Abstract
Purpose: Resurgence in mobile bearing unicompartmental arthroplasty o the knee has come to Canada in last 3 years. This has been attributed to the popularity of minimally invasive surgery, improved instrumentation, and encouraging outcome results from the developers and others. A prospective study was undertaken at an academic institution to evaluate the initial experience with the first 400 Oxford knees.
Methods: Oxford unicompartmental knees have been implanted since Feb 2001 at our institution. A majority of these were entered into the Ontario Joint Registry. All others were retrieved from hospital records to capture 100% of all cases done form our institution. All surgeons attended an Oxford training course. The main outcome of interest was repeat surgery revision for any cause, including revision.
Results: Three hundred and fifty Oxford knees with minimum 1 year follow up were available for study. Three surgeons have implanted 90 % of the implants. Fourteen patients have come to revision surgery as of October 1, 2005 for an incidence of 3,7 %. Causes include rapid lateral compartment deterioration (6), persisting medial pain (6), and medial collateral ligament disruption (1). Ten were revised to ttoal knee arthroplasty (8 cruciate retaining and 2 posterior stabilized), except the ligament disruption, which was reconstructed with Achilles allograft. Two others had open debridement for medial pain. This rate of revision is higher than reported in literature. Severe obesity (BMI > 35) was a factor in 4 failures.
Conclusions: Our experience was not as successful as reported in the literature from the prosthesis designers. Causes include poor technique and inappropriate indications when scrutinized closely. The temptation to stretch indications must be tempered by acceptance of higher revision rate than reported in literature and should be part of informed consent. Survivorship should be institution specific and not that of original published data from the developers.
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
