Poor availability of allografts in South Africa has led to an increased use of synthetic augmentation to stabilize knee joints in the treatment of knee dislocations. This study aims to evaluate multiligament knee injuries treated with a posterior cruciate ligament internal brace. The study included patients with knee dislocations who were treated with a PCL internal brace. The internal brace involved the insertion of a synthetic suture tape, which was drilled into the femoral and tibial footprint. Chronic injuries were excluded. Patient-reported outcome scores (PROMs), range of motion, stress X-Rays, and MRI scans were reviewed to assess outcomes. Acceptable outcomes were defined as a Lysholm score of 84 or more, with grade II laxity in no more than one ligament and a range of motion from full extension to 90° or more. The study included eight patients, with a median age of 42, of which five were female. None of the patients had knee flexion less than 90° or an extension deficit of more than 20°. PROMs indicated acceptable outcomes (EQ5D, Tegner Lysholm). Stress radiographs showed less than 7mm (Grade I) of posterior translation laxity in all patients. Four patients underwent MRI scans 1–2 years after the initial surgery, which revealed healing of the PCL in all patients. However, increased signal in a continuous ligament suggested only partial healing in two patients. Tunnel widening of 200% and 250% was noted around the tibial and femoral PCL footprints, respectively. All patients demonstrated stable knees and acceptable PROMs. Tunnel widening was observed in all patients who had MRI scans. Factors such as suspensory fixation, anisometric tunnel position, and the absence of PCL tear repair may have contributed to the tunnel widening

Background:. For the past four decades controversy surrounds the decision to retain or sacrifice the posterior cruciate ligament during a total knee arthroplasty. To our knowledge no study has been done to describe the effect of releasing the PCL on the range of motion of the knee. Study design:. Case series. Methods:. Computer navigation data (Brainlab) was obtained intra-operatively from thirty patients at total knee arthroplasty. Coronal alignment, maximal passive knee extension and maximal passive flexion was captured before and after release of the PCL. Results:. Releasing the posterior cruciate ligament led to an increase in maximal extension in all patients (av 3,6°) and a decrease in coronal deformity in 63%. The surprising finding was an increase in maximal knee flexion (av 5°, range 0 to 10°.) The increase in maximal flexion was statistically significant. Conclusion:. Sacrificing the posterior cruciate ligament alters the kinematics of the knee and the resultant increase in knee flexion might explain why cruciate sacrificing total knee arthroplasty has superior flexion compared to cruciate retaining designs

To investigate the effectiveness of avulsion fracture of tibial insertion of posterior cruciate ligament using the safe postero-medial approach through analyzing the clinical and radiographic outcomes. We treated 14 cases of acute PCL tibial avulsion fracture with “safe postero-medial approach”. The PCL and avulsion bony fragment was fixed with 1 cannuated screw and washer. The patients were assessed clinically and radiographically at 3 months, 6 months, and 12 months. Clinical examination for each visit included assessment of the knee range of motion, using goniometer and the posterior drawer test. The patients were evaluated according to the Lysholm and Tegner rating scales. Patients were followed-up for 12 to 16 months. X-ray showed that satisfactory reducdtion and bony healing was achieved in all cases. There was no neurovascular complication. All patients had negative posterior drawer tests. Excellent outcomes were reported by all patients with the Lysholm score system. And there was no signicant difference between the Tegner scores before injury and last follow-up. Surgical treatment of acute tibial avulsion fracture of the PCL with this approach can restore the stability and fuction of the joint safely in most patients without neurovascular complication. Therefore “safe postero-medial approach” may be suitable for the treatment of isolated tibial avulsion fracture of the PCL

Computational modeling has been used to simulate the natural and prosthetic kinematic and kinetic function in an attempt to compare designs and/or predict a desired motion path from a design. The levels of soft tissue can range from basic ligaments (MCL, LCL, and ACL & PCL) to more complex models. The goal of this study was to evaluate the sensitivity of the Posterior Cruciate ligament in a virtual model and its effects on the kinematic outcome in a commercially available and validated kinematics package (KneeSim, LifeModeler San Clemente, CA). Methods:. KneeSIM is a musculoskeletal modeling environment that is built on the foundation of the ADAMS (MSC Software, Santa Ana CA), a rigid body dynamics solver to compute knee kinematics and forces during a deep knee bend. All parameters are customizable and can be altered by the user. Generic three dimensional models of cruciate retaining components of the femoral, tibial, and patellar are available with the software and were used to provide a common reference for the study. The following parameters were modified for each simulation to evaluate the sensitivity of the PCL in the model: 1) Model without PCL, 2) PCL with default properties, 3) PCL Shifted at femoral origin, 7 mm anterior, 7 mm inferior; tibial origin maintained; 4) PCL with increased stiffness properties (2x default), 5) position in the femur and tibia remained default position and 6) PCL with default properties and location, joint line shifted 4 mm superior. The standard output of tracking the flexion facet center (FFC) motion of the medial and lateral condyles was utilized (Figure 1). Results:. Figure 2 and 3 displays the output of the six conditions tested above. Comparing the curves for the medial and lateral motion show different patterns with the lateral point having more posterior translation than the medial. After approximately 95° of flexion, all cases exhibit an anterior translation in the model. This motion was consistent for all test cases. The model showed no difference with motion either with or without the PCL and with changing the stiffness. Altering the location of the PCL on the femoral insertion had the greatest effect on motion, while shifting the joint line superior was second. The shift of the ligament insertion and changing of the joint line results in the ligament being more parallel to the tibial surface which provides resistance to anterior motion or posterior translation. Discussion:. Although the model was able to discern differences, the inability to highlight variation in motion with and without the PCL suggests that the default parameters are not representative of an experimental or clinical setup. Although it is apparent that KneeSim can be used for comparative assessments between designs, simulations should be designed so as to provide similar boundary conditions. Publications (Colwell et al 2011) did successfully use KneeSim to provide a comparative assessment of CR components; however, only after the default model was altered to match the outcome of the experimental rig. Further analysis of the complexities in soft tissue modeling is warranted

Objective. The aim of this study was to assess the results of combined arthroscopically assisted posterior cruciate ligament reconstruction and open reconstruction of the posterolateral corner in patients with chronic (3 months or more) symptomatic instability and pain. Patients & methods. A retrospective analysis of all the patients who had a combined reconstruction of the posterior cruciate ligament and the posterolateral corner between 1996 and 2003 was carried out. Nineteen patients who had the combined reconstruction were identified from the database. All the patients were assessed pre- and post-operatively by physical examination and three different ligament rating scores. All the patients also had weight bearing radiographs, MRI scans and an examination under anaesthesia and arthroscopy pre-operatively. The PCL reconstruction was performed using an arthroscopically assisted single anterolateral bundle technique and the posterolateral corner structures were reconstructed using an open Larson type of tenodesis. Results. Pre-operatively all the patients had a grade III posterior sag and demonstrated more than 20 degrees of external rotation as compared to the opposite normal knee on the Dial test. The average follow-up was 66.8 months (range 24 -108). Post-operatively 7 patients had no residual posterior sag, 11 patients had a grade I posterior sag and 1 patient had a grade II posterior sag. Five of the 19 patients demonstrated minimal residual posterolateral laxity. The Lysholm score improved from a mean of 41.2 to 76.5 (P=0.0001) and the Tegner score from a mean of 2.6 to 6.4 (p=0.0001). Conclusions. We conclude that while a combined reconstruction of chronic posterior cruciate ligament and posterolateral corner instability does not restore complete anatomical stability, improvement in symptoms and function demonstrate its value in these difficult injuries

Introduction. Compared with the cruciate-retaining (CR) insert for total knee arthroplasty (TKA), the cruciate-substituting (CS) insert has a raised anterior lip, providing greater anterior constraint, and thus, can be used in cases of posterior cruciate ligament (PCL) sacrifice. However, studies have shown that the PCL maintains femoral rollback during flexion, acts as a stabilizer against distal traction force and aids knee joint proprioception; therefore, the argument for PCL excision in CS TKA remains controversial. The purpose of this study was to analyze CS TKA kinematics and identify the role of the PCL. Methods. Seven fresh-frozen lower-extremity cadaver specimens were analyzed using Orthomap. ®. Precision Knee Navigation software (Stryker Orthopaedics, Mahwah, NJ, USA). They were surgically implanted with Triathlon. ®. components (Stryker Orthopaedics). The CS insert has a raised anterior lip, and the posterior geometry shares the same profile as the CR, so we can choose retaining or sacrificing the PCL. Six patterns were analyzed: (1) natural knee; (2) only anterior cruciate ligament excision; (3) CS TKA, PCL retention, and bony island preservation; (4) CS TKA, PCL retention, and bony island resection; (5) CS TKA and PCL excision; and (6) CR TKA and PCL excision. Center of the knee and center of the proximal tibia were registered using navigation system, and the magnitudes of the condylar translation were evaluated. And then, using trigonometric function, the magnitude of anterior-posterior translation of the femur was calculated. Results. PCL excision patterns showed that the magnitude of anterior-posterior (AP) translation was higher in mid-flexion and lower in deep flexion than in other patterns (Fig. 1). Comparing two PCL excision patterns, in CS insert, the anterior translation magnitude was a little lower in extension and 30° flexion. Comparing two PCL retention patterns, the both posterior translation magnitudes in deep flexion were comparable to that of the natural knee. Discussion. Very few studies have reported about comparison of PCL retention with PCL excision in CS TKA. Omori et al. evaluated the medial pivot type TKA, and found that the design showed no femoral rollback under the PCL-sacrificing condition. In our study, increased anterior translation magnitudes in mid-flexion indicated paradoxical roll-forward, and decreased posterior translation magnitudes in deep flexion indicated decreased rollback. In other words, PCL excision in CS TKA caused mid-flexion instability and decreased the femoral rollback, so raised anterior lip was not likely to contribute to TKA kinematics. Another research is necessary to evaluate the effects of the raised anterior lip. On the other hand, PCL retention in CS TKA maintained physiological femoral rollback. The AP translation magnitude was not dependents on the bony island. Conclusions. We had better retain the PCL in raised anterior lip type CS TKA to ensure physiological knee kinematics. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

INTRODUCTION:. In varus knee, posterior cruciate ligament (PCL) release has been reported to result in the increase of the flexion gap without significant effect on the extension gap. However, the effect of release on gap angle is still obscure. On the other hand, gap angle and distance measured with the tension devices may vary due to different distraction forces. In this study, difference of gap angle and distance before and after PCL resection in knee extension and 90° flexion was inspected. Effect of different distraction force on gap was also assessed. OBJECTIVES:. Fifty cases with medial osteoarthritis undergoing PS-TKA were included in the study. PCL of all the cases were identified intact before resection. METHODS:. After distal femoral and proximal tibial cuts were initially performed and anterior cruciate ligament (ACL) was excised, joint gap angle and distance in full extension and at 90° flexion were obtained by means of a tensioning device, Balancer under 10, 20 and 30 inch-pounds distraction. The gap angle and distance were measured 3 times at each step. Then PCL was excised and the same measurement was performed. RESULTS:. The gap distances significantly enlarged following the increased distraction forces in both knee extension and 90° flexion, before and after the PCL resection (p < 0.0001). The distances were the same before and after the PCL resection in extension under each force. However, after the PCL was resected, the joint distance at 90° flexion significantly enlarged at 10, 20 and 30 inch-pounds for 1.2, 1.6 and 1.8 mm, respectively (p < 0.001). All measured joint gap angles showed varus results. The gap angles significantly increased following the increased distraction forces in both knee extension and 90° flexion, before and after the PCL resection (p < 0.0001). The mean gap angles in extension were 1.9°, 2.9° and 3.6° for 10, 20 and 30 inch-pounds, respectively. The angles significantly decreased after PCL resection in extension at different forces for 0.6°, 0.4° and 0.3°, respectively (p < 0.05). In 90° flexion, the mean angles were 2.9°, 5.5° and 7.3°, respectively, and were decreased after the resection for 0.3° (p = 0.9), 0.6° (p = 0.01) and 1.1° (p = 0.00024). CONCLUSION:. In this study, all the distances and angles had a correlation with the distraction powers of the tensioner. For the joint gap distance, the distance in extension was not influenced by the release of the PCL, but was enlarged at 90° flexion after the release. We found that the varus gap angles were decreased at both extension and flexion. Thirty inch-pounds seem to have more effect on the gap angle than 20 inch-pounds at 90° flexion after the release. It indicated that the evaluation of the joint gap might not be accurate if the distraction power of the tension device is not appropriate. Our study indicated that in varus deformity osteoarthritic knees, PCL resection may have influence on the correction of deformity. The means of modified gap control method and measured bone resection method, and the character of joint gap in CR, CS or PS TKA should be considered independently

Introduction. In posterior cruciate ligament (PCL)-preserving total knee arthroplasty (TKA), it is important to determine whether the PCL is properly functioning after surgery. As the PCL is partly damaged during the operation, we cannot rule out the possibility that excessive tension further damages the remaining PCL resulting in dysfunction or that initial functioning of the PCL is lost due to excessively low tension. However, it is normally difficult to examine whether the PCL has remained intact and is still functional after TKA. The objective of this study was to visualize knee joint flexion after TKA by MRI and evaluate the PCL based on these images. Method. PCL-preserving TKA was performed in 41 knees using the Fine Total Knee System® (Nakashima Medical, Okayama, Japan) where a titanium component can be selected for both the femur and the tibia. We visualized knee flexion positions by MRI at 6 months after surgery and evaluated visualization or non-visualization of the PCL, the relationship between knee flexion angle and PCL elevation angle against the plane of the tibial joint vertical to the tibial axis, and the forms of PCL based on the MRI data. Results. The PCL was visualized in 40 of the 41 knees. These 40 knees showed a strong positive correlation (correlation coefficient 0.85) between the knee flexion angle (mean 95.8 degrees, 59 to 129 degrees) and the PCL elevation angle (mean 60.4 degrees, 38 to 79 degrees) by MRI. As the PCL was visualized as a straight line in 6 of 13 knees at a knee joint flexion angle of less than 90 degrees, sufficient tension was considered to be transmitted; however, 7 knees showed superior protrusion or S-shaped forms, indicating that the tension in the PCL was not strong. No superior protrusion of the PCL was observed in 27 knees at the flexion angle of 90 degrees or more; 19 knees showed straight-line forms and 7 knees showed inferior protrusion due to posterior pressure from the femur, and the flexion angle was 105 degrees or greater in all knees with inferior protrusion. At the knee flexion angle of 90 degrees or greater, the tension in the PCL was confirmed in 26 knees (96%) by MRI. Conclusion. To date, there have been no morphological evaluations of postoperative PCL in PCL-preserving TKA. While tension in the PCL was determined to be insufficient in some knees at the knee flexion angle of less than 90 degrees, the elevation angle of the PCL against the tibia increased with tension as the knee flexion angle increased. Postoperative MRI indicated that the PCL functions as a stabilizer between the femur and the tibia in knees that have undergone PCL-preserving TKA, especially at the knee flexion angle of 90 degrees or greater

Injuries to the posterior cruciate ligament (PCL) and the posterolateral corner (PLC) of the knee remain a challenging orthopaedic problem. Studies evaluating PCL and PLC reconstruction have failed to demonstrate a strong correlation between the degree of knee laxity as measured by uniplanar testing and subjective outcome or patient satisfaction. The effect that changing the magnitude of posterior tibial slope has on multiplanar, rotational stability of the PCL-deficient knee has yet to be determined. We aimed to evaluate the effect that changes in posterior tibial slope would have on static and dynamic stability of the PCL-PLC deficient knee. Ten knees were used for this study. Navigated posterior drawer and standardised reverse mechanised pivot shift maneuvers were performed in the intact knee and after sectioning the PCL, the lateral collateral ligament (LCL), the popliteofibular ligament (PFL) and the popliteus muscle tendon (POP). Navigated high tibial osteotomy (HTO) was performed to obtain the desired change in tibial plateau slope (+5® or −5® from native slope). We then repeated the posterior drawer and the reverse mechanised pivot shift test for each of the two altered slope conditions. Mean posterior tibial translation during the posterior drawer in the intact knee was 1.4 mm (SD = 0.48 mm). In the PCL-PLC deficient knee, posterior tibial translation increased to 18 mm (SD = 5.7 mm) (P < 0.001). Increasing the amount of posterior tibial slope by 5® reduced posterior tibial translation to 12 mm (SD = 4.7 mm) (P < 0.01). Decreasing the amount of posterior slope by 5® compared to the native knee, increased posterior tibial translation to 21 mm (SD = 6.8 mm) (P < 0.01). There was a significant negative correlation between the magnitude of tibial plateau slope and the magnitude of the reverse pivot shift (R2 = 0.71; P < 0.0001). Mean posterior tibial translation during the reverse mechanised pivot shift test in the intact knee was 7.8 mm (SD = 2.8 mm). In the PCL-PLC deficient knee, posterior tibial translation increased to 26 mm (SD = 5.6 mm) (P < 0.001). Increasing the amount of posterior tibial slope by 5® reduced posterior tibial translation to 21 mm (SD = 6.7 mm) (P < 0.01). Decreasing the amount of posterior slope by 5® compared to the native knee, increased posterior tibial translation to 34 mm (SD = 8.2 mm) (P < 0.01). There was a significant negative correlation between the magnitude of tibial plateau slope and the magnitude of the reverse pivot shift (R2 = 0.72; P < 0.0001). Decreasing the magnitude of posterior slope of the tibial plateau resulted in an increase in the magnitude of posterior tibial translation during the posterior drawer and the reverse mechanised pivot shift test in the PCL-PLC deficient knee. Conversely, increasing the slope of the tibial plateau reduced the amount of posterior tibial translation during the posterior drawer and the reverse mechanised pivot shift test. However, the effect of the increase in slope was not sufficient to reduce posterior tibial translation to levels similar to those of the intact knee

Purpose. To report clinical results and demonstrate any posterior femoral translation (PFT) in medial rotation total knee arthroplasty (TKA) of posterior cruciate ligament (PCL) retaining type. Materials and Methods. A prospective study was performed upon thirty consecutive subjects who were operated on with medial rotation TKA of PCL retaining type (Advance® Medial Pivot prosthesis with ‘Double High’ insert; Wright Medical Technology, Arlington, TN, USA) (Fig. 1). between March 2009 and March 2010 and had been followed up for a least 2 years. Inclusion criteria were age between 60 and 75 years and primary degenerative joint disease of knee graded as Kellgren Lawrence grade III or higher. Exclusion criteria were age under 60 years, any inflammatory joint disease including rheumatoid arthritis, early stage of primary degenerative joint disease of knee or any history of previous osteotomy around knee. Clinically, the knee society knee score and function score were used to evaluate pain and function. At last follow-up, all subjects performed full extension, thirty degree flexion and full active flexion sequentially under fluoroscopic surveillance. In each of these lateral radiographs, anteroposterior(AP) condylar position was pinpointed and the magnitude of PFT was determined by degree of transition of AP condylar position from full extension to full active flexion radiograph (Fig. 2 A–B). Statistical methods used were paired t-test, Pearson correlation, Steadman rank correlation and regression analysis. Component migration and radiolucent line were also observed. Results. At last follow-up, the mean knee society knee score and the mean function score improved significantly compared to preoperative scores (from 61.5 to 90.4 and from 57.8 to 84.7 respectively). The mean maximum flexion of knee increased postoperatively compared to preoperative one without any significant difference (105.5Ëš±11.2Ëšvs 109.3Ëš±9.8Ëš, p=0.051, β=0.387). Neverthless, regression analysis showed a good linear association (r = 0.53, p=0.0027) between the pre- and post-operative maximum flexions of knee. The AP condylar positions were consistently posterior to midline throughout the entire range of flexion. The mean maximum PFT was 10.5 mm (± 4.3 mm) and the magnitude of maximum PFT was greater in higher flexion cases (r = 0.57, p = 0.0009) (Fig. 3). There were no cases having either component migration or radiolucent line except for one case showing instability related to trauma. Conclusions. In medial rotation total knee arthroplasty of PCL retaining type, clinical outcomes were satisfactory and the maximum obtainable flexions tended to be in narrower ranges than those of preoperative ones and smaller than those of other TKA prostheses. Nonetheless, reliable posterior femoral translations were observed during progressive flexions of knees, which was considered to be one of important kinematic factors in increasing the level of knee flexion of medial-rotation TKA in longer follow-ups by providing greater posterior clearance and reduced femoro-tibial impingement

Most studies comparing medial pivot to the posterior stabilised (PS) systems sacrifice the PCL. It is unknown whether retaining the PCL in the Medial Congruent (MC) system may provide further benefit compared to the more commonly used PS system.

A retrospective review of a single-surgeon's registry data comparing 44 PS and 25 MC with PCL retained (MC-PCLR) TKAs was performed.

Both groups had similar baseline demographics in terms of age, gender, body mass index, and American Society for Anaesthesiology score. There was no significant difference in their preoperative range of motion (ROM) (104º±20º vs. 102º±20º,p=0.80), Oxford Knee Score (OKS) (27±6 vs. 26±7,p=0.72), and Knee Society Scoring System (KS) Function Score (KS-FS) (52±24 vs. 56±24,p=0.62). The preoperative KS Knee Score (KS-KS) was significantly lower in the PS group (44±14 vs. 54 ± 18,p<0.05). At 3-months postoperation, the PS group had significantly better OKS (38±6 vs. 36±6,p=0.02) but similar ROM (111º±14º vs. 108º±12º,p=0.25), KS-FS (73±20 vs. 68±23, p=0.32) and KS-KS (87±10 vs. 86±9,p=0.26). At 12-months postoperation, both groups had similar ROM (115º±13º vs. 115º±11º,p=0.99), OKS (41±5 vs. 40±5,p=0.45), KS-FS (74±22vs.78±17,p=0.80), and KS-KS (89±10vs.89±11,p=0.75). There was statistically significant improvement in all parameters at 1-year postoperation (p<0.05). The PS group had significant improvement in all parameters from preoperation to 3-month postoperation (p<0.05), but not from 3-month to 1-year postoperation (p≥0.05). The MC-PCLR group continued to have significant improvement from 3-month to 1-year postoperation (p<0.05).

The MC provides stability in the medial compartment while allowing a degree of freedom in the lateral compartment. Preserving the PCL when using MC may paradoxically cause an undesired additional restrain that slows the recovery process of the patients after TKA.

In conclusion, compared to MC-PCLR, a PS TKA may expect significantly faster improvement at 3 months post operation, although they will achieve similar outcomes at 1-year post operation.

INTRODUCTION

Contemporary PCL sacrificing Total Knee Arthroplasty (TKA) implants (CS) consist of symmetric medial and lateral tibial articular surfaces with high anterior lips designed to substitute for the stability of the native PCL. However, designs vary significantly across implant systems in the level of anteroposterior constraint provided. Therefore, the goal of this study was to investigate kinematics of two CS designs with substantially different constraint levels. The hypothesis was that dynamic knee simulations could show the effect of implant constraint on kinematics of CS implants.

Introduction

Recently, tibial insert design of cruciate-substituting (CS) polyethylene insert is employed. However, in vivo kinematics of using CS polyethylene insert is still unclear. In this study, it is hypothesized that CS polyethylene insert leads to stability of femolo-tibial joint as well as posterior-stabilized (PS) polyethylene insert, even if PCL is sacrificed after TKA. The purpose of this study is an investigation of in vivo kinematics of femolo-tibial joint with use of CS polyethylene insert before and after PCL resction using computer assisted navigation system intra-operatively in TKA.

The posterior drawer is a commonly used test to diagnose an isolated PCL injury and combined PCL and PLC injury. Our aim was to analyse the effect of tibial internal and external rotation during the posterior drawer in isolated PCL and combined PCL and PLC deficient cadaver knee.

Ten fresh frozen and overnight-thawed cadaver knees with an average age of 76 years and without any signs of previous knee injury were used. A custom made wooden rig with electromagnetic tracking system was used to measure the knee kinematics. Each knee was tested with posterior and anterior drawer forces of 80N and posterior drawer with simultaneous external or internal rotational torque of 5Nm. Each knee was tested in intact condition, after PCL resection and after PLC (lateral collateral ligament and popliteus tendon) resection. Intact condition of each knees served as its own control. One-tailed paired student's t test with Bonferroni correction was used.

The posterior tibial displacement in a PCL deficient knee when a simultaneous external rotation torque was applied during posterior drawer at 90° flexion was not significantly different from the posterior tibial displacement with 80N posterior drawer in intact knee (p=0.22). In a PCL deficient knee posterior tibial displacement with simultaneous internal rotation torque and posterior drawer at 90° flexion was not significantly different from tibial displacement with isolated posterior drawer. In PCL and PLC deficient knee at extension with simultaneous internal rotational torque and posterior drawer force the posterior tibial displacement was not significantly different from an isolated PCL deficient condition (p=0.54).

We conclude that posterior drawer in an isolated PCL deficient knee could result in negative test if tibia is held in external rotation. During a recurvatum test for PCL and PLC deficient knee, tibial internal rotation in extension results in reduced posterior laxity.

Instability currently represents the most frequent cause for revision total knee replacement. Instability can be primary from the standpoint of inadequately performed collateral and/or posterior cruciate ligament balancing during primary total knee replacement or it may be secondary to malalignment secondary to loosening and settling of the implants which can develop later progressive instability. Revision surgery must take into consideration any component malalignment that may have primarily contributed to instability. Also, collateral ligament integrity may change following total knee replacement slightly after complete correction of a severe deformity that presents rarely as instability after several months. Care should be given to assessing collateral ligament integrity. This can be done during physical examination by manual or radiological stress testing to see if the mediolateral stress of the knee comes to a good endpoint. If there is no sense of a palpable endpoint, then the surgeon must assume structural incompetency of the medial or lateral collateral ligament or both. In posterior cruciate ligament retaining knees, anteroposterior instability must be assessed. For instability, most revisions will require a posterior cruciate substituting design or a constrained unlinked condylar design. Occasionally, a posterior cruciate ligament preserving design can be used in situations where the bone-stock is well preserved and the posterior cruciate ligament shows excellent structural integrity. However, if the patient displays considerable global instability, a linked, rotating platform constrained total knee replacement design will be required. Recent data has shown that the rotating hinges work quite well in restoring stability to the knee with maintenance of the clinical results over a considerable length of time. Revision can range from simple polyethylene insert exchange to a thicker dimension, isolated component revision or complete revision of both femoral and tibial devices. During revision surgery, laminar spreaders may be utilised to assess the flexion and extension spaces after the tibial platform is restored. If a symmetric flexion and extension space is achieved, then the collateral ligaments are intact. Depending on the remaining existing bone stock, a posterior stabilised or constrained condylar unlinked prosthesis may be used for implantation. In cases with considerable asymmetry or a large flexion/extension mismatch, a rotating hinge design should be utilised. Intramedullary stems should be utilised in most cases when bone integrity is suspect and insufficient. Currently, stems should be placed cementless to permit easier future revision. Cementing the stems is only recommended if there is lack of intramedullary isthmic support or there is a hip prosthetic stem that prohibits a stem from engaging the isthmic cortex. However, it should be realised that later revision of the fully cemented revision implant may be quite difficult. Infection should be ruled out by aspiration off of antibiotics prior to any revision operation, especially if loosening of the components represents the cause of instability early. The surgeon should attempt to restore collateral ligament balance whenever possible as this yields the best clinical result

Knee arthroscopy is typically approached from the anterior, posteromedial and posterolateral portals. Access to the posterior compartments through these portals can cause iatrogenic cartilage damage and create difficulties in viewing the structures of the posterior compartments. The purpose of this study was to assess the feasibility of needle arthroscopy using direct posterior portals as both working and visualising portals. For workability, the needle scope was inserted advanced from anterior between the cruciate ligament bundle and the lateral wall of the medial femoral condyle until the posterior compartments were visualised. For visualisation, direct postero-lateral and -medial portals were established. The technique was performed in 9 knees by two experienced researchers. Workability and instrumentation of the posteromedial compartment and meniscus was achieved in 56%. The posterior horns could not be visualised in four specimens as the straight lens could not provide a more medial field of view. Visualisation from the direct medial posterior portal allowed a clear view of the medial meniscus, femoral condyle and posterior cruciate ligament in all specimens. Workability and instrumentation of the posterolateral compartment was not possible with the needle scope. Direct posterior approaches for the posteromedial compartment access are challenging with the current needle scope options and could only be achieved in over 50%. The postero-lateral compartment was not accessible. An angled lens or a flexible Needle scope would be better suited for developing this technique further

Introduction. The range of motion (ROM) obtained after total knee arthroplasty (TKA) is an important measurement to evaluate the postoperative outcomes impacting other measures such as postoperative function and satisfaction. Flexion contracture is a recognized complication of TKA, which reduces ROM or stability and is a source of morbidity for patients. Objectives. The purpose of this study was to evaluate the influence of intra-operative soft tissue release on correction of flexion contracture in navigated TKA. Methods. This is prospective cohort study, 43 cases of primary navigation assisted TKA were included. The mean age was 68.3 ± 6.8 years. All patients were diagnosed with grade 4 degenerative arthritis in K-L grading system. The average preoperative mechanical axis deviation was 10.3° ± 5.3 and preoperative flexion contracture was 12.8° ± 4.8. All arthroplasties were performed using a medial parapatellar approach with patellar subluxation. First, medial release was performed, and posterior cruciate ligament was sacrificed. After all bone cutting was performed and femoral and tibial trials were inserted, removal of posterior femoral spur and capsular release were performed. The degree of correction of flexion contracture was evaluated and recorded with navigation. Results. After the medial soft tissue release, as a first step, the flexion contracture was recorded as 7.2° ± 4.3 and 4.1° ± 4.0 as varus. The second step, posterior cruciate ligament was sacrificed, the flexion contracture was recorded as 7.2° ± 4.4 and 5.5° ± 3.0 as varus. After posterior clearing procedure and capsular release, the flexion contracture was showed as 3.9° ± 1.2 and 1.4° ± 1.2 as varus. The final angles after cemented real implant were recorded as 3.3° ± 1.4 in flexion contracture, 0.9° ± 1.8 in varus. There were significant differences all steps except between medial release step and posterior cruciate sacrifice step and between posterior clearing step and final angle. Conclusions. The appropriate soft tissue balancing could correct flexion contracture intra-operatively. The medial release could correct the flexion contracture around 5° compared with preoperative flexion contracture, and posterior clearing procedure could improve further extension. However, the sacrifice of posterior cruciate ligament provided little effect on correction of the flexion contracture intra-operatively

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

Purpose. We aimed to investigate whether the anterior superior iliac spine could provide consistent rotational landmark of the tibial component during mobile-bearing medial unicompartmental knee arthroplasty (UKA) using computed tomography (CT). Methods. During sagittal tibial resection, we utilized the ASIS as a rotational landmark. In 47 knees that underwent postoperative CT scans after medial UKA, the tibial component position was assessed by drawing a line tangential to the lateral wall of the tibial component. Rotation of the tibial component was measured using two reference lines: a line perpendicular to the posterior cortical rim of the tibia (angle α) and Akagi's line (angle β). Instant bearing position and posterior cruciate ligament fossa involvement were also evaluated. External rotation of the tibial component relative to each reference line and external rotation of the bearing relative to the lateral wall of the tibial component were considered positive values. Results. The mean angle α and β were 8.0 ± 6.1° (range, −4.0 – 24.3) and 8.7 ± 4.8° (range, 1.9 – 25.2), respectively. The mean instant bearing position was 4.3 ± 28.6° (range, −52.9 – 179.7). One bearing showed complete 180° rotation at 2 weeks postoperatively. Fourteen knees (29.8%) showed posterior cruciate ligament fossa involvement of the tibial resection margin. Conclusions. Due to the wide variation in, and inherent difficulty in identification of, the ASIS during the operation, it is not recommended for guidance of sagittal tibial resection during mobile-bearing medial UKA. Level of Evidence: Level IV

Pre-operative planning in revision total knee replacement is important to simplify the surgery for the implant representative, operating room personnel and the surgeon. Revision knee arthroplasty is performed for many different reasons and of variable complexity. Many implant options can be considered including cemented and cementless primary and stemmed revision tibial and femoral components, with posterior cruciate retention or resection, and either with no constraint, varus/valgus constraint, or with rotating hinge bearings. One may also need femoral and tibial spacers, metaphyseal augments, or bulk allograft. It is important to pre-operatively determine which of these implants you may need. If you schedule a revision total knee and ask the implant representative to “bring everything you've got, just in case,” they will have to bring a truck full of instruments and implants. The first step of pre-operative planning is to determine how much implant constraint will be needed. Survivorship of revision total knees with modern varus/valgus constrained or rotating hinge implants are not that unacceptable. Ideally to enhance longevity, the least constraint needed should be used. This requires determination of the status of the ligaments. Varus and valgus stress is applied to the knee in near full extension, mid-flexion, and ninety degrees of flexion. If instability of the knee is noted, then radiographs are reviewed to determine if component malposition or malalignment is the reason for the collateral ligament laxity. If radiographs don't show a reason, then have additional constraint available in case the knee can't be balanced with proper component position and ligament balancing. In cases other than simple revisions, the posterior cruciate ligament is usually inadequate or needs to be resected to balance the knee. Substitution for the posterior cruciate ligament is usually needed for most revisions. The second step of pre-operative planning is to review radiographs to determine the amount and location of any bone loss. Osteolysis induced bone loss is usually worse than seen on plain radiographs. If unsure, a CT scan can be of help. The presence of significant bone loss contraindicates the use of primary components and mandates the need for stemmed implants. Larger defects may warrant having metallic augments or bulk graft present. Most revision knee implants can be conservatively metaphyseal cemented with diaphyseal engaging press-fit stems. The third step of pre-operative planning is to be familiar with what implants are present. Occasionally, one may not need to revise components that are stable and well aligned. Having compatible components available may simplify the surgery. Excellent pre-operative planning will minimise the need to bring in an excessive number of instruments and implants. It will help assure that the patient has a stable revision knee and simplify the surgery for all participants