Disease-specific changes in equine ground reaction force data documented by use of principal component analysis
G E Williams1, B W Silverman, A M Wilson
1Department of Animal Science, De Montfort University, Grantham, England.
Objective:
To assess the force plate as a diagnostic aid in equine locomotor abnormalities, particularly for abnormalities such as navicular disease that 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 and craniocaudal horizontal plots. Principal component analysis (PCA) of group-A data was undertaken on beginning and end of stride data, and the first 2 components were represented graphically. The PCA rotation matrices were applied to equivalent data for horses of groups B and C.
Results:
Asymmetry of peak vertical force (PVF) could not be differentiated among groups A, B, and C. Values for group-B horses, however, were significantly outside mean group-A values on the PCA plot for beginning of stride phase variables. Group-B data were within the group-A range for end of stride phase variables. Values for group-C horses were significantly outside the group-A range for beginning of stride phase variables and were outside mean 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 diagnostic and prognostic tool.
