Impact of implant design and surgical technique on medial stability and outcomes after cruciate-sacrificing total knee arthroplasty.

Abstract

Medial stability has been considered a key determinant of favorable outcomes after total knee arthroplasty (TKA). This study aimed to investigate the association between postoperative medial joint stability and clinical outcomes and to identify factors influencing medial joint stability. One hundred and sixty-five primary cruciate-sacrificing TKAs were analyzed. Three implant designs were used: bicruciate-stabilized (BCS), posterior-stabilized (PS), and cruciate-sacrificing (CS) implants. Surgeries were performed by two surgical teams, with Surgical Team A characterized by a strategy of minimal medial soft-tissue release. Medial joint stability was assessed using stress radiographs under a 150-N varus or valgus load in extension. Knees with a medial opening angle (MOA) <3° were included in the medial tight group, and those with an MOA ≥3° were included in the medial loose group. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was used to evaluate clinical outcomes 1 year after surgery. Multivariate regression analysis was performed to identify factors influencing medial stability. The medial tight group demonstrated significantly higher KOOS activities of daily living, sports, and quality of life scores than the loose group. Among the implant designs, BCS TKA knees demonstrated significantly superior medial stability compared with PS TKA knees. Multivariate analysis revealed that BCS prosthesis (P = 0.033) and Surgical Team A (P = 0.006) were identified as independent predictors of medial stability. Postoperative medial stability in extension was associated with improved clinical outcomes after cruciate-sacrificing TKA. Implant design and surgical technique were factors significantly influencing medial stability.