300 Section - Early Functional Recovery Outweighs Preoperative Status in Predicting Post-TKA Quality of Life: A Decision Tree Analysis

Objectives : Total knee arthroplasty (TKA) aims to improve physical function, enhance quality of life (QOL), and extend life expectancy. Therefore, postoperative QOL is a critical outcome in patients undergoing TKA. Nevertheless, 10–33% continue to experience persistent pain and difficulty in daily activities after surgery. Although preoperative factors influencing postoperative QOL are identified, the interaction between preoperative and early postoperative factors remains unclear. This study aimed to clarify the interrelationship between preoperative and 3 weeks postoperative factors affecting QOL one year after TKA.

Design: This single-center cohort study included patients with knee osteoarthritis who underwent primary TKA. A total of 68 patients were consecutively enrolled between April 2021 and August 2023. Clinical parameters included demographic information, Kellgren–Lawrence grade, range of motion of knee flexion and extension, quadriceps and hamstring strength, self-selected walking speed, and pain severity assessed by the Numerical Rating Scale at rest and during gait. These were evaluated both preoperatively and at 3 weeks postoperatively. Decision tree analysis was performed using the KOOS QOL subscale at 1 year postoperatively as the dependent variable. Model validity was assessed with 10-fold cross validation.


Results:

Decision tree analysis sequentially selected the following variables: knee extensor strength of the operated side at 3 weeks postoperatively (≥ 2.48 N/kg), gait speed at 3 weeks postoperatively (≥ 1.05 m/sec), age at the time of surgery (≥ 72 years), and preoperative gait speed (≥ 0.96 m/sec). A decision tree with four branches was constructed. The coefficient of determination (R²) for the model was 0.58, with a value of 0.52 obtained through 10-fold cross-validation.

Conclusion:

  This study demonstrates that early postoperative functional recovery, particularly quadriceps strength and gait speed within 3 weeks after TKA, has a stronger impact on QOL at 1 year than preoperative status. These findings highlight the importance of early rehabilitation in optimizing long-term patient-reported outcomes after TKA.