BIOMECHANICS IN EQUINE REHABILITATION: A WEIGHT-REDUCTION SYSTEM AND MOVEMENT TRACKING DEVICE

Abstract

Equine musculoskeletal conditions can be challenging to treat and career-ending or result in euthanasia in severe cases. Often it is the secondary complications (weight and immobility related) that develop while treating the initial injury that carries the poor prognosis. For this reason, many attempts have been made to reduce the horse’s weight during recovery. This study aimed to design and test a chest support (breastplate) for use with a rehabilitation lift and test a movement tracking device for monitoring rehabilitation progress. By focusing on the horse's biomechanics, support can be directed to load-bearing structures, minimizing the risk of compromised breathing or restricted blood flow. Tracking movement could assist in early detection of changes in movement patterns that may be indicative of the onset of complications, such as supporting limb laminitis, in horses with ambulatory difficulties. A breastplate was developed to facilitate front limb support, attempting to minimize the risk of complications, such as pressure ulcers. Design testing included strength tests (to 227 kg) for safety, fit tests to minimize discomfort, and weight compensation trials using a computer-controlled rehabilitation lift to reduce load. The goal was to reach a 50% weight reduction of the forelimbs. Weight reduction was incrementally increased, observing the horse’s behaviour and respiratory rate, indicating discomfort and directing design modifications. A 50% weight reduction was achieved after a series of design iterations. To aid in the objective assessment of movement of horses during stall confinement, a readily available motion sensor (inertial measurement unit = IMU) was tested. The IMU was placed at three different locations (withers, right forelimb, and hindlimb) to determine the best location to quantify step count when compared to a video-based step count criterion. Data was recorded in five-minute intervals for three movements (free movement, circles, and figure-eight). An intra-class correlation (ICC) analysis determined that the IMU placement on the limbs was the most accurate using the vertical axis to determine step count with the current algorithm, while the withers location was the least accurate. The movement analysis demonstrated the potential of a limb-mounted IMU to quantify movement during stall confinement.