Aim: To assess the intra- and inter-observer reliability of using pre-operative templates in selecting the appropriate prosthetic size of the unicompartmental knee system (Oxford Phase3, Biomet Merck, Bridgend) Methods: Ten observers estimated the size of the unicondylar knee prosthesis required for thirty randomly selected patients with osteoarthritis. Estimation of the size was gauged using templates pre-operatively. AP and lateral radiographs were taken of each patient. All observers were orthopaedic surgeons with a minimum of þve years experience in orthopaedic surgery and with a general interest in joint arthroplasty. The observations were recorded independently and repeated measurements were taken two weeks later. Results: Intra- and inter-observer discrepancies were evaluated using the weighted kappa (κ) coefþcient with signiþcant intra- and inter-observer variations. The results are shown in the table.

Conclusions: Pre-operative radiological templating is of questionable beneþt in patients undergoing Oxford Phase 3 knee arthroplasty.