Impact of Component Alignment and Soft Tissue Release on 2-Year Outcomes in Total Knee Arthroplasty

The objective of this study was to investigate the impact of alignment and soft tissue release on patient outcomes following total knee arthroplasty (TKA).

In a multicenter study, soft tissue releases during TKA were prospectively documented in 330 robotic-assisted TKAs. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were captured postoperatively. Delphi analysis was used to determine inlier and outlier component alignment boundaries: Tibia Coronal (TC): ±3°, Femur Coronal (FC): ±3°, Femoral Axial (FA): 3°Int-6°Ext, Hip-Knee-Ankle (HKA): 3°Val-4°Var, and Tibiofemoral Axial (TFA): 3°Int-6°Ext. Kruskal-Wallis analysis of variance tests were used to compare groups.

No significant differences were found between any individual or grouped inlier and outlier alignment criterion and KOOS at any timepoint. Outlier alignment frequencies were: TC: 0%, FC: 12%, FA: 8%, HKA: 9%, TFA: 8%, and Any: 23%. Soft tissue releases were performed in 18% of cases. Knees with soft tissue releases reported significantly worse KOOS scores at: 6M: Symptoms (80.0 versus 75.3, P = .03), activities of daily living (ADL) (86.2 versus 80.8, P = .030), quality of life (70.1 versus 60.9, P = .008), 12M ADL (90.0 versus 85.1, P = .023), and 24M ADL (91.9 versus 87.2, P = .016). A higher proportion of patients achieved Minimal Clinically Important Difference for pain at 6 months for those having no releases versus released (92.3% versus 81.0%, P = .021). No significant associations were found between preoperative deformity and preoperative or postoperative KOOS.

The addition of soft tissue releases after bony cuts is associated with worse KOOS scores out to 2 years and was more prevalent in knees with worse deformity, while no such association was found for alignment.