Alignment strategy does not confer clinically meaningful advantages in medial pivot total knee arthroplasty: a systematic review and meta-analysis.

Abstract

<h4>Introduction</h4>Medial pivot total knee arthroplasty (TKA) has been developed to reproduce physiological tibiofemoral kinematics and improve patient satisfaction. The choice of alignment philosophy, whether mechanical alignment (MA) or kinematic alignment (KA), may influence outcomes in this context, yet evidence remains conflicting. This systematic review and meta-analysis aimed to compare clinical, functional, and radiological outcomes as well as revision rates between MA and KA in medial pivot TKA.<h4>Methods</h4>A systematic search was conducted in PubMed, Web of Science, Embase, and Google Scholar in August 2025, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Comparative and non-comparative clinical studies reporting outcomes of medial pivot TKA performed with either MA or KA were included. Data extracted included Knee Society Score (KSS), KSS functional subscale (KSS-F), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), Forgotten Joint Score (FJS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Range of Motion (ROM), and revision rates. Meta-analyses were performed when at least two studies reported comparable data.<h4>Results</h4>Thirty-five studies comprising 5,216 patients were included, of whom 4,325 underwent medial pivot TKA with MA and 891 with KA. The dataset consisted of 12 comparative studies and 22 single-arm cohorts. Mean follow-up across studies was 62.4 months (range 12-180). At baseline, the two groups were comparable in age, sex distribution, and most outcome measures, although the KA group presented with a higher BMI and greater ROM. At final follow-up, there were no qualitatively significant differences in KSS, OKS, WOMAC, KOOS, or FJS between groups. The KA group achieved a statistically greater ROM (mean difference 4.9°, p = 0.01), and pooled analysis demonstrated a higher FJS (MD 8.36, 95% CI 4.18 to 12.55, p < 0.0001). However, the magnitude of these differences did not exceed the minimal clinically important difference. Revision rates and complication profiles were comparable between alignment strategies, although follow-up timepoints varied across studies.<h4>Conclusion</h4>Both kinematic and mechanical alignment in medial pivot TKA yielded reliable improvements in clinical and functional outcomes, with only minor differences in motion and joint awareness that did not reach thresholds of clinical relevance. Surgical decision-making should therefore prioritise intraoperative soft tissue balance, implant-specific design, and surgeon expertise rather than the expectation of meaningful superiority of one alignment philosophy over the other.