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Showing shortening of bone, owing to a lateral approximation of the diaphysis because of muscular contraction. Photo by Dr. Symptomatology. According to Cadiot and Almy, "regardless of the location of femoral fractures, the subject is usually intensely lame, the animal frequently walking on three legs fractures of the diaphysis are characterized by an abnormal mobility." In this case Dr.
When there is marked rarefaction of the bone at the ossifying junction, the epiphysis is liable to be separated epiphysiolysis. The separation usually takes place through the young bone of the ossifying junction, and the surfaces of the diaphysis and epiphysis are opposed to each other by irregular eroded surfaces bathed in pus.
The portion of the diaphysis which has sustained the action of the concentrated toxins has its vitality further impaired as a result of the stripping of the periosteum and thrombosis of the blood vessels of the marrow, so that necrosis of bone is one of the most striking results of the disease, and as this takes place rapidly, that is, in a day or two, the term acute necrosis, formerly applied to the disease, was amply justified.
Any diseased process that affects the periosteum is spoken of as periostitis; the term osteomyelitis is employed when it is located in the marrow. The term epiphysitis has been applied to an inflammatory process in two distinct situations namely, the ossifying nucleus in the epiphysis, and the ossifying junction or metaphysis between the epiphysial cartilage and the diaphysis.
The disease commences and is most intense in the marrow of the ossifying junction at one end of the diaphysis; it may commence at both ends simultaneously bipolar osteomyelitis; or, commencing at one end, may spread to the other. The changes observed are those of intense engorgement of the marrow, going on to greenish-yellow purulent infiltration.
Finally the periosteum gives way, and an abscess forms in the soft parts; and if left to itself ruptures externally, leaving a sinus. The most satisfactory treatment is to resect sub-periosteally the diseased portion of the diaphysis. The situation and extent of the disease are shown in X-ray photographs.
The diaphysis is also nourished by numerous blood vessels from the periosteum, which penetrate the cortex through the Haversian canals and anastomose with those derived from the nutrient artery. The epiphyses are nourished by a separate system of blood vessels, derived from the arteries which supply the adjacent joint. The veins of the marrow are of large calibre and are devoid of valves.
Contraction of muscles also tends to exert traction upon a bone so fractured, resulting in a lateral approximation of the diaphysis and thus preventing union because the broken surfaces are not in proper contact. Fractures are longitudinal when the fissure is parallel with the long axis of the bone. Green stick fractures are essentially those resulting from falls to young animals.
It may be less evident to the eye than to the fingers, and is best appreciated by gently stroking the bone from the middle of its shaft towards the end. The maximum thickening and tenderness usually correspond to the junction of the diaphysis with the epiphysis, and the swelling tails off gradually along the shaft.
It may be instructive to describe the X-ray appearances of a long bone that has passed through an attack of acute osteomyelitis severe enough to have caused necrosis of part of the diaphysis.
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