Early structural changes in vascularized periosteal flaps studied in situ.

This study examines the very early stages of osteogenesis in vascularized periosteal flaps and completes a characterization of their behavior after decortication. Pleuroperiosteal flaps based on the intercostal artery were developed in nine dogs and studied in situ by histologic and tetracycline fluorescence methods over periods varying from 1 to 7 days. The earliest changes were noted at 72 hours and were characterized by cellular and capillary proliferation, osteoid deposition, and bright fluorescence. The potential function of retained osseous spiculae was investigated separately. It was concluded that microscopic fragments of mature bone trapped within the flaps appear to assist and consolidate new bone formation.