Transtibial Pullout Repair Reduces Posterior Extrusion of the Medial Meniscus.

Medial meniscus posterior root tear causes rapid knee cartilage degradation by inducing posteromedial displacement of the medial meniscus. We evaluated medial meniscus posterior extrusion before and after pullout repair for medial meniscus posterior root tear using magnetic resonance images. Twenty-eight patients with symptomatic medial meniscus posterior root tear were included. The inclusion criteria were: acute (< 3 months) or chronic (≥3 months) medial meniscus posterior root tear after painful popping events. The exclusion criteria were: other meniscus and anterior cruciate ligament injuries. We measured medial meniscus posterior extrusion and medial meniscus anteroposterior interval at knee flexion angles of 10° and 90° preoperatively and at 3 months postoperatively. The posterior extrusion at 90° knee flexion decreased from 4.42±1.38 mm preoperatively to 3.09±1.06 mm (p<0.001) postoperatively, while at 10° knee flexion it was -4.17±1.63 mm preoperatively and -3.77±1.72mm postoperatively, showing no significant change. The anteroposterior interval at 10° knee flexion increased from 19.74±4.27 mm preoperatively to 22.15±5.10 mm postoperatively (p<0.001); at 90° knee flexion, it increased from 16.81±4.51 mm preoperatively to 19.20±4.30 mm postoperatively (p<0.001). Medial meniscus posterior extrusion and movement decreased after pullout repair. Pullout repair for medial meniscus posterior root tear improves medial meniscus posterior extrusion, especially at 90° knee flexion.