Abstract
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%.
The abstracts were prepared by Mr Matt Costa and Mr Ben Ollivere. Correspondence should be addressed to Mr Costa at Clinical Sciences Research Institute, University of Warwick, Clifford Bridge Road, Coventry CV2 2DX, UK.
