Impact of Tibiofemoral Compartment Gaps on Patient-reported Outcome Measures Following Robotic-assisted Total Knee Arthroplasty

This study explores the impact of tibiofemoral compartment gaps on patient-reported outcome measures (PROMs) following robotic-assisted total knee arthroplasty (RA-TKA). A retrospective review was conducted on 2,071 patients who underwent RA-TKA between April 2018 and January 2022. Patient demographic data, surgical data, intraoperative tibiofemoral gap measurements, and PROMs (Knee Injury and Osteoarthritis Outcome Score for Joint Replacement [KOOS JR], Visual Analogue Scale [VAS], Forgo!en Joint Score [FJS], and Oxford Knee Score [OKS] scores) were collected. Unadjusted analyses were conducted using Kruskal-Wallis and Mann-Whitney U tests. The mean postoperative medial flexion-extension (FE) gap delta was -0.3 mm, with only 0.6% of cases beyond two millimeters, whereas the mean lateral FE gap delta was 1.1 mm, with 16.1% of cases exceeding two millimeters. No significant PROM differences were observed between extreme quartile gap deltas. However, for one surgeon, patients with higher OKS scores had significantly smaller lateral FE gap deltas (p = 0.004). These findings suggest that differences in tibiofemoral compartment gaps following RA-TKA were not associated with clinically significant differences in PROMs. (Journal of Surgical Orthopaedic Advances 34(4):196–202, 2025)

Key words: total knee arthroplasty, robotic knee arthroplasty, patient-reported outcomes, tibiofemoral gap, Mako robotic surgery