Dynamic variation of tibiofemoral compression force during total knee arthroplasty: Implications for soft tissue balance and functional outcomes

Achieving precise alignment and soft tissue balance is crucial for optimal total knee arthroplasty (TKA) outcomes. We aimed to explore how tibiofemoral compression force (TFCF) varies with knee flexion and its correlation with functional outcomes. This prospective study included 60 patients undergoing cruciate-retaining TKA (FINE Total Knee System). Sensor-equipped trial inserts were used to measure the TFCF at 15° intervals, from full extension to 90° flexion. Patients were classified into anterior and posterior force groups based on whether the medial TFCF was higher in the anterior than in the posterior region at 60° flexion. The 2-year outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS-JR). The total TFCF increased from 0° to 60° flexion and then decreased. The medial compressive forces were consistently higher than lateral forces. Anteromedial TFCF differed significantly between the anterior and posterior force groups at 60°, 75°, and 90° flexion. KOOS-JR scores showed a significant interaction between force type and time, with greater improvements in the anterior force group. Anteromedial TFCF at 60° flexion and KOOS-JR correlated significantly (R = 0.574). Evaluating TFCF at multiple knee flexion angles provides valuable insights into optimising outcomes in TKA. TFCF variations, especially in the anteromedial compartment, considerably impact functional outcomes. Dynamic TFCF measurements during TKA may enhance soft tissue balance and improve outcomes. Further research is needed to validate these findings in diverse populations and with long-term follow ups.