ABSTRACT
Osteonecrosis appeared unexpectedly in sheep that we were using for decompression studies. Their dive history provided a recipe for an animal model of dysbaric osteonecrosis. Ficat and Arlet (1980) emphasized the role of high intramedullary pressure (IMP) in conditions with bone pain and osteonecrosis. This suggested that high IMP might cause both limb bends and dysbaric osteonecrosis. We found elevated IMP in limbs showing signs of bends. Artificially elevated IMP produced necrosis like that from long hyperbaric exposures with no-stop decompression. Fatty marrow can take up large quantities of nitrogen during exposure to compressed air. If bubbles form in the closed, rigid marrow space upon decompression, pressure in the space must rise. Elevated IMP may cause bone pain; blood flow may be impaired, producing a ‘compartment syndrome’ of bone. If high IMP and reduced blood flow are sufficiently prolonged, death of both marrow and calcified bone may occur. Prompt recompression of limb bends will probably prevent development of bone necrosis.
