Abstract
Background
A number of studies have reported on the early failure of the Oxford unicompartmental knee arthroplasty. However, less evidence is available regarding the outcome following revision of failed unicompartmental knee prostheses to total knee arthroplasty.
Study aims
The study aims were to determine the time to failure and mode of failure for the Oxford unicompartmental knee arthroplasty and to assess the short-term outcome following revision surgery.
Methods
Details of consecutive patients undergoing revision of an Oxford unicompartmental knee arthroplasty to a total knee arthroplasty at our centre between January 2000 and December 2009 were collected prospectively. Data was collected on patient demographics, time to revision, and revision indication. Clinical, functional and radiological outcome following revision were assessed.
Results
Of 494 Oxford unicompartmental knee arthroplasties implanted, 20 (4.0%) were revised to a total knee arthroplasty. Mean age at revision was 63.5 yr and 50% were male. Mean time to revision surgery from the index procedure was 3.2 yr (range 1.2-6.2 yr). The commonest reason for revision was aseptic loosening of the femoral (n=9) or tibial component (n=2). All patients were revised to a cemented total knee arthroplasty. Three patients required femoral and/or tibial augments. During follow-up (range 0.5-4.5 yr) there was one case of superficial wound infection. One patient underwent a further revision for instability 1.5 years following the initial revision procedure.
Discussion
The present study demonstrates most failures of the Oxford unicompartmental knee arthroplasty are due to aseptic component loosening, occur within four years, and do not require femoral or tibial augmentation when revised. These findings are consistent with other published reports regarding the early failure of this prosthesis. The short-term outcome following revision surgery appears to be good, however longer follow-up periods are required to determine if these results continue.
