Revision of isolated patellofemoral arthroplasty to total knee replacement

Background Patellofemoral arthroplasty is becoming an established treatment for isolated patellofemoral arthritis. Revision to total knee replacement occasionally is required. Lessons learned from patients requiring revision surgery and their subsequent post-revision outcomes are described. Method This study reviewed 49 patellofemoral arthroplasties in 43 patients who had revision to a total knee replacement. These cases were obtained from a cohort of 487 patellofemoral arthroplasties prospectively reviewed between 1989 and 2006. Results The most common reason for revision was progression of arthritis in the tibiofemoral joint (30 knees in 26 patients). Persistent pain from technical error was found in 11 knees (10 patients), and 4 knees in 4 patients had unexplained persistent pain. The revision procedure was straightforward with no technical difficulties. All patients had a primary cemented total knee replacement without requiring bone grafting or prosthetic augmentation. The patients reported significant improvements in the Oxford Knee Score (26/48 points) P = 0.003 and the Bristol Pain Score (25/40 points) P = 0.0001 compared with the scores before patellofemoral arthroplasty. The outcomes were less favorable than expected and were worse than those seen after a successful primary patellofemoral arthroplasty. Conclusion Reasons for patellofemoral arthroplasty failure were identified. Patellofemoral arthroplasty was easy to revise to a primary knee arthroplasty; however, good clinical results could not be guaranteed. These results emphasize the need for careful patient selection and precise surgical technique during the primary operation.