Secondary Patellar Resurfacing Following Primary Unresurfaced Total Knee Arthroplasty: Beware of the Incidence of Late Patellar Erosion.

INTRODUCTION: The primary aim of this study was to evaluate secondary patellar resurfacing (SPR) indications and rates in a single surgeon series utilizing a modern TKA design and additionally, to review the functional outcomes of patients after undergoing SPR.

METHODS: A retrospective review of a prospectively collected institutional database was performed. All patients undergoing primary TKA by a single surgeon between 2013 and 2021 were included. During this time, the senior surgeon resurfaced the patella selectively. Patients were divided into the primary resurfaced group (PR) and the unresurfaced group (UR). All patients undergoing SPR in the UR group were identified, their radiographs reviewed, and their clinical outcomes assessed. During the study period, 1,511 TKAs were performed, with 73.1% (1,105 TKAs) being unresurfaced.

RESULTS: The all-cause revision rate was 1.2% in the PR group and 3.6% in the UR group. The rate of SPR in the UR group was 2.0% (22 of 1,105 TKAs). No patient in the PR group underwent revision surgery for a patellar complication. The mean age at primary TKA for those undergoing SPR was 65 years (range, 50 to 78). The average time for SPR from primary TKA was 3.4 years (range, 1.1 to 8.8). Postoperative radiographic progression of patellar erosion, in combination with new onset anterior knee pain, was the indication for SPR in 14 of the 22 (63.7%) SPR cases. Post SPR, the Western Ontario and McMaster University Osteoarthritis Index score (P < 0.001) and Knee Society Score (P < 0.001) improved from pre-SPR.

CONCLUSION: Secondary patellar resurfacing was the most common(55%) reason for revision surgery post-primary unresurfaced TKA in this series. A SPR improved clinical outcomes in symptomatic patients. Surgeons should consider patellar resurfacing for all patients undergoing primary TKA to reduce the burden of revision surgery post-TKA. Additionally, the paradigm that late SPR does not improve clinical outcomes needs to be revisited.