Search

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:Cemented unicompartmental knee arthroplasty (UKA) yields good clinical outcome but common revision reasons are loosening and pain. Cementless UKA may reduce the revision rate.Objective:The current study was designed to assess clinical and radiographic outcome of cemented and cementless UKA, using bone quality as determined by the Bone Hardness Test (BHT) as selection criterion for cementless implantation.Methods:In this prospective comparative cohort study we analyzed 50 cementless and 29 Oxford consecutive UKA cases. Patients with sufficient bone quality were eligible for cementless UKA. Bone quality was assessed with the BHT, which consisted of exercising pressure with the thumb on the bone surface created after resection of the tibia.Results:The average surgical times were 62.5 ± 12.6 and 78 ± 16 minutes in the cementless and the cemented group, respectively (p < 0.01). The average thickness of the polyethylene insert was 4.3 ± 1.2 (range, 3 – 9) and 3.7 ± 0.8 (range, 3 – 6) mm, respectively (p = 0.02). Both types of implants yielded excellent clinical and functional results. At an average follow-up time of seven years, we found non-significant differences between clinical results of cementless versus cemented implants.Conclusion:Shorter surgical time makes cementless implantation more attractive to surgeons when considering UKA options for their patients. The average thickness of the polyethylene insert in cementless group was 0.6 mm thinner than in the cemented group. The BHT is a simple and useful test to assess whether patients are eligible for cementless 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.

Dislocation of meniscal bearing insert is a rare but well-recognised complication in meniscal bearing unicompartmental knee arthroplasty (UKA). On the other hand, fracture of meniscal bearing insert of phase III Oxford UKA has only been reported once in the current literature. The authors report a case of fracture and posterior dislocation of one of the fragments of the meniscal bearing insert in a mobile bearing medial UKA. The fracture was only diagnosed during the revision surgery. The posteriorly dislodged fragment was subsequently retrieved through the same skin incision and a new polyethylene insert of the same size was implanted.

WOS: 000470771800002, PubMed: 31363444, Proximal fibular osteotomy (PFO) is a simple, easy and cheap procedure consisting of removing a 10 mm piece of fibula 6 to 9 cm below the fibular head. Proximal osteotomy of the fibula weakens the lateral fibular support and leads to a correction of the varus deformity and provides a widening on the medial joint space. Unicondylar knee arthroplasty (UKA) is intended to treat isolated medial compartment arthritis. However, knees with a varus deformity and tight medial joint space might cause both technical difficulties and poorer outcomes. A 68-year-old female with complaints of pain on the medial side of both knees for more than two years underwent bilateral UKA. While inserting the trial meniscal bearing was not easy due to the varus tight knee, at that stage, instead of performing a deeper cut, a PFO procedure was considered which provided widening of the medial joint space. We report, to our knowledge, the first simultaneous application of these two procedures. Despite being a single case with very short term results, our results suggest that the combination of PFO and UKA may reduce the loads over the implants on the medial compartment based on the widening of the joint space and varus deformity correction.

Meniscal bearing dislocation while rolling over in sleep has never been reported in Oxford unicompartmental knee arthroplasty (UKA). This study reports two cases of meniscal bearing dislocation into the intercondylar ridge while rolling over in sleep. In the case of one patient, closed reduction of the bearing was performed, and the use of a knee brace was effective in preventing re-dislocation. In the second patient, closed reduction was possible; however, bearing dislocation was repeated. Therefore, revision surgery was performed by replacing the tibial component and using a thicker bearing. The common features in dislocation during rolling over while sleeping in both cases were dislocation into the intercondylar ridge, the combination of small femur and AA-size tibia components, and osteonecrosis. As determined by intraoperative testing, valgus position of the knee while rolling over in sleep could induce bearing dislocation into the intercondylar ridge. LEVEL OF EVIDENCE: Retrospective case series, Level IV.

Mobile-bearing Oxford medial unicompartmental knee arthroplasty (UKA) has been widely used and has produced good results in the treatment of medial compartmental osteoarthritis. But it is associated with the potential risk of meniscal bearing dislocation. Symptoms caused by most meniscal bearing dislocations include acute pain, knee swelling, and locking. We report two unusual cases of meniscal bearing spinning of 180° without remarkable symptoms, which would have been easily missed if we had not watched carefully. Therefore, if there is sudden locking, pain, swelling, or a slight locking history, the possibility of meniscal bearing spin out as well as meniscal bearing dislocation should be considered and the direction of meniscal bearing markers should be confirmed, especially on lateral radiographs.

When the Oxford unicompartmental meniscal bearing arthroplasty (UCA) is used in the lateral compartment 10% of the bearings dislocate. A fluoroscopic study was performed to investigate if abnormal mid-sagittal plane kinematics was related to bearing dislocation. Video fluoroscopy is an accepted means of determining in-vivo knee kinematics in the sagittal plane. Video fluoroscopy was obtained of 5 Oxford lateral UCAs 10 years post-operatively and of five normal knees. Patellar tendon angle (PTA), derived from dynamic fluoroscopic images, was used to describe the joint kinematics. This in-vivo experiment demonstrated that the PTA/knee relationship for the Oxford lateral UCA is similar to the normal knee. Both the normal knee ( r 2 =0.99) and the Oxford lateral UCA ( r 2 =0.98) demonstrated a linear relationship between flexion angle and PTA. No significant difference in PTA was found between the normal knee and the Oxford lateral UCA. This study demonstrated normal kinematics, as indicated by PTA, ten years after implantation of the Oxford lateral UCA. It is therefore reasonable to suggest that abnormal kinematics is not a significant factor relating to meniscal bearing dislocation in the lateral compartment.

Polyethylene particulate wear debris continues to be implicated in the aetiology of aseptic loosening following knee arthroplasty. The Oxford unicompartmental knee arthroplasty employs a spherical femoral component and a fully congruous meniscal bearing to increase contact area and theoretically reduce the potential for polyethylene wear. This study measures the in vivo ten-year linear wear of the device, using a roentgenstereophotogrammetric technique. In this in vivo study, seven medial Oxford unicompartmental prostheses, which had been implanted ten years previously were studied. Stereo pairs of radiographs were acquired for each patient and the films were analysed using a roentgen stereophotogrammetric analysis calibration and a computer-aided design model silhouette-fitting technique. Penetration of the femoral component into the original volume of the bearing was our estimate of linear wear. In addition, eight control patients were examined less than three weeks post-insertion of an Oxford prosthesis, where no wear would be expected. The control group showed no measured wear and suggested a system accuracy of 0.1 mm. At ten years, the mean linear wear rate was 0.02 mm/year. The results from this in vivo study confirm that the device has low ten-year linear wear in clinical practice. This may offer the device a survival advantage in the long term.

When the Oxford unicompartmental meniscal bearing arthroplasty is used in the lateral compartment of the knee, 10% of the bearings dislocate. A radiological review was carried out to establish if dislocation was related to surgical technique. The postoperative radiographs of 46 lateral unicompartmental arthroplasties were analysed. Five variables which related to the position and alignment of the components were measured. Dislocations occurred in six knees. Only one of the five variables, the proximal tibial varus angle, had a statistically significant relationship to dislocation. This variable quantifies the height of the lateral joint line. The mean proximal tibial varus angle for knees the bearings of which had dislocated was 9° and for those which had not it was 5°. In both groups it was greater than would be expected in the normal knee (3°). Our study suggests that a high proximal tibial varus angle is associated with dislocation. The surgical technique should be modified to account for this, with care being taken to avoid damage to or over-distraction of the lateral soft tissues.

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.

Total knee arthroplasty (TKA) is considered as a standard procedure for the treatment of the severe degenerative knee joint. The outcomes of TKA have improved over the last few decades because of a better understanding of design features and surgical techniques. Contemporary tibial component designs in TKA can be subdivided into two groups (fixed or mobile-bearing) on the basis of different fundamental principles. The mobile-bearing knee is designed with better biomechanical concepts than the fixed-bearing knee, in terms of providing congruity and mobility of tibial bearing. It is expected that the mobile-bearing knee could resolve the problems of component wear and component loosening as seen in fixed-bearing knees. However, the long-term durability of mobile-bearing knees has not been extensively proven to have better outcomes than that of fixed-bearing knees. There are some potential clinical complications of mobile-bearing knees that must be addressed. On the basis of our previous clinical experience and a retrieval analysis, this article summarizes five specific complications including (1) early or late dislocation of the mobile-bearing component, (2) failure or dislodging of the meniscal bearing, (3) hemarthrosis associated with a failure of the meniscal-bearing knee, (4) failure of the patellar component, and (5) higher prevalence of osteolysis. Before taking advantage of mobile bearing, we should consider these specific clinical complications, which were not found in the fixed-bearing TKA.

Background: Most clinical studies on total ankle replacement (TAR) report assessments based on traditional clinical scores or radiographic analysis. Only a few studies have used modern instrumentation for quantitative functional analysis during the execution of activities of daily living. The aim of this study was to use gait analysis to compare the functional performance of patients who underwent TAR versus a control population. Methods: A retrospective analysis was performed of ten consecutive patients who had undergone meniscal-bearing TAR. Clinical and functional assessments were performed at a mean follow-up of 34 months with a modified Mazur scoring system and state-of-the-art gait analysis. Results: Gait analysis assessment of TAR at medium-term follow-up showed satisfactory results for all patients, with adequate recovery of range of motion. Because the literature reports unsatisfying long-term results, it is important to evaluate these patients over a longer follow-up period. Conclusions: This study showed that TAR yields satisfactory, but not outstanding, general functional results at nearly 3 years’ follow-up. These gait analysis results highlight the importance of integrating in vivo measurements with the standard clinical assessments of patients who underwent TAR while they perform activities of daily living. These results also emphasize the importance of evaluating the functional outcome of TAR over time. (J Am Podiatr Med Assoc 98(1): 19–26, 2008)

This study presents the survivorship data of a consecutive series of primary meniscal-bearing total knee replacements at one institution at 8 to 15 years followup. We reviewed 125 meniscal-bearing knee replacements in 93 patients at a minimum followup of 96 months (mean, 130 months; range, 96-191 months). The tibial and femoral components were cemented in 71 knees; uncemented femurs and tibias were used in 48 knees; and cemented tibias and uncemented femurs were used in six knees. One patient was lost to followup. Seventeen knees failed, three as a result of infection. Five knees were revised for loose tibial components and one for a loose femoral component. A second femoral component was identified as radiographically loose. All the loose components were uncemented. Five knees had reoperation for fractured bearings and one for a dislocated bearing. This knee was later rerevised for a loose uncemented tibia. One knee was revised for instability and a second knee was identified as grossly unstable but not revised. Kaplan-Meier survival analysis showed survivorship of approximately 90% at 9 years, which decreased to 71% at 15 years. Uncemented components had an increased aseptic loosening rate compared with cemented components. Meniscal-bearing replacements with cement fixation appeared successful, although bearing fracture seems to be a predominant failure mode at long-term followup.

To determine polyethylene deformation in well-functioning meniscal bearing PCL-retaining total knee prosthesis a quantitative stereophotogrammetric analysis was carried out over 5 years' follow-up. Polyethylene plastic deformation was obtained by tracking the intermarker distance variations of five tantalum beads inserted into the polyethylene prior to surgery in a known position. Plastic deformation occurred in the posteromedial part of the meniscal bearing. Radiostereometric analysis was a useful tool to monitor the load distribution in vivo on the polyethylene of this meniscal bearing prosthesis. This analysis revealed a very similar pattern of plastic deformation in the polyethylene insert of this prosthesis design to the wear pattern revealed with different methodologies in PCL-retaining fixed-bearing prosthesis.

Luxation and excessive wear of the mobile bearing in modern three-piece total ankle replacement (TAR) is reported. We conducted a systematic review of studies to explore and discuss the rate and causes of these complications.A systematic review of studies since 2000 showed 26 studies with altogether 1,318 followed up TARs which we analyzed. Of these 1,318 TARs, 188 (14.3%) were revised and 56 (4.2%) complications with the mobile bearing were reported. A total of 39 cases (3%), i.e., 20.7% of all revisions, were revised due to failure of the mobile bearing, including 17 cases with subluxation (1.3%), 15 with asymmetric load of the bearing (1.1%), 10 with fracture of the polyethylene (PE) inlay (0.76%), 7 with massive PE wear (0.53%), and 7 with luxation of the meniscal bearing (0.53%).Complications due to the meniscal mobile bearing in TARs such as luxation, subluxation, massive wear, and fracture of the PE inlay are rare complications. The cause of these complications is regularly not found in the design of this three-piece total ankle replacement. Causes of failure of the mobile bearing are mostly found in incorrect indication, incorrect soft tissue balancing, incorrect positioning of components, implantation in ankles with hindfoot malalignment and ankle instability.

Wear performance was affected by several factors to contribute towards wear generation. Prospect of minimize wear is needed further study by using optimize design parameter. Inevitability to optimize the design is to improve the understanding of reducing wear in human ankle joint. Change in implant dimension has been suggested, may result in better implant lifespan. The effect of design parameter towards wear generation were analysed the thickness and radial contact of meniscal bearing.

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.

From December 1991 to April 1995, 70 consecutive New Jersey low-contact stress (LCS) total knee arthroplasties (TKAs) were performed. Twenty two TKAs were done using rotating platform tibial component, and 48 were done using meniscal bearing tibial component. Two patients sustained bearing insert failure at eight years after primary TKA. Subluxation of tibiofemoral articulation occurred in one case, secondary to increased polyethylene wear and ligamentous instability. It was corrected easily by the insertion of a thicker bearing. The other case had patellar bearing breakage with delamination, but patellofemoral maltracking was not seen. The polyethylene of the patellar component was changed, improving the condition of both patients with relief of pain. Component failure, especially polyethylene wear and breakage were found to occur frequently.

Insertion of the bearing can be challenging due to patient body habitus or limited exposure when using a minimally invasive technique. We describe a novel way of inserting the bearing not previously described in the literature. The bearing is positioned on the femoral component in full flexion. Then, with a gentle extension of the knee, the bearing snaps into position and is seated correctly on a consistent basis.

We experienced two cases of atypical lateral dislocations of meniscal bearing in UKA (unicompartmental knee arthroplasty) without manifest symptoms. The dislocated bearing, which jumped onto the wall of tibial components, was found on radiographs in periodic medical examination although they could walk. Two thicker size bearing exchanges were promptly performed before metallosis and loosening of components. Continual examination is important to mobile bearing type of UKA because slight or less symptoms may disclose such unique dislocation. One case showed malrotation of the femoral component on 3D image. Anteroposterior view hardly disclosed the malrotation of the femoral component. Epicondylar view is an indispensable view of importance, and it can demonstrate the rotation of the femoral component. The the femoral distal end is wedge shaped and is wider posteriorly. If the femoral component is set according to the shape of medial condyle, the femoral component shifts to medial site compared with tibial component in flexion. It can account for such rare dislocation as follows. If excessive force applies on most medial side of the bearing during flexion, the lateral part of the bearing pops and the force squeezes it laterally simultaneously. Finally, the bearing jumps onto the lateral wall of the tibial component.

Clinical results of the initial cemented and cementless series of 373 New Jersey Low Contact Stress total knee replacements in 282 patients surviving at least 10 years were analyzed using a strict knee scoring scale. The study showed excellent, good, fair, or poor results in 68.1%, 29.8%, 2.1%, or 0% of primary posterior cruciate-retaining meniscal bearing knee replacements, 46.7%, 53.3%, 0%, or 0% results in primary cemented rotating platform knee replacements, and 68.1%, 29.8%, 2.1%, or 0% results in primary cementless rotating platform knee replacements, respectively. Radiographic evaluation at minimum 10-year followup showed stable fixation of all components, no gross migration but significant osteolysis requiring bearing exchange and bone grafting in three cementless rotating platform knee replacements (1.8%) in three patients who underwent previous surgeries at an average of 10.2 years from the index surgery. Survivorship of the patients who underwent primary cementless posterior cruciate-retaining meniscal bearing knee replacements with an end point of revision for any mechanical reason was 97.4% at 10 years and 83% at 16 years; using an end point of a poor clinical knee score the survivorship was 98.9% at 10 years and at 16 years. Survivorship of the patients who underwent primary cemented rotating platform knee replacements with end points of revision for any mechanical reason or a poor clinical knee score was 97.7% at 10 years and at 20 years. Survivorship of the patients who underwent cementless rotating platform knee replacements with end points of revision for any mechanical reason or a poor clinical knee score was 98.3% at 10 years and at 18 years.

Buts de l'étude: Présentation d'une série de 21 prothèses totales de cheville non cimentées à ménisque et analyse des résultats à court terme. Matériel et méthode: 21 prothèses totales de cheville ont été implantées chez 21 patients d'un âge moyen de 63.5 ans. L'origine de l'arthrose était post-traumatique ou primaire. Notre recul moyen est de 21 mois. Résultats: Les résultats ont été évalués en utilisant le score de Koefod. 11 patients ont obtenu un excellent, 7 un bon résultat et 2 un résultat moyen. Un cas fut un échec et a nécessité une arthrodèse. Discussion: La prothèse totale de cheville non cimentée à ménisque permet d'obtenir à court terme une bonne indolence et une bonne fonction malgré un faible gain des amplitudes articulaires. Ces résultats apparaissent comme encourageants.

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.

From January 1985 to December 1990, 598 consecutive New Jersey low-contact stress (LCS) total knee arthroplasties (TKAs) were performed for gonarthrosis. Among these 598 operations, 322 were with rotating platform elements and 276 were with meniscal bearing elements. During 5 to 8 years of follow-up, eight knees had severe symptomatic polyethylene failure that required revision surgery; all eight cases were meniscal bearing types. The failed polyethylene inserts were retrieved and studied. It was observed that there were four probable failure mechanisms associated with the catastrophic polyethylene wear. First, insufficient thickness of the meniscal bearing was the major reason for wear. Second, the malpositioning of the metal tibial tray in the transverse plane resulted in the breaking of the meniscal bearing. Third, the inability of the patellar to rotate due to tissue ingrowth made the polyethylene break. Last, yellowing of the subsurface of the meniscal bearing was a sign of polyethylene failure. These four possible failure mechanisms are all associated with the design of the meniscal bearing type of LCS knee prostheses. Therefore, it is suggested that the design of the LCS knee prosthesis should be modified.

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.

We present the case of a 79-year-old man who dislocated the mobile bearing of a well-functioning Oxford unicompartmental knee replacement in a fall. The diagnosis was delayed by 14 days during which time the patient remained fully mobile. At the time of arthrotomy, there was some visible burnishing of the femoral articular surface where it had been rubbing on the tibial component. Both components were soundly fixed and had been functioning well for 7 years. The decision was made to leave the components in situ and simply replace the mobile meniscal bearing. The patient returned to full normal activity and has been followed-up for 3.5 years. Serial X-rays reveal no evidence of polyethylene wear and the knee remains pain free and fully functional. We conclude that it is safe to retain the components of an Oxford unicompartmental knee replacement despite some evidence of surface damage. Replacing just the mobile meniscus gave a good result in our patient.

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

Anteroposterior (AP) joint translation is an important indicator of good clinical outcome following total knee arthroplasty (TKA). This study evaluated the in vivo relationship between changes in the degree of voluntary soft tissue tension and flexion angle versus simultaneous AP translation after TKA. A posterior cruciate ligament (PCL)-retaining meniscal-bearing design was investigated in 20 knees of 20 patients. AP translation was measured at 30° and 75° flexion with the KT-2000 arthrometer while patients were anesthetized and non-anesthetized. The mean translations at 30° and 75° were 10.5 and 10.4 mm, respectively, in non-anesthetized patients and 13.8 and 12.7 mm, respectively, in patients under anesthesia. AP translation showed a significant positive correlation with soft tissue tension (p

A new design of 3-part ankle replacement was developed to achieve compatibility with the natural ligaments by allowing certain fibres to remain isometric during passive motion. From July 2003 to April 2008 we have implanted 70 ankle prostheses. The mean age at surgery was 61.5 years (range 29.7-82.5). Mean follow-u is 6,4 years (5-9 years). Radiographs showed good alignment, no loosening and little signs of progressive radiolucency. The preoperative AOFAS score was 38.4 and at last follow-up increased to77,9. Function and Range-of-motion scored better than previous total ankles. Two revisions necessitated component removal, neither for implant failure. These results demonstrate that non-anatomically shaped talar and tibial components, with a fully conforming interposed meniscal bearing, can provide satisfactory clinical results in the short term.

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.

The short-term results of 46 knees in 37 patients treated by LCS total knee systems were evaluated clinically and radiologically. The models used were the Rotating Platform type in 22 knees and the Meniscal Bearing type in 24 knees. Using the criteria described by three universities, the average clinical score after operation achieved by the Rotating Platform type was 88.9 points and 86.4 points for the Meniscal Bearing type. Component placement angle was good and follow-up revealed that the components remained in place. We found radiolucent lines in 69.6% and subsidence in 21.7% of the cases, but no further worsening was observed. The motion of the meniscal insert during bending fell into three groups; forward shift, backward shift and no shift. The range of motion was significantly wider in the backward shift group (flexion: average 132°), but there was no difference among the three groups in regard to clinical results.

Background An original total ankle replacement design was developed with the aim of establishing compatibility between the prosthetic articulating surfaces and the retained ligaments. This was achieved with a special shape of a conforming meniscal bearing, free to move forwards/ backwards on both metal components during dorsi/ plantar flexion. Careful kinematics analyses were carried out in patients after this replacement to assess the functional performance during activity of daily living. A thorough assessment shall include standard gait analysis (GA) and the more accurate motion tracking of the components by 3D fluoroscopic analysis (FA).

Meniscal bearing fracture is a rare complication of phase III Oxford unicompartmental knee replacement (UKR). We report a case of a meniscal bearing fracture that occurred 7 years after phase III Oxford medial UKR. The meniscal bearing showed uneven delamination of the polyethylene in the thinnest articular surface and an impingement lesion. This lesion initiated a fatigue crack that propagated to cause failure of the meniscal bearing. This is the first report of a meniscal bearing fracture without a posterior marker wire.

There are two basic types of unicompartmental knee designs, namely, fixed and mobile-bearing designs. Within the mobile-bearing genre, the bearing can be either constrained (usually on a track) or completely unconstrained. Since the late 1970s, there have been two major designs implanted in patients; the low contact stress (LCS)™ implant (Dupuy Orthopaedics Inc., Warsaw, Indiana) (1) and the Oxford™ unicompartmental knee implant (Biomet Inc., Warsaw, Indiana) (2). Th e LCS™ has partial constraint of the bearing within an articulating tibial track, where as the Oxford™ system consists of a freely moving bearing. More recently, the Preservation™ mobile-bearing UKA (J&J/Depuy Orthopaedics Inc., Warsaw, Indiana) has been introduced with a similar design to the LCS, that is, having partial constraint of the bearing.

This study evaluated changes in the lower extremity 3-dimensional load-bearing mechanical axes in the anteroposterior and mediolateral directions before and at 3 weeks after mobile-bearing total knee arthroplasty. The effects of the degrees of anteroposterior constraint of the designs on the location of the load-bearing mechanical axis at the knee joint level were also assessed. We evaluated 151 knees from 134 patients with 74 knees receiving meniscal bearing-type and 77 knees receiving rotating platform-type prostheses. In the mediolateral direction, both designs showed significant improvements, whereas in the anteroposterior direction, they revealed no improvements postoperatively and were worsened significantly in meniscal bearing type. Differences in the degree of bone and soft tissue involvement for the correction of alignment may explain the findings.

The mobile meniscal bearing of unicompartmental knee arthroplasty is completely free moving, and dislocation of this bearing is a major concern for all mobile-bearing designs. Most dislocations are located in the intracapsular area; however, posterior dislocation of the polyethylene bearing to an extra-articular area of the knee after unicompartmental arthroplasty has not been previously reported. During a revision surgery, separate incision was necessary to remove a dislocated meniscal bearing in the popliteal fossa. The authors present a case of incarceration of a dislocated mobile bearing to the popliteal fossa after unicompartmental knee arthroplasty that was missed during initial diagnosis.

We recovered 23 meniscal bearings from 18 failed bicompartmental Oxford knee prostheses. They had been implanted for one to nine years. The minimum thickness of the retrieved bearings was measured and compared with the thickness of 25 unused bearings. The mean penetration rate, calculated by two methods, was either 0.043 or 0.026 mm per annum. This compares with 0.19 mm per annum reported for the Charnley hip. The use of a fully congruous meniscal bearing prosthesis can reduce wear in knee arthroplasty to a very low rate.

The purpose of this article is to review the early complications of minimally invasive mobile-bearing unicompartmental knee arthroplasty by analyzing the first 100 consecutive cases. All cases were medial unicompartmental arthroplasties with a follow-up of at least 24 months (range, 24-51 months). Seven revision procedures were performed due to 2 fractures of the medial tibial plateau, 1 loosening of the femoral component, and 4 dislocations of the meniscal bearing. The early results as determined by The Knee Society scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and postoperative range of motion were satisfactory. However, there exists a high rate of early failures, which occurred during the initial learning curve. Therefore, surgeons must be aware that in order to minimize these complications, attention to detail is mandatory.