Meniscectomy causes significant in vivo kinematic changes and mechanically induced focal chondral lesions in a sheep model.

Significant meniscal loss with progression to osteoarthritis is common in humans. In vitro work suggests that meniscectomy causes increased joint contact stress, but what other alterations in dynamic joint actions actually occur remains unknown. In a sheep model, we tested the hypothesis that complete lateral meniscectomy increases joint abduction, shifting the in vivo locations of tibiofemoral contact to regions that qualitatively correspond to locations of chondral damage. Nine sheep underwent unilateral arthrotomy (n = 4) or arthrotomy plus complete lateral meniscectomy (n = 5). Kinematics were collected prior to surgery and serially up to 20 weeks post-surgery. Gross cartilage damage was mapped in each joint, graded using a published scoring scheme used in goats, and compared to the locations of minimum tibiofemoral distance. Over the 20 weeks, meniscectomy caused increased stifle abduction and medial tibial translation, shifting the points of minimum tibiofemoral distance 7.5 ± 2.1 mm laterally and 3.3 ± 1.1 mm anteriorly (mean ± SEM), which corresponded to the locations of focal chondral damage. Locations of new tibiofemoral contact in the meniscectomized compartment qualitatively correspond to subject-specific locations of early chondral damage in an ovine model.