The relative velocity of the tibiofemoral surfaces during gait before and after partial-ACL and full MCL transection (p-ACL/MCL Tx) was examined in an ovine model (N = 5) and the relation between the variation in the relative sliding velocity component and gross morphological damage was investigated. We defined the in vivo kinematics of the tibiofemoral joints by using an instrumented spatial linkage and then determining the relative velocity components on the reconstructed femoral condyle surfaces. One major finding was that the magnitude of the relative velocity components was relatively high during the initial stance period of the gait and oscillated with a decaying envelope. Interestingly, for most subjects, the highest value of relative sliding velocity occurred during the stance phase, and not swing. The magnitude of the relative velocity components was increased in 3/5 subjects during stance after an injury. For the lateral compartment, there was a significant correlation (p value = 0.005) between the joint gross morphological damage and the increase in the maximum relative sliding velocity during stance. For the medial compartment, there was a trend (p value < 0.1) between the joint gross morphological score and the increase in the maximum relative sliding velocity during stance, 20 weeks after injury. In conclusion, a connection between an increase in the relative surface velocity and gross morphological damage might be due to an increase in the normal stress and the plowing friction between the surfaces.
Keywords: Gait; Kinematics; Knee injury; Post-traumatic osteoarthritis; Sliding velocity.