Augmentation of a Nonanatomical Repair of a Medial Meniscus Posterior Root Tear With Centralization Using Three Knotless Anchors May Be Associated With Less Meniscal Extrusion and Better Compressive Load Distribution in Mid-Flexion Compared With Non-Anatomical Root Repair Alone in a Porcine Knee Model

Abstract

Purpose: To investigate the biomechanics of the centralization augmentation using knotless soft anchors to a nonanatomical transtibial pull-out root repair in a porcine medial meniscus posterior root tear (MMPRT) model.

Methods: Porcine knee joints (N = 10) were used to perform one of the following procedures: (1) intact; (2) MMPRT; (3) nonanatomical root repair; (4) nonanatomical root repair with centralization using 2 anchors: anchors were inserted at the posterior medial collateral ligament (MCL) border and 10 mm anterior to the posterior MCL border; and (5) nonanatomical root repair with centralization using 3 anchors: another anchor was placed 10 mm posterior to the posterior MCL border. Contact area on the medial meniscus (MM), contact pressure in the MM and tibial cartilage, and MM extrusion were evaluated at 30°, 45°, 60°, and 90° knee flexions under 200 N compressive force.

Results: MM extrusion at the posterior MCL border was significantly reduced after root repair with centralization using 3 anchors than after root repair alone at 30° (-0.063 mm vs 1.5 mm, P = .017), 45° (0.21 mm vs 1.7 mm, P = .018), and 60° (0.78 mm vs 2.3 mm, P = .019). There were no significant differences in MM extrusion between the root repair alone and root repair with centralization using 2 anchors at all flexion angles. The contact area in the middle and posterior MM was significantly greater after centralization with 3 anchors than after root repair alone at all flexion angles (except the posterior MM at 90°). The mean contact pressure in the tibial cartilage was significantly lower after centralization with 3 anchors than after root repair at all angles.

Conclusions: Augmentation of a nonanatomical repair of a medial meniscus posterior root tear with centralization using three knotless anchors may be associated with less meniscal extrusion and better compressive load distribution between 30° and 60° flexion compared with nonanatomical root repair alone in a porcine model.

Clinical relevance: This biomechanical study at time zero suggests that the addition of centralization using 3 knotless anchors may reduce MM extrusion and restore the load-distributing function of the MM.