Associations of force plate and body-mounted inertial sensor measurements for identification of hind limb lameness in horses.

This research investigates the relationship between measurements from two types of sensors – inertial sensors and stationary force plates – to identify back leg lameness in horses. The researchers make use of various statistical models to understand the strength of these relationships and conclude that looking at both the rise and fall of the horse’s pelvic area could be important in assessing lameness.

Introduction and Methodology

• The research conducts measurements on 21 adult horses. Some of the horses had no lameness whilst others had mild lameness in their hind legs. These horses were made to trot in a straight line, while these sensors collected data.
• Two types of sensors were used to monitor each horse. Inertial sensors were used to record the maximum and minimum differences in pelvic height during the stride (each left and right step), while stationary force plates were used to measure the vertical and horizontal ground reaction forces (GRFs) the horse exerted whilst trotting.
• The researchers used stepwise linear regression, a statistical method, to examine the strength of the association between these two types of measurements.

Results

• The difference in minimum pelvic position, as measured by the inertial sensors, showed a moderate association of 0.60 (Ra(2)) with the difference in peak vertical GRFs. This suggests that when the horse’s minimum pelvic position was changing, their peak vertical ground reaction force was also likely to change. However, this measurement did not correlate well with any horizontal GRFs.
• On the other hand, the difference in maximum pelvic position correlated strongly (with an Ra(2) of 0.77) with a change in direction of the GRFs in the second half of the stance (when the horse was in the act of stepping). However, there was no association with the difference in peak vertical GRFs.

Conclusions

• The study concludes that the use of inertial sensor-derived measurements is useful for identifying hind limb lameness in horses. Particularly, the measurements of a change in minimum pelvic position (described as asymmetric pelvic fall) and maximum pelvic position (known as asymmetric pelvic rise) are indicative of changes in how the force is distributed when the horse is moving.
• This suggests that in cases of lameness, there is a decrease in vertical GRF when the pelvic falls, and a shift of force from vertical to horizontal in the second half of the stance period when the pelvis rises.
• As such, the assessment of both pelvic rise and fall is likely to be important when assessing lameness in horses, with these measurements offering potential avenues for further research or development of diagnostic tools.