Nonanatomic Location of the Posterior Horn of a Medial Meniscal Autograft Implanted in a Cadaveric Knee Adversely Affects the Pressure Distribution on the Tibial Plateau.

Nonanatomic placement of the posterior horn may occur during arthroscopic implantation of a meniscal transplant. The objective of this study was to determine whether nonantomic placement adversely affects the contact pressure distribution on the medial tibial plateau. Medial meniscal autografts were placed in eight cadaveric knees with the posterior horn tunnel in nonanatomic locations (5 mm medial and 5 mm posterior) and in the anatomic location. The contact pressure distribution of the medial articular surface of the tibia was measured with pressure-sensitive film under a 1200-N compressive load at 0 degrees, 15 degrees, 30 degrees, and 45 degrees of flexion. The maximum pressure, mean pressure, contact area, and anterior/posterior and medial/lateral locations of the centroid of contact area were compared. Placement of the posterior horn tunnel in the nonanatomic medial location caused a significant increase in the normalized maximum pressure over all flexion angles, an increase in the normalized mean pressure at 45 degrees, and a posterior shift in the centroid of contact area over all flexion angles. Placement in the nonanatomic posterior location caused a significant posterior shift in the centroid of contact area over all flexion angles. Surgeons should place the posterior horn tunnel of a medial meniscal transplant within a tolerance tighter than 5 mm medial and 5 mm posterior to the anatomic location because nonanatomic placement significantly alters the contact pressure distribution.