Arthrosis in the elbow joint of young rapidly growing dogs. V. A pathoanatomical investigation.

During a 3 year period the elbow joints of dogs subjected to autopsy were specially subjected to autopsy were specially investigated regarding the lesions A Ununited or fragmented coronoid process, B Fissure of the coronoid process, C Osteochondritis dissecans of the humeral condyle, and D Ununited anconeal process. Other findings as erosions, wear and tear furrows and degree of osteophyte formation at different locations, are described. The lesions A, B, C and D were seen in 120 dogs and the Rottweilers, the Retriever breeds and the German Shepherd Dogs were most disposed although lesions of the coronoid process were seen in dogs of different size as in a Miniature Poodle and a Pomeranian. Fragmented coronoid process was the lesion most frequently seen among the affected breeds. Fissure of the coronoid process was most frequently seen among Rottweilers while osteochondritis dissecans of the humeral condyle was a frequent finding among Golden Retrievers. Ununited anconeal process was only seen in 7 of the 236 joints investigated. This lesion was the one leading to the highest degree of osteophyte formation. Next to this were fragmented coronoid process and osteochondritis dissecans, while fissure of the coronoid process led to a small degree of osteophyte formation. Histopathological investigation of the coronoid process revealed that fissure and fracture lines occurred in joints in which no degeneration of the joint cartilage was detected, as well as in joints in which thickened and degenerated hyalin cartilage (osteochondrosis) was seen. The authors conclude that fissures seem to be an early stage of fragmentation, but do not necessarily lead to fracture. The condition may be due to osteochondrosis, to general or local overloading of normal tissue or to generalized weakness of the joint cartilage and the bone in combination with mechanical overloading. The term fragmentation of the coronoid process, as proposed by Olsson in 1976, is a more appropriate term for the condition than the previously used ununited coronoid process.