Periosteum and bone marrow in bone lengthening - A DEXA quantitative evaluation in rabbits

We quantitatively studied the role of periosteum and bone marrow-endosteum during lengthening in 18 growing rabbits, comparing four surgical procedure s: I)periosteum and bone marrow preservation, 2) periosteum preservation, b one marrow destruction, 3) periosteum destruction, bone marrow preservation , 4) periosteum and bone marrow destruction. An external fixator was set on one femur, the other serving as a control. Distraction began on day 5 and stopped on day 25 (0.25 mm/12 hours). On day 30, femora were harvested with a layer of muscle. Area, bone mineral content and density were measured by dual-energy x-ray absorptiometry. Procedure 2 showed the highest increase in bone mineral content around the elongated callus (127%) compared to proc edures: 1 (81%), 3 (25%) and 4 (-8%, i.e., resorption of bone ends). A stat istically significant effect on bone formation was observed when preserving (vs. destroying): 1) periosteum, 2) bone marrow (effect observed only arou nd the distraction gap), 3) periosteum and bone marrow in combination. Peri osteum alone forms a larger callus, with more mineral content than bone mar row alone, and destruction of both results in the absence of bone formation around the distraction area. Careful preservation of periosteum is essenti al to bone healing. Formation of bone with a large mineral content does not require bone marrow preservation, but there is an interaction effect on he aling between bone marrow and periosteum.