Lameness in the horse's stifle joint can result in shortened stride length, reluctance to work or a rough canter. While lameness is more commonly attributed to problems with the hock joint, stifle lameness is seen frequently in performance horses. The stifle is considered the most complex joint in the horse's body with a similar function to the human knee. Stifle injuries can result from repetitive stress, trauma, excessive use, changes in direction and rapid deceleration. Horses engaged in jumping and barrel racing are most at risk of these injuries.