Impact of implant generation on the outcomes in medial pivot total knee arthroplasty: a systematic review.

Abstract

Medial pivot total knee arthroplasty (TKA) was developed to reproduce native knee kinematics and improve function. Second-generation designs introduced refinements to enhance medial conformity and lateral rollback, but their clinical benefit remains uncertain. This systematic review compared outcomes of first- and second-generation medial pivot implants. A comprehensive search of PubMed, Web of Science, Embase, and Google Scholar was performed in August 2025 following PRISMA guidelines. Comparative and non-comparative studies reporting outcomes after first- or second-generation medial pivot TKA were included. Primary endpoints were Knee Society Score (KSS), functional subscale (KSS-F), Oxford Knee Score (OKS), WOMAC, Forgotten Joint Score (FJS), range of motion (ROM), and revision rates. Twenty-four studies including 4686 patients (3541 first-generation; 1145 s-generation) were analysed. Most baseline variables were comparable, though BMI, follow-up duration, and baseline WOMAC and ROM showed minor differences. At the latest follow-up, KSS, KSS-F, WOMAC, and FJS showed no significant differences. Revision rates were similar. OKS was slightly lower in the second-generation cohort (MD -2.5, p = 0.04), and ROM was greater (MD 4.6°, p = 0.01), but both fell below minimal clinically important difference thresholds. First- and second-generation medial pivot TKAs achieved comparable outcomes and survivorship. Although second-generation designs showed statistical improvements in ROM and OKS, these were not clinically relevant. These findings suggest that while design refinements of second-generation implants may offer minor biomechanical advantages, they do not translate into significant improvements in patient-reported outcomes. Surgical decision-making should be based on the surgeon's experience, implant availability, and patient-specific factors rather than expectations of superior performance from newer designs. Level III.