Association between lower limb muscle strength and musculoskeletal ambulation disability symptom complex in patients with medial meniscus posterior root tears

Abstract Purpose In this study, we aimed to evaluate the changes in and the relationship between lower limb muscle strength and physical function before and after medial meniscus posterior root (MMPR) repair. Methods Thirty-three patients who underwent MMPR repair were evaluated. Pain was evaluated with the numerical rating scale (NRS), and knee flexor/extensor muscle strength was assessed using a handheld dynamometer. Physical function was evaluated using a timed up and go (TUG) test. The NRS, knee flexor/extensor muscle strength, and TUG were compared preoperatively and 1 year postoperatively using the Wilcoxon signed-rank test. The correlation of patient characteristics, NRS score, knee flexor/extensor muscle strength, and preoperative TUG with the postoperative TUG was analyzed using Spearman’s correlation coefficient. Results NRS (3.5 ± 2.1 to 0.1 ± 0.5 points), knee flexor strength (111.9 ± 50.2 to 146.7 ± 51.5 Nm), knee extensor strength (181.9 ± 92.8 to 256.9 ± 107.1 Nm), and TUG (12.3 ± 5.7 to 9.2 ± 2.2 s) all improved significantly from preoperatively to 1 year postoperatively ( p < 0.001). The postoperative TUG was negatively correlated with the preoperative TUG (r = 0.578, p < 0.001), preoperative knee flexor muscle strength (r = − 0.355, p = 0.042), preoperative knee extensor muscle strength (r = − 0.437, p = 0.010), and postoperative knee extensor muscle strength (r = − 0.478, p = 0.004). Conclusion In patients undergoing MMPR repair, surgery and rehabilitation significantly improve lower limb muscle strength and physical function. There was a significant correlation between lower limb muscle strength and TUG, and further strengthening of the lower limb muscles from the preoperative level is desirable to improve patients’ physical function further. Level of evidence IV.