No difference in outcomes and gait analysis between mechanical and kinematic knee alignment methods using robotic total knee arthroplasty

PURPOSE: The purpose of this study was to compare clinical outcomes and perform gait analysis during walking to identify differences in kinematic and kinetic parameters between two alignment methods in robotic-assisted total knee arthroplasty (TKA). METHODS: Sixty patients were randomly assigned to undergo robotic-assisted TKA using either mechanical (30 patients) or kinematic (30 patients) alignment method. Clinical outcomes including varus and valgus laxities, range of motion (ROM), Hospital for Specific Surgery (HSS), Knee Society Score (KSS), and Western Ontario and McMaster Universities (WOMAC) scores and radiological outcomes were evaluated. Gait analysis of 3D spatiotemporal, kinetic, and kinematic parameters during walking was then performed for 10 age and gender matched patients of each group to determine differences between the two alignment methods. RESULTS: The median follow-up duration of the mechanical method group was 8.7 (range 8.1-9.4) years and that of the kinematic method group was 8.4 (range 8.0-9.1) years. Clinical outcomes between the two groups showed no significant difference in HSS, WOMAC, ROM, KS pain, or function score at the last follow-up. No significant difference in varus and valgus laxity assessment, mechanical alignment of the lower limb, or perioperative complications was shown between the two groups. In gait analysis, no significant difference in kinematic or kinetic parameters was found except for varus angle (p < 0.05) and mediolateral ground reaction force (p < 0.05). CONCLUSIONS: Results of this study show that mechanical and kinematic knee alignment methods provide comparable clinical and radiological outcomes after robotic total knee arthroplasty with an average follow-up of 8 years. There were no functional difference during walking between the two alignment methods either. LEVEL OF EVIDENCE: II.