Placing the transtibial centralisation stitch at the posterior horn of the medial meniscus best restores tibiofemoral contact mechanics and extrusion following medial meniscus posterior root tears: An in vitro biomechanical study using porcine knee joints.

Purpose: To evaluate whether the position of the transtibial centralisation tunnel, on the background of an anatomical transtibial pull-through root repair (ATPR), affects the tibiofemoral contact mechanics and meniscal extrusion for medial meniscus posterior root tears (MMPRT). Methods: Meniscal extrusion and contact mechanics were measured using two-dimensional imaging and pressure films in 10 porcine knee joints. The posterior root was tested under six states: (1) intact; (2) MMPRT; (3) ATPR; (4) ATPR with TTC at the posterior horn (TTC-PH); (5) ATPR with TTC midway between the PH and posterior border of medial collateral ligament (MCL) (TTC-MID) and (6) ATPR with TTC behind the MCL (TTC-MCL). The testing protocol loaded knees with 200-N axial compression at four flexion angles (30°, 45°, 60° and 90°). At each angle and state, meniscal extrusion was measured as the difference in its position under load to that of the unloaded condition in the intact state. Contact area and pressure were recorded for all states at all angles and were analysed using a MATLAB programme. Results: ATPR + TTC-PH led to greater reduction in extrusion compared to both ATPR and ATPR + TTC-MCL at 60° and 90° ( Conclusion: Combining ATPR with TTC-PH provides the most appropriate biomechanical properties in reducing extrusion and improving contact mechanics following a MMPRT in porcine knees. Level of Evidence: Not applicable (laboratory study).