To evaluate the relationship between medial collateral ligament (MCL) injury and degree of internal tibial torsion in patients who had undergone arthroscopic resection due to tears in the posterior one third of the medial meniscus.Seventy-one patients were allocated into two groups with respect to foot femur angle (FFA) and transmalleolar angle (TMA) (Group 1 31 patients with FFA<8° and Group 2 40 patients with FFA≥8°). The groups were compared in terms of valgus instability, Lysholm score, magnetic resonance view, FFA, and TMA, both before and after the operation.Lysholm scores were higher in Group 2 at both postoperative week 1 (p<0.001) and month 1 (p=0.045) relative to Group 1. Preoperative cartilage injury was encountered more frequently in Group 1 (p=0.037) than in Group 2. MCL injury was detected more frequently in Group 1 compared to Group 2 postoperatively at week 1 (p=0.001).We conclude that FFA and TFA, indicators of internal tibial torsion, may serve as markers for foreseeing clinical improvement and complications following arthroscopic surgery.level III retrospective comparative study.