Abstract
Background
Unicompartmental knee arthroplasty provides a good alternative to total knee arthroplasty in patients with isolated medial compartment osteoarthritis. There has been variable reporting in the literature as to whether age and sex affect the survival of unicompartmental knee arthroplasty. The aim of this study was to determine whether age and sex were predictors of failure for the Oxford unicompartmental knee arthroplasty.
Methods
Details of consecutive patients undergoing Oxford unicompartmental knee arthroplasty at our centre between January 2000 and December 2009 were collected prospectively. Failure of the implant was defined as conversion to total knee arthroplasty. Survival was determined using the Kaplan-Meier method. A Cox proportional hazard model was used to determine the affect of age and sex on survivorship of the prosthesis.
Results
There were 494 Oxford unicompartmental knee arthroplasties implanted in 425 patients for isolated medial compartment osteoarthritis. Mean age was 62.8 yr (range 34.6–90.1 yr) and 53.4% were female. During a mean follow-up time of 3.0 yr (range 0.5–9.2 yr), twenty-two knees (4.5%) were revised to a total knee arthroplasty with an 8-year survival for the cohort of 87.4%. Age had a statistically significant impact on survival (p=0.018), with increasing age associated with improved survival of the prosthesis. Sex was not demonstrated to be a statistically significant predictor of failure.
Discussion
Our findings demonstrate that decreasing age was a predictor of failure of the Oxford unicompartmental knee arthroplasty, but sex had no impact on failure of the prosthesis. It is therefore recommended that age should be taken into account when younger patients are being considered for Oxford unicompartmental knee arthroplasty. In addition, preoperatively patients should be counselled appropriately regarding the increased risk of revision surgery.
