HOW THE HORSE MOVES .2. SIGNIFICANCE OF GRAPHICAL REPRESENTATIONS OF EQUINE HIND-LIMB KINEMATICS

Kinematic data of the equine hind limb are presented graphically and r elated to functional aspects of the hind limb in locomotion. The trot of 24 two-year old Dutch Warmblood horses was recorded at 4 m/s on a h igh-speed treadmill using kinematic analysis equipment. Joint angle-ti me, angle-angle, stick and marker diagrams were used to present graphi cally the data following standardised procedures. As the kinematic dat a were expressed with reference to the joint angles of the horse stand ing squarely and were time-standardised to the duration of the stride cycle, mean joint curves for the total group could be calculated and t herefore describe the function of the different segments of the equine hind limb. The motion of the hind limb in the sagittal plane appeared to be pendular around a rotation point in the acetabulum. During the stance phase the extension of the fetlock joint and stance flexion of the stifle, tarsal and coffin joints illustrate the shock absorption o f the hind limb. In the swing phase the reciprocal apparatus, which fo rms the coupling mechanism between stifle and tarsal joint, also influ ences the fetlock joint because synchronous flexion and extension betw een these 3 joints were demonstrated. By graphically presenting hind l imb motion we were able to illustrate the relation between kinematics and function. This graphic analysis can be used in clinical studies in volving quantification of equine hind limb coordination in tile sagitt al plane.