DYSBARIC OSTEONECROSIS (DON) IN THE FEMUR OF AN EXPERIMENTAL DOG: PATHOPHYSIOLOGICAL ASPECTS

A 32 months old male beagle dog developed a sign of limb bends in the left posterior limb after a single 24-hour hyperbaric exposure to 3.2 atm abs. with acute decompression. It showed transient MRI lesions in the left femur. Eight weeks after the hyperbaric exposure, histopathological examination disclosed an apparent lesion of dysbaric osteonecrosis (DON), which consists mainly of a cicatrized fibrous tissue including many small necrotic foci in the bone marrow of the left femoral lower shaft. This study supports the potential use of the dog as a model for human DON. The present case and a review of the literature suggest that as for the pathophysiological aspect of DON, changes of the intraosseous nutrient artery and its peripheral microvasculature under stasis of bubbling blood with activation of both Hageman factor and blood platelets are very important.