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Type of publication: Doctoral Thesis
Type of document:

Year: 2002

Authors: Fitzthum, E

Title: Biomechanische Untersuchungen im Belastungsversuch zur Pathogenese der Ulnafraktur beim Pferd.

Source: Dissertation, Vet. Med. Univ. Wien, pp. 127.


Peham Christian

The aim of this study was to evaluate the different reasons for the occurence of ulnar fractures in the horse. Four trials with 23 bone specimens from slaughter-house horses were conducted in a material testing machine. The force leading to fracture was recorded, and its configuration was analysed radiographically. In the first trial, the elbow joint underwent hyperextension,resulting in 2 fractures of the humerus. The exerted forces were 7.8 and 7.9 kN. The tension forces on the olecranon created by the m. triceps brachii during the second and the third trial were stated as the reason for the ulnar fracture. The tension force was simulated by pressure on the caudal part of the olecranon. In the second trial 6 ulnar fractures occured. 2 of those were comminuted fractures and in 4 cases the fracture was approximately parallel to cranio-proximal edge of the olecranon. The exerted force was 8.7 - 23.5 kN. In the third trial the angle of the acting force was changed resulting in 10 fractures, which were similar to in vivo observed fractures. The needed force was 5.7 - 22 kN. In the fourth trial a lateral force was exacted on the olecranon. It resulted in 4 comminuted fractures and 1 fracture of the proc. anconeus. The necessary force was 4.8 - 12 kN. These trials led to the conclusion, that hyperextension of the elbow joint as a single reason of ulnar fracture in the horse is highly unlikely. A lateral force, like a fall or kick from another horse, can very potentially lead to an ulnar fracture. The tension force of the m. triceps brachii apparently plays a major role in the pathogenesis of ulnar fractures and might be the single cause of an ulnar fracture in some cases.

Horse / Ulna / Fracture / Pathogenesis / Biomechanics / Material Testing Machine

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