PATELLA RESURFACING DOES NOT IMPROVE OUTCOMES IN PATIENTS WITH POSTOPERATIVE FLEXION CONTRACTURE AFTER PRIMARY TOTAL KNEE ARTHROPLASTY

Objective: Biomechanical studies have shown that flexion contracture leads to higher patellofemoral compressive forces with potentially poorer outcomes. We studied the outcome of primary knee arthroplasty with or without patella resurfacing in patients presenting with postoperative flexion contracture to determine if patella resurfacing improves the outcome. Materials and Methods: We retrospectively reviewed the registry data at the Singapore General Hospital from 1998-2014. Of 18074 primary knee replacements carried out, 665 knees were identified with postoperative flexion contracture greater than 10 degrees at 2 years follow-ups, out of which 562 knees were included in the study. One hundred and three patients were lost to follow-ups. All the infected cases were excluded from the study. Knees with patella resurfaced (227) were compared with knees with patella non-resurfaced (335) using Oxford Knee Score, Knee Society Clinical Scoring System, and SF-36. A handheld goniometer was used for measurements by an independent assessor and a physiotherapist. Analysis of factors for prognostic importance was performed using the R statistics. Results: At two years follow-ups, the non-resurfaced patella group had significantly higher median knee flexion compared to the resurfaced group. Age, male gender, preoperative flexion, and patella resurfacing were found to be significant predictors for knee flexion at two years. Outcome scores did not differ significantly between the two groups. Conclusion: No significant difference in outcome scores was observed in resurfaced versus non-resurfaced patella groups in patients with more than 10 degrees’ postoperative flexion contracture after primary knee arthroplasty. Keywords: Patella Resurfacing, Flexion contracture