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

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

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

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

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

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

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

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

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment/loosening which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability.

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

For instability, most revisions will require a posterior cruciate substituting design or a constrained condylar design that is unlinked. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Articular cartilage on metal has not been shown to be a good long term bearing surface. Cushner et al has also shown that cartilage in the arthritic knee has significant pathologic abnormalities.

Patella surfacing has excellent long-term results with a low complication rate. Anterior knee pain is a common complaint after knee replacement and is even more common in TKA with unresurfaced patella. Pakos et al had more reoperations and greater anterior knee pain when the patella was NOT resurfaced. Parvizi et al also found less patient satisfaction with unresurfaced patellas.

Meta-analysis results indicate higher revision rates with unresurfaced patellas. Bilateral knee studies also favor resurfaced patella. Higher revision rates were also confirmed in the Swedish Registry with a 140% higher revision rate in TKA with unresurfaced patellas.

In addition second operations to resurface the patella often are unsuccessful at alleviating pain.

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

Introduction

Positioning of a femoral sizing guide has been cited as being a critical intraoperative step during measured-resection based TKA as it determines femoral component rotation. Consequently, modern femoral sizing guides permit surgeons to ‘dial in’ external rotation when placing the guide. Although this feature facilitates guide placement, its effect on posterior femoral condylar resection and flexion gap stability is unknown. This study examines the effect of rotation on posterior femoral condylar resection among different posterior-referencing TKA designs.

Introduction

Superficial wound complications can occur in up to 10% of total knee arthroplasty (TKA) patients and have been associated with deep infection. The ideal material for TKA closure should fulfill the following requirements: 1) fast intraoperative application, 2) minimal wound complications and discomfort, and 3) can be removed by patients without a home care visit. We present our experience with a novel, non-invasive, removable skin closure system compared to conventional staple closure.

Total knee arthroplasty has been shown to provide relief of pain and improved function; however studies have shown that younger active patients still note limitations in performing higher level activities such as dancing, golfing, skiing and gardening. Journey II BCS is designed to have physiological matching which more accurately reproduces the normal knee anatomy and kinematics. By providing more anatomic restoration of the articular geometry and substituting for both cruciate ligaments, Physiological Matching TKA has been shown, with in-vivo kinematic studies, to better reproduce the normal bending, rollback and rotational motions of knees.

Patient matched instruments are patient specific custom designed cutting blocks. These instruments utilise pre-operative MRI and full leg x-rays to design guides that will position the knee in the desired mechanical alignment. The purpose of these instruments is to increase efficiency and accuracy, and possibly reduce cost.

Efficiency occurs through the elimination of multiple steps compared to the standard operative technique. A single patient matched femoral guide is easily placed and can align the valgus angle with the mechanical axis, and determine the level of resection, rotation, size, and AP position of the implant. A single tibial instrument can determine tibial alignment, depth of resection, slope and rotation. Efficiency also results by eliminating the need for many standard instruments and trays. Implant size is determination pre-operatively so fewer implant trials are necessary.

In summary, this Physiological Matching TKA surgery combines Journey II BCS with patient specific instruments to optimise kinematics, fit and efficiency in order to improve outcomes and patient satisfaction.

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

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

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

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

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

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 radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate retaining knees, anteroposterior instability must be assessed.

For instability, must revisions will require a posterior cruciate substituting design or a constrained condylar design that are unlinked. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time.

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 are 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. If there is 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. However, revision of fully cemented revision implants may be quite difficult later.

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.

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

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

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

Total Knee Arthroplasty has proven to be a successful procedure for improving pain and function. Long-term studies have shown survivorship to be 90% or greater at 20 years. Most patients in those studies were over 60 years old. There has been a large increase in patients under 60 years old who are undergoing knee arthroplasty. Younger patients have much greater demands on the artificial articular surfaces. The average 55 year old is likely to perform two to three time as many gait cycles as the average 65 or 70 year old. Long-term studies demonstrate that polyethylene wear is a major cause of long-term failure.

Newer bearing materials such as cross-linked polyethylenes show promise in reducing wear in THA and more recently in TKA. Femoral component material can significantly influence wear. Studies reveal that in vivo femoral component scratching significantly increases polyethylene wear.

Oxidised Zirconium (OxZr) has been shown to significantly reduce polyethylene wear in knee simulators. The ceramic surface has greater lubricity and is harder. We have examined the in vivo performance on Oxidised Zirconium in several studies. These studies reveal that the harder Oxidised Zirconium femoral surface is much more resistant to scratching than CrCo femurs. Retrieval analysis revealed a 12 fold increase in scratching of CrCo femoral components compared to OxZr. Profilometry analysis of matched pairs of femoral components demonstrates that the surfaces of the CrCo implants significantly roughen over time while the OxZr do not significantly change in vivo. These comparative studies also showed less damage to the tibial polyethylene bearings with the OxZr femoral components compared to CrCo.

Extending longevity of TKA requires improved materials to reduced wear. To optimise this, bearing surfaces must be coupled with improvements in both tibial polyethylene and femoral component materials.