Restoration of the anterior compartment after robotic total knee arthroplasty significantly improves functional outcome and range of motion at 1 year.

Abstract

This study aims to assess the functional outcomes based on restoring the anterior compartment after total knee arthroplasty (TKA). This retrospective study included 96 primary TKAs performed between 2021 and 2022. Functional positioning principles were applied using an image-based robotic-assisted system. The mean age was 69.2 ± 7.9 years. Knee Society Score (KSS), Kujala score, Forgotten Joint Score (FJS) and knee flexion were collected preoperatively and at 1 year. The depth difference between native and prosthetic trochlea was measured to assess anterior compartment restoration at full extension, 30°, 70° and 90° flexion. The global anterior compartment restoration combined the anterior compartment restoration and the patellar thickness restoration. The trochlear offset was mostly understuffed after TKA compared to the native anatomy, mainly for medial and lateral condyles at 30° and 70° of flexion. The global anterior compartment restoration was understuffed in full extension (-0.7 mm ± 2), at 30° (-4.4 mm ± 2) and 70° of flexion (-3.6 mm ± 2.5). At 90°, the global anterior compartment restoration was overstuffed (2.2 mm ± 1.8). Functional scores were not significantly influenced by the anterior compartment stuffing at 0° and 30° (n.s.). The anterior compartment overstuffing at 70° and 90° was associated with decreased KSS function score (p = 0.009) and flexion (p = 0.04). Moderate anterior understuffing was frequently observed after TKA performed with functional positioning and an image-based robotic-assisted system. This understuffing did not influence the functional outcomes. The overstuffing of the anterior compartment led to a reduction in KSS function score and flexion measurements at 1 year. Level III, retrospective cohort study.