MEASUREMENT OF SERUM ANGIOGENIC FACTOR IN DEVASCULARIZED EXPERIMENTALTIBIAL FRACTURES

Early recovery of the vasculature is of profound importance in healing fractures, but the exact role of the regenerating endothelium remains controversial. Serum activity of endothelial cell-stimulating angioge nesis factor (ESAF) was measured after tibial osteotomy in two groups of sheep over a period of 42 days. Each osteotomy was held in an instr umented external fixator, and in one group the musculoperiosteal vascu lature was excluded from the osteotomy site. In the well-vascularized group (n = 4), ESAF activity was significantly higher 2-5 days after o steotomy, with a peak at 4 days (21.1 +/- 5.4, p < 0.05), and displaye d a biphasic pattern of secretion with a second peak at 7 days (24.3 /- 5.5). In the devascularized group (n = 4) overall activity was lowe r, with only a single peak occurring at 9 days (17.5 +/- 3.2). These f indings were correlated with significant differences in structural pro perties and on histological examination. The early detection of such r egional vascular responses may prove to be of significant clinical val ue in high-energy trauma, enabling prediction of those fractures at ri sk of delayed or nonunion.