A single root repair and centralisation tunnel best restores tibiofemoral contact mechanics and extrusion following a medial meniscus posterior root tear: An in vitro biomechanical study

Purpose: To evaluate what tunnel combination, with respect to anatomical transtibial pull-through root repair (ATPR) and transtibial centralisation (TTC), best restores tibiofemoral contact mechanics and meniscal extrusion following a medial meniscus posterior root tear (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) one tunnel ATPR and one tunnel TTC (1-ATPR + 1-TTC); (4) two tunnel ATPR and one tunnel TTC (2-ATPR + 1-TTC); (5) 1-ATPR + 2-TTC; and (6) 2-ATPR + 2-TTC. The testing protocol loaded knees with 200-N axial compression at 4 flexion angles (30 degrees, 45 degrees, 60 degrees and 90 degrees). 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. ResultsMME was significantly reduced with both the 1-ATPR + 2-TTC and 2-ATPR + 2-TTC tunnels in comparison to the 1-ATPR + 1-TTC and 2-ATPR + 1-TTC tunnels at 60 degrees and 90 degrees (p < 0.05). The intact meniscus and 1-ATPR + 1-TTC technique had higher contact area at 60 degrees (p = 0.01 and 0.04, respectively) and lower contact pressure at 90 degrees (p = 0.01 and 0.04, respectively) compared to the 2-ATPR + 2-TTC technique. Otherwise, all tunnel combinations were similar to one another for contact mechanics and restored the loading profile to that of an intact meniscus (p > 0.05). Conclusion: When there are concerns of extrusion following a MMPRT, a combination of one centralisation and one root repair tunnel may provide better biomechanical properties compared to the addition of extra tunnels. Level of EvidenceNot applicable (laboratory study).