Motion pattern of the forelimbs in horses with irregular conformation: a computer based kinematographic analysis

Abstract

In this study on earlier developed tool, consisting of a high-speed video camera with appropriate analysis software, is used to analyse limb conformation and hoof landing characteristics as seen from the frontal plane in horses walking an a traedmill. Gait analysis was performed with an s-VHS camera and a high frequency videocamera (KODAK motion corder analyser SR 500, 250 fps) using an analysis software (WINanalyse®, Cie. Mikromak, Erlangen; ProTrack*, Cie. Prophysics, Zürich and Microsoft Excel®). The study is conducted in 2 study populations. Population A (n= 15) was filmed before, during and after farrier treatment in order to assess limb conformation and hoof landing in a frontal view. In study B (n = 28) the same was done, but in this population swing phase characteristics were measured as well. A comparison was made between visual and computer based analysis of the videos. Results were that the computer based cinematographic method allowed for more detailed judgement than visual observation, even if slow motion is used. During the stance phase, the correlation between an uneven first ground contact of the hoof and the horizontal movement of the fetlock joint at the beginning of the stance phase was highly significant. Most horses showed a lateral landing. Trimming and shoeing was performed on the basis of the slow-motion films recorded with the s-VHS camera but improved the type of landing only insignificantly. During the swing phase, all horses had an irregular limb motion in the front view. The segment near the carpus showed predominantly a monophasic movement, arching towards the outside, away from the contralateral limb. In contrast, the hoof and the fetlock joint showed several oscillations in their motion pattern with an overall movement arching inwards, towards the contralateral limb. The conformation of the forelimbs had no influence on the way of landing but tended to influence the movement of the toe during the swing phase. In particular in horses with a base-narrow conformation the anatomic variations of the digits affected the swing phase of the hoof. Horses with a broken limb-axis had significantly more and larger latero-medial out-of-plane movements than did other horses. The trajectory of the proximal part of the forelimb affected the way of landing significantly. In this kinematographic analysis we were able to demonstrate new and more complicated correlations between the conformation of horses, the limb motion during the swing phase and the way of landing of the hoof than we previously expected.