Mechanical Versus Kinematic Alignment in Total Knee Arthroplasty: Relationship Between Postoperative Alignment and Short-Term Functional Outcomes

Background/Objectives: Mechanical alignment (MA) has traditionally been the reference alignment strategy in total knee arthroplasty (TKA), whereas kinematic alignment (KA) has emerged as an individualized alternative intended to approximate patient-specific knee anatomy. However, the relationship between postoperative mechanical-axis alignment and functional recovery remains incompletely understood. This study aimed to compare short-term functional outcomes and postoperative mechanical-axis alignment between MA and KA following primary TKA and to investigate the relationship between measured postoperative alignment parameters and functional outcomes.

Methods

This single-center retrospective comparative cohort study included 120 patients who underwent primary unilateral TKA for end-stage knee osteoarthritis (KOA) between January 2022 and December 2024; 51 underwent MA and 69 underwent KA. Radiographic assessment included the hip–knee–ankle (HKA) angle, mechanical-axis deviation (MAD), residual varus deformity, and radiographic knee extension deficit. Functional outcomes were assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Knee Society Score (KSS). Preoperative, postoperative, and change-from-baseline (Δ) functional scores were evaluated. Analysis of covariance (ANCOVA) was used to assess associations between alignment strategy and postoperative functional outcomes after adjustment for baseline functional scores and relevant covariates. Associations between postoperative radiographic parameters and functional outcomes were additionally assessed.