Long-term clinical results of the Oxford medial unicompartmental knee arthroplasty.

The purposes of this study were to investigate the mode of failure and survivorship of an independently performed series of medial Oxford unicompartmental knee arthroplasties. The study included 43 knees in 40 patients with a mean follow-up of 14.88 years: 13 knees (11 patients) had revision surgery (30%), and ten patients required conversion to total knee prosthesis. The mean International Knee Society (IKS) scores at the time of the revision were 145.52 [standard deviation (SD): 39.90, range: 167-200]. The overall alignment of the knee was restored to neutral, with a hip-knee-ankle (HKA) angle average of 178° (SD: 3.21°, range: 170-186°). Survivorship, as defined by an endpoint of failure for any reason, showed that the survival rate at five years was 90%, at ten years 74.7% and at 15 years 70%. Excluding inappropriate patient selection and surgeon-associated failures, our survival analysis plot is much improved: survivorship at five years is 94.5%, at ten years 85.7% and at 15 years 80.4%. The Oxford meniscal bearing arthroplasty offers long-term pain relief with good knee function. Unfortunately, we demonstrated a high complication rate, with some of the failures encountered indicating that the surgical technique is very demanding.