The level of compressive load affects conclusions from statistical analyses to determine whether a lateral meniscal autograft restores tibial contact pressure to normal: a study in human cadaveric knees.

Abstract

This study addressed the question of whether the level of compressive load would affect the conclusions from statistical analyses aimed at determining how well a lateral meniscal autograft restores tibial contact (as indicated by the maximum contact pressure, mean pressure, and contact area) to that of the intact knee. If statistical analyses indicated that normal tibial contact was not restored with a higher, more physiologic load, then a secondary question was whether an autograft surgically implanted with bone plugs would improve tibial contact compared to that in a meniscectomized knee. Nine, fresh-frozen human cadaveric knees were subjected to a low, non-physiologic compressive load of 400 N and a higher, more physiologic compressive load of 1200 N under three conditions (lateral meniscus intact, lateral meniscus removed and reimplanted as an autograft, and lateral meniscus removed). Contact pressure on the lateral plateau was measured with pressure sensitive film at 0 degrees, 15 degrees, 30 degrees, and 45 degrees of flexion. At 400 N, p-values from statistical analyses indicated that both the maximum and mean pressures with the autograft were comparable to those of the intact knee (p> or =0.685). However, at 1200 N, p-values from statistical analyses indicated that both the maximum and mean pressures with the autograft were significantly greater than those of the intact knee (p< or =0.0001). Therefore studies designed to evaluate tibial contact pressure for a meniscal transplant should use a higher, more physiologic compressive load, because lower loads overestimate the transplant's effectiveness. Although none of the contact variables was restored to normal when the compressive load was increased to 1200 N, all of the contact variables were more normal than those of the meniscectomized knee. Thus, lateral meniscal allografts implanted using bone plugs can significantly improve contact pressure relative to a meniscectomized knee at the time of implantation.