Quantification of hoof deformation using optical motion capture.
Deformation of the hoof capsule occurs during stance phase as a result of loading by the distal phalanx. The objective of this study was to evaluate optical motion capture as a technique for measuring hoof deformation during locomotion, and to quantify the deformation of the dorsal wall during stance phase. The front left feet of 3 clinically sound horses were used for this study. The hoof wall was cleaned and 9 retroreflective markers were glued to the lateral and dorsal hoof wall, and shoe. Each horse was trotted in a straight line at constant speed while marker positions during stance phase were recorded at 240 frames/s using a 3-dimensional (3-D) motion capture system. Similar patterns of hoof deformation were seen in all horses; the dorsal wall moved inwards towards the axis of the limb with displacement increasing proximally. Mean peak deformation varied between 0.17 and 0.92 mm in the dorsal hoof wall, and 0.18 and 0.76 mm in the lateral hoof wall. In all horses, movement of the shoe relative to the ground was < 0.7 mm throughout stance phase and movement of the hoof relative to the shoe was < 0.3 mm. Calibration using a micrometer indicated the motion capture system was accurate to < 0.1 mm in the configuration used for the study. This study showed that optical motion capture can be used to measure hoof deformation and successfully addresses some of the limitations of existing methods.