Biochemical and density assessment of the new bone in late remodeling after callus distraction

Biochemical changes in a canine bone-lengthening model were characterized 5 months after surgery. The mineral content and the total amount of EDTA-extractable noncollagenous proteins, insulin-like growth factor-I, and osteocalcin were determined for the lengthened callus, and a gradient density fractionation analysis of bone powder particles was performed. The results were compared with two other areas of the lengthened tibia and one region of the contralateral tibia. The mineral and osteocalcin contents showed significant decreases, whereas the hydroxyproline concentration was significantly increased. Neither the insulin-like growth factor-I content nor the concentration of EDTA-extractable proteins was significantly different in any of the examined regions.