General Medical Information

Bone Healing

David J. Terris

Bone shares with the liver the distinction of being the only organs capable of spontaneous regeneration with restoration of lost structure. Because of this property, bone has the capacity to heal through regeneration, rather than scar formation, when certain conditions are present. These conditions include accurate anatomic reduction, lack of mobility, and adequate vascular supply. The potential for this type of healing is provided by rigid fixation with plates and screws but must be weighed against the increased incidence of infection. A significant innovation in the field of bone plating has been the refinement of absorbable plates, which are enjoying widespread use for facial fracture repair.

Under most circumstances, fractured bones undergo secondary healing. This process is similar to the wound healing described at the beginning of this chapter but includes the intermediate stages of soft (cartilagenous) callus and hard (bony) callus formation. These calluses serve to stabilize the fracture, allowing the influx of osteoclasts and osteoblasts that work in concert to calcify the callus. These activities are modulated by bone morphogenetic proteins, cytokines that have the ability to induce differentiation of mesenchymal cells into osteoblasts, and proliferation of cells involved in bone healing.