Does patellar resurfacing matter in robotic-assisted total knee arthroplasty with functional alignment principles?

Purpose: While new philosophies in total knee arthroplasty (TKA) aim to optimize alignment and ligament balancing, restoring the anterior compartment and understanding the consequences of patella resurfacing remain challenging. This study evaluates the functional consequences of anterior compartment restoration, with a specific focus on patella resurfacing when performing robotic-assisted TKA using functional alignment (FA) principles.

Methods: This retrospective comparative study included 268 patients affected by an end-stage varus osteoarthritis who underwent robotic TKA according to FA principles. Patients were divided into two main groups based on whether patellar resurfacing procedure was performed (study group) or not (control group). Restoration of the anterior compartment and functional outcomes were evaluated using radiographic assessments, along with the Knee Society Score (KSS Knee and KSS Function), Forgotten Joint Score (FJS) and Kujala Score, all recorded at a minimum follow-up of 2 years.

Results: One hundred thirty-eight cases underwent patellar resurfacing and 130 did not. Patellar tilt and patellar translation were reduced by 74.63% (p < 0.005) and 69.89% (p < 0.005) in the resurfaced group compared to the non-resurfaced group, respectively. The patellar offset values showed no significant differences between the two groups (p = 0.873), although both groups showed a significant reduction in patellar offset in the post-operative compared to the preoperative, 10.31% and 14.29%, respectively, in the resurfaced and non-resurfaced groups (p < 0.05). KSS knee and functional scores were higher in the non-resurfaced group compared to the resurfaced group (p = 0.023 and p = 0.017, respectively). Kujala and FJS scores were similar between the two groups.

Conclusion: Both resurfaced and non-resurfaced approaches improve radiographic outcomes regarding the anterior knee compartment after TKA performed with FA and image-based robotic system, without signs of superiority in clinical outcomes in the resurfaced group. The decision of patella resurfacing can be made on an individualized basis.

Level Of Evidence: Level II.