Abstract
1. The processes of repair and union were studied in six fractures of the lower end of the radius, ranging in age from ten days to five and a half months.
2. The major pathway to union is medullary, through the proliferation around the fracture of vascular granulation tissue with osteogenic power. This invades and then bridges the fracture and is followed by the laying down of trabeculae of new bone.
3. Success depends on the growth of new capillaries across the fracture line, some of which mature and re-establish the meduilary circulation.
4. Indriving of the lateral cortex of the proximal fragment into the distal spongy medulla at the time of injury (in Colles's fractures) permits bridging between proximal periosteal and distal meduliary callus. Otherwise periosteal proliferation plays only a subsidiary role in union.
5. Fissure fractures of the lower articular surface were frequent and they also healed by the invasion of granulation tissue proliferating in the medulla nearby.
