocation due to acetabular size:femoral head ratio.

The techniques for a successful jumbo revision acetabular component involve: sizing-“reaming” of the acetabulum, careful impaction to achieve a “press-fit”, and multiple screw fixation. We recommend placement of an ischial screw in addition to dome and posterior column screw fixation. Cancellous allograft is used for any cavitary defects. The contraindications for a jumbo acetabular cup are: pelvic dissociation; inability to get a rim fit; inability to get screw fixation; and the presence of <50% living host bone. If stability cannot be achieved with the jumbo cup alone, then use of augment(s), bulk allograft, or cup-cage construct should be considered.

Our results with the jumbo acetabular cups in revision arthroplasty have been reported. Using predominantly titanium fiber-metal mesh components, we reported the 15-year survival of 129 revisions. There was 3% revision for deep infection and only 3% revision for aseptic loosening. There were 13 reoperations for other reasons: wear, lysis, dislocation, femoral loosening, and femoral fracture fixation. The survival was 97.3% at 10 years, but it dropped to 82.8% at 15 years. Late loosening of this fiber metal mesh component is likely related to polyethylene wear and loss of fixation. Dislocation is the most common complication of jumbo acetabular revisions, approximately 10%, and these are multifactorial in etiology and often require revision. Based on our experience, we now recommend use of an acetabular component with an enhanced porous coating (tantalum), highly cross-linked polyethylene, and large femoral heads for all jumbo revisions.

Highly porous metal surfaces have transformed acetabular revision surgery by providing (1) enhanced friction which potentially provides greater primary fixation, (2) enhanced bone ingrowth potential, (3) enhanced screw fixation options. These characteristics have led many surgeons to use these devices routinely in acetabular revision and have led to an expansion of the indications for porous uncemented hemispherical cups in acetabular revision. Mid-term results suggest that the historical indications for hemispherical cups in revision surgery can be moderately expanded with some implants with these characteristics. In a recent study of 3448 revision total hip arthroplasties, we found porous tantalum cups had a statistically lower revision rate than other materials/designs. Highly porous metals also have provided the options of metal augments to fill selected bone defects—which can both enhance cup fixation and manage bone loss simultaneously. A number of different highly porous metals are now available, and how each will perform is not yet known.

Highly porous metal shells may be used in combination with highly porous metal augments to make up for segmental bone deficiency. Examples will be shown. Finally, highly porous metal shells may be used as a “cup-cage” combination to provide extra initial cup mechanical stability in extreme cases. Examples will be shown.

The custom triflange acetabular component has been advocated for severe acetabular defects and pelvic discontinuity, cases in which a porous-coated hemisphere will not work. These are AAOS type III or IV defects, or alternatively classified as Paprosky 3B. Many have a pelvic discontinuity. A preoperative CT of the pelvis is sent to the manufacturer who generates a one-to-one scale 3D model of the hemipelvis. The surgeon can review either a pdf file or an actual model. If the visualised defect cannot be treated with traditional methods then a triflanged component is created. The components have backside porous and hydroxyapatite coating. Initial rigid fixation is obtained with screw fixation to the ilium and ischium. Subsequent bone ingrowth can provide long term fixation. The goal is to span the acetabular defect and obtain fixation to ilium and ischium with a third arm which rests on the pubis. Christie first reported on 67 hips (half with a discontinuity) with a mean follow-up of 53 months. No components were removed. There was an 8% reoperation for dislocation, 6% partial sciatic nerve palsy. 46% walked without support. Dennis reported 26 hips with a mean 54 month follow-up. 88% were considered successful. One implant was removed and left with a resection arthroplasty and 2 others had loose components but refused reoperation. Loosening of the ischial screws was a sign of failure in the three cases. Taunton reported 57 cases with a pelvic discontinuity treated with a triflange at mean follow-up of 65 months. 81% has a stable component and a healed pelvic discontinuity. These authors also compared a custom triflange to a trabecular metal cup-cage construct finding similar implant costs of $12,500 and $11,250, respectively. All advocates of custom triflange acetabular components believe the results are similar or superior to other options in these very challenging cases at early follow-up. The primary disadvantage of the technique is the preoperative time required to manufacture the device – typically 4–8 weeks.

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

At our center we use three types of cage constructs: (A) Conventional cage ± structural or morselised bone grafting. This construct is used where there is no significant bleeding host bone. This construct is susceptible to cage fatigue and fracture. This reconstruction is used in young patients where restoration of bone stock is important; (B) Conventional cage in combination with a porous augment where contact with bleeding host bone can be with the ilium and then by the use of cement that construct can be unified. The augment provides contact with bleeding host bone and if and when ingrowth occurs, the stress is taken off the cage; (C) Cup Cage Construct – in this construct there must be enough bleeding host bone to stabilise the ultra-porous cup which functions like a structural allograft supporting and eventually taking the stress off the cage. This construct is ideal for pelvic discontinuity with the ultra-porous cup, i.e., bridging and to some degree distracting the discontinuity. If, however, the ultra-porous cup cannot be stabilised against some bleeding host bone, then a conventional stand-alone cage must be used.

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

Laxity Differences in CR & PS TKA -Achieving Total Knee Balancing Using Bone Cut Adjustments and Correlation with Varus-Valgus Lift-Off

The Incidence and Mid Term Functional Effect of Partial PCL Recession in Fixed and Mobile Bearing PCL Retaining TKA

Clinical and Radiographic Results of a Modern Design, Onlay Patellofemoral Arthroplasty at a Minimum Two-Year Follow-Up

Custom Cutting Guides Do Not Improve Total Knee Arthroplasty Outcomes at 2 Years Follow-up

Tourniquet Use During TKA -Effect on Recovery of Strength and Function: a randomised, double-blind, control trial

Prospective, Randomised Trial of Standard vs Cross-linked Tibial Poly

Crosslink vs. Conventional TKA Poly Retrieval Analysis

Unplanned Readmissions after TKA Using a Statewide Database

Does Prior Cartilage Restoration Negatively Impact Outcomes of TKA

Periprosthetic Femur Fracture: Better to Revise than to Fix

Increased Non-stemmed Tibial Failures in Patients with a BMI ≥ 35

The Effect Of Canal Fit And Fill in Revision THA With Modular, Fluted, Tapered Stems

The Wagner Cone Stem For The Challenging Femur In Primary Total

Will Metal Heads Restore Integrity of Corroded Trunnions at Revision THR?

Influence of Head Size, Materials and Taper Design on Fretting and Corrosion of Metal on Polyethylene THR

Delta Ceramic on Ceramic THA – Midterm IDE Study Results

Refining Acetabular Safe Zone for Posterior Approach in THA

Comparison of a Pain Program for THA with and without Liposome Bupivacaine

Instability after total hip arthroplasty is the primary cause for revision surgery and is a frequent complication following revision surgery for any reason (Bozic et al, JBJS 2009). Surgical management of the unstable hip has not been uniformly successful with the best results occurring in those hips in which an identifiable cause of instability can be determined (Daly & Morrey, JBJS 1992). It was these sobering findings that led to the development of and increased use of constrained acetabular components.

While the results of revision surgery for instability using constrained components have been encouraging (Shapiro, Padgett, Sculco J Arthroplasty 2003) with a re-dislocation rate of less than 3%, reoperation for other reasons have noted to increase with time. The commonly used tripolar configuration has been susceptible to bearing damage at both the inner and outer bearing surface by the nature of the constrained mechanism (Shah, Padgett, Wright, J Arthroplasty 2009). In addition, we have noted instances of fixation failure directly related to the constrained acetabular device either from loss of implant fixation to the pelvis with or without cement (Yun, Padgett, Dorr, J Arthroplasty 2005).

The observation of these failure modes ranging from either fixation failures to overt biomaterial failure have led us to be extremely cautious in the “routine” use of constrained liners in revision THR.

Stratification of the recurrent dislocator has been nicely described by Wera et al (J Arthroplasty, 2012). The etiology of dislocation includes: acetabular malposition, femoral malposition, abductor deficiency, impingement, late bearing wear and unknown causes.

Implant instability due to malposition, impingement, and poly wear should be revised as appropriate to correct the underlying problem in addition to the use of either larger diameter heads. The emerging use of dual mobility articulations remains to be determined. However, the indiscriminate use of constrained liners should be avoided as the risk of problems outweighs their benefits.

A well designed constrained liner does not have a “hood” nor a wide poly brim that extends beyond the metal shell because these cause impingement. The failure of a good design is almost always technique.

Size the liner so the poly is press fit against the metal rim of the cup. Cement thickness does not matter. Remove any derotation tabs on metal rim with a carbide burr so there is a firm press fit with no toggle. Do NOT angle the poly to change the anteversion.

Use the carbide burr to scratch the inner surface of the cup and a soft tissue burr to scratch the backside of the poly.

Cement must be liquid enough to fully seat the poly against the metal rim. If cement too doughy it resists full seating.

Put metal ring in groove during implantation and cementing to prevent cement into the groove.

If this is a primary cup use screws with the cup or cement the poly into the acetabular bone.

Dry the head and inner surface of the poly to facilitated reduction. Align the head concentrically into the mouth of the poly and push simultaneously on the knee and over the greater trochanter.

The bi-cruciate retaining (BCR) total knee arthroplasty (TKA) is based on sound biomechanics to produce kinematics close to normal, which is the goal of BCR TKA. This assumes that the joint line is maintained and both cruciates are functional with a range of motion greater than 125 degrees.

The technical difficulties of implanting such a knee in correct anatomical position with preservation of both cruciate ligaments with proper tension is challenging and may not be possible in the hands of most surgeons.

Patient selection for consideration of BCR TKA assumes that both ligaments are normal and ROM is greater than 125 degrees. If this assumption is correct, why does one need a knee replacement in such a patient? If we assume that the patient has normal cruciate ligaments, there is no scientific evidence to suggest that they will remain normal in the environment of a TKA with longer follow-up. Lastly, fixation with cement may be compromised because of the lack of a stem and less surface area. This can be argued both ways, but the long-term data on this matter favors stemmed designs. Moreover, insertion of cruciate ligaments (ACL) limits the robustness of the connecting bar for bicruciate knees. Lastly over 30 years, surgeons have tried BCR TKA without significant market share. Remember “all good things in life should ultimately prevail”.

The major benefit of TKA with tourniquet is operating in a bloodless field. A possible secondary benefit is a better cement bone interface for fixation.

The disadvantages of tourniquet use for TKA include multiple risk factors both local and systemic - Nerve damage; Altered hemodynamics with limb exsanguinations (15‐20% increase in circulatory volume) and reactive hyperemia with tourniquet release (10% increase in limb size increasing soft tissue tension and secondary pain); Delay in recovery of muscle function; Increased risk of DVT with direct trauma to vessel walls and increased levels of thrombin-antithrombin complexes; A 5.3x greater risk for large venous emboli propagation and transesophageal echogenic particles; Vascular injury with higher risk in atherosclerotic, calcified arteries; Increase in wound healing disturbances.

Our initial experience with TKA without tourniquet was in high risk patients with previous DVT or PE, multiple scarring, or compromised cardiovascular status. We have used this method on all patients for the last eight years. The protocol includes regional anesthesia, incision and approach made with 90-degree knee flexion, meticulous hemostasis, jet lavage and filtered carbon dioxide delivered to dry and prepare bone beds for cementation, application of topical tranexamic acid and routine closure. We have encountered no differences in blood loss or transfusion rates, less postoperative pain, faster straight leg raise and knee flexion gains, and fewer wound healing disturbances. We recommend TKA sans tourniquet. Let it bleed!

During TKA, a surgeon has 4 options: not to use a tourniquet at all, use it from incision to closure, from incision until cementing, and only during cementing. The potential advantages of using a tourniquet are: to reduce blood loss, to have a clear operative field, to facilitate preparation of bony surfaces that are optimal for cementation and longevity of fixation of implants, and to reduce the potential for blood-borne disease transmission through needlestick injuries. Potential disadvantages of tourniquet use have been outlined by the previous speaker. In particular, using a tourniquet from incision until closure has several disadvantages and is generally not a preferred option.

While this paper opposes tourniquetless TKA, it supports using a tourniquet from incision until cementing. We will present in support the findings of our prospective, randomised, double-blind study in patients undergoing cemented, navigated, bilateral simultaneous TKA wherein a tourniquet was used from incision until cementing was complete on one side and compared with the other knee in which a tourniquet was used only during cementing. We compared knee pain, thigh pain, blood loss, hemodynamic changes, functional outcome and complications. We concluded that total knee arthroplasty can be safely and effectively performed with the use of the tourniquet from skin incision until cementing without adverse effects.

Cartilage is known to have limited intrinsic repair capabilities and cartilage defects can progress to osteoarthritis (OA). OA is a major economic burden of the 21st century, being among the leading causes of disability. The risk of disability from knee OA is as great as that derived from cardiovascular disease; a fact that becomes even more concerning when considering that even isolated cartilage defects can cause pain and disability comparable to that of severe OA.

Several cartilage repair procedures are in current clinical application, including microfracture, osteochondral autograft transfer, osteochondral allograft transplantation, and autologous chondrocyte implantation (ACI). Given the economic challenges facing our health care system, it appears prudent to choose procedures that provide the most durable long-term outcome. Comparatively few studies have examined long-term outcomes, an important factor when considering the substantial differences in cost and morbidity among the various treatment options.

This study reviews the clinical outcomes of autologous chondrocyte implantation at a minimum of 10 years after treatment of chondral defects of the knee. Mean age at surgery was 36 ± 9 years; mean defect size measured 8.4 ± 5.5cm2. Outcome scores were prospectively collected pre- and postoperatively at the last follow up. We further analyzed potential factors contributing to failure in hopes of refining the indications for this procedure.

Conclusions: ACI provided durable outcomes with a survivorship of 71% at 10 years and improved function in 75% of patients with symptomatic cartilage defects of the knee at a minimum of 10 years after surgery. A history of prior marrow stimulation as well as the treatment of very large defects was associated with an increased risk of failure.

There are many reasons that the surgically inclined orthopaedic surgeon should be responsible for the medical management of osteoarthritis of the knee. These include: 1) The nonoperative treatment of OA is often highly effective for all stages of the disease; 2) A nonoperative treatment program is the best preparation for a successful surgical outcome; and 3) Patients appreciate a surgeon's interest in their overall care and are likely to return if surgery is needed; 4) Medicare and many insurance companies are refusing to pay for a TJA until many months of conservative management has been administered. There are many potential causes of pain in an arthritic knee. These include intra-articular (e.g. degenerative meniscal tears, loose bodies, synovitis) and extra-articular (tendonitis, e.g. ilio-tibial band syndrome, bursitis, muscle overload syndromes and referred pain) sites. The potential sources of pain in an arthritic knee produce a wide range of symptoms that are not necessarily correlated with objective measurements (e.g. x-rays, MRI). Moreover, the natural history of an arthritic knee is unpredictable and variable.

The treatment of the young, arthritic knee patient of all stages requires a systematic and consistent non-surgical approach. This approach includes the use of: 1) analgesics/anti-inflammatory agents; 2) activity modification; 3) alternative therapies; 4) exercise; 5) injections/lavage. The response to each form of non-surgical treatment is unpredictable at each stage (Kellgren 1–4) of OA. The placebo effect of each from of treatment, including the physician-patient interaction, is 50–60% in patients with mild-moderate OA.

The components of a nonoperative treatment program include: 1) Education-emphasising the importance of the patient taking charge of his/her care; 2) Appropriate activity/life style modifications-emphasising the importance of remaining active while avoiding activities that aggravate symptoms (e.g. running to biking); 3) medications-oral, topical, intra-articular; 4) Physical therapy. There are extensive data to support each of these interventions. The AAOS has issued guidelines highlighted the literature based effectiveness of conservative interventions.

Osteotomy is one of the oldest orthopaedic interventions and has evolved significantly over the years. The procedure is well established as a biomechanical solution in the treatment of arthritis and instability of the knee. The operation is technically demanding and carries risks of neurovascular injury, inadequate fixation and under- or overcorrection. These technical problems have given osteotomy significant headwind in the orthopaedic community. The relative success of knee arthroplasty (uni or total) in the past decade has fed the perception that this procedure is the only remaining treatment to be trusted for patients with knee arthritis. However, both registry data and single center studies often show disappointing results for knee arthroplasty in the young, active and demanding patient population. Osteotomy has a significant role for these patients, provided they have unicompartmental arthritis with constitutional malalignment. Also, more complex deformities as seen in the post-traumatic setting often need a biomechanical approach based upon osteotomy principles.

Recently, technology was developed to allow the surgeon perform a three-dimensional evaluation of the deformity and prediction of postoperative alignment. Patient specific guides with a broad fit on the femur or tibia can guide the osteotomy and fixation accurately, within 2 degrees of accuracy. With this technological approach, a new dawn for osteotomy appears on the horizon.

Enhanced appreciation of normal knee kinematics and the inability to replicate these in the replaced total knee has led to increased enthusiasm for partial knee arthroplasty by some. These arthroplasties more closely replicate normal kinematics since they inherently preserve the anterior cruciate ligament (ACL). Indications for medial UKA are: anteromedial osteoarthritis with an intact ACL, posterior cruciate ligament, and medial collateral ligament (MCL), full thickness cartilage loss, and correctable deformity demonstrated radiographically with valgus stress view; full thickness cartilage laterally with no central ulcer; <15 degrees of flexion contracture, < 15 degrees varus and > 90 degrees flexion. The state of the patellofemoral joint, chondrocalcinosis, obesity, age and activity level are NOT contraindications to medial mobile-bearing UKA. The only certain contraindications are the presence of inflammatory arthritis or a history of previous high tibial osteotomy (HTO). Advantages of medial UKA are that it preserves undamaged structures, it is a minimally invasive technique with low incidence of perioperative morbidity, preservation of the cruciate mechanism results in more “normal” kinematics versus TKA, it normalises contact forces and pressures in the patellofemoral joint, and it provides better range of motion than TKA. Furthermore, medial UKA results in better function than TKA in gait studies, with demanding activities, such as climbing stairs, having a better “feel”. Pain relief with medial UKA is equivalent or better than TKA, and morbidity and mortality are decreased compared with TKA, as well as venous thromboembolism. Recommended preoperative imaging studies consist of plain radiographs with the following views obtained: standing AP, PA flexed, lateral, Merchant or axial, and valgus stress. There are several surgical perils associated with performing medial UKA. First, in regard to patient selection, avoid medial UKA in patients with residual hyaline cartilage – the joint must be bone on bone. Second, perform a conservative tibial resection with respect to depth to prevent tibial collapse as well as excessive overload of weakened bone, and avoid excessive posterior slope. Perform the tibial resection coplanar with tibial spine/ACL insertion to maximise tibial coverage. Avoid overcorrection of deformity. Do not perform a medial release. Balance flexion/extension gaps meticulously. For mobile-bearing designs, remove all impinging osteophytes. Over 55 published studies report results with mobile-bearing medial UKA, with survival ranging 63.2–100% at mean follow-up ranging from 1 to 17.2 years.

Lateral unicompartmental replacement is performed less frequently than medial replacement and is technically more difficult. The ratio of medial to lateral arthroplasties is approximately 10:1.

Differences in technique include the following:

The patella is more vulnerable to impingement on the leading edge of the femoral component and must be carefully recessed. Because the wear pattern in lateral disease is more posterior than in medial disease, there is often residual cartilage on the distal femoral condyle. This is also the case when UKA is performed for the sequella of a lateral plateau fracture. To avoid this impingement, residual cartilage should probably be removed from the distal condyle before its resection and the femoral component should be under-sized anteriorly.

Initial tibial resection should be very conservative to avoid the need for very thick tibial components to restore alignment and stability.

Err toward shifting the femoral component laterally and the tibial component medially to maximise M-L congruency.

Consider a medial parapatellar approach (avoiding the anterior horn of the medial meniscus) to facilitate visibility and component alignment.

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

It is important to remember that osteoarthritis is a noninflammatory condition that can affect 1, 2 or all 3 compartments of the knee. Moreover, this disease is a continuum from very mild to very severe involvement of the soft tissue, articular cartilage and bone. For this reason, a variety of nonsurgical and surgical options are indicated. The rheumatologist and/or orthopedist must understand the stage of the disease and fit that both to the pathology, age, activity level, and functional needs of the patient. For that reason, each of the options discussed today have an indication.

The important issue about tricompartmental replacement is that we have improved technology and technique and the indications of today are broader than those of 20 years ago. Hopefully, they will continue to evolve both in terms of materials and instruments. The American Rheumatologic Association (ARA) has stated that joint replacement has been the major improvement in the care of the arthritic patient. The tricompartmental solution is the treatment of choice in patients with inflammatory arthritis such as rheumatoid arthritis as well as the solution in osteoarthritic patients with tricompartmental disease. There is an indication for osteotomy, unicompartmental replacement and perhaps patellofemoral replacement. I think the next frontier will be to find disease modifying osteoarthritic drugs (DMOADS) that will provide disease intervention as the DMARDs have done in rheumatoid arthritis. Moreover, cartilage repair combined with osteotomy will hopefully allow us to prevent progression of this disease.

The goals of total knee arthroplasty (TKA) are to relieve pain, restore function, and provide a stable joint. In regard to types of implants, the workhorses are posterior cruciate retaining (CR), posterior stabilised (PS), and posterior stabilised constrained (PSC) designs. However, the continuum of constraint now ranges from standard cruciate retaining (CR-S) to CR lipped (CR-L), to anterior stabilised (CR-AS), to posterior stabilised, to a PS “plus” that fits with a PS femoral component but provides a small degree of varus-valgus constraint, to a PSC or constrained condylar type of device, to a rotating hinge. As the degree of deformity, bone loss, contracture, ligamentous instability and osteopenia increases, so does the demand for prosthetic constraint. When deformity is minimal and the posterior cruciate ligament (PCL) is intact and functional, a CR-S device is appropriate. For moderate deformity with deficiency or compromise of the PCL, a CR-AS or posterior stabilised device is warranted. In severe cases, with attenuation or absence of either of the collateral ligaments, a constrained condylar device, with options of stems, wedges and augments, is advisable. In salvage situations, when both collaterals are compromised, a rotating hinge should be utilised. Prerequisites for use of a CR-S device are an intact PCL, balanced medial and lateral collateral ligaments, and equal flexion and extension gaps. With a CR-L bearing, a slight posterior lip is incorporated into the sagittal profile of the component to provide a small amount of extra stability in the articulation. It is important for the surgeon to be aware of the design features of the implant system he or she is using. For example, in a system where the CR-S bearing has 3 degrees of posterior slope and the CR-L bearing has no slope, the thickness of a CR-L bearing posteriorly is approximately 2mm greater than the CR-S. A CR-L bearing is indicated for to provide stability where the flexion gap is just slightly looser than the extension gap and the PCL is intact. If the patient's knee is somewhat lax in flexion and stable in extension, a CR-L bearing may help to stabilise both the flexion and extension gaps yet still allow the knee to obtain full extension, whereas if a CR-S bearing in the next thicker size is used to stabilise the flexion gap, a flexion contracture may result. CR-AS bearings are indicated when the flexion and extension gaps are balanced, but the PCL is deficient, and the surgeon does not want to change to a PS design, which requires additional bony resection of intercondylar notch. The PCL is one of the strongest ligaments in the knee, and affords inherent stability to the TKA. In flexion, the PCL not only affords AP stability, but also imparts flexion gap stability, acting as a lateral stabiliser of the medial compartment and a medial stabiliser of the lateral compartment. The PCL has a crucial role with respect to femoral rollback, which imparts added efficiency to the extensor mechanism. PCL retention is a more biologically preserving operative intervention than PS-TKA.

It is clear in 2013 that there is a substantial opportunity to improve patient outcomes after total knee replacement. Much attention in the last decade has focused on the apparent satisfaction gap between patients who have had total hip arthroplasty and those who have had total knee arthroplasty. Most authors note that a higher proportion of total hip patients claim to have complete satisfaction or note that they have forgotten that they had the joint replaced. The concept of “the forgotten joint replacement” is an interesting one because as surgeons and researchers we all recognise that neither total hip replacement nor total knee replacement will completely restore the native hip or knee joint's dynamic 3D biomechanics or kinematics. What the concept of the forgotten joint does tell us however is that there is a level of kinematic function above which humans cannot detect a difference with normal function. The inherent simplicity of the ball-and-socket design of the hip joint means we can achieve this level of function more reliably and reproducibly than we do in the knee joint. The knee joint presents a more difficult challenge.

Recent data suggests that there is a definable trade-off in total knee prosthesis design, and likely with component position and limb alignment, between those optimised for the best kinematics and those optimised for the best durability using contemporary biomaterials (namely metal, ceramic and ultra-high molecular weight polyethylene). Given this inherent trade-off then there will be an almost never-ending debate about what constitutes “the best” overall knee implant design because that will inevitably require an individual value-judgement about the relative merit of better kinematics or better durability. Currently, we have some insights into this trade-off when we consider the role of unicompartmental knee replacement in 2013. There is little debate that unicompartmental knee replacement results in closer-to-normal knee kinematics than does total knee replacement and that many patients seem to benefit from a quicker recovery and easier rehabilitation. Data from multiple national joint registries however shows that UKR is not quite as durable as total knee replacement (mean yearly failure rate 1.53% for UKR versus 1.26% for TKR). Different surgeons and different surgeons will look at that data however and come to markedly different conclusions about how to act — some will discount the difference in durability and favor the better function/quicker recovery of UKR while other equally intelligent persons will discount the difference in function and prefer the demonstrated better durability of TKR. Like any value-judgement there is no right answer or wrong answer.

As surgeons and researchers we do have opportunities in regard to surgical technique that remain unexplored. We have been limited over the past several decades by thinking primarily in terms of 2D static analyses of alignment, rotation and ligament balance. This is primarily because most assessments have been done using plain radiographs. The last decade however has seen a marked improvement in our capabilities for 3D imaging and dynamic assessment of knee joint function. The promise of computer-navigated and robotic-assisted surgery has largely remained unfulfilled as the limitations of 2D targets have come into focus. It is my belief that tomorrow's gains in total knee replacement will not involve dramatic changes in prosthesis design but instead on defining and then hitting more precise 3D targets for alignment, rotation and ligament balance in surgery. For surgeons and researchers this is an exciting time as there is a distinct opportunity to improve outcomes for millions of total knee replacement patients over the coming decades.

Perhaps the most significant developments in joint replacement surgery in the past decade have been in the area of multimodal pain management. The hallmark of this program is preemptive pain control with oral anti-inflammatory agents, gabapentin, IV acetaminophen, regional anesthetic blocks that preserve quadriceps function for TKA (adductor canal block) and pericapsular local anesthetics. Over the past two years utilising this type of program over 50% of our joint replacement patients are now returning home the day of surgery.

Perioperative blood conservation remains an important topic today in order to reduce complications, improve function, and facilitate recovery after a total knee replacement (TKR). Studies have shown that the degree of postoperative anemia is related to an increase in complications. A greater blood loss and need for transfusion is associated with a higher risk of infection, a slower recovery process, increased morbidity to patients, as well as an increased cost to the healthcare system.

Typical blood loss estimates range from 800cc to over 1700cc, when accounting not only for intraoperative but postoperative blood loss. Several strategies have been developed to help mitigate the risk of perioperative blood loss and need for subsequent transfusion.

Firstly, preoperative measures such as vitamin and mineral supplementation can ensure the starting hemoglobin and red cell count are maximised. Additionally, erythropoietin can be helpful in refractory cases of preoperative anemia. Preoperative autologous blood donation was used extensively in the past, but has fallen out of favor due to its inefficiency and cost.

Intraoperatively, measures such as the use of a tourniquet, meticulous technique, and expeditious surgery can help reduce blood loss. The most effective method, however, has been the use of tranexamic acid (TXA). TXA, an antifibrinolytic compound, has been extremely effective at reducing perioperative blood loss without increasing the risk of thromboembolic events. TXA can be used topically or intravenously. Other methods that can reduce intraoperative blood loss include the use of fibrin sealants, applied to the soft tissues and bony surfaces around the knee.

Postoperatively, the avoidance of wound drains is associated with a higher blood count and reduced transfusion risk. Alternatively, drainage reinfusion systems can be used to raise the postoperative blood count, particularly in cases of bilateral TKR.

The goals of any rehabilitation protocol should be to control pain, improve ambulation, maximise range of motion, develop muscle strength, and provide emotional support. Over 85% of TKA patients will recover knee function regardless of which rehabilitation protocol is adopted but the process can be facilitated by proper pain control, physical therapy, and emotional support. The remaining 15% of patients will have difficulty obtaining proper knee function secondary to significant pain, limited preoperative motion, and/or the development of arthrofibrosis. This subset will require a special, individualised rehabilitation program, which may involve prolonged oral analgesia, continued physical therapy, more diagnostic studies and occasionally manipulation. Controlling pain is the mainstay of any treatment plan. The program described herein has been used at Ranawat Orthopaedics over the last 10 years in more than 2000 TKAs.

Outcomes in arthroplasty have 3 general sources of variability: the patient, the prosthesis, and the medical-surgical-rehab. services. There are numerous factors that can contribute to earlier-than-usual clinical failure of a TKA (failure = need for revision). There are intense debates regarding design and material factors. There are technical factors such as misalignment, soft tissue imbalance, and inadequate fixation. The greatest source of variability in the outcome equation is, however, the patient.

In cohort studies, the amount and type of patient activity influences the longevity of TKA. Quantitative studies have demonstrated >45-fold variation in the number of steps per day. Semi-quantitative data and survey studies show variability in the types of recreational activities and in the intensity. Age is often used as a surrogate, but BMI has a better correlation with activity than age. There is no formula, however, that can predict the longevity of an arthroplasty in a specific patient. For this reason, activity recommendations following arthroplasty continue to be debated. Which do you prioritise; lifestyle or longevity? More importantly, which does the patient prioritise?

“Expert opinion” is the lowest totem on the academic pole- and yet, “evidence based” medicine does not always provide us answers for the particular, the unusual clinical problem. Well-controlled studies are precisely that: “well controlled”. Life may be randomised, but falls short of being “well controlled”.

The challenge and honor of moderating a panel of experienced and articulate colleagues is to bring out “how they think” and how they formulate a plan for complex cases. The panel members are not only experienced practitioners, but they are the authors of studies that shape our profession. What are the limits to the studies they have published? What insight can they provide us to help understand “level 1” data more astutely? What biases and assumptions support their methods? Nothing achieves that with greater clarity than presentation of complex cases to an accomplished panel.

Several ordinary clinical problems are presented to establish current practice, followed by the unexpected outcomes to illustrate how experts deal with adversity.

Modifiable Risk Factors

Preoperative Screening

Preoperative Skin Cleansing

Skin Preparation

Perioperative Antibiotics

Controlling the OR Environment

Intraoperative Irrigation and Lavage

Postoperative Wound Management

Infection is still a major problem in implant surgery. Most infections are caused by bacteria that enter the wound at the time of the operation. Although prophylactic antibiotics given intravenously have been shown to be effective if given during the correct time frame, the concentration of local antibiotics in the knee in response to intravenous antibiotics is about 1/3 that achieved in the serum, and the level is transient. 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 costs analysis shows a remarkable monetary benefit to this effect.

Local antibiotic irrigation during implant surgery is inexpensive, easy, and effective.

The two-staged exchange for periprosthetic joint infection (PJI) has become the “gold standard” worldwide. Based on the first implementation of mixing antibiotics into bone cement by Prof. Buchholz in the 70's, the ENDO-Klinik followed a distinct one staged exchange for PJI in over 85% of all our infected cases until today. Looking carefully at current literature and guidelines for the PJI treatment, there is no clear evidence, that a two-staged procedure has a clearly higher success rate than a one-staged approach. Although postulated in relevant articles, most recommendations, e.g. duration of antibiotics, static vs. mobile spacer, interval of spacer retention, cemented vs. uncemented implant fixation, are based on level IV to III evidence studies or expert opinions, rather than on prospective randomised or comparative data.

Potentially a cemented one-stage exchange offers certain advantages, as mainly based on need for only one operative procedure, reduced antibiotics & hospitalization time and reduced relative overall costs. In order to fulfill a one-staged approach with the above described potential success, there are obligatory pre-, peri- and post-operative details, which need to be meticulously respected. The absolute mandatory infrastructural requirement is based on the clear evidence of the bacteria in combination with a distinct patient specific plan, by an experienced microbiologist, for following antibiotics in the bone cement with combined systemic antibiotics.

Mandatory preoperative diagnostic test is based on the joint aspiration with an exact identification of the bacteria. The presence of a positive bacterial culture and respective antibiogramm is essential, to specify the antibiotics loaded to the bone cement, which allows a high topic antibiotic elution directly at the surgical side. A specific treatment plan is generated by an microbiologist. Contraindications for a one staged exchange include: failure of >2 previous one-staged procedures, infection spreading to the nerve-vessel bundle, unclear preoperative bacteria specification, unavailability of appropriate antibiotics, high antibiotic resistance.

The surgical success relies not only on the complete removal of all preexisting hardware material (including cement and restrictors), furthermore an aggressive and complete debridement of any infected soft tissues and bone material is needed. Mixing antibiotics to the cement needs to fulfill the following criteria: Appropriate antibiogramm, adequate elution characteristics, bactericidal (exception clindamycin), powder form (never use liquid AB), maximum addition of 10%/PMMA powder. Current principles of modern cementing techniques should be applied.

Postoperative systemic antibiotic administration is usually followed for only 10–14 days (exception: streptococci). We recommend an early and aggressive mobilization within the first 8 days postoperatively, due to the cemented fixation an immediate mobilization under full weight bearing becomes possible in most cases.

Persistence or recurrence of infection remains the most relevant complication in the one-staged technique. As failures rates with a two-staged exchange have been described between 9% and 20% in non-resistant bacteria, the ENDO-Klinik data shows comparative results after 8–10 years of follow up, which were confirmed independently also by some other international reports and study groups.

In summary a cemented one-stage exchange offers various advantages. Mainly the need for only one operation, shorter hospitalization, reduced systemic antibiotics, lower overall cost and relative high patient satisfaction. However, a well-defined preoperative planning regime including an experienced microbiologist are absolutely mandatory.

A “two-stage exchange” remains the gold standard for treatment of the infected TKA in North America. Although there is interest in “one-stage exchange” this technique is not as familiar to many US surgeons and it is unclear if the reported results of Europe can be translated to North American practice. Specific concerns include the “radicalness” of the debridement required (which oftentimes includes the collateral ligaments, hence the popularity of hinged implants where this approach is common) and the use of fully cemented stems, which are extremely difficulty to remove if infection recurs. Thus while the idea of a one stage exchange is attractive to many North American surgeons, careful study will be required to determine if success can be achieved with a more “conservative” debridement and the use of cementless stems which are preferred by some surgeons.

The basic principles of a two-stage exchange include: Thorough debridement of all infected appearing foreign material and all cement; Placement of an interval antibiotic loaded spacer (note that the addition of antibiotics to bone cement is NOT FDA approved) – 4–6g of antibiotics per pkg of cement; typically vancomycin + tobramycin; Higher viscosity cement may be associated with higher elution; The combination of antibiotics also leads to higher elution.

Antibiotic spacers can be “articulating” or “static”. Potential advantages of an articulating spacer include greater patient comfort and an easier approach at the second stage exchange as soft tissue tension and range of motion is maintained. However, these spacers are oftentimes more costly and can break or dislocate.

The first stage is followed by approximately 6 weeks of organism specific IV antibiotics. An interdisciplinary approach with an infectious disease specialist, internal medicine and a nutritionist optimises outcomes.

Our protocol then includes weekly ESR and CRP to monitor their trend. These labs are re-checked two weeks after cessation of antibiotics to ensure the trend has not changed. The knee is routinely aspirated at this time point and the fluid obtained sent for a synovial fluid WBC count with differential and cultures (although the value of such cultures is controversial). We have found that while the ESR and CRP are significantly lower than prior to removal of the infected implant, they often times DO NOT normalise and there is no specific cut-off value that predicts persistent infection.

Wound complications are much more common following knee arthroplasty as compared to hip arthroplasty, due in part to the precarious blood supply to the knee, as well as the subcutaneous position of the joint. Many, if not most, infections are related to wound problems, and thus avoiding wound problems is a critical issue in knee replacement surgery.

Many wound problems are avoidable and can be minimised by care to detail by the surgeon. The important steps are to first identify patients at risk and optimally addressing these risk factors. Patient risk factors include: chronic corticosteroid use, diabetes, rheumatoid arthritis, malnutrition, obesity, and smoking.

Soft tissue handling is a second major issue. Minimal incision surgery should be used with great caution for knee replacements since the skin is much less forgiving than in hip replacements. A midline skin incision should be utilised when possible. When multiple incisions are present it is usually advisable to use the lateral most incision through which it is feasible to perform a knee replacement. In rare cases, a soft tissue expander may be used preoperatively for thin, adherent skin.

Perioperative steps that can be taken include delaying CPM in high risk wounds, and using a wound vac system in obese or other high risk wounds to minimise persistent drainage. Furthermore, anticoagulation should be used judiciously to avoid prolonged drainage. The final step in salvaging the problem wound is early recognition and aggressive management of wound healing problems. Prolonged, serous drainage is the most common clinical scenario. Drainage that is increasing beyond 5–7 days frequently requires evacuation, irrigation, debridement, and liner exchange. Early aspiration can decompress a hematoma and also rule out infection.

For medial compartment disease UKR has many advantages over TKR. They give better function, faster recovery, lower morbidity and mortality but have a higher revision rate. Matched studies from the England and Wales National Joint Registry showed they are 60% more likely to achieve excellent outcomes (OKS>41) and 30% more likely to have excellent satisfaction. UKR patients were discharged 1.4 days earlier, had 35% less readmissions and 50% less major complications such as DVT/PE, infection, CVA and MI. The death rate was significantly lower: The hazard ratios being 0.2x at 30 days, 0.5x at 90 days and 0.85x at 8 years. However at 8 years the revision rate was 2x higher and the reoperation rate was 1.4x. If 100 patients receiving TKR had UKR instead, the result would be around one fewer death and three more reoperations in the first 4 years. If patients were aware of this most would select a UKR.

The main reason why UKR have a high revision rate in registries is that most surgeons do small numbers and restrict their use to patients with very early disease, who often do badly. In the NJR 8% of knees are UKR and surgeons do on average 5 per year. Surgeons doing more than 20% of knees as UKR have a much lower re-operation rate which is similar to that of TKR. The Mobile bearing UKR can safely be used in up to 50% allowing many patients to have the advantages of UKR and a low re-operation rate.

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

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

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

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

Historical studies in TKA suggest that 82–89% of patients are satisfied with TKA. Bourne et al. reviewed 1703 patients and reported that in newer designs that things have not improved much. Approximately one in five (19%) primary TKA patients were not satisfied with the outcome. Satisfaction with pain relief varied from 72–86% and with function from 70–84% for specific activities of daily living. The burden of OA is increasing in society and younger patients are undergoing TKA.

A customised, individually made (CIM) knee arthroplasty (iTotal, ConforMIS Inc., Bedford, MA USA) has been introduced by individualising component geometry; exact sizing- medial – lateral and anterior–posterior, restoring medial and lateral joint lines, and restoring individual “J Curves” of the patients’ native femur as it was prior to the arthritic condition. This is done by preoperative CT scanning to include hip-knee-ankle and software to CAD-CAM manufacture of the individualised implants, with accompanying individualised cutting jigs. The hypothesis is to restore form and ultimately function. Will this lead to improved patient satisfaction?

Cadaveric comparison on an “Off The Shelf ” (OTS) implant to CIM implant in 9 matched pair analyses before and after TKA demonstrated that the CIM implant motion was not different than their preoperative kinematics of the knee but the OTS implant was.

In vivo comparisons performed fluoroscopically of CIM implants versus OTS implants further demonstrated a more normal knee in terms of kinematics and stability in the CIM knee.

Follow up of 110 consecutive patients undergoing a CIM CR TKA revealed patient satisfaction of 98%. Patient average age was 56.1 years old, average follow up 20 months. Two patients required revision- (both dissatisfied)- one for tibial subsidence 18 months after TKA (osteoporosis and obesity) the other developed global laxity at 9 months postoperatively. Both revised with stabilised PS OTS implants. At this early average follow up of <2 years it appears that patient satisfaction improves over prior OTS implant satisfaction with a CIM TKA that restores native size and geometry.

Total knee replacement is one of the most successful procedures in orthopaedic surgery. Although originally limited to more elderly and less active individuals, the inclusion criteria have changed, with ever younger, more active and heavier patients receiving TKA. Currently, wear debris related osteolysis and associated prosthetic loosening are major modes of failure for TKA implants of all designs.

Initially, tibial components were cemented all polyethylene monoblock constructs. Subsequent long-term follow-up studies of these implants have demonstrated excellent durability in survivorship studies out to twenty years. Aseptic loosening of the tibial component was one of the main causes of failure in these implants. Polyethylene wear with osteolysis around well fixed implants was rarely (if ever) observed. Cemented metal-backed nonmodular tibial components were subsequently introduced to allow for improved tibial load distribution and to protect osteoporotic bone. Long-term studies have established that many one-piece nonmodular tibial components have maintained excellent durability. Eventually, modularity between the polyethylene tibial component and the metal-backed tray was introduced in the mid-80s mainly to facilitate screw fixation for cementless implants. These designs also provided intraoperative versatility by allowing interchange of various polyethylene thicknesses, and also aided the addition of stems and wedges. Since the late 1980's, the phenomena of polyethylene wear and osteolysis have been observed much more frequently when compared with earlier eras. The reasons for this increased prevalence of synovitis, progressive osteolysis, and severe polyethylene wear remain unclear, but there is no question that it was associated with the widespread use of both cementless and cemented modular tibial designs.

Mayo Data: Modular versus All Polyethylene Tibial Components in Primary TKA

The study population included 10,601 adult (>18 years) patients with 14,524 primary TKA procedures performed at our institution between 1/1/1988 and 12/31/2005. Mean age was 68.7 years and 55% were female. Overall revision rates and revisions for loosening, wear/osteolysis were compared across different designs using Cox proportional hazards regression models adjusting for age, sex, calendar year and body mass index (BMI). Over an average 9 years follow-up, a total of 865 revisions, including 252 tibia revisions were performed, corresponding to overall survival of 89% (Confidence intervals (CI): 88%, 90%) at 15 years. In comparison to metal modular designs, risk of tibial revision was significantly lower with all-poly tibias (HR 0.3, 95% CI: 0.2, 0.5). Overall, posterior cruciate-retaining (CR) designs performed better than the posterior-stabilised (PS) designs (p=0.002). With any revision as the endpoint, there were no significant differences across the 18 designs examined. Similarly, there were no significant differences across the 18 designs when we considered revisions for aseptic loosening, wear, osteolysis. Among patient characteristics, male gender, younger age, higher BMI were all significantly associated with higher risk of revisions (p<0.008).

Summary: Available data support the use of nonmodular tibial designs in TKA in order to prevent or reduce the chance of backside wear, third body particles from resulting metallic debris and associated polyethylene induced osteolysis. In all patients, (not just older individuals) use of an all polyethylene tibial component is an attractive and more cost effective alternative, and is associated with the best survivorship and lowest risk of revision.

There is no question that excellent long-term results have been demonstrated with all-polyethylene tibial components. Moreover, improvements in polyethylene to increase wear resistance, maintain mechanical strength, and improve oxidative resistance lend even greater credence to the use of an all-polyethylene tibial component. There are several issues of concern. In revision knee replacement for reasons such as patellofemoral problems where the components are otherwise ideal, the arthrotomy performed during the revision usually creates a slight laxity requiring a thicker polyethylene or even a different tibial conformity. With an all-polyethylene tibia, this would require full component revision. It is also true that, even after careful trial reduction, the surgeon occasionally will find that the final construct is slightly lax requiring a thicker final insert. This again is difficult in the situation of all-polyethylene tibia. One of the advantages of an all-polyethylene tibia is to avoid back-sided wear that posed a substantial problem in the past. Most component systems have successfully dealt with a problem of back-sided wear making the advantage of a nonmodular all-polyethylene tibia moot. Finally, in a modular system, the surgeon has the advantage of cementing all components with the tibial trial and then having the ability to remove the trial component, clear the back of the knee and insert the final insert. Lowering health care costs is a laudable and necessary endeavor. We must choose TKR implants to fit patient demand and not overuse or underuse technology and know the true cost of the implants we use.

Yes the paradigm is changing!!!

Refinement of surgical techniques, anesthesia protocols, and patient selection has facilitated this transformation to same day discharge for arthroplasty care. The trend for early discharge has already happened for procedures formerly regarded as “inpatient” procedures such as upper extremity surgery, arthroscopy, ACL reconstruction, foot and ankle procedures, and rotator cuff repair. Our program began focused on Partial Knee Arthroplasty (PKA) and has now expanded to primary TKA and THA, and select revision cases. Over the past few years we have performed: 138 TKA, 111 THA, 244 Partial KA, 6 RevTKA, and 6 RevTHA with no readmissions for pain control. With preoperative Hgb above 11 combined with Tranexamic Acid we have had no transfusions. Medical optimization is critical to the safety and success of patient selection for same day discharge. We utilise a standardised format for preadmission testing.

The program centers on the patient, their family, home recovery, preoperative education, efficient surgery, and represents a shift in the paradigm of arthroplasty care. It can be highly beneficial to patients, surgeons, anesthesia, facility costs, and payors as arthroplasty procedures shift to the outpatient space.

Despite the widely accepted advantages of total knee arthroplasty surgery, not all patients are completely satisfied. This was initially reported with studies from the Swedish Registry and indicates room for improvement in our craft. But who says this is a “growing concern”? First of all are the third party payers and government agencies who would like to curtail expenditures and retain funds. Next are manufacturers promoting new, and one would hope, improved products and finally surgeons similarly promoting new techniques.

But who are the minority of dissatisfied patients and why are they unhappy? There is no reduction in demand for arthroplasty surgery by patients worldwide.

Deformity can be associated with significant bone loss, ligament laxity, soft-tissue contractures, distortion of long bone morphology, and extra-articular deformity. Correction of varus, valgus, or flexion deformity requires soft tissue releases in conjunction with bone cuts perpendicular to the long axes of the femur and tibia. Cruciate-retaining or -substituting implants can be used based on surgeon preference if the ligaments are well balanced. However, in presence of severe deformity, additional measures may be warranted to achieve alignment and balance. TKA then becomes a more challenging proposition and may require the surgeon to perform extensive releases, adjunct osteotomies and deploy more constrained implants. Merely enhancing constraint in the implant however without attending to releases and extra-articular correction may not suffice. Certain myths in deformity correction will be presented.

Technical tips with regard to preoperative planning, i.e., whether intra-articular correction alone will suffice or extra-articular correction is required, will be highlighted. Surgical principles and methods of performing large releases, reduction osteotomy, lateral epicondylar sliding osteotomy, sliding medial condylar osteotomy, and closed wedge diaphyseal/metaphyseal osteotomy concomitantly with TKA will be illustrated with examples. Technique of performing TKA with concomitant extra-articular deformity resulting from coronal bowing of femoral or tibial diaphysis, malunited fractures, prior osteotomies, and stress fractures will be presented. The techniques reported can successfully restore alignment, pain-free motion, and stability without necessarily using more constrained implants.

There are two types of pain, mechanical and non-mechanical. Mechanical pain hurts with movement/use, is not constant and is helped by morphine-type products. Non-mechanical pain is different. It is present 24 hours a day, often worse at night, and except for the pain of infection, is not relieved by morphine-type products.

If the cause of mechanical pain can be determined, it can be corrected by an operation. The usual cause of postoperative mechanical knee pain nowadays is multifactorial, i.e. a combination of minor errors, none of which on their own would require revision.

Non-mechanical pain, other than infection, is much more difficult to handle. The commonest cause is not really a pain complaint, it is disappointment due to a failure of expectation. It does not matter how often you tell patients, some patients still think they should step in a drive away. A lot of these failures of expectations become much more realistic by the end of year one.

There are several other categories. Incipient osteoarthritis or sensitive people (The Princess and the Pea). If the pain complaints were severe with minimal arthritis, an operation is not likely to help.

The patient on disability for no clear reason is unlikely to get a good result and Workmen's Compensation Board and motor vehicle accident patients are also a very bad prognostic sign and will often produce the postoperative painful knee. Preoperative use of large doses of morphine is also a very bad sign. It is not clear if it is the morphine, which influences the patient or the patient, who influences the morphine.

There are several pain syndromes, some of which are purely psychiatric such as Conversion Disorders and Somatoform Pain Disorders. Treatment of purely psychiatric conditions should be a referral to a psychiatrist is in order.

Complex regional pain syndrome is an organic pain disorder. Type 2 is causalgia or an actual nerve injury. This is unusual following knee replacement other than the odd drop foot, which even after recovery, leaves an area of dysaethesia on the dorsum of the foot. Type 1 used to be called reflex sympathetic dystrophy. This is not uncommon after total knee replacement. I managed to collect more than 40 cases. One problem is that the diagnosis to some extent is a diagnosis of exclusion. If the diagnosis can be made, then treatment is available including Cymbalta, Lyrica or Gabapentin. I have found most success with lumbar sympathetic blocks, but it is difficult to find someone, who can do these. Some patients have been treated with implantable electrical spinal stimulators with variable results.

The current flavour of the month pain syndrome is called central sensitization. The theory is that if someone has pain for more than six months, then there will be changes in the brain, which will remain after the original pain goes away, hence, the title the pain in the brain syndrome. If this theory were correct, then we as arthroplasty surgeons have been collectively wasting our time for the last 40 years as no patient would have recovered. The likelihood, therefore, of this theory having any basis in reality is pretty remote.

Fortunately, by the end of year one, the vast majority of our knee replacement patients are reasonably content with the procedure.

Knee stiffness is a well-recognised postoperative problem that has been reported to occur in 6% to 15% of all patients who undergo total knee arthroplasty (TKA), and there are multiple preoperative, intraoperative, and postoperative risk factors that may predispose patients to postTKA knee stiffness. Preoperative risk factors include poor baseline range of motion (ROM), obesity, and a history of previous knee surgery and/or trauma. Potential intraoperative risk factors for having a stiff knee are malalignment, gap imbalance, and under-resection of patella. Possible postoperative risk factors include heterotopic ossification, pain, poor patient motivation, and poor physical therapy compliance. Three commonly used adjuvant treatments for this condition are custom knee devices, Botox, and ASTYM. These treatment modalities are most effective when used within 6 weeks after surgery. Multiple case series have reported that CKD can improve range of motion while maximising patient-reported functional outcomes. Botox can improve range of motion by paralyzing the muscle where the contracture is located. ASTYM therapy has recently been reported to resolve muscle contractures by effectively stimulating tissue turnover, scar tissue resorption, and regeneration of the normal soft tissue structure. When these adjuvant therapies fail, manipulation under anesthesia has been reported to be efficacious in restoring some of the original ROM. If this fails, there are surgical treatment options such as arthroscopic debridement, surgical release, revision TKA, or peroneal nerve release.

General Principles

Repairs should be immobilised in full extension for 6–8 weeks. Gradual resumption of motion in a hinged brace over an additional 6–8 weeks almost always yields flexion to at least 90 degrees.

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 can provide additional structural 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 turn-down 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. A loose component and/or >20-degree extensor lag requires ORIF +/− component revision.

Chronic Disruptions - While standard repair techniques are possible, tissue retraction usually prevent a “tension-free” repair. In most chronic disruptions complete allograft extensor mechanism reconstruction is preferable. If the patella itself has not retracted proximally and remains intact other allograft soft tissues are a viable alternative. All grafts should be repaired tightly with the knee in full extension.

Periprosthetic fractures around a TKA typically involve the distal femur above a well-fixed femoral component. ORIF is typically indicated, using a retrograde nail or some form of locked plating. Tibial fractures after TKA are quite rare. In distinction to femoral fractures, fractures around a tibial component are typically associated with a loose prosthesis. Revision is indicated in this situation. Dealing with bone loss with augments, sleeves, cones, or allograft as well as stem bypass is typically necessary. Varus malalignment is often noted in these situations and should be corrected. More distal fractures can be managed with closed treatment if displacement and angulation is acceptable. A period of time in a long leg cast followed by conversion to a short leg or so-called PTB cast can be effective. More unstable fractures can be managed with plating techniques. Percutaneous so called MIPPO techniques can be particularly useful. Modern locking plates allow polyaxial proximal fixation that can be effective around the keels of tibial components. Malalignments are common so careful fluoroscopic scrutiny is necessary when using percutaneous techniques.

The use of constrained condylar components (CCK) in primary total knee arthroplasty is infrequent and unusual. The usual indications are a severe fixed valgus deformity with a stretched or incompetent medial collateral ligament (MCL). This may occur in an elderly female patient with valgus osteoarthritis, advanced rheumatoid arthritis, or other less common disorders: polio, Parkinson's disease, and Paget's disease involving the knee. It may also be seen in younger patients with post-traumatic arthritis. Beware of the patient with a prior history of a knee injury in which staples were placed at the medial epicondyle of the femur or proximal tibia, indicating likely MCL injury, or a knee with extensive medial joint heterotopic ossification. An unusual indication for a primary CCK component is inadvertent injury or sectioning of the MCL during the procedure. This can occur with over-zealous medial ligament release or division with the saw during the posterior femoral condylar or proximal tibial resection. This has been reported to occur in <1% to 2.7% of knees. Treatment alternatives are to attempt repair and brace the knee or perform “internal bracing” with a CCK component. The author strongly favors the use of CCK components in this situation. We permit early full-weightbearing and range of motion, without restrictions. Careful intraoperative attention to component rotation is crucial to avoid patellar complications. The results of CCK components by the author and others have demonstrated a high rate of survival at 10 years, even in younger patients.

Controversy remains regarding the optimal treatment for iatrogenic injury to the medial collateral ligament (MCL) during primary total knee arthroplasty (TKA). Some authors have recommended converting to a prosthesis that provides varus/valgus constraint while others have recommended primary repair. In this study we report the results of a 45 patients who sustained intraoperative MCL injuries during primary TKA that were treated with primary repair.

Of 3922 consecutive primary TKA there were 48 (1.2%) intraoperative MCL lacerations or avulsions. One patient was lost and one died before 24 months follow up. All but one patient underwent primary repair with placement of components without varus/valgus constraint. This left 45 knees with a mean follow up of 89 months (range, 24–200). The mean HSS knee scores increased from 46.8 to 84.8 points (p<0.001). No patients had subjective complaints of instability. No patients had excessive varus/valgus laxity when tested in full extension and 30 degrees of flexion. The range of motion at the time of final follow-up averaged 110 degrees (range, 85 degrees to 130 degrees). Five knees required treatment for stiffness with 4 knees undergoing manipulation under anesthesia and 1 knee undergoing open lysis of adhesions with polyethylene articular surface exchange. Two knees underwent revision for aseptic loosening of the tibial component. In the three knees that underwent open revision, the MCL was noted to be in continuity and without laxity.

Primary repair with 6 weeks of postoperative hinged bracing after iatrogenic injury to the MCL during primary TKA was successful at preventing instability although stiffness was seen in approximately 10% of patients. The increased morbidity associated with implantation of a semiconstrained or constrained implant may be unwarranted in this situation.

To consider bilateral simultaneous knee replacement, both knees must have significant structural damage. It is best if the patient can't decide which knee is more bothersome. In borderline cases, ask the patient to pretend that the worse knee is normal and if so, would they be seeing you for consideration of knee replacement on the less involved side. If the answer to this question is “yes,” consider the patient a potential candidate for bilateral knee replacement. If the answer is “no,” recommend operating only on the worse knee, and expect that the operation on the second knee can probably be delayed for a considerable period of time.

Strong indications for bilateral simultaneous TKA are bilateral severe angular deformity, bilateral severe flexion contracture, and anesthesia difficulties, i.e., patients who are anatomically or medically difficult to anesthetise, such as some adult or juvenile rheumatoid arthritis patients or patients with severe ankylosing spondylitis.

Relative indications for bilateral simultaneous TKA include the need for multiple additional surgical procedures to achieve satisfactory function and financial or social considerations for the patient. Contraindications to bilateral TKA include medical infirmity (especially cardiac), a reluctant patient, and a patient with a very low pain threshold.

When performing bilateral simultaneous TKA, both limbs are prepped and draped at the same time. An initial dose of an intravenous antibiotic is given (usually 1g of a cephalosporin) before inflation of the tourniquet. Surgery begins on the more symptomatic side or on either side if neither knee is significantly worse than the other. The reason for starting on the more symptomatic side is in case surgery has to be discontinued after only one procedure owing to anesthetic considerations.

After the components have been implanted on the first side, the tourniquet is deflated and a second dose of intravenous antibiotic is administered (usually 500mg of a cephalosporin). After the joint capsule is closed and flexion against gravity is measured, one team completes the subcutaneous and skin closure on the first side while the other team inflates the second tourniquet and begins the exposure of the second side. When the second tourniquet is deflated, a third dose of antibiotic is given (usually 500mg of a cephalosporin for a total dose of 2g for both knees).

Because of concern about the potential for cross-contamination of the knee wounds when instruments used during the final stages of skin closure on the first knee are maintained on the field and used on the second knee, they should probably be handed off the field and outer surgical gloves changed.

Most patients will report after their complete recovery that they are glad they did both knees at the same time. A patient who has any uncertainty about proceeding with bilateral surgery should have only one knee done at a time. In many cases, the second side receives a “reprieve,” becoming more tolerable after the first side has been operated on.

In properly chosen patients, cementless total knee arthroplasty has achieved success rates equal to cemented designs. The initial variable results of early cementless total knee replacements were a function of design, surgical technique and patient selection. Important design considerations that have enhanced biologic ingrowth include the use of commercially pure titanium with optimal pore size and porosity, and avoidance of porous-coated stems and plugs that cause stress shielding of the bone-implant interface. Factors in surgical technique that enhance bone ingrowth include precise bone cuts that maximise bone-implant contact, and the application of autogenous bone slurry to cut surfaces. Additional factors are restoration of normal alignment, appropriate ligament balance, and the reproduction of the patient's native tibial slope in order to prevent tibial component subsidence. Young and active patients are ideal biological hosts for the use of cementless knee fixation. Their relatively dense cancellous bone and rich blood supply provides for robust purchase for initial fixation and the appropriate milieu for long-term biologic fixation. With increasing life expectancy, this more durable interface is desirable. With avoidance of porous-coated stems and pegs and prevention of fibrous tissue attachment, potential future revisions are more bone-sparing relative to methylmethacrylate fixation. Numerous reports, as well as the authors’ published 10- to 14-year results, demonstrate that cementless fixation in appropriately selected patients provides results comparable to cemented TKA, with the advantage of conserving bone stock and eliminating the potential problems of cement fixation.

The initial application of bone ingrowth technology to the fixation of total knee arthroplasty (TKA) components without bone cement was based on the premise that bone cement was “not biologic”, and so over time would undergo fatigue failure with subsequent loosening. It was hoped that this problem could be obviated by cementless fixation by bone ingrowth, which would remodel over time and not fatigue. In addition, it was anticipated that the failed cementless TKA might be easier to revise and leave the surgeon with more bone to work with. Whether or not cementless fixation of TKA components was justified on any of these counts was uncertain through the first 2 decades of their use. Much of the data accumulated during that period poorly supported these contentions, while cemented TKA was increasingly reported as a reliable, consistent and less complicated form of TKA fixation. However, over the past decade, new evidence has accumulated demonstrating greater success with this technology in several well designed studies as well as from registry studies. Most of this evidence involves the use of Porous Tantalum. However, increasing evidence that loosening of well done, well designed cemented TKA is rare along with some evidence that a certain percentage of cementless TKA patients fail to achieve stability remains concerning. In addition, no studies have justified improved longevity to the extent that the increased cost of cementless devices can be justified.

Preoperative planning in revision total knee replacement is important to simplify the surgery for the implant representative, operating room personnel and the surgeon. In revision knee arthroplasty, many implant options can be considered. This includes cemented and cementless primary and 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 preoperatively 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 delivery van full of instruments and implants.

Ideally, the least constraint needed should be used. This requires determination of the status of the collateral ligaments preoperatively. If there is instability present, use physical examination with confirmation from radiographs. Predict the constraint needed and have the next level as a back-up. Substitution for the posterior cruciate ligament is usually needed for most revisions.

Intraoperative determination of the joint line position is difficult due to lack of anatomic landmarks. Having intact collateral ligaments with an appropriate anatomic joint line position will usually negates the need for increased implant constraint. Radiographically, one can determine the appropriate joint line position relative to the existing femoral component to simplify the surgery.

Preoperative review of radiographs should determine the amount and location of bone loss. This will help determine if having cementless and/or primary components available can be eliminated. Larger defects may warrant having metallic augments or bulk graft present. Determine if bony deficiencies will mandate use of stems. Most revision knee implants can be conservatively cemented with diaphyseal engaging press-fit stems.

Occasionally, one may not need to revise all components, so the surgeon needs to be familiar with the implants they are revising. Consider having some or all compatible components available.

Excellent preoperative planning will minimises 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.

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment secondary to loosening 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 manual or radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate ligament retaining knees, anteroposterior instability must be assessed.

For instability, most revisions will require a posterior cruciate substituting design or a constrained unlinked condylar design that, although sometimes a posterior cruciate ligament preserving design can be used in situations where the bone-stock is well preserved. 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.

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

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

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

From 1985 through 1997, 56 isolated tibial insert exchange revisions were performed at our institution. Fifty-five patients with wear or instability were included. Those with loosening of any of the components, history of infection, severe knee stiffness or problems with the extensor mechanism were excluded. There were 29 males (1 bilateral) and 26 female patients with a mean age of 66 years (range 35 to 83 years) at the time of revision surgery. Twenty-seven inserts were exchanged based on ligamentous instability, 24 because of insert wear or breakage including two cases of polyethylene dislodgment from the tibial base-plate and 5 for other reasons. Twelve knees had one to three prior revisions. Surveillance from index arthroplasty averaged 8.3 years (range 1.6 to 16.2 years) and since revision 4.6 years (range 2 to 14 years).

Knee Society and Function Scores improved from 56 and 50.9 prior to revision to 76 and 59 at final surveillance, respectively. Fourteen (25%) of the 56 knees subsequently required re-revision after a mean of only three years (range 0.5 to 6.8) from tibial insert exchange. The cumulative survival at 5.5 years was 63.5% (95% CI=+/−14.4, n=19). Of the 27 patients with preoperative instability, eight were revised and another four were considered as failures due to severe pain. Of the 24 failed inserts, five were re-revised, one was amputated as a result of chronic ankle osteomyelitis concomitant to a chronically painful arthroplasty, and another two inserts failed due to severe pain.

Isolated tibial insert exchange led to a surprisingly high early failure rate. Tibial insert exchange should therefore be undertaken with caution as an isolated method of total knee revision surgery even in those circumstances for which the modular insert was designed and felt to be of greatest value.

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

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

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

Periprosthetic joint infection (PJI) is one the most devastating complications of joint arthroplasty. Although PJI is an infrequent complication (the reported incidence is 1%-2% in the United States), it is the most common indication for revision total knee arthroplasty in the Medicare population and the third most frequent indication for revision total hip arthroplasty. Moreover, the prevalence of PJI appears to be on the rise, with a projected number exceeding 60,000 to 70,000 cases in the United States by 2023.

It is estimated that more than 25% of revision procedures annually are attributed to PJI and this number is expected to increase in the upcoming years. The increase in the prevalence of obesity, diabetes, and other comorbidities among the patient population and the emergence of resistant infecting organisms are some of the reasons for the expected rise in the number of infections that medical community will witness.

The challenges that PJI presents to the orthopaedic community are on many fronts. Prevention of PJI has proven to be a difficult task indeed. Effective strategies for prevention of PJI are being refined. The Center for Disease Control will be publishing its updated Surgical Site Prevention Guidelines in the next few months that consists of specific recommendations for prevention of PJI. In recent years, strides are made in introducing novel molecular techniques for diagnosis of PJI, which may stand to change our practices. The current surgical technique for management of PJI, besides the immense cost, fall short of delivering high success to the patients. The major problem in eradication of infection relates to formation of biofilm, on the implant surface and internalization of the organisms by affected cells. Biofilm is a sophisticated structure comprising of organisms embedded in multiple layers of glycoccalyx that allows the organisms to evade host immunity and is impenetrable to antibiotics. These organisms are capable or communicating through molecular mechanisms such as quorum sensing that affords them advantage for survival in the host environment. In recent years strategies to prevent colonization of the implant surface, an essential first step in formation of biofilm, or biofilm disruption techniques have been introduced. A recent International Consensus meeting on PJI that assembled more than 350 experts identified some of the best practices in this field and identified areas in need of future research. Moving into the future, the field of orthopaedics in general and PJI in particular stand to benefit from the discoveries in the field of molecular diagnostics, metabolomics and epigenetics.

Obtaining adequate exposure is key to optimising outcomes in revision total knee arthroplasty. Goals of the exposure include protecting the extensor mechanism, safe removal of the components that are in place and implantation of the revision components. Challenges to these goals include prior skin incisions, arthrofibrosis, and patella baja.

Choosing a skin incision is the first important step. The blood supply to the skin is predominantly derived MEDIALLY and thus the most LATERAL skin incision that works for obtaining exposure is selected. If skin flaps are required, they MUST be full thickness as the blood supply to the skin runs deep just over the fascial layer and partial thickness flaps risk skin necrosis. Avoid acute angles between old skin incisions of <60 degrees and kin bridges, if necessary must be at least 6cm in width.

The work-horse of revision TKA is the medial parapatellar approach. It includes a generous medial release that allows the surgeon to externally rotate and deliver the tibia by pivoting on the extensor mechanism. An anterior synovectomy is then performed to re-establish the medial and lateral gutters followed by re-establishment of the space behind the patellar tendon to free it from the proximal tibia and finally subluxation of the patella (preferable to formal eversion). A lateral release (or peel of the soft tissue off of the lateral side of the patella) is a final step to mobilise the extensor mechanism (if required). After the components are removed, a posterior capsular release and re-establishment of the flexion space behind the femur further enhances tibial exposure for both bony preparation and revision component implantation.

If the above maneuvers are performed, and exposure is still inadequate, the easiest way to improve exposure is by performing a quadriceps snip. This is an oblique, apical extension of the arthrotomy ACROSS THE PATELLAR TENDON (NOT in the muscle; it is hard to repair if performed in the muscle). It is repaired side to side with no need to alter postoperative physical therapy and heals reliably.

A V-Y Quadricepsplasty is a proximal release of the extensor mechanism; essentially perform by connecting the apical extension of the medial parapatellar arthrotomy with a lateral release across the quadriceps tendon. It is classically indicated for patients with extensor mechanism contracture where the surgeon wishes to attempt lengthening the extensor mechanism. Usually results in increased flexion at the expense of an extensor lag and is used rarely in contemporary practice.

Tibial Tubercle Osteotomy is a distal release of the extensor mechanism that is most useful for accessing the canal to remove long-stemmed cemented tibial components. It is a coronal osteotomy made from the medial side of the tubercle that is usually made 5–8cm in length, tapering from approximately 1cm thick proximally to 5mm distally.

Instability remains a common reason for revision after primary TKA. Careful preoperative examination is necessary to determine the exact direction of and reason for the instability. Radiographs and CT can be useful to evaluate component alignment and rotation. Obviously, ruling out concurrent infection should be a part of the routine preoperative workup. PCL insufficiency can be treated by conversion to a more “dished” insert if available, and all other component issues are acceptable. If dished inserts are not available, then revision to a posterior stabilised component can be effective. Flexion instability can occur with PCL substituting designs, and may require revision as well. Up-sizing, and posteriorising the femoral component (often requiring posterior augmentation) to tighten the flexion gap can be an effective strategy. With collateral ligament problems, so called CCK or “constrained” implants can be effective. While ligament advancement or augmentation techniques have been described, few surgeons are familiar with these techniques, and most “back up” such reconstructions with constrained implants. With more severe collateral ligament deficiencies, multi-directional instabilities, or massive flexion-extension gap mismatches, the use of so-called “hinged” implants can be effective. It is wise to have various levels of constraint available preoperatively when undertaking these challenging revisions.

Total knee arthroplasty in the setting of osseous defects has multiple management options. However, the optimal treatment strategy remains controversial. The purpose of this study is to report the clinical and radiographic results of trabecular metal cones in managing osseous defects in the setting of complex primary and revision total knee arthroplasty.

There were 129 consecutive total knee arthroplasty procedures performed utilising trabecular metal cones reviewed for clinical and radiographic outcomes. Twenty-five had less than 2 years of follow-up and seven died, leaving 96 patients for evaluation. This cohort included a total of eighty-six (86) tibias with eleven (11) having Type 1 defects, twenty-five (25) having Type 2A defects, forty-three (43) with Type 2B defects and seven (7) with Type 3 defects. There were twenty-seven (27) femurs with one (1) Type 1 defect, nine (9) Type 2A defects, sixteen (16) with Type 2B defects and one (1) Type 3 defect based on the AORI classification. There were 28 male patients and 68 female patients, with an average age of 68 years and an average BMI of 35.0. There were six primary procedures and ninety revision procedures. Continuous variables were evaluated using a t-test.

Twelve patients required revision leaving 84 knees (87.5%) with the cones in place at an average of 31 months of follow-up (range, 24–77.3 months). The mean KSS score increased from 51.0 preoperatively to 80.2 postoperatively (p<0.0001). The mean KSS functional score increased from 32.9 preoperatively to 47.8 postoperatively (p=0.0002). Including the twelve revisions, there were twenty-two knees requiring re-operation (22.9%) with another seventeen requiring manipulation under anesthesia and there were four additional non-operative complications (1 foot drop, 1 stress fracture, 2 superficial infections).

Arthrodesis

Today, knee arthrodesis is most commonly performed for cases of chronic sepsis after total knee arthroplasty in patients who are not candidates for reimplantation. This is typically a host in whom the risk of recurrent infection is high, especially when extensor mechanism problems such as patellar tendon rupture is present. Local and systemic host factors place the patient at this high risk for failure of reimplantation. Local factors include chronic lymphedema, major vessel disease, venous stasis, extensive scarring and radiation fibrosis. Systemic problems include malnutrition, malignancy, extremes of age, hepatic or renal failure, diabetes mellitus and alcohol abuse. Also, at least in one study, patients who fail one two-stage reimplantation have at least a 50% change for recurrence the second time.

Methods of knee arthrodesis include external fixation, single or double plate fixation and intramedullary nailing either monolithic or modular. External fixation can be performed as a single procedure. With external ring fixators leg lengthening has been described. Plate and nailing procedures are commonly performed after the infection is eradicated. If infection recurs but fusion has occurred, removal of a modular nail may be difficult although techniques have been described. Fusion rates of 85% to 100% have been reported with the newer techniques and fusion rates are usually correlated with the amount of bone loss after removal of the prosthesis. Optimal position of fusion is slight anatomic valgus and slight flexion. Placing a bowed intramedullary nail with the bow anteromedially can facilitate this alignment. One study comparing arthrodesis after failed knee arthroplasty with primary total knee replacement found nearly identical Short-Form 36 scores. Physical mobility was better with knee arthroplasty but pain control was better with arthrodesis.

Resection Arthroplasty

Indication: Low demand patient with comorbidities

Results: Falahee et al.; 28 knees;15 patients walked independently; Most severely disabled more satisfied. Less disabled least satisfied.

Amputation - Above the Knee Amputations after TKA (Sierra et al)

Prevalence: 0.36% (all causes – most common was peripheral vascular disease), 0.14% (for causes related to TKA: infection, periprosthetic fracture, pain, bone loss, vascular complication)

Results: 25 amputations for causes related to TKA; Avg 8.6 years after TKA

Complications: deep infection 5, superficial infection 1, skin necrosis 1, perioperative death 1. 9 of 25 fitted with above knee prosthesis; Only 5 were walking even to limited degree with prosthesis

Osteoarthritis (OA) is a highly prevalent disease that has a debilitating role in every day function and activity. In 2002, the indirect cost of OA was 5 billion dollars, secondary to absenteeism and loss of productivity. There are multiple management options available for OA, with surgery usually being a last resort. Total knee arthroplasty (TKA) provides a long-lasting treatment option with excellent results. However, a high proportion of patients still express dissatisfaction following surgery, possibly due to a combination of pain, continued limitation of function, and high expectations. The use of bracing provides a non-operative treatment option as well as a useful therapy adjunct in patients who undergo TKA. Bracing may aid in rehabilitation prior to TKA as well as postoperatively, and it also plays a beneficial role in problematic situations, such as patients who have undergone revision surgery or who have extensor mechanism problems. They are thought to aid in gait ‘retraining’, quadriceps muscle strengthening, improving joint alignment, and increasing stability of the joint. Although the American Academy of Orthopedic Surgeons remains inconclusive on the role of bracing, multiple studies have highlighted that they may be of benefit. The use of valgus bracing has been shown to provide short-term treatment for activity, bracing for uni-compartmental OA has shown an improvement in outcome measures, and the use of an unloader brace has led to improved general physical health and function outcomes, as measured by the SF-12 and WOMAC, respectively.

Minimal or Less Invasive Approaches

Limited medial parapatellar incision – 2–3 inch medial incision; Best for unicompartmental implant; patellar visualization poor; Less invasive but limited visualization therefore overall joint inspection is compromised.

MIS TKR approaches - Mini midvastus approach popularised by S.B. Haas - Ideal BMI 30 or less; Incision length 10cm; Vastus incision about 2–3cm; Vastus incision beyond 5–6cm places motor branch to VMO at risk; Coupled with downsized cutting blocks, allows predictable ability to perform TKR; Sliding window concept; Patella eversion not necessary.

Mid Subvastus approach – 10cm skin incision; Sub vastus dissection up to septum (watch for bleeders!); VERY difficult in muscular males!

Standard Incisions

Standard medial parapatellar approach - Familiar to most surgeons; Medial arthrotomy facilitates exposure for almost all procedures; Can become more extensile by incising the quad tendon further proximal; Release of posteromedial capsule and semi-membraneosus allows exposure posteriorly.

Quad snip - Used occasionally in the fixed varus, flexion contracted knee; More commonly used in revisions; Allows patella eversion without risk of distal avulsion; Motor strength appears to return to baseline level postoperatively.

V-Y quadriceps turndown - Technique: initial medial parapatellar arthrotomy, an oblique tenotomy angled toward the tendinous portion of the vastus lateralis and then extended distally; The quadriceps segment is than retracted downward to expose the joint; Tenotomy is closed with robust non-absorbable sutures holding the knee in extension; Postoperative flexion is dictated by integrity of repair while flexing knee at time of closure. Disadvantages include extensor lag, as well as effecting ultimate ROM.

Tibial tubercle osteotomy a la Whiteside - Medial arthrotomy; Tubercle segment is 6–8cm long, 2cm wide and 1–1.5cm thick; Segment is beveled distally so as to avoid stress riser; Leave lateral soft tissue intact; Closure with wires preferred although screws or cables have been used as well.

Computer navigation is an attractive tool for use in total knee arthroplasty (TKA), as it is well known that alignment is important for the proper function of a total knee replacement. Malalignment of the prosthetic joint can lead to abnormal kinematics, unbalanced soft-tissues, and early loosening. Although there are no long term studies proving the clinical benefits of computer navigation in TKA, studies have shown that varus alignment of the tibial component is a risk factor for early loosening.

A handheld, accelerometer based navigation unit for use in total knee replacement has recently become available to assist the surgeon in making the proximal tibial and distal femoral cuts. Studies have shown the accuracy to be comparable to large, console-based navigation units. Additionally, accuracy of cuts is superior to the use of traditional alignment guides, improving the percentage of cuts within 2 degrees of the desired alignment.

Because the registration is based on the mechanical axis of the knee, anatomic variables such as femoral neck-shaft angle, femoral length, and presence of a tibial bow do not affect the results. The handheld aspect of this navigation unit allows its use without additional incisions or array attachment. Furthermore, the learning curve and usage time is minimal, supporting its use in primary TKA.

Ligament release in knee arthroplasty can be limited with accurate placement of implants, correct sizing and anatomic geometry of the implants. Still, in some instances a release of the medial collateral ligament can be necessary. In the proposed minimally invasive technique, multiple punctures in the MCL are made, using an 19-gauge needle, in order to progressively stretch the MCL until a correct ligament balance is achieved. This technique requires no additional soft tissue dissection and can even be performed percutaneously when necessary.

We analyzed 61 cases with varus deformity that were intraoperatively treated using this technique. In 4 other cases the technique was used as a percutaneous procedure in order to correct postoperative medial tightness. The procedure was considered successful when 2–4mm mediolateral joint line opening was obtained in extension and 2–6mm in flexion. In 62 cases (95%) a progressive correction of medial tightness was achieved according to the above described criteria. We therefore consider needle puncturing as an effective and safe technique for progressive correction of MCL tightness during minimally invasive TKA.

Valgus deformity is less common than varus. There is an associated bone deformity in many cases – dysplasia of the lateral femoral condyle. There are also soft tissue deformities, including tightness of the lateral soft tissues, and stretching of those on the medial side.

Unlike varus, where the bone deformity is primarily tibial, in valgus knees it is most often femoral. There is both a distal and a posterior hypoplasia of the lateral femoral condyle. This results in a sloping joint line, and failure to correct this results in valgus malalignment. Posterior lateral bone loss also results in accidental internal rotation of the femoral component, which affects patellar tracking. Using the trans-epicondylar axis and Whiteside's line helps to position the femoral component in the correct rotation.

Soft tissue balancing is more complex in the valgus knee. Releases are performed sequentially, depending on the particular combination of deformities. It is important to note whether the knee is tight in flexion, in extension, or both. Tightness in extension is the most common, and is corrected by release of the iliotibial band. Tightness in flexion as well as extension requires that the lateral collateral ligament +/− the popliteus tendon be released.

Cruciate substituting designs are helpful in many cases, and in extreme deformity with medial stretching, a constrained or “total stabilised” design is needed. Patellar maltracking is common, and a lateral retinacular release may be needed. Beware of over-releasing the posterolateral corner, as excessive release may cause marked instability. Use the pie-crust technique of Insall.

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

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

New technology of “smart trials” with embedded microelectronics and accelerometers, used in the knee with the medial retinaculum closed, can provide dynamic, intraoperative feedback regarding knee and component alignment along with quantitative compartment pressures and component tracking. After visualising the resultant data on a graphical interface, the surgeon can decide whether to perform a soft tissue balance or redo the bone cuts. If soft tissue balancing is performed, the surgeon can assess the pressures effect of sequential soft tissue releases performed to balance the knee.

A multi-center study using smart trials has demonstrated dramatically better outcomes at six months and one year.

Historically correction of deformity in primary TKA has involved release of collateral ligaments to correct deformity. This has been common to both measured resection and gap balancing techniques but particularly the former. Essentially the collateral ligaments have been released to balance the bone cuts. Another philosophy is to consider that the collateral ligaments do not contract and should never be released. After sacrificing both cruciates I use a tibia first technique. The AP femoral cuts are done by using collateral ligament tension to set femoral rotation and create a rectangular flexion gap which is then measured

A five degree conservative or precut is then made on the distal femur. Critically all osteophytes have now been removed. The extension gap is assessed using a spacer block. In a varus knee the definitive cut is frequently made in more varus to create a balanced extension gap to equal the flexion gap. It is rare to have to release the posteromedial capsule.

In contrast in severe fixed valgus the posterolateral capsule frequently has be cut before the definitive distal femora cut is made. The latter is often in more valgus. I never resurface the patella but ensure good patellar tracking after inserting a cementless mobile bearing knee which is used irrespective of deformity. I am more concerned about gap balance than the mechanical axis.

Essentially the concept proposed is to cut the bone to balance the soft tissues as opposed to the reverse. The aim is to restore pre-morbid alignment and not necessarily a neutral mechanical axis.

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

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

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

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

Total knee arthroplasty causes unresolved pain and swelling in about 10% of patients despite good alignment, ligament balance, and fixation. Metal sensitivity becomes more common in total knee patients as time passes, wear continues to be a clinically relevant issue, loosening increases in frequency with time, and infection continues to plague implant surgery. Ceramic bearing surfaces address all of these issues. New technologies make possible stronger, more flexible ceramic materials, and one ceramic in particular (magnesia-stabilised zirconia) is especially interesting because of its ability to accept a commercially pure titanium porous coating. These materials do not release metal debris or ions, wear is reduced by a factor of three, and biofilm formation is reduced by a factor of three or more when compared with cobalt-chromium.

After clearing regulatory requirements, this new ceramic technology is likely to advance our solutions to many of the most important clinical problems in knee arthroplasty.

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

Knee replacements may be unstable in the: 1. Plane of motion instability, due to recurvatum or buckling (in flexion). 2. Coronal plane or varus-valgus instability and 3. Flexed position. The third, flexion instability, has been well described and is characterised clinically by early, easy, superior flexion that is then compromised by difficulties with ascending and descending stairs, recurrent effusions and peri-articular tenderness. This “flexion instability” results generally from a flexion gap that is more spacious than the extension gap, where the polyethylene insert has been selected to permit full extension.

The term “mid-flexion” instability should not be used as a synonym for “flexion instability”. The concept of mid-flexion instability implies that the knee is stable in extension and stable in flexion (90 degrees) but unstable at points in between. The most common error in assessment probably occurs when surgeons observe stability to varus-valgus stress with the knee locked in full extension, where it is not appreciated that the posterior structures are tight and stabilising the knee. Once the knee if flexed enough to relax these structures, the true “flexion instability is revealed. This is not “mid-flexion” instability.

It is conceivable, that an arthroplasty might be designed where the geometry of the femoral condylar curve is such a large, recessed radius that the collateral ligaments are tight in both full extension and 90 degrees of flexion, but unstable in between. There have been marketing allegations that one product or another has been designed in a way to result in “mid-flexion instability. The only published information is based on finite element analysis models.

There is scant literature on “mid-flexion” instability”. Laboratory investigations with cadavers, concluded that proximal elevation of the joint line may create “mid-flexion” instability as a result of altering collateral ligament function. Computer models have questioned this effect. One clinical report describes “mid-flexion” (rotational) instability in a revision arthroplasty. So-called “anatomic alignment”, posterior stabilization and resection of distal femur to correct flexion contractures have been alleged to cause “mid-flexion” instability.

Complications involving the knee extensor mechanism occur in 1% to 12% of patients following total knee arthroplasty (TKA), and have negative effects on patient outcomes. While multiple reconstruction options have been described for complete disruption of the extensor mechanism, the results in patients with a prior TKA are inferior to those in patients without a TKA, and frequently have required the use of allograft tendon grafts which can attenuate and stretch over time. However, encouraging results have been reported by Browne and Hanssen in treatment of patellar tendon disruption with the use of a synthetic mesh (knitted monofilament polypropylene). In this technique, a synthetic graft is created by folding a 10 × 14 inch sheet of mesh and securing it with non-absorbable sutures. A burr is then used to create a trough in the anterior aspect of the tibia to accept the mesh graft. The graft is inserted into the trough and secured with cement. After the cement cures, a transfixion screw with a washer is placed. A portal is subsequently created in the soft tissues lateral patellar tendon remnants to allow delivery of the graft from deep to superficial. The patella and quadriceps tendon are mobilised, and the graft is secured with sutures to the lateral retinaculum, vastus lateralis, and quadriceps tendon. The vastus medialis is then mobilised and brought in a pants-over-vest manner over the mesh graft, and secured with additional sutures. Finally, the distal arthrotomy is closed tightly to completely cover the mesh graft with host tissue. In their series, Browne and Hanssen noted that 9 of 13 patients achieved an extensor lag of <10 degrees with preserved knee flexion and significant improvements in the mean Knee Society scores for pain and function. A similar modified method has been used at our institution for chronic quadriceps tendon disruptions as well. The reconstructions have shown less of a tendency to late attenuation, stretch and recurrent extensor lag beyond two years compared to our experience with tendon allograft reconstructions and remains our procedure of choice at our institution for the majority of these challenging problems.

Rotating Hinge total knee replacement designs are currently more frequently used for revision total knee replacement. As the designs of these implants have improved over time, the threshold for using them has been lowered. Cases of global instability and severe bone loss have not been adequately addressed by the standard use of unlinked constrained designs. Recurrent dislocation and polyethylene post failure due to cold flow and wear make the use of the unlinked designs insufficient to address the mechanical forces developed in a grossly unstable knee.

The linked rotating hinge designs have been able to address global ligamentous instability in four planes. Medial-lateral instability is well addressed by these implants. In cases of severe ankylosis with large flexion contractures, it is often necessary to resect the distal femur above the femoral insertions of the medial and lateral collateral ligaments. The absence of the tethering effect of severely contracted collateral ligaments demand the need for linked designs, although there has been reported success with the use of unlinked designs. Rotating hinges are particularly important for use in cases of recurvatum where an extension stop is incorporated in the design. The design permits slight hyperextension which permits application to clinical situations with incompetent quadriceps strength or paralysis.

The clinical results are quite acceptable even though most reports present 65–75% success rates. However, it should also be stated that these patient cohorts represent the most severe cases of revision surgery. Current hinged designs should continue to lower the threshold for use.