Comparison of Patellar Tracking Following Kinematic Alignment Versus Mechanical Alignment Total Knee Arthroplasty via the Mini-Subvastus Approach.

Abstract

Objectives: Different alignment strategies (kinematic alignment [KA] versus mechanical alignment [MA]) during total knee arthroplasty (TKA) significantly influence postoperative patellar tracking. This study aimed to compare radiological parameters of patellar tracking and clinical outcomes between KA-TKA and MA-TKA via the mini-subvastus approach.

Methods: This prospective randomized controlled study included 234 patients who underwent KA-TKA and MA-TKA from January 2022 to October 2023. The preoperative and postoperative patellar tilt, lateral patellar shift, knee society score (KSS), oxford knee score (OKS), and intraoperative patellar lateral retinacular release (LRR) rate were measured. In addition, radiological parameters and clinical outcomes were compared between the LRR and non-LRR groups. Independent samples t test and chi-square test were used to compare the differences between groups.

Results: Two-hundred and thirty-four patients were followed up for 12 months post-TKA. No significant differences were observed between the two groups in terms of the demographics and pre- or post-operative radiological parameters of patellar tracking (p > 0.05). The postoperative KSS and OKS were significantly higher in the KA group than in the MA group (p < 0.05). The LRR rate was 6.7% (8/120) in the KA group and 25.4% (29/114) in the MA group, and the difference was statistically significant (x² = 15.476, p < 0.001). The preoperative patella tilt and lateral patellar shift were greater in the LRR group (p < 0.001) and the postoperative OKS was lower (p < 0.05).

Conclusions: KA-TKA via the mini-subvastus approach can achieve both good patellar tracking and clinical outcomes. Avoiding muscle damage and refraining from excessive soft tissue release are crucial to improving postoperative patient comfort. In our opinion, KA-TKA via the mini-subvastus approach may be a more suitable surgical option.