Functional, patient-reported, and radiographic outcomes of kinematic versus mechanical alignment in robotic total knee arthroplasty: A systematic review and meta-analysis.

BACKGROUND

Robotic-assisted total knee arthroplasty (TKA) has emerged as a promising approach to enhance precision in implant positioning and alignment, yet the optimal alignment strategy remains unresolved. This study aimed to systematically compare radiographic and patient-reported outcomes of kinematic (KA) and mechanical alignment (MA) in robot-assisted TKA.

METHODS

A comprehensive search of PubMed, Embase, and Scopus was performed from inception until July 2025, as per the PRISMA guidelines. Eligible studies included randomized control trials and comparative observational studies directly comparing KA and MA in primary robotic-assisted TKA. Outcomes assessed included Visual Analog Scale (VAS) pain, Oxford Knee Score (OKS), range of motion (ROM), Forgotten Joint Score (FJS), and radiographic parameters (hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA)). Pooled standardized mean differences (SMDs) and 95% confidence intervals were calculated using a random effects model. Heterogeneity was evaluated using I2 statistics, and sensitivity analyses were performed.

RESULTS

Twelve studies (1470 patients) were included in the meta-analysis. KA demonstrated significant advantages over MA in OKS (SMD: 0.27, P = 0.02), FJS (SMD: 0.50, P = 0.0007), ROM (SMD: 0.21, P = 0.01) and early pain reduction (<6 months; SMD: -0.77, P = 0.05). Radiographically, KA better preserved native limb anatomy, reflected by lower HKA (SMD: -0.57, P < 0.0001), MPTA (SMD: -2.04, P = 0.0001), and mLDFA (SMD: 0.91, P < 0.0001).

CONCLUSION

Robot-assisted KA-TKA yields improved short- to mid-term functional outcomes and more anatomical joint restoration than MA. These findings support KA as a promising alignment strategy; however, long-term, multicentric trials are essential to confirm its durability and safety.