Contact Analysis of Horizontal Cleavage Tear Treatment.

Horizontal cleavage tears (HCT) commonly occur in the posterior horn of the medial meniscus due to aging and degeneration. The purpose of this study was to investigate the surgical treatment of HCTs and their effect on dynamic tibiofemoral contact mechanics. The tibiofemoral contact mechanics of 10 cadaver knees were investigated using a custom dynamic loading apparatus, pressure sensor, and motion sensing camera. Three loading conditions were analyzed: 500 N compressive load, 500 N compressive load with 100 N posterior shear, and 500 N compressive load with 2.5 Nm of internal torque. Real-time peak contact pressures and contact areas were recorded throughout the full range of motion. After testing the intact meniscal state, a horizontal cleavage tear was created and included 50% of the width of the meniscus. The following procedures were performed, and the loading conditions described above were analyzed: HCT superior flap removal (5 specimens), HCT inferior flap removal (remaining 5 specimens), and both flaps removed (all 10 specimens). Statistical analysis was performed using a mixed linear effects model using the R-statistical package. The mixed linear effects statistical model identified statistically significant differences between independent variables, including the procedure performed, meniscal flap removed, meniscal region, loading condition, and knee flexion angle with respect to contact area and peak contact pressure. Peak contact pressure and contact area were not affected by selective flap removal (superior vs. inferior) or removal of both flaps of the HCT. We recommend that in the treatment of horizontal cleavage tears of the posterior horn of the medial meniscus, the outer 50% of the posterior horn of the medial meniscus should be maintained for load transmission.