Revision of unicompartmental knee arthroplasty versus primary total knee arthroplasty.

The risk of revision following unicompartmental arthroplasty (UKA) is greater compared with primary total knee arthroplasty (TKA). Some surgeons report that UKA revision is straightforward with outcomes comparable to TKA. We reviewed all Oxford medial UKAs and TKAs performed at our institution over a five year period. Patient reported outcomes were compared between revised UKAs, successful UKAs and primary TKAs. Out of 546 Oxford medial UKAs, twenty-nine (5.3%) were revised at a mean of 25months. The commonest indications for revision were aseptic loosening and progression of osteoarthritis. Ten patients (34%) required augments, stemmed implants or bone grafts. Outcomes following revision were poorer than those following successful UKA and primary TKA, and were a consequence of poor pre-operative function rather than the complexity of surgery.