To characterize knee movements before and after unilateral hindlimb deafferentation in dogs with stable joints.
High speed cinematography and frame by frame analysis were used to analyze knee kinematics of 6 dogs serially for 26 weeks following L4-S1 dorsal root ganglionectomy, which was performed to deafferentate one hindlimb.
Overall knee movements were not reduced, but knee extension increased during most of the gait cycle. Few changes occurred in knee velocity, and none at touchdown or during weight acceptance.
We previously showed that unilateral hindlimb deafferentiation does not cause osteoarthritis or reduce ipsilateral peak vertical forces in dogs with stable knee joints over an observational period of 16 months. We now show that joint protection in the deafferented stable joint occurs, paradoxically, in the presence of increased knee extension. We conclude that whereas sensory nerves may limit knee extension during ambulation, the health of the joint is not dependent upon this "extension limiting" function.