Total Knee Arthroplasty Improves Locomotive Syndrome in Patients with Knee Disease: A Prospective Cohort Study Focused on Total Clinical Decision Limits Stage 3

Background: In 2020, the Japanese Orthopaedic Association added a new clinical decision limit (CDL), stage 3, to evaluate the stages of locomotive syndrome (LS). However, so far there has been no study of total knee arthroplasty (TKA) to examine the efficacy of LS treatment and there are no motor function indicators to predict LS improvement, focusing on stage 3. The purpose of this study is to investigate the treatment efficacy of TKA on LS focusing on total CDL stage 3 leading to revealing the motor function indicators that can predict LS improvement in patients who had received TKA. Methods: : This prospective cohort study was conducted with 59 patients among 70 patients who underwent TKA, with total CDL stage 3 before TKA evaluation. LS was evaluated using stand-up test, two-step test, and 25-Question Geriatric Locomotive Function Scale. In addition, the motor function indicators which could predict the LS improvement were examined. All assessments were conducted before TKA and three months after TKA. Results: : Of the 59 subjects who were evaluated to be in total CDL stage 3 before TKA, 17 patients (28.8%) were determined to show improvements in total CDL. From the result of the decision tree analysis, when the CDL of the two-step test before TKA was 1 or less, the improvement rate was 77.8%. Even if the CDL of the two-step test before TKA was higher than 2 and if the 3m-Timed Up & Go test (3m-TUG) before TKA was 9.15 or less, the improvement rate was 60%. Conclusions: : As of three months after surgery, TKA can improve LS in about 30% of patients. A two-step test before TKA and 3m-TUG before TKA can be used as motor function indicators to predict LS improvement. This study provides useful information for setting the goal for rehabilitation prior to surgery.