Objective movement assessment

Advances in wireless data transmission and miniaturisation of sensors have led to a ‘revival’ of gait analysis in horses which can now be performed outside the gait lab and provide quantitative measurements of a horse during the clinical lameness examination. Here we are giving an overview of inertial sensor based gait analysis, a technology providing freedom of movement to the horse and accurate and precise measurements in particular for upper body movement.
The 2 major indicators of front and hindlimb lameness are head nod [1] and hip hike [2]. In contrast to some other limb movement related parameters, these 2 upper body movement parameters are directly related to the biomechanical mechanism of providing weight support and propulsion. Hence they provide quantitative information using a limited number of asymmetry measurements readily comparable between exercises, such as during lungeing [3], after flexion [4,5] and diagnostic analgesia [6,7] and with rider [8].
In horses with movement symmetry values ‘within normal limits’ when trotted in-hand on the straight, the following movement adaptations have been reported on the lunge [3,9]: a mild increase in head downward movement during the outside front limb stance and a mildly increased movement amplitude of the inside tuber coxae. Due to the horses leaning into the circle (more so the faster they go and the smaller the circle) circle dependent asymmetries will be exacerbated. It is therefore paramount to control circle radius and speed when judging small measured movement asymmetries (below the threshold of 25% of the human eye, [10]). When lungeing horses with induced lameness [11], compensatory movement adaptations mimicking an ipsilateral head asymmetry of almost the same magnitude as the primary induced pelvic movement asymmetry have been reported. On the lunge, horses with an induced forelimb lameness commonly show a mixed ipsilateral weightbearing and contralateral push-off hindlimb asymmetry, however resulting in only 20% of the primary induced head asymmetry. In particular on the lunge, a head nod may be related to an ipsilateral hindlimb problem. […]