Quadriceps muscle strength of the affected limb in medial meniscus posterior root tears is negatively correlated with the progression of postoperative medial joint space narrowing

Purpose: The effect of quadriceps muscle strength on medial joint space (MJS) narrowing after repair for medial meniscus (MM) posterior root tears (MMPRTs) has not yet been determined. This study aimed to evaluate the effect of preoperative and postoperative quadriceps muscle strength on the change in MJS (ΔMJS) in MMPRTs.
Methods: Thirty patients who underwent pullout repair for MMPRTs were retrospectively evaluated. The MJS width using fixed-flexion view radiographs, MM extrusion (MME) using magnetic resonance imaging, quadriceps muscle strength using the Locomo Scan-II and clinical scores were measured and compared preoperatively and 1 year postoperatively. Correlations between the ΔMJS, change in MME (ΔMME), and preoperative and postoperative quadriceps muscle strength were evaluated using Spearman's rank correlation coefficient.
Results: MJS narrowing and MME progressed significantly at 1 year postoperatively (p < 0.001). Quadriceps muscle strength in MMPRT knees and all clinical scores significantly improved at 1 year postoperatively (p < 0.001). ΔMJS and ΔMME showed a significant positive correlation (0.50 ± 0.70 and 1.22 ± 0.92 mm, respectively; r = 0.516, p = 0.004). Both preoperative and postoperative quadriceps muscle strength in MMPRT knees showed significant negative correlations with ΔMJS (preoperative: r = −0.529, p = 0.003; postoperative: r = −0.477, p = 0.008) and ΔMME (preoperative: r = −0.431, p = 0.018; postoperative: r = −0.443, p = 0.014).
Conclusions: In pullout repair for MMPRTs, preoperative and postoperative quadriceps muscle strength in MMPRT knees was negatively correlated with the progression of MJS narrowing and MME. Rehabilitation with a focus on quadriceps muscle strengthening, including preoperative rehabilitation, may delay knee-osteoarthritis progression after pullout repair for MMPRTs.
Level of Evidence: Level IV.