Investigation of return-to-sport criteria based on the results of the single-leg standing-up test

Background Anterior cruciate ligament (ACL) reconstruction typically requires a hamstring-to-quadriceps muscle strength ratio (H/Q ratio) of at least 55% for safe return to sports, as measured via isokinetic dynamometry. The single-leg standing-up (SLS) test is sometimes used to assess lower extremity strength. Establishing SLS as a return-to-sport criterion may provide a clinically accessible alternative. Objective This study aimed to evaluate whether SLS performance could serve as an alternative return-to-sports criterion. Methods Eighty-five patients who underwent ACL reconstruction were enrolled in this study. Knee extension and flexion strengths were assessed to calculate the H/Q ratio. SLS was initiated at a height of 30 cm, with the height reduced by 10 cm per attempt until success. The participants were categorized according to their maximum height and knee strengths, and H/Q ratios were compared. Results Knee extension strength did not vary significantly across the groups; however, knee flexion strength and H/Q ratio showed notable differences. The participants who completed SLS from 20 cm demonstrated an H/Q ratio of 55% or higher, meeting the threshold for sports resumption. Conclusion These results indicate that achieving SLS from a 20 cm height may be a feasible criterion to assess readiness for sports resumption after ACL reconstruction.