Aims

The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

Aims

The objectives of this study were to compare postoperative pain, analgesia requirements, inpatient functional rehabilitation, time to hospital discharge, and complications in patients undergoing conventional jig-based unicompartmental knee arthroplasty (UKA) versus robotic-arm assisted UKA.

Aims

The role of high tibial osteotomy (HTO) is being questioned by the use of unicompartmental knee arthroplasty (UKA) in the treatment of medial compartment femorotibial osteoarthritis. Our aim was to compare the outcomes of revision HTO or UKA to a total knee arthroplasty (TKA) using computer-assisted surgery in matched groups of patients.

We present detailed information about early morbidity after aseptic revision knee replacement from a nationwide study. All aseptic revision knee replacements undertaken between 1st October 2009 and 30th September 2011 were analysed using the Danish National Patient Registry with additional information from the Danish Knee Arthroplasty Registry. The 1218 revisions involving 1165 patients were subdivided into total revisions, large partial revisions, partial revisions and revisions of unicondylar replacements (UKR revisions). The mean age was 65.0 years (27 to 94) and the median length of hospital stay was four days (interquartile range: 3 to 5), with a 90 days re-admission rate of 9.9%, re-operation rate of 3.5% and mortality rate of 0.2%. The age ranges of 51 to 55 years (p = 0.018), 76 to 80 years (p < 0.001) and ≥ 81 years (p < 0.001) were related to an increased risk of re-admission. The age ranges of 76 to 80 years (p = 0.018) and the large partial revision subgroup (p = 0.073) were related to an increased risk of re-operation. The ages from 76 to 80 years (p < 0.001), age ≥ 81 years (p < 0.001) and surgical time > 120 min (p <  0.001) were related to increased length of hospital stay, whereas the use of a tourniquet (p = 0.008) and surgery in a low volume centre (p = 0.013) were related to shorter length of stay. . In conclusion, we found a similar incidence of early post-operative morbidity after aseptic knee revisions as has been reported after primary procedures. This suggests that a length of hospital stay ≤ four days and discharge home at that time is safe following aseptic knee revision surgery in Denmark. Cite this article: Bone Joint J 2014;96-B:1649–56

Current analysis of unicondylar knee replacements (UKRs) by national registries is based on the pooled results of medial and lateral implants. Consequently, little is known about the differential performance of medial and lateral replacements and the influence of each implant type within these pooled analyses. Using data from the National Joint Registry for England and Wales (NJR) we aimed to determine the proportion of UKRs implanted on the lateral side of the knee, and their survival and reason for failure compared with medial UKRs. By combining information on the side of operation with component details held on the NJR, we were able to determine implant laterality (medial versus lateral) for 32 847 of the 35 624 unicondylar replacements (92%) registered before December 2010. Of these, 2052 (6%) were inserted on the lateral side of the knee. The rates of survival at five years were 93.1% (95% confidence interval (CI) 92.7 to 93.5) for medial and 93.0% (95% CI 91.1 to 94.9) for lateral UKRs (p = 0.49). The rates of failure remained equivalent after adjusting for patient age, gender, American Society of Anesthesiologists (ASA) grade, indication for surgery and implant design using Cox’s proportional hazards method (hazard ratio for lateral relative to medial replacement = 0.88 (95% CI 0.69 to 1.13); p = 0.32). Aseptic loosening/lysis and unexplained pain were the main reasons for revision in both groups, although the reasons did vary depending on whether a mobile- or a fixed-bearing design was used. At a maximum of eight years the mid-term survival rates of medial and lateral UKRs are similar

We carried out a prospective investigation into the radiological outcomes of uncemented Oxford medial compartment unicondylar replacement in 220 consecutive patients (231 knees) performed in a single centre with a minimum two-year follow-up. The functional outcomes using the mean Oxford knee score and the mean high-activity arthroplasty score were significantly improved over the pre-operative scores (p < 0.001). There were 196 patients with a two-year radiological examination performed under fluoroscopic guidance, aiming to provide images acceptable for analysis of the bone–implant interface. Of the six tibial zones examined on each knee on the anteroposterior radiograph, only three had a partial radiolucent line. All were in the medial aspect of the tibial base plate (zone 1) and all measured < 1 mm. All of these patients were asymptomatic. There were no radiolucent lines seen around the femoral component or on the lateral view. There was one revision for loosening at one year due to initial inadequate seating of the tibial component. These results confirm that the early uncemented Oxford medial unicompartmental compartmental knee replacements were reliable and the incidence of radiolucent lines was significantly decreased compared with the reported results of cemented versions of this implant. These independent results confirm those of the designing centre.

Anterior knee pain and/or radiological evidence of degeneration of the patellofemoral joint are considered to be contraindications to unicompartmental knee replacement. The aim of this study was to determine whether this is the case.

Between January 2000 and September 2003, in 100 knees (91 patients) in which Oxford unicompartmental knee replacements were undertaken for anteromedial osteoarthritis, pre-operative anterior knee pain and the radiological status of the patellofemoral joint were defined using the Altman and Ahlback systems. Outcome was evaluated at two years with the Oxford knee score and the American Knee Society score.

Pre-operatively 54 knees (54%) had anterior knee pain. The clinical outcome was independent of the presence or absence of pre-operative anterior knee pain. Degenerative changes of the patellofemoral joint were seen in 54 patients (54%) on the skyline radiographs, including ten knees (10%) with joint space obliteration. Patients with medial patellofemoral degeneration had a similar outcome to those without. For some outcome measures patients with lateral patellofemoral degeneration had a worse score than those without, but these patients still had a good outcome, with a mean Oxford knee score of 37.6 (SD 9.5). These results show that neither anterior knee pain nor radiologically-demonstrated medial patellofemoral joint degeneration should be considered a contraindication to Oxford unicompartmental knee replacement. With lateral patellofemoral degeneration the situation is less well defined and caution should be observed.

A postal questionnaire was sent to 10 000 patients more than one year after their total knee replacement (TKR). They were assessed using the Oxford knee score and were asked whether they were satisfied, unsure or unsatisfied with their TKR. The response rate was 87.4% (8231 of 9417 eligible questionnaires) and a total of 81.8% (6625 of 8095) of patients were satisfied. Multivariable regression modelling showed that patients with higher scores relating to the pain and function elements of the Oxford knee score had a lower level of satisfaction (p < 0.001), and that ongoing pain was a stronger predictor of this. Female gender and a primary diagnosis of osteoarthritis were found to be predictors of lower levels of patient satisfaction. Differences in the rate of satisfaction were also observed in relation to age, the American Society of Anesthesiologists grade and the type of prosthesis.

This study has provided data on the Oxford knee score and the expected levels of satisfaction at one year after TKR. The results should act as a benchmark of practice in the United Kingdom and provide a baseline for peer comparison between institutions.