Long-term results of per-operative knee arthroscopy in confirming suitability for unicompartmental arthroplasty

Patient selection is key to the success of medial unicondylar knee arthroplasty (UKA). Progression of arthritis is the most common indication for revision surgery. Per-operative arthroscopy is a means of directly assessing the integrity of the lateral compartment. The aim of the study is to assess the long-term survivorship of UKA performed when per-operative arthroscopy is used as a final means of deciding whether to proceed with UKA. We used per-operative arthroscopy as a means to confirm suitability for UKA in a consecutive series of 279 Oxford medial UKA. Our series of UKA with per-operative arthroscopy (Group 1) was compared to all Oxford UKA (Group 2) and all UKA in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) (Group 3). The 14-year cumulative percentage revision (CPR) was 18.5% (95% CI 12.7, 26.4) for group 1, 19.7% (95% CI 18.8, 20.6) for group 2, and 19.2% (95% CI 18.5, 19.8) for group 3. There was no statistically significant difference in the (CPR) for the entire period when group 1 was compared to groups 2 or 3. Progression of arthritis was least in Group 1 compared to groups 2 and 3; 3.6 versus 4.4 and 4.1% respectively. Following per-operative arthroscopy 21.6% (77/356) of knees underwent a change of surgical plan from UKA to TKA. In our practice, which includes per-operative arthroscopy, we have identified a reduced risk of revision due to progression of arthritis but no difference in overall long-term implant survivorship.