Disease-specific changes in equine ground reaction force data documented by use of principal component analysis

Objective-To assess the force plate as a diagnostic aid in equine locomotor abnormalities, particularly for abnormalities such as navicular disease th at do not have specific diagnostic criteria. Animals-17 Thoroughbreds without observable locomotor abnormalities (group A), 6 Thoroughbreds with superficial digital flexor tendon injury (group B) , and 8 Thoroughbreds with navicular disease (group-C), Procedure-Using a force plate, ground reaction force patterns were recorded at the trot. Peak limb vertical force and force/time curve parameters were derived from 4 identifiable points at the beginning and end of vertical an d craniocaudal horizontal plots. Principal component analysis (PCA) of grou p-A data was undertaken on beginning and end of stride data, and the first 2 components were represented graphically. The PCA relation matrices were a pplied to equivalent data for horses of groups B and C, Results-Asymmetry of peak vertical force (PVF) could nor be differentiated among groups A, B, and C, Values for group-B horses, however, were signific antly outside mean group-A values on the PCA plot for beginning of stride p hase variables. Group-B data were within the group-A range for end of strid e phase variables, Values for group-C horses were significantly outside the group-a range for beginning of stride phase variables and were outside mea n group-A values for end of stride phase variables. Conclusions-PCA of force/time data provides a sensitive method to evaluate the force/time curve associated with 2 specific injury/disease processes, Clinical Relevance-Horses alter weight-bearing in biomechanically distinct ways, thus creating potential for the force plate to become an important di agnostic and prognostic tool.