Purpose: This study attempts to quantify the influence of constraint and various indications upon functional outcome following aseptic first-time revision knee arthroplasty.
Methods: A single-centre prospective study was performed to examine the outcome for 175 consecutive total revision knee replacements performed between 2003 and 2008 with a minimum follow-up of 2 years. Patient-reported outcome data were used to determine the influence of final level of component constraint, its relationship with primary indication for surgery and the predictor variable for functional outcome at 1 year.
Results: All patients were found to have a significant improvement for WOMAC pain, function and stiffness score and physical functioning, role physical, bodily pain and social functioning components of SF-36 score. About 69% were satisfied with the overall procedure. WOMAC function, pain and stiffness score was significantly worse for patients revised for instability (27%) compared to that for aseptic loosening (46%). A significantly higher proportion of patients were satisfied with the procedure, had a better quality of life and would have the surgery again in the aseptic loosening group as compared to the instability group. Revision to a higher level of constraint did not improve knee function irrespective of the primary indication for surgery.
Conclusion: This study has found that revision for instability, irrespective of choice of new device, was met with significantly poorer functional outcome. The level of constraint did not influence functional outcome.
Level of evidence: II.