Introduction

The use of irrigation solution during surgical procedures is a common and effective practice in reduction of bioburden and the risk of subsequent infection. The optimal irrigation solution to accomplish this feat remains unknown. Many surgeons commonly add topical antibiotics to irrigation solutions assuming this has topical effect and eliminates bacteria. The latter reasoning has never been proven. In fact a few prior studies suggest addition of antibiotics to irrigation solution confers no added benefit. Furthermore, this practice adds to cost, has the potential for anaphylactic reactions, and may also contribute to the emergence of antimicrobial resistance. We therefore sought to compare the antimicrobial efficacy and cytotoxicity of irrigation solution containing polymyxin-bacitracin versus other commonly used irrigation solutions.

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

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

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

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

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

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

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

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

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

Among the most critical factors to reducing the risk of infection include the use of pre-incisional antibiotics, appropriate skin preparation with clippers (as opposed to a razor for hair removal) and the use of an alcohol-based skin preparation. Host factors are also likewise critically important including obesity, diabetes, inflammatory arthritis, renal insufficiency, skin disorders and patients who are otherwise immune-compromised. If modifiable risk factors are identified, it would seem reasonable to delay elective surgery until these can be optimised.

One other factor to consider is the nutritional status of the patient. In a study of 501 consecutive revisions, we found that serological markers suggestive of malnutrition (albumin, transferrin or total lymphocyte count) were extremely common. Specifically, 53% of patients who presented for treatment of a chronic infection had at least one marker for malnutrition, compared to 33% in the group of patients undergoing revision for an aseptic reason. Malnutrition was found to be an independent risk factor for septic failure (p < 0.001 and OR 2.1). Interestingly, malnutrition was most common among patients of normal weight but was also common among obese patients (so-called “paradoxical” malnutrition). What was more disturbing, however, was that of those patients undergoing an aseptic revision, serum markers of malnutrition were associated with a 6× risk of acute post-operative infection complicating the patient's aseptic revision. We have confirmed this association using the NSQIP database where hypoalbuminemia was associated with a higher risk of infection, pneumonia and readmission.

At our center, we also have studied the use of dilute betadine at the end of the case, prior to wound closure, in an attempt to decrease the load of bacteria in the wound. In a retrospective review the prevalence of acute post-operative infection was reduced from just under 1% (18/1862) to 0.15% (1 of 688; p = 0.04). It is critical that the betadine utilised be STERILE and the dilution we use is 0.35% made by diluting 17.5cc of 10% povidone-iodine paint in 500cc of normal saline.

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

Type 1:

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

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

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

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

Introduction

Preservation of the anterior cruciate ligament (ACL), along with the posterior cruciate ligament, is believed to improve functional outcomes in total knee replacement (TKR). The purpose of this study was to examine gait differences and muscle activation levels between ACL sacrificing (ACL-S) and bicruciate retaining (BCR) TKR subjects during level walking, downhill walking, and stair climbing.

INTRODUCTION

As the demographic of the patient population requiring revision total knee arthroplasty (rTKA) continues to expand, varying preoperative conditions and activity levels need to be taken into consideration when analyzing postoperative outcomes. Factoring in preoperative activity levels can help manage the expectations of patients. The purpose of this study was to analyze the outcomes of low and high activity patients receiving a contemporary rTKA.

Introduction

The benefits of femoral head-neck modularity in hip surgery have been recognized for decades. However, reports of head/neck taper fretting & corrosion has led to research being conducted, yet the clinical effect of these processes remains unclear. Whilst femoral head size, material and the characteristics of the taper have been a focus of research, potential contributing variables such as in vivo head-neck assembly technique on the performance of these connections is not clear. We performed an observational study to investigate variation in femoral head-neck taper assembly during surgery, with the initial focus being the number of head impactions.

Introduction

The first highly crosslinked and melted polyethylene acetabular component for use in total hip arthroplasty was implanted in 1998 and femoral heads larger than 32mm in diameter introduced 2004.

The purpose of this study was to re-assemble a previous multi-center patient cohort in order to evaluate the radiographic and wear analysis of patients receiving this form of highly crosslinked polyethylene articulating against large diameter femoral heads at a minimum of 10 years follow-up.

Introduction

The first highly crosslinked and melted polyethylene acetabular component for use in total hip arthroplasty was implanted in 1998. Numerous publications have reported reduced wear rates and a reduction in particle induced peri-prosthetic osteolysis at short to mid-term follow-up.

The purpose of this study was to re-assemble a previous multi-center patient cohort in order to evaluate the radiographic and wear analysis of patients receiving this form of highly crosslinked polyethylene articulating against 32mm femoral heads or less at a minimum of 13 years follow-up.

Minimizing the risk of periprosthetic joint infection (PJI) is of interest to all surgeons performing hip and knee arthroplasty. Among the most critical factors to reducing the risk of infection include the use of pre-incisional antibiotics, appropriate skin preparation with clippers (as opposed to a razor for hair removal) and the use of an alcohol-based skin preparation. Host factors are also likewise critically important including obesity, diabetes, inflammatory arthritis, renal insufficiency, skin disorders and patients who are otherwise immune-compromised. If modifiable risk factors are identified, it would seem reasonable to delay elective surgery until these can be optimised.

One other factor to consider is the nutritional status of the patient. In a study of 501 consecutive revisions, we found that serological markers suggestive of malnutrition (albumin, transferrin or total lymphocyte count) were extremely common in the revision population. Specifically, among patients who presented for treatment of a chronic infection, 53% (67 of 126) had at least one marker for malnutrition. The prevalence of serological markers of malnutrition was lower (33%) in the group of patients undergoing revision for an aseptic reason suggesting that malnutrition was a risk factor for septic failure (p < 0.001 and OR 2.1). Interestingly, malnutrition was most common among patients of normal weight but was also common among obese patients (so-called “paradoxical” malnutrition). What was more disturbing, however, that of those patients undergoing an aseptic revision, serum markers of malnutrition were associated with a 6x risk of acute postoperative infection complicating the patient's aseptic revision.

At our center, we also have studied the use of dilute betadine at the end of the case, prior to wound closure, in an attempt to decrease the load of bacteria in the wound. In a retrospective review the prevalence of acute postoperative infection was reduced from just under 1% (18/1862) to 0.15% (1 of 688; p = 0.04). It is critical that the betadine utilised be STERILE and the dilution we use is 0.35% made by diluting 17.5cc of 10% povidone-iodine paint in 500cc of normal saline. Although this is a retrospective review, it does suggest a benefit and we have not seen any problems associated with its use.

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

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

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

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

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

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

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

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

We reviewed 75 hips revised for instability and at a mean 35.3 months 11 re-dislocations occurred (14.6%). Acetabular revisions were protective against re-dislocation (p<0.015). The number of previous operations (p=0.0379) and previously failed constrained liners (p<0.02) were risk factors for failure. The highest risk of failure was in patients with abductor insufficiency with revisions for other etiologies having a success rate of 90%.

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

Wound closure is typically not the surgeon's favorite part of the case. It is critical, however, for preventing infection, avoiding early re-operation and is the portion of the procedure that is most directly visible to the patient. The purpose of this study was to investigate the use of bidirectional, barbed suture for wound closure in primary total hip (THA) and knee arthroplasty (TKA) to determine whether its use is safe, cosmetic and associated with time savings when compared with traditional suture.

We carried out a blinded, randomised controlled trial comparing bidirectional, barbed suture (Quill™ SRS; Angiotech Pharmaceuticals) and a traditional absorbable layered closure following primary THA and TKA. We randomised 20 THAs (10 Quill; 10 traditional) and 31 TKAs (16 Quill; 15 traditional). Power analysis determined that a minimum of 23 patients per arm of the study were required to show a significant difference in closure times using an alpha of 0.05 and a beta of 0.80.

Wound closure in the Quill group was significantly faster than traditional suture by a mean of 4.1 minutes (9.2 vs. 13.2 minutes; p = 0.0005). Traditional closure required a mean 5.6 sutures, compared to a mean 2.7 sutures (p < 0.0001). The unit cost of the barbed suture was 5–12 times that of conventional suture. One patient who had undergone Quill closure developed a superficial reaction that was managed non-operatively.

Our results have been confirmed by a similar recently published randomised study by Gilland et al, who showed a mean reduction in closure time of 4.7 minutes. However, these authors concluded that overall costs were lower with a barbed suture based on a reduction in operative times. This method of closure has also been shown to provide a stronger and more water-tight closure than traditional interrupted sutures.

Minimizing the risk of periprosthetic joint infection (PJI) is of interest to all surgeons performing hip and knee arthroplasty. Among the most critical factors to reducing the risk of infection include the use of pre-incisional antibiotics, appropriate skin preparation with clippers (as opposed to a razor for hair removal) and the use of an alcohol-based skin preparation. Host factors are also likewise critically important including obesity, diabetes, inflammatory arthritis, renal insufficiency, skin disorders and patients who are otherwise immune-compromised. If modifiable risk factors are identified, it would seem reasonable to delay elective surgery until these can be optimised.

One other factor to consider is the nutritional status of the patient. In a study of 501 consecutive revisions, we found that serological markers suggestive of malnutrition (albumin, transferrin or total lymphocyte count) were extremely common in the revision population. Specifically, among patients who presented for treatment of a chronic infection, 53% (67 of 126) had at least one marker for malnutrition. The prevalence of serological markers of malnutrition was lower (33%) in the group of patients undergoing revision for an aseptic reason suggesting that malnutrition was a risk factor for septic failure (p < 0.001 and OR 2.1). Interestingly, malnutrition was most common among patients of normal weight but was also common among obese patients (so-called “paradoxical” malnutrition). What was more disturbing, however, that of those patients undergoing an aseptic revision, serum markers of malnutrition were associated with a 6× risk of acute post-operative infection complicating the patient's aseptic revision.

At our center, we also have studied the use of dilute betadine at the end of the case, prior to wound closure, in an attempt to decrease the load of bacteria in the wound. In a retrospective review the prevalence of acute post-operative infection was reduced from just under 1% (18/1862) to 0.15% (1 of 688; p = 0.04). It is critical that the betadine utilised be STERILE and the dilution we use is 0.35% made by diluting 17.5 cc of 10% povidone-iodine paint in 500 cc of normal saline. Although this is a retrospective review, it does suggest a benefit and we have not seen any problems associated with its use.

This session will present a series of challenging and complex primary and revision cases to a panel of knee arthroplasty experts. A variety of cases representing the spectrum of not uncommonly presenting pathologies will be discussed in terms of appropriate work-up, clinical management, surgical approach, and aftercare. This will be an interactive case-based session that at its conclusion should leave the attendee with a more thorough approach to these challenging issues.

Constrained liners are a tantalizing solution to both prevent and treat instability, as they markedly increase the force needed for a dislocation to occur. They have, however, several important negatives that the surgeon must consider before entertaining their use including: Increased stresses at the implant bone interface which can increase the risk of loosening or cause catastrophic failure in the early post-operative period; Decreased range of motion with a greater risk of impingement; and Usually require an open reduction if they dislocate or otherwise fail.

Given the limitations of constrained liners, we have looked to dual mobility articulations as an alternative to constrained liners in the past five years in our practice, including patients with abductor deficiency.

We retrospectively compared a consecutive series of revision THA that were at high risk for instability and treated with either a constrained liner or a dual mobility articulation. Indications for both groups included abductor insufficiency, revision for instability, or inadequate intra-operative stability when trialing. Forty-three hips were reviewed in the constrained group (mean follow-up 3.4 years) and thirty-six in the dual-mobility group (mean follow-up 2.4 years). The rate of failure was compared using a Fisher's exact test with a p-value of < 0.05 considered significant.

At a minimum of two years, there were 10 dislocations in the constrained group (10/43 or 23.3%) compared to 3 in the dual-mobility group (3/36 or 8.3%; p = 0.06). There were 15 repeat revisions in the constrained group (10 for instability, 4 for infection, and 1 broken locking mechanism) compared to 4 in the dual mobility group (2 mechanical failures of cemented dual mobility liners with dislocation and 2 for infection); 34.9% vs. 11.1% (p = 0.01). With repeat revision for instability as an endpoint, the failure rate was 23% for the constrained group and 5.5% for the dual mobility group (p = 0.03). Mean Harris Hip Score (HHS) improved from 45 to 76 points in the constrained liner group, and from 46 to 89 points in the dual-mobility group.

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

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.

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.

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.

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 skin 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 capsulectomy is performed followed by 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 post-operative physical therapy and heals reliably.

The 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 lengthen it. It 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 5–8 cm in length, tapering from approximately 1cm thick proximally to 5mm distally.