We systematically reviewed the published literature on the complications of closing wedge high tibial osteotomy for the treatment of unicompartmental osteoarthritis of the knee. Publications were identified using the Cochrane Library, MEDLINE, EMBASE and CINAHL databases up to February 2012. We assessed randomised (RCTs), controlled group clinical (CCTs) trials, case series in publications associated with closing wedge osteotomy of the tibia in patients with osteoarthritis of the knee and finally a Cochrane review. Many of these trials included comparative studies (opening wedge versus closing wedge) and there was heterogeneity in the studies that prevented pooling of the results

Aims

The aim of this study was to compare ten-year longitudinal healthcare costs and revision rates for patients undergoing unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA).

This randomised trial evaluated the outcome of a single design of unicompartmental arthroplasty of the knee (UKA) with either a cemented all-polyethylene or a metal-backed modular tibial component. A total of 63 knees in 45 patients (17 male, 28 female) were included, 27 in the all-polyethylene group and 36 in the metal-backed group. The mean age was 57.9 years (39.6 to 76.9). At a mean follow-up of 6.4 years (5 to 9.9), 11 all-polyethylene components (41%) were revised (at a mean of 5.8 years; 1.4 to 8.0) post-operatively and two metal-backed components were revised (at one and five years). One revision in both groups was for unexplained pain, one in the metal-backed group was for progression of osteoarthritis. The others in the all-polyethylene group were for aseptic loosening. The survivorship at seven years calculated by the Kaplan–Meier method for the all-polyethylene group was 56.5% (95% CI 31.9 to 75.2, number at risk 7) and for the metal-backed group was 93.8% (95% CI 77.3 to 98.4, number at risk 16) This difference was statistically significant (p <  0.001). At the most recent follow-up, significantly better mean Western Ontario and McMaster Universities Arthritis Index Scores were found in the all-polyethylene group (13.4 vs 23.0, p = 0.03) but there was no difference in the mean Knee injury and Osteoarthritis Outcome scores (68.8; 41.4 to 99.0 vs 62.6; 24.0 to 100.0), p = 0.36). There were no significant differences for range of movement (p = 0.36) or satisfaction (p = 0.23). This randomised study demonstrates that all-polyethylene components in this design of fixed bearing UKA had unsatisfactory results with significantly higher rates of failure before ten years compared with the metal-back components. Cite this article: Bone Joint J 2015;97-B:786–92

Aims. There has been a recent resurgence in interest in combined partial knee arthroplasty (PKA) as an alternative to total knee arthroplasty (TKA). The varied terminology used to describe these procedures leads to confusion and ambiguity in communication between surgeons, allied health professionals, and patients. A standardized classification system is required for patient safety, accurate clinical record-keeping, clear communication, correct coding for appropriate remuneration, and joint registry data collection. Materials and Methods. An advanced PubMed search was conducted, using medical subject headings (MeSH) to identify terms and abbreviations used to describe knee arthroplasty procedures. The search related to TKA, unicompartmental (UKA), patellofemoral (PFA), and combined PKA procedures. Surveys were conducted of orthopaedic surgeons, trainees, and biomechanical engineers, who were asked which of the descriptive terms and abbreviations identified from the literature search they found most intuitive and appropriate to describe each procedure. The results were used to determine a popular consensus. Results. Survey participants preferred “bi-unicondylar arthroplasty” (Bi-UKA) to describe ipsilateral medial and lateral unicompartmental arthroplasty; “medial bi-compartmental arthroplasty” (BCA-M) to describe ipsilateral medial unicompartmental arthroplasty with patellofemoral arthroplasty; “lateral bi-compartmental arthroplasty” (BCA-L) to describe ipsilateral lateral unicompartmental arthroplasty with patellofemoral arthroplasty; and tri-compartmental arthroplasty (TCA) to describe ipsilateral patellofemoral and medial and lateral unicompartmental arthroplasties. “Combined partial knee arthroplasty” (CPKA) was the favoured umbrella term. Conclusion. We recommend bi-unicondylar arthroplasty (Bi-UKA), medial bicompartmental arthroplasty (BCA-M), lateral bicompartmental arthroplasty (BCA-L), and tricompartmental arthroplasty (TCA) as the preferred terms to classify CPKA procedures. Cite this article: Bone Joint J 2019;101-B:922–928

Abstract. Introduction. Patient selection is key to the success of medial unicondylar knee arthroplasty (UKA). Progression of arthritis is the most common indication for revision. Various methods of assessing the lateral compartment have been used including stress radiography, radioisotope bone scanning, MRI, and visualisation at the time of surgery. Arthroscopy is another means of assessing the integrity of the lateral compartment. Methods. We used per-operative arthroscopy as a means to confirm suitability for UKA in a consecutive series of 279 Oxford medial UKA. This study reports the long-term results of a previously published cohort of knees. Our series of UKA with per-operative arthroscopy (Group 1) was compared to all Oxford UKA (Group 2) and all UKA in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) (Group 3). Results. The 14-year cumulative percentage revision (CPR) was 18.5% (95% CI 12.7, 26.4) for group 1, 19.7% (95% CI 18.8, 20.6) for group 2, and 19.2% (95% CI 18.5, 19.8) for group 3. There was no statistically significant difference in the (CPR) for the entire period when group 1 was compared to groups 2 or 3. Progression of arthritis was the indication for revision in similar proportions for the three groups (Group 1: 32.3%, Group 2: 35.7% and Group 3: 33.5%). Following per-operative arthroscopy 21.6% (77/356) of knees underwent a change of surgical plan from UKA to TKA. Conclusion. Per-operative arthroscopy may improve medium-term medial unicompartmental knee survivorship but does not improve long-term survivorship nor reduce revision due to progression of arthritis

The purpose of this paper was to investigate the predictability of outcome of a consecutive series of cemented unicompartmental or total knee replacements in a single surgeon series. Between September 2006 and February 2009, ninety-nine cemented, fixed bearing TKR were performed with patellar resurfacing. 52 cemented Miller Galante (Zimmer) Tibio-femoral UKR were performed in the same time interval. The minimum follow up was 6 months. Oxford and AKSS knee scores were collected prospectively at pre-operative and at routine follow up appointments. Pre-operative mean AKSS Knee score for TKR group was 33.9 and improved to 84.2 at 1 year. Mean scores for Tibiofemoral UKR were 40.4 improving to 84.3 at 1 year. Pre-operative mean Oxford knee score for TKR group was 34.6 (28%) and improved to 16.6 (65%) at 1 year. Mean scores for UKR were 28.5 (41%) improving to 14.0 (71%) at 1 year. These data would suggest that unicompartmental replacement performs as well as TKR. However, in the TKR group, 59% achieved a knee score >85 and 23% an Oxford score >80%. In the UKR group, 67% achieved knee score >85 and 45% an Oxford score >80%. Conversely, only 5% of TKR achieved knee score <50 and 20% Oxford score <50% whilst 10% of UKR had a knee score <50 and 26% and Oxford score <50%. These data show that whilst mean outcomes for TKR and UKR look similar, TKR offers a more predictable outcome with fewer clinical failures but also fewer excellent results. UKR offers a more polarised set of outcomes with far more clinically excellent results but also more clinical failures. These data can inform the ongoing debate regarding the role of unicompartmental arthroplasty. Patient selection is clearly critical but remains an inexact process

Patellofemoral unicompartmental joint replacement is a controversial subject with a relatively small evidence base. Of the 50,000 total knee arthroplasties performed each year in the UK, approximately 10% are performed for predominantly patellofemoral arthritis. There are several patellofemoral unicompartmental prostheses on the market with the National Joint Registry recording 745 such prostheses used in 2007. Most evidence in favour of this procedure comes from experience with the Avon prosthesis (Stryker) predominantly from designer-surgeons. The FPV patellofemoral joint replacement (Wright Medical) has been in use in Europe for several years. The instruments have recently been redesigned and the device marketed in the UK. In 2007 the FPV had 5.9% market share (n=44). We present our early experience with the FPV patellofemoral joint replacement, which to our knowledge, is the first clinical outcome series for this prosthesis. 33 consecutive FPV joint replacements in 29 patients were performed between April 2007 and September 2009 for unicompartmental patellofemoral OA. All cases were performed or directly supervised by the senior author. Results are presented with a minimum follow-up of six months. Oxford and American Knee Society scores (AKSS) were obtained on all patients preoperatively and at subsequent outpatient visits. Mean preoperative AKSS knee score was 49.7 points and postoperative scores at 6 months and 1 year were 82.5 and 86.4 respectively. Mean Oxford score preoperatively was 30.4 (37%) and at 6 months and 1 year were 21.3 (56%) and 11.2 (77%) respectively. There were no complications related to the implant. One knee required a secondary open lateral release due to inadequate balancing at the index procedure. Further medium to long-term follow up data are required, but our initial experience with this device is encouraging

Aims. Primary (or spontaneous) and secondary osteonecrosis of the knee can lead to severe joint degeneration, for which either total or unicompartmental arthroplasty may be considered. However, there are limited studies analyzing outcomes of unicompartmental knee arthroplasties (UKAs) for osteonecrosis involving an isolated compartment of the knee. The aims of this study were to analyze outcomes of UKAs for osteonecrosis with specific focus on 1) survivorship free of any revision or reoperation, 2) risk factors for failure, 3) clinical outcomes, and 4) complications. Patients and Methods. A total of 45 patients underwent 46 UKAs for knee osteonecrosis between 2002 and 2014 at our institution (The Mayo Clinic, Rochester, Minnesota). Twenty patients (44%) were female; the mean age of the patients was 66 years, and mean body mass index (BMI) was 31 kg/m. 2. Of the 46 UKAs, 44 (96%) were medial UKAs, and 35 (76%) were fixed-bearing design. Mean mechanical axis postoperatively was 1.5° varus (0° to 5° varus); 41 UKAs (89%) were performed for primary osteonecrosis. Mean follow-up was five years (2 to 12). Results. Survivorship free of any revision in the cohort was 89% (95% CI 77 to 99) and 76% (95% CI 53 to 99) at five and ten years, respectively. In patients undergoing UKA for primary osteonecrosis survivorship free of any revision was 93% (95% CI 83 to 100)at both five and ten years. Secondary osteonecrosis was a significant risk factor for poorer survivorship free of any revision or reoperation (hazard ratio 7.7, p = 0.03). Three medial UKAs (6.5%) were converted to total knee arthroplasties (TKAs): two for lateral compartment degeneration and one for development of lateral osteonecrosis. No implants were revised for loosening, fracture, or wear. Knee Society scores improved from a mean of 60 (44 to 72) preoperatively to a mean of 94 postoperatively (82 to 100) (p < 0.001). There were no surgical complications. Conclusion. When done for primary osteonecrosis of the knee, UKA resulted in reliable clinical improvement, minimal complications, and durable estimated implant survivorship free of revision at ten years. UKA done for secondary osteonecrosis was substantially less durable at mid-term follow-up. Progression of knee degeneration, rather than implant failure or loosening, was most common indication for conversion to TKA. Cite this article: Bone Joint J 2018;100-B:450–4

Retrieval studies have shown that the use of fully congruent meniscal bearings reduces wear in knee replacements. We report the outcome of 143 knees with anteromedial osteoarthritis and normal anterior cruciate ligaments treated by unicompartmental arthroplasty using fully congruous mobile polyethylene bearings. At review, 34 knees were in patients who had died and 109 were in those who were still living. The mean elapsed time since operation was 7.6 years (maximum 13.8). We established the status of all but one knee. There had been five revision operations giving a cumulative prosthetic survival rate at ten years (33 knees at risk) of 98% (95% CI 93% to 100%). Considering the knee lost to follow-up as a failure, the ‘worst-case’ survival rate was 97%. No failures were due to polyethylene wear or aseptic loosening of the tibial component. One bearing which dislocated at four years was reduced by closed manipulation. The ten-year survival rate is the best of those reported for unicompartmental arthroplasty and not significantly different from the best rates for total knee replacement

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

Progressive degenerative changes in the medial compartment of the knee following lateral unicompartmental arthroplasty (UKA) remains a leading indication for revision surgery. The purpose of this study is to evaluate changes in the congruence and joint space width (JSW) of the medial compartment following lateral UKA. The congruence of the medial compartment of 53 knees (24 men, 23 women, mean age 13.1 years; . sd. 62.1) following lateral UKA was evaluated pre-operatively and six weeks post-operatively, and compared with 41 normal knees (26 men, 15 women, mean age 33.7 years;. sd . 6.4), using an Interactive closest point algorithm which calculated the congruence index (CI) by performing a rigid transformation that best aligns the digitised tibial and femoral surfaces. Inner, middle and outer JSWs were measured by sub-dividing the medial compartment into four quarters on pre- and post-operative, weight bearing tunnel view radiographs. The mean CI of knees following lateral UKA significantly improved from 0.92 . (sd . 0.06) pre-operatively to 0.96 . (sd . 0.02) (p < 0.001) six weeks post-operatively. The mean CI of the healthy control group was 0.99 sd 0.01. Post-operatively, the mean inner JSW increased (p = 0.006) and the outer decreased (p = 0.002). The JSW was restored post-operatively as no significant differences were noted in all three locations compared with the control group (inner JSW p = 0.43; middle JSW p = 0.019, outer JSW p = 0.51). . Our data suggest that a well conducted lateral UKA may improve the congruence and normalise the JSW of the medial compartment, potentially preventing progression of degenerative change. . Cite this article: Bone Joint J 2015;97-B:50–5

Background. The cemented mobile bearing metal backed low contact stress patellofemoral arthroplasty (LCS PFA) is a newer design belonging to the second generation of inlay type implant, based on the more successful knee arthroplasty model. The advantage is the patella can articulate with the trochlear implant as well as the femoral component of a total knee replacement (TKR). Patients. This series is a cohort of 21 patients who underwent 24 (3 bilateral) unicompartmental PFA replacements for isolated patellofemoral osteoarthritis. We have used the mobile bearing LCS PFA in all of them. There were 3 males and 18 females. Average age was 51(40-58) years. The Oxford Knee score was used to assess the results. Results. At the latest follow-up averaging 2.7 (0.5 to 4) years, 9 patients showed excellent improvement in their knee scores, 5 patients showed fair improvement and 7 patients very little. There were 9 revisions in 7 patients either due to mechanical problems or with persistent symptoms. We had 4 patients with mechanical complications who underwent revision and 4 patients had a conversion to TKR. The revision rate at 2 years was 33%. There were no infections or loosening of trochlear implants. Conclusion. The revision rate for this implant seems to be very high and mainly with the patellar implant (at the metal polyethylene interface). The Australian Orthopaedic association annual joint registry report 2008 reported a higher revision rate for the same implant at 5% from a pool of 1057 patients. The young active patient having a patellofemoral replacement may put extreme force on their patellar implant. We strongly advocate patellofemoral arthroplasties to be analysed separately from the unicompartmental knees in the National Joint Registries to highlight any persistent issues with this implant

The Oxford unicompartmental knee replacement (UKR) is an established treatment option in the management of symptomatic end-stage medial compartmental osteoarthritis (MCOA), which works well in the young and active patient. However, previous studies have shown that it is reliable only in the presence of a functionally intact anterior cruciate ligament (ACL). This review reports the outcomes, at a mean of five years and a maximum of ten years, of 52 consecutive patients with a mean age of 51 years (36 to 57) who underwent staged or simultaneous ACL reconstruction and Oxford UKR. At the last follow-up (with one patient lost to follow-up), the mean Oxford knee score was 41 (. sd. 6.3; 17 to 48). Two patients required conversion to TKR: one for progression of lateral compartment osteoarthritis and one for infection. Implant survival at five years was 93% (95% CI 83 to 100). All but one patient reported being satisfied with the procedure. The outcome was not significantly influenced by age, gender, femoral or tibial tunnel placement, or whether the procedure was undertaken at one- or two-stages. In summary, ACL reconstruction and Oxford UKR gives good results in patients with end-stage MCOA secondary to ACL deficiency

The Oxford mobile-bearing unicompartmental knee replacement (UKR) is an effective and safe treatment for osteoarthritis of the medial compartment. The results in the lateral compartment have been disappointing due to a high early rate of dislocation of the bearing. A series using a newly designed domed tibial component is reported. The first 50 consecutive domed lateral Oxford UKRs in 50 patients with a mean follow-up of three years (2.0 to 4.3) were included. Clinical scores were obtained prospectively and Kaplan-Meier survival analysis was performed for different endpoints. Radiological variables related to the position and alignment of the components were measured. One patient died and none was lost to follow-up. The cumulative incidence of dislocation was 6.2% (95% confidence interval (CI) 2.0 to 17.9) at three years. Survival using revision for any reason and aseptic revision was 94% (95% CI 82 to 98) and 96% (95% CI 85 to 99) at three years, respectively. Outcome scores, visual analogue scale for pain and maximum knee flexion showed a significant improvement (p < 0.001). The mean Oxford knee score was 43 (. sd. 5.3), the mean Objective American Knee Society score was 91 (. sd. 13.9) and the mean Functional American Knee Society score was 90 (. sd. 17.5). The mean maximum flexion was 127° (90° to 145°). Significant elevation of the lateral joint line as measured by the proximal tibial varus angle (p = 0.04) was evident in the dislocation group when compared with the non-dislocation group. Clinical results are excellent and short-term survival has improved when compared with earlier series. The risk of dislocation remains higher using a mobile-bearing UKR in the lateral compartment when compared with the medial compartment. Patients should be informed about this complication. To avoid dislocations, care must be taken not to elevate the lateral joint line.

Aims

In the last decade, interest in partial knee arthroplasties and bicruciate retaining total knee arthroplasties has increased. In addition, patient-related outcomes and functional results such as range of movement and ambulation may be more promising with less invasive procedures such as bicompartmental arthroplasty (BCA). The purpose of this study is to evaluate clinical and radiological outcomes after a third-generation patellofemoral arthroplasty (PFA) combined with a medial or lateral unicompartmental knee arthroplasty (UKA) at mid- to long-term follow-up.

We determined the outcome of 56 ‘Oxford’ unicompartmental replacements performed for anteromedial osteoarthritis of the knee between 1982 and 1987. Of these, 24 were in patients who had died without revision, one was lost to follow-up and two had been revised. Of the remaining 29 knees, 26 were examined clinically and radiologically, two were only examined clinically and one patient was contacted by telephone. The mean age of the patients was 80.3 years. At a mean follow-up of 11.4 years (10 to 14) the measurements of the knee score, range of movement and degree of deformity were not significantly different from those made one to two years after operation, except that the range of flexion had improved. Comparison of fluoroscopically-controlled radiographs at a similar interval of time showed no change in the appearance of the lateral compartments. The retained articular cartilage continued to function for ten or more years which suggests that anteromedial osteoarthritis may be considered as a focal disorder of the knee. This justifies continued efforts to develop methods of treatment which preserve intact joint structures

Background

Lateral Unicompartmental Knee Arthroplasty (UKA) is a recognised treatment option in the management of lateral Osteoarthritis (OA) of the knee. Whilst there is extensive evidence on the indications and contraindcations in Medial UKA there is limited evidence on this topic in Lateral UKA. The aim of this study was to assess our experience of mobile lateral UKR and to look specifically at the effect of Contraindications on the outcome.

Between 1989 and 1992 we had 102 knees suitable for unicompartmental knee replacement (UKR). They were randomised to receive either a St Georg Sled UKR or a Kinematic modular total knee replacement (TKR). The early results demonstrated that the UKR group had less complications and more rapid rehabilitation than the TKR group. At five years there were an equal number of failures in the two groups but the UKR group had more excellent results and a greater range of movement.

The cases were reviewed by a research nurse at 8, 10 and 12 years after operation. We report the outcome at 15 years follow-up. A total of 43 patients (45 knees) died with their prosthetic knees intact. Throughout the review period the Bristol knee scores of the UKR group have been better and at 15 years 15 (71.4%) of the surviving UKRs and 10 (52.6%) of the surviving TKRs had achieved an excellent score. The 15 years survivorship rate based on revision or failure for any reason was 24 (89.8%) for UKR and 19 (78.7%) for TKR. During the 15 years of the review four UKRs and six TKRs failed.

The better early results with UKR are maintained at 15 years with no greater failure rate. The median Bristol knee score of the UKR group was 91.1 at five years and 92 at 15 years, suggesting little functional deterioration in either the prosthesis or the remainder of the joint. These results justify the increased use of UKR.

Aims

It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee arthroplasty (TKA) because conversion surgery to a primary TKA is a less complicated procedure. The purpose of this study was to determine if there is a lower threshold for revising a UKA compared with TKA based on Oxford Knee Scores (OKSs) and range of movement (ROM) at the time of revision.

Aims

Approved by the Food and Drug Administration in 2004, the Phase III Oxford Medial Partial Knee is used to treat anteromedial osteoarthritis (AMOA) in patients with an intact anterior cruciate ligament. This unicompartmental knee arthroplasty (UKA) is relatively new in the United States, and therefore long-term American results are lacking.