Exploring inertial sensing technology to quantify gait patterns in Thoroughbred foals before and after corrective trimming for angular limb deformities

Angular limb deformities are a common orthopaedic problem in Thoroughbred foals. In some cases, these deformities resolve naturally but in other cases treatment, such as farriery intervention consisting of remedial trimming and/or shoeing, or surgery, is required to correct associated movement abnormalities. With advances in inertial measurement unit (IMU) technology, foal movement patterns can now be objectively measured. This study used IMU technology to determine whether Thoroughbred foals presenting with angular forelimb deformities had differences in their gait asymmetry, upper body range of motion (XSens MTw sensors, n = 10 foals) or the duration of stride cycle phases and stride length (HoofBeat forelimb hoof sensors, n = 5 foals) at walk before and after corrective trimming. Paired sample t-tests indicated that there was no significant difference in gait asymmetry parameters or range of motion at the poll, withers, tubera coxae and sacrum before and after trimming (p > 0.05). Linear mixed models were used to compare before/after trimming data for the stride cycle phase durations and stride length and included speed as a covariate and foal as a random factor. After trimming, forelimb landing duration significantly decreased by 5.5 ms (25 %), while mid-stance and breakover durations increased by 26.8 ms (7.0 %) and 7.6 ms (4.8 %), respectively; total stride duration post-trim was 24.0 ms (2.6 %) longer than pre-trim. Stride length was also 3.3 cm (2.4 %) longer after trimming. Further investigation in a larger cohort of foals is needed as part of a longitudinal assessment to evaluate gait changes during development, and to relate this to their locomotor performance as adult horses.