Kinematic alignment versus mechanical alignment in total knee arthroplasty: a systematic review and meta-analysis of medium to long-term outcomes.

PURPOSES: To compare medium- to long-term patient-reported outcomes, objective function, pain, range of motion, and revision/reoperation risk between kinematic (KA) and mechanical alignment (MA) in primary total knee arthroplasty (TKA) using randomized trials. METHODS: A systematic review and meta-analysis followed PRISMA and Cochrane guidelines. Randomized controlled trials comparing KA and MA in primary TKA with ≥ 24 months follow-up were identified through PubMed, Scopus, Cochrane, and Web of Science. Pooled mean or standardized mean differences and risk ratios were calculated using random-effects models. Outcomes were stratified into mid-term (24-60 months) and long-term (> 60 months) windows. Certainty of evidence was assessed using GRADE. RESULTS: Ten unique RCTs (13 articles, 934 knees, follow-up 2-13 years) were included. Mid-term analyses favored KA in Forgotten Joint Score (MD 4.06, 95% CI 2.39-5.74), WOMAC (MD -5.51, 95% CI -10.27 to -0.74), and VAS pain (MD -0.39, 95% CI -0.58 to -0.19). Long-term follow-up revealed no significant functional differences. Revision risks were comparable (RR 1.32, 95% CI 0.59-2.93). Certainty of evidence ranged from moderate (OKS, VAS) to very low (FJS, WOMAC, KSS, ROM). CONCLUSION: KA yields modest mid-term improvements in awareness and pain over MA, though differences rarely reached clinical importance thresholds. Long-term outcomes, survivorship, and complications were comparable. KA is a viable personalized TKA strategy, pending confirmation from larger randomized trials.