Three-dimensional kinematics of the equine distal forelimb: effects of a sharp turn at the walk

Sharp turns are suspected to increase expression of several distal forelimb lamenesses even at the walk but the biomechanical consequences of such a movement remain unknown.

To quantify the effects of a sharp turn at the walk on the 3-dimensional movements of the distal segments of the forelimb.

Kinematics of the distal segments were measured in 4 healthy horses invasively with an ultrasonic system. Three-dimensional rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained for a turn at the walk were compared to those obtained in a straight line.

During the stance phase in a turn, the inside forelimb underwent an adduction that induced lateromotion and medial rotation in the distal interphalangeal joint and medial rotation in the proximal interphalangeal joint. These movements were maximal at heel-off and decreased during breakover as the hoof underwent a sudden lateral rotation.

Walking in a sharp turn affects the kinematics of the digital joints outside the sagittal plane.

This knowledge offers the opportunity to derive hypotheses on biomechanical factors that could contribute to the pathogenesis of digital injuries and on consequences for rational shoeing.