Biomechanische Untersuchungen am Fesselgelenk (Articulatio metacarpophalangea) des Pferdes

The fetlock joint (articulatio metacarpophalangea) plays an exceptional role within the limb, as it is the only joint which is in hyperextension in the standing horse. It is therefore exposed to special loading situations compared to other joints. The objective of this study is to describe in a detailed way the morphological parameters of loading in the equine fetlock joint (metacarpophalangeal articulation). 45 specimens of 26 horses of different breeds and sizes, male and female were examined. Their age ranged from foal to 30 years. Using Computertomographic Osteoabsorptiometry (CT-OAM) and Chondrocrassometry (CT-CCM) the distribution of the subchondral bone density and the cartilage thickness were determined topographically in the 3D reconstruction of the joint. Generally the subchondral bone density increases in all bones forming the fetlock joint with increasing age of the horses. Up to the age of 2 years no significant increase in the subchondral bone density can be stated. From the age of 3 years onward a distinct increase can be measured until it comes to stagnation in horses older than 13 years of age. In most cases the areas with homogeneous subchondral bone density extend within the articular surface. In the dorso-distal area of the trochlea a broad transversal band of high bone density can be observed, which at the angle of stance corresponds to a respectively dense part of the phalangeal articular surface. The dorsal and palmar area at the edge of the trochlea, as well as the palmar edge of the fovea articularis show low bone density. Altough the lateral edges of the trochlea and the fovea articularis show a higher density. The method of split lines showed no definite preferential orientation of the collagen fibres in the subchondral bone of the fetlock joint. Therefore it is not possible to draw any conclusions concerning physiological incongruence of this articulation. In animals from 3 months to 2 years of age a change in the trochlear profile can be observed from a cylindrical condyle to a concave - convex shape in abaxial direction. This could be related to the results described above. Surfaces of the trochlea (palmar area) and the sesamoid bones articulating in the standing horse show a higher subchondral density. In contrast to the subchondral bone density the cartilage thickness generally decreases in older horses. After the period of maximum growth in horses the decrease of cartilage thickness stagnates at the age of 3 to 4 years. Articular surfaces in the trochlea, the proximal phalanx and the sesamoid bones which are in contact during stance show low cartilage thickness. It seems that areas which are loaded more statically way are covered by a thinner cartilage layer while areas loaded more dynamically are covered by a thicker cartilage layer. Generally speaking the tendency towards a negative correlation between subchondral bone density and cartilage thickness can be observed in the fetlock joint of the horse. An exception to this rule is the vertex area in the sagittal groove, where both a high density and a high cartilage thickness can be found.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Ludwig-Maximilians-Universität

Year

2001

Author dc:creator

• Schäfer, Jens Christian

Repository record source_url

https://edoc.ub.uni-muenchen.de/56/

OAI identifier oai:identifier

oai:edoc.ub.uni-muenchen.de:56