EARLY RE-INTERVENTION FOLLOWING OXFORD UNI-COMPARTMENTAL KNEE REPLACEMENT

Introduction: Unicompartmental knee replacement (UKR) is a popular alternative to total knee replacement (TKR) in medial compartment disease. Early problems include bearing dislocation, persistent pain, stiffness and infection. Revision to TKR is well described as a late endpoint. Objective: Investigate the early surgical management of persistent pain and debility following UKR, identify common themes and rate effectiveness of any re-intervention. Methods: 381 UKRs implanted over 5 years included, and patients requiring re-operation reviewed retrospectively. Findings: 27 re-operations performed on 17 patients at a mean 16.8 months (95% CI 9.5 to 24.1), with symptom onset post-operatively at 9 months (95% CI 4–14). There were 10 arthroscopies, 10 total knee replacements (revision), 4 manipulations under anaesthesia, 2 bearing exchanges, and 1 tibial-plateau fracture fixation. Manipulation under anaesthesia improved stiffness in 2 of 3 patients. Arthroscopy was successful in 2 patients with loose cement-bodies but did not provide a diagnosis in 8 patients, of whom 7 were revised subsequently after 17.1 months (95% CI 10.1 to 24.1) with 6 reporting symptom resolution. Overall there were 10 revisions: 9 were performed for persistent pain and 9 reported symptom improvement. Intra-operative findings included aseptic loosening (n=4), synovitis (n=2), increased posterior slope of the tibial cut (n=1), dislocated bearing (n=1), and no cause of failure in 2. Only two cases required revision implants with medial augments for bone loss. There were no deep infections. Conclusions: The early re-intervention rate at our unit is 4.5% (95% CI 2.4 to 6.5), with a revision rate of 2.6% (95% CI 1.0 to 4.2) after a mean (±SD) follow-up of 40.1 (±16) months. Arthroscopy is a poor diagnostic and therapeutic option against persistent pain following UKR. In contrast, the decision to revise, although initially disappointing for both patient and surgeon, gave symptom improvement in 90%.