Distraction osteogenesis promotes angiogenesis in the surrounding muscles

Distraction osteogenesis is used to treat atrophic nonunion and focal osteomyelitis. It enhances blood vessel formation in the distracted callus and in the surrounding soft tissues. Long-term angiogenesis, however, is not well described. We hypothesized newly formed blood vessels persist in the surrounding muscles until the late consolidation period. We performed unilateral tibial lengthening in eight adult Beagles. Seven days after tibial osteotomy, we began lengthening for 30 days, following which consolidation was allowed to proceed for another 60 days. We took bilateral microangiograms of the bilateral tibialis anterior, extensor digitorum longus, and gastrocnemius muscles. We determined the blood vessel volume density and the longitudinal and transverse microangiographic scores. The number of blood vessels in specified diameter ranges was determined histologically. The blood vessel volume density of the distracted limb was higher in all three muscles. The longitudinal microangiographic score was higher for the tibialis anterior and extensor digitorum longus muscles on the distracted side, whereas the transverse microangiographic score was not higher. Histologically, the number of blood vessels less than 100 mum in diameter on the distracted side was higher in the tibialis anterior and extensor digitorum longus muscles. Our data suggest distraction osteogenesis activates angiogenesis and maintains increased vascularity until the late consolidation period.