Evaluation of three-dimensional kinematics of the distal portion of the forelimb in horses walking in a straight line.

The research is focused on evaluating the three-dimensional movements of the lower part of the forelimb in horses when they are walking straight on a hard track. The study also aims to quantify these movements using a new methodology.

Methodology

• The study involved four healthy French Trotter horses. The researchers surgically attached ultrasonic kinematic markers to the four lower segments of the digits of the left forelimb of each horse.
• The horses were monitored as they walked in a straight line and the three-dimensional coordinates of these markers were recorded. This data was used to calculate the angles of rotation of each digital joint, as well as the three-dimensional orientation of the hoof and the third metacarpal bone.
• The researchers developed a calibration process to turn the data from the markers into information about the anatomically relevant coordinate system. This is necessary because the coordinate system of the measurement device is different from the biological coordinate system in which the horses move.

Results and Interpretation

• The precision of the method was observed to be 0.5 degrees, which indicates a high level of accuracy. The repeatability of the calibrations resulted in variations of 1.4 degrees which showcases consistency in results.
• The study discovered noticeable extrasagittal (movements in directions other than straight forward) movements of the proximal and distal interphalangeal joints during landing. This happens because the hoof’s impact is on the lateral side.
• The average extension of the proximal interphalangeal joint – the joint closest to the body in the “finger” of the horse – was found to be 10.0 +/- 2.5 degrees.

Conclusion

• This research provides a detailed explanation of the methodology, error analysis, and procedures used to measure the three-dimensional rotations of the four lower segments of the forelimb in walking horses.
• The significant involvement of the proximal interphalangeal joint in both the sagittal (forward and backward) and extrasagittal planes indicates its functional importance. This should encourage investigators and clinicians to pay more attention to this joint in their future studies and treatments.