Aims

The treatment of patients with allergies to metal in total joint arthroplasty is an ongoing debate. Possibilities include the use of hypoallergenic prostheses, as well as the use of standard cobalt-chromium (CoCr) alloy. This non-designer study was performed to evaluate the clinical outcome and survival rates of unicondylar knee arthroplasty (UKA) using a standard CoCr alloy in patients reporting signs of a hypersensitivity to metal.

Aims

The aim of this independent multicentre study was to assess the mid-term results of mobile bearing unicondylar knee arthroplasty (UKA) for isolated lateral osteoarthritis of the knee joint.

Introduction:

The os-calcis is the most common tarsal bone to fracture. It can lead to a debilitating arthritis and has considerable socio-economic implications.

In the literature there is great debate as to whether operative or non-operative management has a better outcome. Previous smaller case series report improved results from surgery whereas the one randomised trial showed no overall benefit from surgery. However sub-group analysis identified patients that had a better outcome with operative management. Results from the UK heel fracture trial are awaited. We present a 5 year series from a single centre, single surgeon that includes 143 fractures. There are currently no comparable published data.

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.

There are a multitude of studies internationally that have considered the rates of redislocation of shoulders, where, after first time anterior dislocation, initial management has consisted of an internal rotation sling immobiliser or no immobility. The majority of these have indicated poor results. This is in comparison with recurrence rates of dislocation, post shoulder stabilisation (arthroscopic or open), after first time anterior dislocation, which have demonstrated excellent results.

The question remains, is there a non-operative alternative that will give similarly good results for these patients.

A selection criteria was set up for use of the external rotation brace for first time anterior dislocators. Thirty-five patients were used that fit the criteria and were able to be followed over time. A physiotherapy program was initiated at the two-week stage in combination with clinic reviews. We encouraged use of the brace for six weeks in total, with removal only for hygiene purposes. At two years, post first time anterior dislocation, patients were reviewed clinically and a quick DASH score performed. Any recurrence of dislocation was recorded and an MRI was also undertaken to show residual injury.

The compliance with the brace and physiotherapy program were excellent, with only one reported redislocation, during this period, in the 31 patients that were followed up. The majority of patients were functioning at predislocation levels at review and no one had required surgical intervention for instability. Quick-Dash results were also very good, with a vast majority scoring less than 2/100 level of disability.