Changes in Tibiofemoral Contact Mechanics Following Radial Split and Vertical Tears of the Medial Meniscus

Abstract

The biomechanical effects of radial split tears and vertical tears of the medial meniscus are not well characterized. The goal of the present study was to determine the effects of these meniscal tears and meniscal repair on tibiofemoral joint contact pressure and area. Eleven fresh-frozen cadaveric knees were loaded to 1000 N of axial load at 0, 30, 60, and 90 of flexion with use of a custom testing apparatus attached to a materials testing machine. Tibiofemoral translations and internal-external and varus-valgus rotations were unconstrained. The knees were tested under four conditions: intact, medial meniscal tear, repaired meniscal tear, and total medial meniscectomy. Radial split tears were created in six knees, and vertical tears were created in five knees. Pressure-sensitive film was used to measure tibiofemoral contact pressure and area. Radial split tears of the medial meniscus did not cause significant changes in tibiofemoral joint contact pressure and area. Vertical tears of the medial meniscus caused increases in tibiofemoral joint contact pressure and reductions in contact area in the medial and lateral compartments that were not significantly different from those associated with total medial meniscectomy. The exception was at 90, where the lateral compartment pressure associated with the vertical tear of the medial meniscus was higher than that associated with total medial meniscectomy. In general, after repair of the vertical tear, contact pressure and area values were similar to those in the intact condition. Radial split tears of the medial meniscus that extend from the inner rim to the peripheral third of the meniscus do not cause significant changes in joint contact area and pressure. Vertical tears of the medial meniscus cause nonsignificant increases in joint contact pressure and reductions in contact area in the medial and lateral compartments.Repair of the vertical tear reverses these contact changes, resulting in contact pressure and area similar to the intact state.