bonehealing

Bone healing is the physiological process by which a fractured bone restores its continuity and mechanical strength. After a fracture, healing occurs in several overlapping stages. The inflammatory phase begins at the time of injury, with hematoma formation and recruitment of inflammatory cells. This is followed by soft callus formation, where fibrocartilaginous tissue bridges the fracture. In the hard callus phase, woven bone replaces the soft tissue, providing stability. The final remodeling phase gradually replaces woven bone with lamellar bone and reshapes the cortex to resemble preinjury anatomy.

Healing is influenced by patient factors (age, nutrition, smoking, diabetes, vascular disease), injury factors (fracture location, severity, displacement), and treatment factors (stability of fracture fixation, infection). Adequate stabilization and blood supply are critical; excessive movement can delay healing. General nutrition and adequate calcium, phosphorus, and vitamin D support bone formation. Medications such as NSAIDs may transiently affect healing in some cases; smoking markedly impairs it.

Healing timelines vary: children heal faster than adults; simple fractures of long bones may unite in about 6 weeks in children and 8–12 weeks in adults, while tibial and femoral fractures may take longer. Radiographic union and absence of pain on function typically indicate healing; persistent tenderness, lack of callus, or instability may signal delayed union or nonunion.

Management ranges from conservative immobilization for stable fractures to surgical stabilization for unstable fractures or nonunions. Surgical options include internal fixation (plates, screws, intramedullary nails) and bone grafting to provide osteoconductive or osteoinductive support. In difficult nonunions, bone grafts, BMPs, or bone growth stimulators may be used, sometimes combined with vascularized grafts or revision fixation. Rehabilitation with progressive loading and physical therapy supports recovery.

Complications include nonunion, delayed union, malunion, infection, refracture, and loss of function.