Tensile Forces on Repaired Medial Meniscal Root Tears

Purpose: The goals of this study were to measure the tensile forces acting on repaired medial meniscal root lesions and to investigate how they depend on femorotibial rotation, flexion, and compressive load. Methods: In 6 human cadaveric knees, the posterior medial meniscal root was completely detached and then repaired with a pullout suture. A force transducer was installed such that it measured tensile forces acting on the suture. The resultant tension at the posterior medial meniscal root was measured for flexion angles up to 120 degrees at 2 levels of femorotibial compressive load (100 and 500 N) in neutral, internal, and external rotation of the knee. Results: Rotation had a highly significant effect on root tension (P < .001). Internal rotation of the femur increased the resultant tension, whereas external rotation decreased it. The tension at the meniscal root was related to the femorotibial load (P < .001). Although no significance was reached, a trend toward higher flexion angles causing more tension was observed. The highest mean tension of 60.1 +/- 20.2 N was generated with internal rotation, a 500-N load, and 90 degrees flexion. Conclusions: Our study shows in a human in vitro model that motion and weight loading of the knee can generate considerable tensile forces in the posterior medial meniscal root. Internal rotation of the femur increases the resultant tension substantially, whereas external rotation has the opposite effect. Clinical Relevance: The data can potentially aid the surgeon in finding appropriate rehabilitation exercises after a medial meniscal root repair.