Morphological studies on the early healing process of diaphyseal fractures in humans.

The healing process of diaphyseal fractures have been largely investigated in animals, but extremely little informations are available for humans. We analyzed in patients with diaphyseal fractures, the morphological features of the medullary and periostal callus in the early stages of the repair process. Specimens were obtained from 15 patients aged 20 to 62 years, who underwent open internal fixation of the fractures at 2 to 15 days after injury. The samples were taken at the fractures site at 2 to 6 cm. proximally or distally. There were processed for histological, histochemical and microscopic examination. In the first 3 days after injury, the fractures gap was filled by blood clot. At 3 to 6 days, the clot was invaded by numerous mesechymal cells, probably originating from marrow cells or marrow endothelial cells of capillary or venous vessels undergone enlargement and transformation. No chondrocytes were visible even at 15 days from injury. From the 6th day the periosteum appeared to be thickened due to marked proliferation of fibroblasts like cells. At 6 to 8 days, areas of membranous ossification were visible in the periosteum situated close to the fracture site. At 10 to 15 days, small visible in the periosteum situated close to the fracture site. At 10 to 15 days, small areas of membranous ossification were also visible far from the fracture site. Our knowledge of the healing process of a fracture is presently based on experimental models. We found significant differences in the early stages of healing of diaphyseal fractures between human and animal specimens. The main difference was the absence of humans of a cartilaginous callus, which in animals precedes the formation of bone callus.