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Highlights • Medial Uni-compartmental Knee Arthroplasty (MUKA) is a newer minimally invasive procedure that gained recent spotlight. • Cheaper, less blood loss, faster hospitalization and less pain and makes it more favorable compared to the conventional TKA (Total Knee Arthroplasty). • Fewer studies compared to TKA have been reporting its complication. • Meniscal bearing dislocation is one of the most common complication in UKA. • We reported simple open reduction technique which is lest costly, effective with satisfying result., Introduction Dislocation of polyethylene insert is one of the most common complications of mobile bearing-medial unicompartmental knee arthroplasty (MUKA). Bearing dislocation was diagnosed by radiograph examination in these cases upon trivial injury. Case presentation We reported one case of meniscal bearing dislocation after an Oxford MUKA treated with a simple open reduction technique. Clinical discussion Simple open reduction surgery without change of the bearing and the use of knee brace for 6 months was effective in preventing re-dislocation. Conclusion Mobile bearing dislocation is one of the most common complications in mobile-bearing MUKA. Besides the prevention of technical errors, usage of UKA with a frequency of 10–15 per year is recommended to increase the surgeon’s learning curve.

Background National joint registries report increasing revision rates with decreasing patient age for all types of joint arthroplasty. This study aimed to explore the effect of age on function and revision risk in patients undergoing medial meniscal-bearing UKA. Methods A prospectively followed cohort of 1000 consecutive medial meniscal-bearing UKAs at a designer center was analyzed. All knees were implanted for recommended indications and had mean 10-year follow-up. Patients were grouped by age at surgery ( Results Mean patient age at surgery was 66.6 years (range, 33-88). All age-groups had significant (P < .001) improvement in OKS over time, and at 5 years achieved a median OKS of 44. At 10 years, median OKS, from youngest group to eldest, were 44, 45, 42, and 39, with the eldest group having a significantly lower OKS (P < .01). Ten-year implant survival rates were 97%, 94%, 94%, and 93%, respectively, and was not significantly associated with age at UKA. Conclusion Medial meniscal-bearing UKA provides good functional outcomes in all age-groups; however, in older patients (75+), the functional outcome deteriorated at 10 years presumably due to deteriorating health. Contrary to registry observations, the revision rate was not higher in younger patients. These results suggest that, with correct indications, patient age should not be considered a contraindication to medial meniscal-bearing UKA.

Background: A new design of 3-part ankle replacement was developed to achieve compatibility with the natural ligaments by allowing certain fibers to remain isometric during passive motion. Methods: We evaluate 75 ankle prostheses implanted from July 2003 to December 2008, at a mean follow-up 6.5. ±. 1.1. years (range 5-9 years). The mean age at surgery was 62. ±. 13. years (range 29-82). Results: The mean AOFAS scores achieved at pre-op and at last follow-up were respectively 37. ±. 5 (23-45) and 78. ±. 8 (64-98). (p.

Background The Oxford Medial Partial Knee Replacement (PKR) has been in clinical use for more than 20 years. The current surgical technique requires a number of judgements to be made, and even in the most experienced hands surgery can be challenging. We present an alternative surgical technique, which we believe addresses the unpredictability of the current method. The technique is based on precise femoral positioning prior to tibial resection. Method A prospective series of 125 Oxford Medial PKRs was performed using this new technique and a radiographical analysis was performed. We used meniscal thickness, meniscal position and femoral position as measures of reproducibility of the procedure. Results Variability in meniscal thickness has been minimised with a 3 mm meniscal bearing used in 21 knees (15%), 4 mm (the target thickness) in 73 knees (59%) and 5 mm in 30 knees (24%). The mean meniscal position relative to the tibial tray upright was 2 mm (SD 1 mm). Femoral component position relative to the tibial tray, which defines the excursion of the meniscus was also assessed. Mean coronal plane alignment was 2° of valgus (SD 2.8). Mean flexion/extension was 3.8° (SD 3.1). The mean rotation was 10° internal (SD 5°). Conclusion We believe this new technique makes this procedure more reproducible, and should be considered as a viable alternative to the current recommended technique. It may be a better technique for those surgeons who are relatively inexperienced with this prosthesis.

Unicondylar knee arthroplasty (UKA) has become a popular alternative to total knee arthroplasty or high tibial osteotomy for unicompartmental knee conditions. This study investigated the effects of kinematics and femoral liftoff on the wear of fixed and mobile versions of a UKA design. The fixed bearing had lower wear than the mobile bearing under all conditions. Wear was higher in lateral bearings than medial bearings, indicating that the increased sliding distance laterally had a greater effect than the greater loading medially. Femoral condylar liftoff resulted in increased wear in the medial UKAs but reduced wear in the lateral UKAs for both the bearing designs. The reduced wear rates observed for the fixed UKA bearings highlight the potential for a longer osteolysis-free clinical outcome for these devices.

The Rotaglide knee arthroplasty has a highly congruent mobile meniscal bearing allowing both rotation and antero-posterior translation. We reviewed 137 consecutive primary arthroplasties in 120 patients at mean 11.1 years (10-12.9) following surgery. No cases were lost to follow-up. Hospital for Special Surgery (HSS) and American Knee Society (AKSS) scores were recorded at a review clinic. Radiographs were assessed using the Knee Society's roentgenographic evaluation system. Forty-two patients had died, leaving 78 patients (87 knees) available for review. Sixty-four patients (70 knees) were assessed at a clinic and in 14 (17 knees) clinical outcomes were obtained via telephone and their most recent radiographs were assessed. There were three cases of aseptic loosening and one deep infection requiring revision surgery. Two meniscal bearings were replaced with thicker inserts, one following bearing fracture and one following bearing dislocation. Survival at 11 years for aseptic loosening was 97.6% (95% CI 94.3 to 1.0) and survival using re-operation for any cause was 95.3% (95% CI 90.8 to 99.8). The Rotaglide mobile-bearing total knee replacement demonstrates good survivorship and outcome scores at 11 years following surgery.

Our initial experience with mobile bearing medial compartment unicompartmental arthroplasty (UKA) is presented to highlight lessons that have been learned to avoid short-term failures. Consecutive cases of the Oxford medial UKA performed between February 2001 and April 2006 were reviewed to derive those cases that were revised to total knee arthroplasty (TKA). There were 545 patients available with mean age and body mass index of 65.0 and 30.1, respectively. At final follow-up, 32 patients were revised for lateral compartment arthritis, aseptic component loosening, persisting medial or anterior pain and dislocated meniscal bearing. Revisions were performed with primary unconstrained TKA implants with no stems or wedges required. Our results seem to reflect those seen in registries confirming an earlier higher revision rate and highlight the technical issues of overstuffing the compartment, inadequate cementation technique, and strict adherence to patient selection.

Summary Reconstructive surgery with an ankle prosthesis for a painful ankle joint is of extreme benefit for the rheumatoid patient. In contrast to ankle fusion, ankle arthroplasty maintains mobility with early remobilisation of the patient. The success of ankle arthroplasty depends on indication, implant design and surgical technique as well as postoperative treatment. The performance of the first ankle prosthesis generation, developed in the early 1970s, was poor, being plagued by high loosening and revisions rates up to 50%. The two main reasons for failure were constrained designs and cement fixation. Buechel and Pappas, with the BP-ankle prosthesis and H. Kofoed with the S.T. A.R.-prosthesis first developed the second generation of ankle prosthesis. The three-component type consists of amobile polymeric bearing that is interposed between the flat metallic tibial and the metallic talar component. The key of success has been the use of a meniscal bearing device that provides unconstrained motion and stability. In the last 10 years, the ankle prostheses currently used have achieved encouraging midterm results. Despite all the progress in ankle arthroplasty made over the last few years, there remain some drawbacks concerning malleolar fracture, stiff ankle joint and impingement. Based on their experience with the current ankle prosthesis designs, the authors developed a new ankle prosthesis design. The in vitro testing was promising and we hope to report our first clinical results soon.

Aim: A biomechanical study was conducted to determine the in-vitro modification of the posterior cruciate ligament tension following different types of total knee arthroplasty (TKA). Materials and methods: The Genesis CR (non-mobile tibial inlay, n =9) and LCS meniscal bearing prostheses (mobile meniscal bearings, n =8) were compared with the human cadaveric knee joint. Posterior cruciate ligament (PCL) tension was assessed with implantable force transducers. A six-degree-of-freedom manipulator was used to measure knee kinematics at 10° intervals from 0° to 120° of flexion with [300 Newton (N)] and without load application (0 N). Statistical analysis was performed with the Wilcoxon rank sum test. Results: Analysis of the PCL tension following TKA using the Genesis CR prosthesis revealed a non-significant ( P =0.20) decrease of transducer output with load (300 N) and a non-significant ( P =0.73) increase without load (0 N). Concerning the LCS meniscal bearing prosthesis a significant ( P =0.01) decrease of transducer output was assessed with load (300 N) whereas a non-significant ( P =1.0) modification was seen without load (0 N). Conclusion: The Genesis CR prosthesis allows PCL tension to be close to normal as the knee flexes, which is contradictory to the assumed evidence for a missing restorability of a regular PCL tension after TKA. Our results hence indicate, that the effected tension of the PCL strongly depends on the balance and interaction between design of the implant and the functional role of the retained PCL.

A prospective study of early clinical and radiologic outcome of the Motus (Osteo, Selzach, Switzerland) meniscal bearing total knee arthroplasty was performed. We reviewed the first 75 consecutive prostheses in 62 patients, implanted over a 4-year period. The mean follow-up was 2.5 years. Average preoperative knee score was 97 out of 200 (Knee Society score, 43; functional score, 54) and at 2-year review was 179 out of 200 (Knee Society score, 87; functional score, 92). Average postoperative flexion at 2 years was 113°. No meniscal bearing subluxation, dislocation, or breakages occurred. Radiologically, there was no evidence of subsidence or osteolysis. Our results support the continued use of this meniscal bearing knee prosthesis. It is important to confirm, however, an equal flexion and extension gap without proximal joint line migration. Copyright 2003, Elsevier Science (USA). All rights reserved.

Summary We investigated the tibio-talar mobility clinico-radiographically in 11 ankle joint prostheses before surgery and after 6 and 12 months. The radiologist and the orthopaedic surgeon were not involved in the radiographic procedures. The total preoperative radiographic range of motion was median 16° (range 13–50). At 6 months after operation it had increased to median 22° (range 15–36) and at 12 months to median 27° (range 19–38). The difference at 6 and 12 months was significant compared to the preoperative value ( P = 0.05). The gain in motion took place in dorsiflexion that at 6 months had increased by 7° and at 12 months by 10°. There was no significant change in plantarflexion. The clinical measurements showed the same trend. However, the motion was significantly larger (45°, range 40–55). There was no correlation between clinical and radiographic measurements. True tibio-talar motion for ankle arthroplasty is determined best by radiography.

The preliminary results of the Minns meniscal bearing total knee replacementare presented with an average follow-up of 62.5 months (range 38–78 months). A total of 90 cemented meniscal bearing total replacements of this design were performed on 67 consecutive patients. Three died of unrelated causes and four failed to attend for follow-up investigation. Consequently, 80 knees in 60 patients were reviewed with an average follow-up time of 62.5 months. Using the American Knee Society scoring system (see Appendix 1), 82% rated good or excellent, 11% were rated fair and 6% poor. There was a clinical improvement in all cases except one patient and pain relief was achieved in most cases (96%). Five knees had some mild pain on activity post-operatively. The average range of motion post-operatively was 98° and there were no cases of dislocation of the polyethylene bearings. There was a single case of radiological loosening which subsequently proved to be an infected prosthesis requiring revision surgery. Survivorship analysis (Kaplain-Meier survival curve) shows that 98.9% of the knees survived at five years follow-up.

A complication of meniscal bearing total knee replacements is subluxation/dislocation of the rotating platform. In this article we describe two cases of platform dislocation occurring after several years, with no history of trauma.

We report the results of 53 knees with lateral compartmental osteoarthritis treated by unicompartmental arthroplasty with the Oxford Meniscal Knee. The mean follow-up was 5 years. Eleven knees required further surgery. Six of the revisions were for early dislocation of the meniscal bearing, three because of late infection, one because of loosening of the tibial component and one because of a stress fracture that occurred in the tibial plateau. Since introducing techniques to prevent bearing dislocation, 14 knees have been operated on and there has been one dislocation. This bearing was exchanged for one of a larger size, and the knee subsequently functioned well. Forty of the 42 knees that did not require further surgery had good relief of symptoms and restoration of function, and two had persistent pain. The risk of bearing dislocation in the lateral compartment with the Oxford Unicompartmental Knee replacement is greater than in the medial compartment. In other respects the results are similar. New techniques have reduced the risk of bearing dislocation but have not prevented the complication.

Summary A consecutive series of eight cases, five men and three women, of mean age 56 years (42–79) with unilateral meniscal-bearing total ankle arthroplasty was analysed with stabilometry in the standing phase in order to compare the in vivo stability of the artificial joint to that of the opposite normal ankle joint. The tests were performed as a one-legged balance test on a fully computerized static force plate, with or without shoes, and with open and closed eyes. The force plate registered the area used to keep balance, the length and direction of the corrective movements and their velocity. A system (maximum 100 points) with a pain score, normal daily-life ankle function score and ankle mobility score was used for clinical evaluation (excellent: 85–100 points, good 75–84, fair 70–74, and

In the Swedish Knee Arthroplasty Study, all 699 Oxford meniscal bearing cemented unicompartmental prostheses (Biomet, Bridgend, UK) were identified and analyzed regarding failure pattern and compared with all Marmor prostheses (Smith & Nephew Richards, Orthez, France) and with a time-, age-, and sex-matched subset of Marmor prostheses using survival statistics expressed as cumulative revision rates. After 1 year there was already a higher rate, and after 6 years the rate of the Oxford group was more than twice that of the Marmor group. There were 50 revisions in the Oxford group: dislocating meniscus in 16, loosening of the femoral component in 6, tibial component in 4, both components in 4, contralateral arthrosis in 10, infection in 4, and technical failure with instability, pain, and/or impingement of the meniscal bearing anterior in the femoral condyle in 6. It is still unclear if the design with the sliding menisci will, in the long turn, reduce wear and loosening, thereby compensating for the initially inferior results. It is recommended that until this question is clarified, the Oxford knee should be used on a limited scale for long-term comparative studies only.

Unicompartmental knee arthroplasty (UKA) is a well-established procedure for isolated medial compartment osteoarthritis. Meniscal dislocation is a well-recognized complication in mobile bearing UKA especially when performed for the lateral compartment. Dislocation in medial UKA is relatively uncommon and is usually anterior when encountered. We would like to report a case of posterior dislocation of the bearing insert in a mobile bearing medial UKA presenting as a Baker cyst, which was subsequently revised to total knee arthroplasty.

Dislocation and early fracture of meniscal bearing elements have been reported after New Jersey low-contact-stress (DePuy, Warsaw, IN) total knee arthroplasty. Delayed wear and subsequent failure of meniscal bearing elements in two cases, 8 and 9 years after surgery, are reported.

Sixty-seven consecutive Oxford Meniscal total knee arthroplasties (TKAs) were compared prospectively with 66 Kinematic I TKAs. At follow-up examination an average of 5.5 (range, 5-8) years later, 20 (30%) of the Oxford Meniscal TKAs had been revised (nine due to aseptic loosenings, seven to aseptic loosening and patellofemoral syndrome, two to patellofemoral syndrome, one to meniscal bearing dislocation, and one to sepsis) and in 16% one or more of the remaining tibial components was radiographically at risk. Three (5%) Kinematic I TKAs had been reoperated upon (one for anterior dislocation, one for a loose patellar component, and one for sepsis) and no component was considered radiographically at risk. The remaining cases demonstrated good and excellent knee ratings (Oxford, 82 +/- 11; Kinematic I, 88 +/- 6; P less than .01; Hospital for Special Surgery). This study suggests that the results of Kinematic I TKA are superior to those of Oxford Meniscal TKA; that patellofemoral resurfacing is advisable; and that Kinematic I TKA yields 5-year data comparable to those of total hip arthroplasty.

Unicompartmental knee arthroplasty is an attractive concept, but some reports on its use are unfavorable. A meniscal bearing prosthesis has many advantages in this mode of arthroplasty. The authors present preliminary results of 25 unicompartmental knee replacements done with the Oxford Meniscal knee, with a follow-up period of 12-54 months (mean, 21 months). They discuss the scientific basis of unicompartmental knee arthroplasty, which they conclude may be the most appropriate treatment for selected cases of degenerative arthritis of the knee.