Fracture healing

Fracture healing

  • Multistage healing process (union)
    • Fracture hematoma
      • Bleeding creates a hematoma that surrounds the ends of the bone fragments
      • The hematoma is extravasated blood that changes from a liquid to a semisolid clot.
      • This occurs in the first 72 hours after injury.
    • Granulation tissue
      • Active phagocytosis absorbs the products of local necrosis.
      • The hematoma converts to granulation tissue.
      • Granulation tissue (consisting of new blood vessels, fibroblasts, and osteoblasts) forms the basis for new bone substance (osteoid) during days 3 to 14 after injury.
    • Callus formation
      • As minerals (calcium, phosphorus, and magnesium) and new bone matrix are deposited in the osteoid, an unorganized network of bone is formed and woven about the fracture parts.
      • Callus is primarily composed of cartilage, osteoblasts, calcium, and phosphorus.
      • It usually appears by the end of the second week after injury
    • Ossification
      • Callus ossification is sufficient to prevent movement at the fracture site when the bones are gently stressed.
      • During this stage of clinical union, the patient may be allowed limited mobility or the cast may be removed.
    • Consolidation
      • As callus continues to develop, the distance between bone fragments decreases and eventually closes
      • Ossification continues and can be equated with radiologic union, which occurs when an x-ray shows complete bony union.
      • Can occur up to 1 year after the injury
    • Remodeling
      • Excess bone tissue is resorbed in the inal stage of bone healing, and union is complete.
      • Gradual return of the injured bone to its preinjury structural strength and shape occurs.