Abstract
BACKGROUND: Posterior tibial slope (PTS) is believed to influence range of motion (ROM) and functional outcomes after total knee arthroplasty (TKA), particularly in cruciate-retaining and posterior-stabilized designs. However, limited data exist on its impact in mobile-bearing systems. This study evaluated whether variations in PTS affect ROM and patient-reported outcome measures (PROMs) following mobile-bearing TKA using the Buechel-Pappas design. METHODS: This was a retrospective, single center cohort study on 359 patients who underwent cemented mobile-bearing TKA between 2018 and 2022, with a minimum follow-up of 2 years. Patients were stratified into three PTS categories: <4°, 4-7°, and >7° and analyzed. Functional outcomes were assessed using the Oxford Knee Score (OKS), Forgotten Joint Score (FJS), maximal knee ROM, and complications. RESULTS: Patient had a mean follow-up of 2.8 years (SD = 0.9) with a mean age was 61.3 (SD = 7.7) years. Baseline demographic characteristics were comparable between the 3 cohorts. Mean postoperative ROM improved significantly from 75.2° to 95.3°, and mean OKS from 16.2 to 34.5 (p < 0.001). However, no significant differences in ROM, OKS, or FJS were observed between PTS groups (p > 0.05). Analysis of change in PTS between pre-operative to post-operative showed no significant difference. ROC analyses and logistic regression demonstrated poor predictive ability of PTS for functional outcomes. CONCLUSION: Variations in posterior tibial slope within typical clinical ranges (<4°, 4-7°, >7°), as well as the degree of change in slope achieved from preoperative to postoperative alignment, did not significantly affect postoperative range of motion or patient-reported outcomes following mobile-bearing total knee arthroplasty.