To compare posterior cruciate ligament substituting (PCS) total knee arthroplasty (TKA) and posterior cruciate ligament retaining (PCR) total knee arthroplasty (TKA) to determine if greater overall flexion is obtained with the PCS TKA versus the PCR TKA at two year postoperative follow up. Secondarily, to determine whether there is a difference in the recovery of range of motion over time between the two groups from initial presentation, to discharge, and to follow up visits at three months, one year, and two years. Prospective, randomised double-blind clinical trial consisting of one hundred male and female patients scheduled for primary TKA. Sample size allows detection of a difference of six degrees of knee range of motion using two-tailed tests, =0.05, and 0.20 (80% power). SCORPIO PCL substituting total knee system and the SCORPIO PCL retaining total knee system were implanted for evaluation in this study. Patients were assessed at initial presentation, at postoperative discharge from hospital, and at follow up visits at three months, one year and two years for flexion knee range of motion. Additional data were collected utilizing the WOMAC Osteoarthritis Index, the Knee Society Clinical Rating Scale, the SF-36, and the Knee Society Radiographic Evaluation as well as data on length of stay and surgical time. Subjects were similar in demographic characteristics and all measurements at the baseline initial assessment. No differences were seen in knee flexion at two year follow up as measured using an independent t-test (p> 0.05). Recovery of knee range of motion over time was not different as measured using a two way repeated measures ANOVA (p=0.88 for group effect). Postoperative flexion and recovery of kneww range of motion was not altered following TKA by using PCS or PCR prostheses

Purpose: At a time when total knee arthroplasty (TKA) with an ultra-congruent tibial plateau or a mobile plateau are advocated by many, the question is whether TKA with a fixed plateau preserving the posterior cruciate ligament (PCL) should be abandoned. We analysed the results of 500 Wallaby I TKA with preservation of the PCL and presenting asymmetrical and divergent femoral condyles with a fixed, also assymetrical tibial plateau, at mean follow-up of seven years (1–10). Material and methods: This prospective multicentric study was performed by junior and senior surgeons. Mean patient age was 70.11 years and 91.4% of the patients had primary or secondary degenerative disease. Prior surgery had been performed in 130 knees, mainly for osteotomy (n=40, mostly tibial) and revision of uni-compartmental or total prostheses (n=18). The mean preoperative IKS knee score was 26.11 points, the function score was 29.54. Preoperative alignment was correct for 11.26% of the knees, 27.16% presented > 4° valgus and 61.56% > 3° varus. Nearly all tibial and patellar pieces were cemented. 5.8% of the femoral pieces were not cemented. A prosthesis was implanted on the patella in all knees except four. There were two early infections, one popliteal sciatic paralysis and twelve wound healing problems. General mobilisation under general anaesthesia was performed in 53 knees (10.6%). Results: Twenty-two patients were not retained for analysis, fifteen lost to follow-up and seven deceased at one year. Among the 478 knees followed for one to ten years, there were six late infections (1.25%), one aseptic bipolar loosening (0.2%), 25 patellar fractures (5.23%) including three which required revision (two cerclage, one prosthesis removal), three periprosthetic femur fractures without effect on the clinical or radiographic outcome, one traumatic tear of the medial collateral ligament, and two secondary tears of the PCL without clinical consequences. There were no revisions for instability, generally considered the most frequent reason for TKA revision. The mean postoperative IKS score was 90.6 points and the function score was 59.7 points basically due to patient age and comorbidity. The eight-year survival (Kaplan-Meier method) was 98.2% (95%CI: 99.4–96.9) irrespective of the reason for revision and 99.2% (95%CI 100–98.4%) if the revision was performed for a mechanical problem. Radiographically, more than 70% of the knees were aligned (between 3° valgus and 2° varus) and more than 90% were between 5° valgus and 5° varus. Although it was difficult to measure radiographically polyethylene wear, there was only one case of > 2 mm wear with osteolysis found in 50 knees selected randomly among the knees with more than seven years follow-up. Conclusion: This study, like others reported by authors preserving the PCL, show that preservation of the PCL limits the risk of instability, allowing excellent clinical and radiographic outcome without important polyethylene wear, opening perspectives for good long-term results

Aims. The aim of this study was to assess the effect of posterior cruciate ligament (PCL) resection on flexion-extension gaps, mediolateral soft-tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilized (PS) total knee arthroplasty (TKA). Patients and Methods. This prospective study included 110 patients with symptomatic osteoarthritis of the knee undergoing primary robot-assisted PS TKA. All operations were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps before and after PCL resection in extension and 90° knee flexion. Measurements were made after excision of the anterior cruciate ligament and prior to bone resection. There were 54 men (49.1%) and 56 women (50.9%) with a mean age of 68 years (. sd. 6.2) at the time of surgery. The mean preoperative hip-knee-ankle deformity was 4.1° varus (. sd. 3.4). Results. PCL resection increased the mean flexion gap significantly more than the extension gap in the medial (2.4 mm (. sd. 1.5) vs 1.3 mm (. sd. 1.0); p < 0.001) and lateral (3.3 mm (. sd. 1.6) vs 1.2 mm (. sd. 0.9); p < 0.01) compartments. The mean gap differences after PCL resection created significant mediolateral laxity in flexion (gap difference: 1.1 mm (. sd. 2.5); p < 0.001) but not in extension (gap difference: 0.1 mm (. sd. 2.1); p = 0.51). PCL resection significantly improved the mean FFD (6.3° (. sd. 4.4) preoperatively vs 3.1° (. sd. 1.5) postoperatively; p < 0.001). There was a strong positive correlation between the preoperative FFD and change in FFD following PCL resection (Pearson’s correlation coefficient = 0.81; p < 0.001). PCL resection did not significantly affect limb alignment (mean change in alignment: 0.2° valgus (. sd. 1.2); p = 0.60). Conclusion. PCL resection creates flexion-extension mismatch by increasing the flexion gap more than the extension gap. The increase in the lateral flexion gap is greater than the increase in the medial flexion gap, which creates mediolateral laxity in flexion. Improvements in FFD following PCL resection are dependent on the degree of deformity before PCL resection. Cite this article: Bone Joint J 2019;101-B:1230–1237

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

We have examined the relationship between the size of the flexion gap and the anterior translation of the tibia in flexion during implantation of a posterior cruciate ligament (PCL)-retaining BalanSys total knee replacement (TKR). In 91 knees, the flexion gap and anterior tibial translation were measured intra-operatively using a custom-made, flexible tensor-spacer device. The results showed that for each increase of 1 mm in the flexion gap in the tensed knee a mean anterior tibial translation of 1.25 mm (SD 0.79, 95% confidence interval 1.13 to 1.37) was produced. When implanting a PCL-retaining TKR the surgeon should be aware that the tibiofemoral contact point is related to the choice of thickness of the polyethylene insert. An additional thickness of polyethylene insert of 2 mm results in an approximate increase in tibial anterior translation of 2.5 mm while the flexed knee is distracted with a force of between 100 N and 200 N

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

The significance of the posterior cruciate ligament in the stability of the knee was investigated in dogs and it was compared with that of the anterior cruciate ligament by studying the changes produced in the knee after transection of either ligament. Osteophyte formation and changes in articular cartilage were less prominent after division of the posterior cruciate ligament. A complete longitudinal tear of the medial meniscus was found in eight out of the 10 dogs who had undergone section of the anterior cruciate but in none of the 10 with section of the posterior cruciate. It appears that, in dogs at least, the posterior cruciate ligament is less important than the anterior in the stability of the knee

Aims. Total knee arthroplasty (TKA) with a highly congruent condylar-stabilized (CS) articulation may be advantageous due to increased stability versus cruciate-retaining (CR) designs, while mitigating the limitations of a posterior-stabilized construct. The aim was to assess ten-year implant survival and functional outcomes of a cemented single-radius TKA with a CS insert, performed without posterior cruciate ligament sacrifice. Methods. This retrospective cohort study included consecutive patients undergoing TKA at a specialist centre in the UK between November 2010 and December 2012. Data were collected using a bespoke electronic database and cross-referenced with national arthroplasty audit data, with variables including: preoperative characteristics, intraoperative factors, complications, and mortality status. Patient-reported outcome measures (PROMs) were collected by a specialist research team at ten years post-surgery. There were 536 TKAs, of which 308/536 (57.5%) were in female patients. The mean age was 69.0 years (95% CI 45.0 to 88.0), the mean BMI was 32.2 kg/m. 2. (95% CI 18.9 to 50.2), and 387/536 (72.2%) survived to ten years. There were four revisions (0.7%): two deep infections (requiring debridement and implant retention), one aseptic loosening, and one haemosiderosis. Results. Kaplan-Meier analysis demonstrated no difference in implant survival according to sex, age, or obesity status. Ten-year PROMs were available for 196/387 (50.6%) surviving patients and were excellent: mean Oxford Knee Score 34.4 (95% CI 32.7 to 36.1); mean Forgotten Joint Score (FJS) 51.2 (95% CI 16.1 to 86.3); mean EuroQol five-dimension five-level questionnaire score 69.9 (95% CI 46.8 to 93.0); 141/196 (71.9%) achieved the 22-point FJS patient-acceptable symptom state (PASS); and 156/196 (79.6%) were “very satisfied or satisfied”. Conclusion. This is the only large study reporting ten-year implant survival and functional outcomes of TKA using a cemented single-radius design and with a CS tibial bearing construct. The findings of excellent implant survival, safety, and functional outcomes indicate that this combination is a safe and effective option in routine TKA. Further investigation of this single-radius design TKA with CS tibial bearings with well-matched patient study groups will allow further insight into the performance of these implants. Cite this article: Bone Joint J 2024;106-B(8):808–816

We investigated the role of a functional brace worn for four months in the treatment of patients with an acute isolated tear of the posterior cruciate ligament to determine whether reduction of the posterior tibial translation during the healing period would give an improved final position of the tibia. The initial and follow-up stability was tested by Rolimeter arthrometry and radiography. The clinical outcome was evaluated using the Lysholm score, the Tegner score and the International Knee Documentation Committee scoring system at follow-up at one and two years. In all, 21 patients were studied, 21 of whom had completed one-year and 17 a two-year follow-up. The initial mean posterior sag (Rolimeter measurement) of 7.1 mm (5 to 10) was significantly reduced after 12 months to a mean of 2.3 mm (0 to 6, p < 0.001) and to a mean of 3.2 mm (2 to 7, p = 0.001) after 24 months. Radiological measurement gave similar results. The mean pre-injury Lysholm score was normal at 98 (95 to 100). At follow-up, a slight decrease in the mean values was observed to 94.0 (79 to 100, p = 0.001) at one year and 94.0 (88 to 100, p = 0.027, at two years). We concluded that the posterior cruciate ligament has an intrinsic healing capacity and, if the posteriorly translated tibia is reduced to a physiological position, it can heal with less attentuation. The applied treatment produces a good to excellent functional result

We report the results of a prospective randomised trial which assessed the role of the posterior cruciate ligament (PCL) following total knee replacement (Genesis I; Smith and Nephew, Memphis, Tennessee). Over a four-year period, 211 patients underwent total knee replacement by the senior author (TJW). They were randomised at surgery to have the PCL either retained, excised or substituted with a posterior stabilised insert. If it was not possible to retain the ligament due to soft-tissue imbalance, it was released from its tibial insertion until suitable tension was obtained. This created a fourth group, those who were intended preoperatively to have the ligament retained, but in whom it was partially released as a result of findings at the time of surgery. All patients were evaluated using the Knee Society rating system (adapted from Insall). A total of 188 patients (212 knees) was available for follow-up at a mean of 3.5 years after surgery. Preoperatively, there was a varus deformity in 191 knees (90%) and a valgus deformity in 21 (10%). There were no statistical differences in the knee or function scores or the range of movement between the excised, retained and substituted groups. There were, however, significantly worse knee and function scores in the group in whom the PCL was released (p = 0.002)

1. Seventeen cases of knee injury are described in which the predominant lesion was rupture of the posterior cruciate ligament. Seven were treated conservatively and ten by surgical repair. 2. Most cases occurred in motor cyclists. 3. The extent of the rupture should be determined by examination under anaesthesia. 4. Early surgical repair is indicated for complete rupture. 5. An effective method of repair is described

The issue of preservation or sacrifice of the posterior cruciate ligament in total knee arthroplasty remains unresolved. We report the results of 200 consecutive total knee arthroplasties performed at our hospital under the direction of the senior author. Pre-operatively, patients were randomly chosen to receive either a Kinemax (posterior cruciate retaining) or a Press-Fit-Condylar (posterior cruciate sacrificing) prosthesis. We implanted 97 Kinemax and 103 Press-Fit-Condylar prostheses which were prospectively followed-up by clinical and radiographic assessment. Review at mean follow-up of 2.7 years showed a satisfactory clinical result in both groups [Surace, et al., 1994]. We present the results of our further review, with maximum follow-up of over nine years (mean: 5.9 years). Revision of the implant has been performed in five knees (three Kinemax and two Press-Fit-Condylar). The polythene spacer had to be replaced in one patient with a Press-Fit-Condylar implant. Patients were assessed with the Hospital for Special Surgery Knee Score and radiologically assessed with the Knee Society Roentgenographic Evaluation and Scoring System. Pre-operative demographics and disease states of the patients were similar, with an average Hospital for Special Surgery Knee Score of 63. At the latest assessment the average knee score was good (85). Remarkably, the mean knee score for the posterior cruciate sacrifice and the PCL groups remains similar (mean: 85). Radiographic evaluation demonstrated that the prosthetic components of both groups were in comparable alignment. The posterior cruciate ligament retained (Kinemax) patient group showed a mean 5.9 degrees of the valgus angle at the knee. The angle in the posterior cruciate ligament sacrifice (PFC implant) group was 6.2 degrees. Evaluation of the radiolucent depths below the femoral, tibial and any patella component showed a mean total depth of 1.5 mm (pcl retaining) and 1.7 mm (pcl sacrificing). Our study presents a quantitative perspective of the results of total knee replacement with proven implant systems and performed in a general orthopaedic unit by both consultants and surgeons in training. The Kinemax (Howmedica) and Press-Fit-Condylar (DePuy Johnson and Johnson) implant systems have both previously demonstrated good results and continue to be available with little subsequent modification. To our knowledge, there have been no other large prospectively randomised studies of posterior cruciate ligament preservation or sacrifice in total knee replacement

High-flexion knee replacements have been developed to accommodate a large range of motion (ROM > 120°) after total knee arthroplasty (TKA). Femoral rollback or posterior translation of the femoral condyles during knee flexion is essential to maximise ROM and to avoid bone-implant impingement during deep knee flexion. The posterior cruciate ligament (PCL) has been described as the main contributor to femoral rollback. In posterior-stabilised TKA designs the PCL is substituted by a post-cam mechanism. The main objective of this study was to analyse the mechanical interaction between the PCL and a highflexion cruciate-retaining knee replacement during deep knee flexion. For this purpose, the mechanical performance of the high-flexion cruciate-retaining TKA design was evaluated and compared with two control designs including a highflexion posterior-stabilised design. Materials & Methods: Prosthetic knee kinematics and kinetics were computed using a three-dimensional dynamic finite element (FE) model of the knee joint. The FE knee model consisted of a distal femur, a proximal tibia and fibula, a quadriceps and patella tendon, a non-resurfaced patella, TKA components and a posterior cruciate ligament in case cruciate-retaining designs were evaluated. Tibio-femoral and patello-femoral contact were defined in the FE knee model and the polyethylene insert was modelled as a non-linear elastic-plastic material. Three different rotating platform TKA systems were analysed in this study: the high-flexion cruciate-retaining PFC Sigma CR150, the high-flexion posterior-stabilised PFC Sigma RP-F and the conventional cruciate-retaining PFC Sigma RP (Depuy, J& J, UK). Both the polyethylene stress characteristics and the tibio-femoral contact locations were evaluated during a squatting movement (ROM = 50° – 150°). Results: During deep knee flexion (ROM > 120°), the high-flexion cruciate-retaining TKA design showed a lower peak contact stress (74.7 MPa) than the conventional cruciate-retaining design (96.5 MPa). The posterior-stabilized high-flexion TKA design demonstrated the lowest peak contact stress at the condylar contact interface (54.2 MPa), although the post was loaded higher (77.4 MPa). All three TKA designs produced femoral rollback in the normal flexion range (ROM ≤ 120°), whereas the cruciate-retaining designs showed a paradoxical anterior movement of the femoral condyles during high-flexion. Discussion: PCL retention is a challenging surgical aim and affects the prosthetic knee load and kinematics as shown in this study. In addition, for adequate functioning the PCL should not be too tight or too lax after surgery. Hence, we investigated the effect of PCL laxity on the prosthetic performance and the best-balanced PCL was used in our simulations. Although PCL balancing is not an issue for posterior-stabilized TKA, we found the tibial post to be loaded relatively high for this implant type

Introduction: Much debate exists regarding sparing or sacrificing the posterior cruciate ligament (PCL). The posterior cruciate ligament is said to maintain proprioception and stabilization post knee arthroplasty. Substitution of the PCL can require more femoral bone resection, but is thought to improve range of motion. Release of the PCL can restore extension and enhance flexion through greater femoral rollback. Bicruciate implants potentially offer greater flexion and enhanced stability. Each implant design with mechanical instruments requires a different surgical technique making it difficult to directly compare the patient and surgical outcomes. Computer navigation eliminates the differences in implantation between the various implant designs and theoretically allows a more direct comparison of implants based on design characteristics and not surgical technique. The purpose of this paper is to review four different implant designs implanted by a single surgeon with a computer assisted, gap balancing technique to determine if there was any difference in patient outcome. Methods: A total of 504 implants consisting of posterior cruciate sparing (PFC-RP), PCL substituting (PFC-RPC), PCL sacrificing (LCS) and bicruciate (Journey) implants performed by a single surgeon were reviewed. The PFC-RP group (260) was the largest, followed by the LCS (124), the PFC-RPF (80) and the Journey Knee (40). Outcomes reviewed were range of motion, function, pain and radiographic data to include alignment and evidence of radiolucency. Results: Demographic data of groups compared included 175 men and 329 women. Mean ages ranged from 61 to 74 years. Preoperative scores among all groups were similar with the cruciate substituting group slightly lower in function, flexion and with more pain before surgery. Overall function improved across all groups through two years, with better scores in the Journey and LCS implants (77 and 73 points) versus RPF (47) and PFC retaining group at (68) at one year (A perfect score is 100). Flexion values were comparable between all groups at one and two year intervals with Journey the highest mean flexion (116 degrees) at one year and with the PFC-RP offering the highest mean flexion at the two year mark (115 degrees). The RPF group at the one year mark had more pain overall (28) versus the other three groups (Journey 45, LCS 42, Sigma RP 45). No patients in any group were revised for instability. Other surgical complications were equal in each group. Discussion: While the PCL substituting knee patients (PFC-RPF) had lower pain, function and flexion at 12 months compared to all other groups, they started with lower overall knee scores. After accounting for the differences in patients preoperatively, no difference could be found between implant designs when implanted with a similar surgical technique employing a computer assisted gap balancing protocol

The role of posterior cruciate ligament (PCL) in total knee replacement (TKR) has been a matter of debate for long time and remains controversial. In this study, the effect of posterior cruciate ligament (PCL) sacrifice on the tibiofemoral joint gap was analysed in 30 varus osteoarthritic knees undergoing posterior stabilized total knee replacement. Medial soft tissue was released and bone cut was made without preserving the bone segment of tibial PCL insertion. Then the medial and lateral joint gaps in full extension and 90□& lsaquo; flexion were measured before and after PCL sacrifice using a tensioning device (V-STAT tensor(tm), Zimmer). After PCL sacrifice, the flexion gap significantly increased both in medial and lateral side (4.8 □} 0.4 and 4.5 □} 0.4 mm respectively, mean □} SE) compared to those seen in the extension gap (0.9 □} 0.2 and 0.8 □} 0.2 mm, p < 0.001 ANOVA). There was no significant difference between the changes in the medial and lateral gap (p = 0.493). In conclusion, results of this intraoperative measurement showed that PCL sacrifice leads to a selective increase in the size of flexion gap by an average of 4.7 mm whereas it had little impact on the correction of varus deformity. These findings provided insights as for the role and necessity of PCL sacrifice in the correction of varus and flexion deformity. Because the flexion gap surpassed the unchanged extension gap during PCL sacrifice, PCL release could be used as a surgical technique to balance the gaps without additional bone cut

We report a retrospective analysis of the results of combined arthroscopically-assisted posterior cruciate ligament reconstruction and open reconstruction of the posterolateral corner in 19 patients with chronic (three or more months) symptomatic instability and pain in the knee. All the operations were performed between 1996 and 2003 and all the patients were assessed pre- and post-operatively by physical examination and by applying three different ligament rating scores. All also had weight-bearing radiographs, MR scans and an examination under anaesthesia and arthroscopy pre-operatively. The posterior cruciate ligament 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. The mean follow up was 66.8 months (24 to 110). Pre-operatively, all the patients had a grade III posterior sag according to Clancy and demonstrated more than 20° of external rotation compared with the opposite normal knee on the Dial test. Post-operatively, seven patients (37%) had no residual posterior sag, 11 (58%) had a grade I posterior sag and one (5%) had a grade II posterior sag. In five patients (26%) there was persistent minimal posterolateral laxity. The Lysholm score improved from a mean of 41.2 (28 to 53) to 76.5 (57 to 100) (p = 0.0001) and the Tegner score from a mean of 2.6 (1 to 4) to 6.4 (4 to 9) (p = 0.0001). We conclude that while a combined reconstruction of chronic posterior cruciate ligament and posterolateral corner instability improves the function of the knee, it does not restore complete stability

The posterior cruciate ligament (PCL) was imaged by MRI throughout flexion in neutral tibial rotation in six cadaver knees, which were also dissected, and in 20 unloaded and 13 loaded living (squatting) knees. The appearance of the ligament was the same in all three groups. In extension the ligament is curved concave-forwards. It is straight, fully out-to-length and approaching vertical from 60° to 120°, and curves convex-forwards over the roof of the intercondylar notch in full flexion. Throughout flexion the length of the ligament does not change, but the separations of its attachments do. We conclude that the PCL is not loaded in the unloaded cadaver knee and therefore, since its appearance in all three groups is the same, that it is also unloaded in the living knee during flexion. The posterior fibres may be an exception in hyperextension, probably being loaded either because of posterior femoral lift-off or because of the forward curvature of the PCL. These conclusions relate only to everyday life: none may be drawn with regard to more strenuous activities such as sport or in trauma

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

We analysed the long-term results with a mean follow-up of 10.2 years, of 66 total knee replacements in 42 patients with rheumatoid arthritis. In all cases the posterior cruciate ligament was retained. There were only three complications (4.5%). Revision surgery was necessary in five knees (7.6%), including one (1.5%) with infection. At the final follow-up, 75.8% of knees were rated excellent clinically. Only 15% had an excellent function score. The survival rate of the implant was 90.7% at 19 years. The clinical, radiological and survivorship analysis shows that the posterior-cruciate-retaining knee arthroplasty performs well in rheumatoid arthritis

We compared function in two groups of high demand patients who had undergone total knee arthroplasty (TKA), one group using a posterior cruciate sacrificing (PCS) prosthesis and the other a posterior cruciate retaining (PCR) prosthesis of similar design. Patients were eligible for the study if surgery had been performed more than two years ago and they were under 65 years of age and had no coexisting morbidity that markedly decreased their physical activities. One surgeon operated on 28 patients in group A (20 TKAs), routinely retaining the posterior cruciate ligament (PCL). A second surgery operated on 19 patients in group B (25 TKAs) and routinely sacrificed the PCL. A mobile bearing prosthesis of similar design was used in each group. Patients were independently selected and assessed using a questionnaire specifically developed to assess higher levels of activity not usually assessed by other knee scores. Patients in the two groups were matched in terms of age, range of motion and follow-up. The gross activity score was 3.36 in group A and 3.12 in group B. The combined walking, running and stair-climbing score was in group A (7.68) than in group B (6.64). Patients in group B had decreased anterior knee pain and perceived their TKA closer to a normal knee (2.00 compared to 2.32). We conclude that retaining the PCL in TKA results in better patient function without obvious complications

We have assessed the clinical and radiological outcome of traumatic knee injuries resulting in open reconstruction of the posterior cruciate ligament using synthetic ligaments at the University of Toronto, Ontario. Pre and post-operative stress radiographs at 30 and 90 degrees were performed, along with IKDC, Lysholm and Tegner scoring. Between 1995 and 2002, 11 patients were operated on. The average time to surgery was 42.3 months (range 1 to 252 months). The average age at time of surgery was 34.1 (26 – 48). The length of follow up ranged from 6 to 87 months. IKDC scoring showed that no patient returned to normal. 5 were nearly normal, 4 abnormal and 2 severely abnormal. The average Lysholm score was 83 (58 – 95). 2 scored excellent, 6 good, 2 fair and 1 poor. The average Tegner score pre-injury was 6.3, prior to surgery 1.8 and post-operatively 3.9 (twice weekly jogging). Stress radiographs showed a decrease in antero-posterior laxity at 30 and 90 degrees although statistical significance was not achieved (p = 0.229 and 0.474 respectively). We conclude that PCL reconstruction restores the normal biomechanics of the knee allowing a more normal function. The synthetic ligament allowed early weight bearing and range of movement mobilisation. The Tegner scores showed a considerable improvement from pre to post-operative values. The stress radiographs showed a decrease in the antero-posterior laxity. Although the IKDC scores did not show any normal knees post-operatively, this was expected due to the severity of the initial injuries. The authors recommend the use of synthetic ligaments to reconstruct the PCL

We assessed arthroscopically 22 young athletes with an isolated acute posterior cruciate ligament (PCL) injury. Four had significant damage to the articular cartilage of the medial femorotibial compartment and were advised not to resume sports. Three underwent PCL reconstruction because of a reparable meniscal tear or instability. The other 15 were treated conservatively and resumed sport. At an average follow-up of 51 months, one had developed arthritic symptoms due to newly-developed severe chondral damage to the medial femoral condyle, but none of the other 14 had developed arthritic symptoms and most remained athletically active. Severe chondral damage should be seen at an early arthroscopy. Knees with an isolated injury to the PCL with concomitant articular damage may be successfully managed by conservative treatment

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

Purpose. We conducted a prospective study to investigate the role of the LARS ligament system to reconstruct the posterior cruciate ligament and the postero-lateral corner of the knee. We present a prospective single surgeon case series to evaluate early clinical and functional outcomes of postero-lateral corner and posterior cruciate ligament reconstruction in the knee using the LARS (ligament Augmentation and Reconstruction System) artificial ligament. 23 patients with multi-ligament knee injuries or isolated PCL injuries were treated with a mean follow up of 8 months (range: 2-37 months). Outcomes were assessed using the modified International Knee Documentation Committee score, and a modified Tegner- Lysholm score. 2 patients had acute reconstructive surgery within 7 days of injury, 5 patients within 3 months (semi-acute) and 16 were chronic cases that were operated on after three months from the date of injury. The LARS ligament reconstruction achieved a significant improvement between preoperative and postoperative assessment in relation to knee stability, function and patient satisfaction. The sooner the patients were treated the greater the improvements in functional scores were noted. Most patients achieved a full functional range of movement within six months. We had 2 complications, one superficial wound infection and one stiff knee requiring a manipulation. To date we have had no LARS ligament failures. In the short term the LARS functions well, with high clinical patient satisfaction, no signs of progressive laxity, synovitis or failure. We found no significant difference in functional score post reconstruction between the isolated PCL reconstructions and the multi ligament reconstructions. Our results show no early signs of the problems associated with synthetic grafts used in the past. Such grafts appear to be an attractive alternative to the use of autografts and allografts

Purpose: To introduce modified tibial inlay technique for autogenous bone-patellar tendon-bone (BPTB) posterior cruciate ligament (PCL) reconstruction and evaluate the outcomes of PCL reconstruction by this method. Methods: Fifty patients who underwent autogenous BPTB PCL reconstruction using modified tibial inlay technique were evaluated at average 30.9 months (range 12–52). The outcomes were assessed by stress radiographs, maximal manual test with KT-2000 arthrometer, IKDC grading and OAK knee score. Results: Average side to side difference in push view with Telos stress device decreased from 11.7mm to 3.2mm. Difference in maximal manual test with KT-2000 arthrometer also decreased from 11.5mm to 3.1mm. Final IKDC grading was A in six patients, B in thirty four, C in nine and D in one. Average OAK score improved from 64.3 to 86.4. Conclusion: We consider that the modified tibial inlay technique is a method to reduce technical effort and contribute to satisfactory clinical results in autogenous BPTB PCL reconstruction

Aim: To analyse the posterior and external rotational laxities in single bundle PCL (sPCL) and double bundle PCL reconstruction (dPCL) in a PCL and PLC deficient knee.

Methods: Ten fresh frozen were used. A custom made wooden rig with electromagnetic tracking was used to measured knee kinematics. Each knee was tested with posterior and anterior drawer forces of 80N and an external rotation moment of 5Nm when intact, after PCL resection, after dividing the PLC and after performing dPCL and sPCL reconstructions with a bone patellar tendon bone allograft and tibial inlay technique.

Results: The one-tailed paired Student’s t test with Bon-ferroni correction was used. There was a significant difference between the ability of the dPCL and sPCL reconstruction to correct the posterior drawer in extension (p=0.002). There was no difference between the dPCL reconstruction and the intact condition of the knee near extension (p=0.142, Fig 1). There was no significant difference between the intact condition and both sPCL (p=0.26) and dPCL (p=0.20) reconstructions in flexion in restoring posterior laxity. Neither of the reconstructions could restore the rotational laxity (Fig 3).

Conclusion: In a combined PCL and PLC deficient knee the posterior laxity can be controlled by both the sPCL as well as the dPCL reconstructions except near extension where the dPCL reconstruction was better.

Introduction. t is accepted dogma in total knee arthroplasty (TKA) that resecting the posterior cruciate ligament (PCL) increases the flexion space by approximately 4mm, which significantly affects intra-operative decisions and surgical techniques. Unfortunately, this doctrine is based on historical cadaveric studies of limited size. This study purpose was to more accurately determine the effect of PCL resection on the tibiofemoral flexion gap dimension in vivo in a large sample. Methods. Tibiofemoral joint space measurements were made during 127 standardized TKAs by two arthroplasty surgeons. A medial parapatellar approach, computer navigation and provisional tibial and femoral bone cuts were performed in all cases with particular attention to preserving PCL integrity. Cases with an incompetent or damaged PCL were excluded. The tibiofemoral gap dimension was measured with a calibrated tension device at full extension, 45-degrees, and 90-degrees before and after complete PCL resection. Results. 52% of patients were female (66/127), with mean age and BMI of 69.4 years and 34.3 kg/m. 2. , respectively. After PCL resection, the mean joint space dimension increased 0.3mm (range, 0–3mm) at extension, 0.9mm (range, 0–4mm) at 45-degrees, and 1.7mm (range, 0–5mm) at 90-degrees (p<0.001). The 90-degree flexion space opened ≤1mm in 48% of patients and ≥3mm in only 10%. Dividing the flexion gap change by the femoral implant dimension to account and calibrate for patient size, the joint space at 90-degrees increased more in females (0.031 vs. 0.023, p=0.022). Conclusion. The tibiofemoral joint space increases progressively from extension, to mid-flexion through 90-degrees flexion after PCL resection, yet is substantially less than reported in historical studies. However, large variation in the degree of flexion space opening was observed with some patients failing to increase their flexion space whatsoever with PCL resection. This runs counter to conventional TKA understanding and should be considered in modern surgical techniques and education. For figures, tables, or references, please contact authors directly

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

Aim: To compare the function in two groups of high demand patients with a total knee arthroplasty (TKA) – one group using a posterior cruciate sacrificing (PCS) prosthesis and the other a posterior cruciate retaining (PCR) prosthesis of similar design. Method: Patients were eligible for the study if they were greater than two years from surgery, less than 65 years of age and without other co-existing morbidity to significantly decrease their physical activities. Group A underwent surgery by one surgeon who routinely retained the posterior cruciate ligament whereas Group B underwent surgery by one surgeon who routinely sacrificed the PCL. A mobile bearing TKA of similar design was used in each group. All patients were selected and assessed by an independent assessor using a questionnaire developed specifically to assess higher levels of activity not usually assessed by other knee scores. Results: Group A (28 TKA in 20 patients) were matched with Group B (25 TKA in 19 patients) for age, length of follow-up and range of motion. The gross activity score was 3.36 in Group A compared with 3.12 in Group B. The combined walking, running and stair climbing score was significantly better in Group A (7.68 compared to 6.64 in Group B). Group B perceived their TKA was closer to a normal knee (2.00 compared to 2.32) with decreased anterior knee pain. Conclusions: Retaining the PCL in TKA results in better function without significant complications

Introduction: The amount of loading on the cruciate ligaments depends on the tension of the external muscular structures. In vivo studies using EMG have observed a proprioreceptive eccentric co-contraction of the hamstrings during isokinetic knee extension motion. This antagonistic co-contraction increases the quadriceps force necessary to produce the same extension moment on the knee, whereas the loading on the anterior cruciate ligament was measured to be reduced, with the loading on the posterior cruciate ligament to be increased. The objective of this study was thus to investigate the effect of simulated proprioreceptive co-contraction of the hamstrings muscles on quadriceps force, as well as on the relative loading on the cruciate ligament structures during knee extension under dynamic conditions and physiologic loads. Methods: Five fresh frozen knee specimen were tested in isokinetic extension. Bow shaped loading transducers were fixed in the medial fibres of the anterior (ACL) and posterior cruciate ligament (PCL). The test cycle simulated an isokinetic extension cycle from 120 degrees of flexion to full extension, a hydraulic cylinder thereby applied sufficient force to the quadriceps tendon in a closed-loop control cycle to produce a constant extension moment of 31 Nm about the knee. A second hydraulic cylinder simulated a 200 N co-contraction force of the hamstrings tendons. The loading on the ACL and PCL was first measured in the absence of hamstrings force, and subsequently under constant co-contractive flexion force. Results: In the absence of hamstring tension, the maximum quadriceps force was 1190 N ( SD 204 N) at 105 degrees of knee flexion. The loading on the ACL was reduced at larger flexion angles, the loading pattern of the PCL showed an inverse relationship with less loading at full extension. The maximum loading in the ACL was 161 N (SD138 N) and maximum tension in the PCL was 38.2 N (SD 34.9). With hamstring co-contraction, maximum quadriceps force increased 19.9 % ( SD 21.0% p= 0.33), maximum tension in the ACL decreased 71.9% (SD 74.3%, p=0.03), and maximum tension in the PCL increased 73.0% (SD 40.9%, p=0.03). Discussion: This experimental setup enabled direct in vitro measurement of ACL and PCL loading during simulated isokinetic extension motions. The loading on the ACL was dependent on the knee flexion angle. We observed that co-contraction of the hamstrings reduces loading on the anterior cruciate ligament without a significant concomitant increasing the quadriceps muscle force. Our results support the hypothesis that antagonistic co-contraction of the hamstrings during extension of the knee provides an important protective function. In contrast, loading in the posterior cruciate ligament increased during hamstring activation at higher knee flexion angles

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 pos-terolateral corner instability does not restore complete anatomical stability, improvement in symptoms and function demonstrate its value in these difficult injuries

Objectives. Because posterior cruciate ligament (PCL) resection makes flexion gaps wider in total knee replacement (TKR), preserving or sacrificing a PCL affects the gap equivalence; however, there are no criteria for the PCL resection that consider gap situations of each knee. This study aims to investigate gap characteristics of knees and to consider the criteria for PCL resection. Methods. The extension and flexion gaps were measured, first with the PCL preserved and subsequently with the PCL removed (in cases in which posterior substitute components were selected). The PCL preservation or sacrifice was solely determined by the gap measurement results, without considering other functions of the PCL such as ‘roll back.’. Results. Wide variations were observed in the extension and flexion gaps. The flexion gaps were significantly larger than the extension gaps. Cases with 18 mm or more flexion gap and with larger flexion than extension gap were implanted with cruciate retaining component. A posterior substitute component was implanted with the other cases. Conclusions. In order to make adequate gaps, it is important to decide whether to preserve the PCL based on the intra-operative gap measurements made with the PCL intact. Cite this article: Bone Joint Res 2014;3:95–100

Purpose: The purpose of this work was to evaluate function of 256 total knee arthroplasties (TKA) (Wallaby) with preservation of the posterior cruciate ligament and to compare the femorotibial angle obtained postoperatively. Material and methods: This prospective study included 256 consecutive TKA (cemented Wallaby 1) in 249 patients (mean age 68 years) with osteoarthritis (n=249) or rheumatoid polyarthritis (n=7). Pre- and postoperative clinical findings (HKS score, flexion, extension, laxity, walking distance, use of crutches) and AP full leg views with 20° loaded lateral views pre- and postoperatively (mechanical femoral, mechanical tibial, and femorotibial angles, tibial slope, patellar height, anterior tibial translation) were recorded. Results: The 256 TKA were reviewed at a mean 3-year follow-up. Flexion amplitude was the evaluation criterion. Mean preoperative flexion was 109° (40–130°) with mean persistent flexion of 5° (0°–40°). Mean postoperative flexion was 98° (30–130°) with no persistent flexion. The mean preoperative femorotibial angle was 181.8° (160–201°) and was 180.4° (172–195°) postoperatively. The mean preperative mechanical femoral angle was 88° (82–96°) and 89.8° (80–96°) postoperatively. Mean mechanical tibial angle was 93° (85–104°) and 90.4° (84–86°) postoperatively. Discussion: For certain authors, the only parameter predictive of postoperative flexion after gliding TKA with preservation of the posterior cruciate ligament is preoperative flexion. The statistical analysis of our series showed that correction of the femorotibial malalignement in the frontal plane was not correlated with postoperative knee function and precisely with postoperative flexion. Postoperative flexion was correlated with preoperative flexion. Our results on postoperative flexion of TKA related to preoperative flexion are in agreement with earlier analyses reported in the literature that do not find any absolute correlation with a neutral femorotibial angle in the frontal plane. Conclusion: The quality of the functional outcome after total knee arthroplasty cannot be predicted solely on the correction of the initial deformity

Purpose: We report the results at more than five years of a consecutive series of total knee arthroplasties (TKAs) implanted without cement and with preservation of the posterior cruciate ligament (PCL). Material and methods: This series included 98 patients who underwent 109 primary TKAs between 1994 and 1998. Mean patient age was 67.7 years. The press-fit Interax prosthesis has a macroporous hydroxyapatite coating since 1996. The patella was resurfaced in 92% of the cases with a cemented polyethylene button. Ligament balance and joint space were controlled by progressive release of the ligaments with a tensor derby. Clinical assessment was based on the KSS. Radiological assessment included the femorotibial axis, the position of the implants, and the bone-implant interfaces. Results: Seven (6.4%) of the patients were lost to follow-up. Fifteen (13.4%) died or were demented and two (1.8%) developed late infection and were not included in the primary analysis. Thus, 85 patients (77.9%) were retained for analysis at a mean 5.2 years follow-up. The KSS improved from 33.4 preoperatively to 79.4 at last follow-up. The KSS function score improved from 55.1 to 82.4. Knee flexion was 124.5° preoperatively and 113.1° at last follow-up. Anteroposterior laxity greater than 5 mm was observed in 4.8% at last follow-up. Radiologically, the mechanical femorotibial axis changed from 184.4° to 180.6°. Alpha 95.6°, geta 89.1°, omega 4.77°, gamma 3.8°, sigma 89.4°. Patellar height was 0.84 preoperatively and 0.65 at last follow-up. Lucent lines were observed 3.5 times less frequently with hydroxyapatite coated implants. Patellar loosening and femorotibial loosening were observed in one patient each. Revision procedures were necessary for three prostheses for bipolar loosening, painful stiff knee, and anteroposterior instability. Non-infectious survival rate was 94.1% at 5.2 years. Discussion: These mid-term clinical results are comparable with those reported in the literature for cemented or non-cemented implants with or without preservation of the posterior cruciate ligament. Longer follow-up is however necessary to assess the anteroposterior stability. The radiographic measurements provide a good demonstration of the operative precision and proper ligament balance. Hydroxyapatite coating improves bony fixation of the implants and provides a fixation comparable with cemented implants. Conclusion: This series confirms the mid-term reliability of the non-cemented Interax THA with preservation of the posterior cruciate ligament

Purpose: The posterior cruciate ligament (PCL) has two strands, an anterolateral strand (AL) and a posteromedial strand (PM). Its femoral insertion fans out over 3 cm and cannot be replaced by a unique transplant during surgical reconstruction. The purpose of this study was to define the anatomic centre of the femoral insertion of each stand in order to identify precise and reproducible landmarks for the bone tunnels (one for each strand) used to fix the transplants during reconstruction of the PCL. Material and methods: A metallic landmark was placed on the centre of the femoral insertion of the two PCL strands in ten cadaver knees. The Metros software package was used to analyse the digitalised radiograms of each knee to determine the position of the strands on the medial condyle. Intra- and inter-observer variability was determined. Results: The AL strand was situated 31.6 + 2.45% (47.2 + 6.02% for the PM strand) from the anterior border of the notch or 41.18 + 2.73% (54.46 + 5.07% for the PM) from the anterior border of the medial condyle relative to the Blumensaat line and 16.12 + 4.45% (33.68 + 7.2 for the PM) from the apex of the notch. Discussion: Clinical and objective results of reconstruction depend on the ideal, basically femoral, position of the PCL insertions. Intraoperative identification of the ideal point for the femoral insertion can be improved with measurements made on cadaver knees. The values observed in the present study are reproducible. Presented in the form of percentages of length limiting the errors related to patient morphotype can be integrated into navigation systems

Purpose of the study: Total knee arthroplasty (TKA) is considered to be an effective treatment for degenerative knee joint disease when the functional impairment and the pain fail to respond to medical treatment. The success of TKA is determined by the degree of pain relief, functional recovery, and implant survival. For many years, those advocating or not preservation of the posterior cruciate ligament (PCL) have animated lively debates. Although a consensus has not been reached, posterior stabilised prostheses and prostheses with a mobile plateau are commonly implanted. The purpose of our study was to compare the outcomes obtained with fixed plateau TKA with preservation of the PCL with those obtained with other prostheses with or without sacrifice of the PCL with a fixed or mobile plateau. Material and methods: This was a prospective study in a single centre including a homogenous consecutive series of 12 TKA (cemented EUROP) with a fixed plateau and preservation of the PCL implanted from 1994 to 1996 in 117 patients aged 73 years on average. The International Knee Society scores were used for the clinical and radiographic assessment at ten years. Results: At ten years follow-up, 23 patients had died, 14 were lost to follow-up and 80 (82 knees) were evaluated clinically and 43 (45 knees) radiographically. The IKS knee score varied from 31 points (0–60) preoperatively to 88 points (30–98) postoperatively at last follow-up. The IKS function score was 40 points (0–90) preoperatively and 80 (25–100) at last follow-up. Lucent lines were noted for 59% of the condyles and 60% of the tibial plateaus. The lucencies were mainly located in the anterior and posterior zones of the femur (zones 1 and 4) and medially on the tibia (zones 1 and2). Two prostheses were revised at 8 and 11 years for loosening. The overall survival was 98.8% at ten years using the Kaplan-Meier method. Discussion: The clinical and radiological outcomes of prostheses with fixed plateaus and preserving the PCL in our series with one revision at 10 years were very satisfactory. Our results are comparable with earlier reports in the literature with or without sacrifice of the PCL with a fixed or mobile plateau. Conclusion: Longer term follow-up will be needed to confirm these results beyond ten years

Medial pivot total knee arthroplasty is designed to permit posterior rolling and sliding of the lateral femoral condyle around a stable medial femoral condyle. The purpose of the current study was to analyze the weight-bearing kinematics of medial pivot TKA’s with three different treatments of the posterior cruciate ligament: PCL resected, PCL partially released and PCL retained, to determine if the PCL status had a significant effect on tibiofemoral translations or rotations in a medial pivot TKA design. In vivo kinematics were determined for 17 clinically successful total knee arthroplasties during a stair-climbing activity using lateral fluoroscopy and shape matching techniques. All three groups showed similar medial pivot motions. PCL retained knees showed significantly greater tibial internal rotation than PCL resected knees for flexion of 30° and greater. Rotation of the PCL released knees was midway between PCL resected and PCL retained knees. Regardless of PCL treatment, patients with medial pivot total knee arthroplasties had medial pivot motion patterns during stair climbing activities. This study showed a clear and intuitive trend in motions with PCL-treatment, such that knees with partially released PCL’s had kinematics midway between those where the PCL was either fully maintained or fully resected

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 and Aims: The effects of injury to the posterior cruciate ligament (PCL) and posterior-lateral corner (PLC) on physical function are not as well documented compared to the more common injury to the anterior cruciate ligament. This study aimed at improving our understanding of PCL/PLC injury through gait analysis and electromyographic (EMG) testing. Method: We studied 19 patients, average age 30 years (20–55) with clinically and radiologically confirmed PCL/PLC deficiency in isolation. Ninety percent of patients complained of instability when performing the activities of daily living and all complained of pain. All patients were assessed using the Lysholm and Gillquist functional knee score as well as gait analysis, including Kinematics, Kinetics and EMG of the quadriceps, hamstrings and gastrocnemius muscles. Findings were compared to our normal database. The mean Lysholm score was 51/100 (24–90). Those with a Lysholm greater than 50 were designated as ‘copers’. Results: There were 12 ‘non-copers’ and seven ‘copers’. Fifty percent of patients demonstrated a varus thrust through stance. Forty-two percent of patients demonstrated hyperextension of the knee through stance. Sixty-three percent of patients demonstrated premature and prolonged hamstring activity. Thirty-seven percent of patients had premature activity of the gastrocnemius muscle in stance. Fifty-seven percent of the ‘copers’ demonstrated premature and prolonged hamstring activity through the gait cycle compared to forty-five percent of ‘non-copers’ (non-significant p=0.25 Fishers Exact Test). Fifty-five of ‘non-copers’ demonstrated premature activity of the gastrocnemius muscle in stance compared to none of the ‘copers’ (significant p=0.025 Fishers Exact Test). Conclusion: The observed varus thrust may be responsible for the development of medial and patellofemoral compartment osteoarthritis, a recognised problem in PCL deficient knees. Hyperextension that occurs dynamically during gait could explain failure of PCL/PLC reconstruction over time. The observed abnormal hamstrings activity is unlikely to be a compensatory mechanism

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

Purpose: Treatment of recent lesions of the posterior cruciate ligament (PCL) is not standardised. Decisions depend on the patients age and activity level, the degree of laxity, and the presence of combined lesions. Surgical solutions included PCL repair with suture, reconstruction with an autograft or allograft, or synthetic plasty. The purpose of this study was to analyse the results of synthetic reconstruction plasty for knees with important recent laxity of the PCL alone or in association with other lesions (triads, pentades, dislocations). We hypothesised that the synthetic ligament serves as a tutor guiding healing of the ruptured ligament. Material and methods: The series included 14 consecutive patients, 1 women, 13 men, mean age 27 years who were reviewed retrospectively. These patients were treated for isolated PCL tears (laxity > 15 mm) (n=3), PCL tears combined with laxity (medial or lateral) (n=6) or dislocation (n=5). Mean posterior laxity was 24 mm. The operation was performed 3 to 50 days after trauma using the LARS method (polyester ligament, 6 or 8 mm, 1 or 2 strands). All associated lesions were repaired during the same procedure except one A CL and one posterolateral angle which were treated secondarily. Mean follow-up was 36 months (10–88). All patients were seen for consultation except one who responded to a questionnaire. The IKDC score and Telos laxity measurements were noted. Results: In five knees, stiffness required mobilisation or arthroscopic arthrolysis. A secondary tear confirmed arthroscopically occurred in one case after a new trauma. Subjectively, two patients were very satisfied, eight were satisfied and three were disappointed. Final motion was: 6/0/130. Direct clinical posterior drawer was present in twelve cases: the Telos differential was 8 mm (24 mm preoperatively). The overall IKDC score was A=0, B=7, C=3, D=2. Persistent posterior laxity was the worst item. Outcome was less satisfactory for all items for posterolateral laxity. There was no difference between the one- and two-strand plasties. Discussion: We did not have any complications directly related to the synthetic ligament (synovitis, spontaneous tear). There was a significant gain in posterior laxity. Outcome depended on associated lesions, particularly lateral lesions (stiffness, IKDC score), rather than the surgical technique used to repair the PCL. The synthetic ligament appears to play its role as a tutor, a single strand measuring 6 mm in diameter is sufficient. Conclusion: This technique spares the tendon stock and can be proposed for recent tears of the PCL with major laxity. A longer term follow-up is needed to confirm the persistence of the improvement in laxity

Purpose of the study: The purpose of this study was to use weight-bearing radiographies to study the mobility of the polyethylene insert in relation to the femoral and tibial components of a total knee arthroplasty (TKA) with preservation of the posterior cruciate ligament and a mobile plateau with rotation and anterioposterior translation (INNEX. ®. Anterior-Posterior Glide, Zimmer). Material and methods: A 3D kinematic study of the femoral and tibial component and the mobile insert was conducted on a series of 51 first-intention TKA using a computer-assisted matching system between 3D prosthetic models and the radiographic silhouette of the implants. Results: At mean 23 months postoperatively, the poly-ethylene tibial insert exhibited an increase in its internal rotation during flexion. This rotation, knee extended, was limited to rotation between the insert and the tibial base. With increased flexion, there was an increase in the value and the portion of rotation involving the femoral component in relation with the mobile tibial insert. Discussion: The degree of insert mobility has varied depending on the report. Certain authors have reported relatively limited mobility because of a minimally congruent superior surface allowing anteroposterior and mediolateral translation as the femur glided over the insert. Others report mobility of the mobile plateau in relation to the tibial base and minimal rotation of the femoral component. Rotation of the polyethylene insert in TKAs with a mobile plateau appears to be quite variable. With the LCS AP Glide prosthesis, anteroposterior translation of the mobile plateau was measured at a mean 5.6 mm (1–1.125 mm). Paradoxical anterior translation, rather than posterior translation, of the mobile plateau with flexion has been reported in a few patients. Conclusion: The mobile plateau has exhibited progressive increase in internal rotation with flexion. We have concluded that the major part of the mobility occurs between the mobile plateau and the tibial base. However, with flexion, the femoral component increased its mobility over the plateau. During flexion, anteroposterior translation occurred between the femoral piece and the tibial insert, and between the tibial insert and the tibial base, but the direction of the translation of the mobile tibial insert appeared to be unpredictable with the non-constrained prosthesis used for this study

The influence of Posterior Cruciate Ligament (PCL) removal and re-establishment of the posterior condylar recess on flexion and extension gaps width during posterior-stabilized Total Knee Arthroplasty (TKA) is still controversial. It has been reported that PCL resection lead to a selective increase of the flexion space of 3–4 mm, creating a potential for instability in flexion. Our hypothesis was that these surgical steps will equally increase both gaps. Measurements of the flexion and extension gaps heights were obtained during different surgical phases in 50 consecutive primary posterior-stabilised TKAs using a tensor device and a calibrated torque wrench. There was a slight symmetrical increase in both gaps after PCL release. In extension the width of the gap increased on average 1.3 mm and 1.0 mm in the medial and lateral compartment respectively. The same pattern was observed in flexion, averaging 1.3 mm medially and 1.3 mm laterally. Another increase of the two gaps was observed after the posterior condylar osteophytes were removed and the posterior recess was re-established. The gaps in extension increased, with respect to the baseline value, on average 1.8 mm medially and 1.8 mm laterally, while in flexion the increase averaged 2.0 mm and 2.2 respectively on the medial and lateral side. Again there were no statistical differences between flexion and extension gaps. No independent differences between the flexion and extension gaps were found in any considered surgical phase. PCL removal and re-establishment of posterior condylar recess does not seem to require any additional consideration in gap balancing during posterior-stabilized TKA

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: Patellar complications are among the most frequent after total knee arthroplasty. Encasing the patellar piece is one way of resisting the shear forces leading to loosening. Material and Methods: We studied at more than five years the results obtained with a total knee prosthesis implanted with preservation of the posterior cruciate ligament (PCL). This prosthesis has an asymmetric encased patellar insert with a cemented central pivot. The instrumentation ensures patellar thickness. We reviewed 104 implants at more than five years. Six had been lost to follow-up. Ninety-eight implants were still in place. Results: The following complications were observed: four fractures of the upper rim with little displacement (these fractures healed and pain regressed but the insert had moved); three vertical patellar fractures with little displacement (these fractures healed; two were symptomatic temporarily); one transverse fracture of the upper pole with displacement causing a defect in active extension; eight moderate asymptomatic impactions which were visible on the lateral x-ray (modified orientation of the insert with cement fracture). There was no significant difference for functional results (pain 40.9; movement 21.9; knee score 84.3) between patients with or without a patellar complication. Discussion: Insertion of an asymmetric prosthesis increased the risk of an orientation error (two cases early in our experience). Encasing the patellar insert limits medialisation yet the centering was satisfactory (centred patella 95.2%, shift 3.6%, subluxation 1.2%). Encasing provides a peripheral wall protecting against transverse sheer forces. The lateral wall did not fracture, demonstrating its efficacy. The upper wall can fracture under the force of flexion without functional consequences. The other fractures, favoured by section of the lateral patellar wing (p< 0.05), were not treated. Moderate but certain impaction was noted in eight cases at a mean 3.5 years (1–6 years). It was due to failure of bony support under the effect of the compression forces applied on a small surface. The diameter of the encased patellar inserts was rarely more than 25 mm. Once the prosthesis is in place, the periphery of the patella is the only component articulating with the trochlea and its impaction does not cause further aggravation. This contact did not lead to pain in any patients. Conclusions: Complications observed with encased patellar components differ from the better known apposed prostheses

Purpose: Patellar complications are among the most frequent after total knee arthroplasty. Encasing the patellar piece is one way of resisting the shear forces leading to loosening. Material and methods: We studied at more than five years the results obtained with a total knee prosthesis implanted with preservation of the posterior cruciate ligament (PCL). This prosthesis has an asymmetric encased patellar insert with a cemented central pivot. The instrumentation ensures patellar thickness. We reviewed 104 implants at more than five years. Six had been lost to follow-up. Ninety-eight implants were still in place. Results: The following complications were observed: four fractures of the upper rim with little displacement (these fractures healed and pain regressed but the insert had moved); three vertical patellar fractures with little displacement (these fractures healed; two were symptomatic temporarily); one transverse fracture of the upper pole with displacement causing a defect in active extension; eight moderate asymptomatic impactions which were visible on the lateral x-ray (modified orientation of the insert with cement fracture). There was no significant difference for functional results (pain 40.9; movement 21.9; knee score 84.3) between patients with or without a patellar complication. Discussion: Insertion of an asymmetric prosthesis increased the risk of an orientation error (two cases early in our experience). Encasing the patellar insert limits medialisation yet the centering was satisfactory (centred patella 95.2%, shift 3.6%, subluxation 1.2%). Encasing provides a peripheral wall protecting against transverse sheer forces. The lateral wall did not fracture, demonstrating its efficacy. The upper wall can fracture under the force of flexion without functional consequences. The other fractures, favoured by section of the lateral patellar wing (p< 0.05), were not treated. Moderate but certain impaction was noted in eight cases at a mean 3.5 years (1–6 years). It was due to failure of bony support under the effect of the compression forces applied on a small surface. The diameter of the encased patellar inserts was rarely more than 25 mm. Once the prosthesis is in place, the periphery of the patella is the only component articulating with the trochlea and its impaction does not cause further aggravation. This contact did not lead to pain in any patients. Conclusions: Complications observed with encased patellar components differ from the better known apposed prostheses

Purpose of the study: Opinions vary concerning results after knee arthroplasty with preservation of the posterior cruciate ligament (PCL) in patients with rheumatoid disease. We report our findings in patients reviewed more than ten years after implantation in comparison with patients treated for osteoarthritis. Material and methods: One surgeon implanted 43 knee arthroplasites (Kali) with preservation of the PCL (9 bilateral cases) in 31 women and 3 men, mean age 53 years (range 30–70 years). Outcome was assessed with the AKS clinical and radiological scores. Passive recur-vatum and posterior drawer at 90° flexion were measured radiographicaly at last follow-up. Outcome was compared with the results observed in a control group of 29 prostheses of the same type implanted for osteoarthritis (among a total of 203 implantations). Results: There were no patients lost to follow-up: two patients were removed from the analysis due to infection on early wound necrosis and late metastatic infection. Eleven patients (16 prostheses) died before ten years follow-up; outcome was satisfactory for the prosthesis. Twenty-one patients (25 prostheses) were reviewed at more than ten years, mean follow-up 136 months. There was one case of supracondylar fracture which healed without sequela after osteosynthesis. The mean knee score was 34.3 preoperatively and 87.2 postoperatively with a mean function score improvement from 17 to 44 points. The pain score (47.3 points on average, was significantly improved while joint range of motion remained unchanged (117°). There were no worrisome lucent lines. Mean recurvatum measured radiographically was 6.9° (range 3–14°) and mean posterior drawer at 90° flexion was 4.2 mm. Outcome in the control group was the same excepting (p< 0.05) for lesser range of motion (109.7°) and better function score (62 points). Laxity (clinical and radiographic scores) were the same. Discussion: The results obtained in patients with rheumatoid disease were satisfactory and the same as those obtained in patients with osteoarthritis and were comparable to those with prostheses sacrificing and replacing the PCL. There were no cases of prosthesis loosening. Complications were very limited and less frequent than among the entire population of 203 prostheses for degenerative disease. Conclusion: Ligament alterations are not a contraindication for preservation of the PCL in patients with rheumatoid arthritis. Irrespective of the etiology, the main limitation on prosthesis longevity is polyethylene wear observed beyond ten years (ten changes of the plateau because of wear among 246 prostheses)

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.