Competent fracture care requires a basic knowledge of bone biology and healing, a systematic approach to fracture evaluation and description, and a practical understanding of basic splinting and casting techniques. The general principles of bone healing and proper fracture description will be reviewed here. Fractures that are complicated, high risk, or unresponsive to appropriate conservative management should be promptly referred to an orthopedic surgeon.
For information on specific fractures, please see the relevant topic reviews. Stress fractures and pediatric fractures are reviewed separately. (See "Overview of stress fractures" and "General principles of fracture management: Fracture patterns and description in children".)
BIOLOGY OF BONE HEALING
Bone is a composite structure with mineral and organic components. The mineral component contains calcium, phosphate, and hydroxyl ions which are organized into a compound called hydroxyapatite (Ca5(PO4)3(OH)). This mineral skeleton provides the strength, stiffness, and rigidity characteristic of bone. The organic or protein component consists primarily of type I collagen, which lends tensile strength and resiliency. The outer covering of bone, the periosteum, provides the vascular supply that plays an essential role in fracture healing. The periosteum in children is substantially thicker and more robust than in adults, accounting in part for the more rapid healing of pediatric fractures [1,2]. (See "Normal skeletal development and regulation of bone formation and resorption".)
Bone healing is usually divided into three slightly overlapping stages: inflammatory, reparative, and remodeling [2-7]. It is difficult to provide an approximate time frame for each phase because healing rates vary widely according to age and comorbidities. As an example, a simple toe fracture in a healthy young child may heal completely in four weeks while the same fracture in a 65 year old smoker may not heal completely for several years.
The initial inflammatory phase is dominated by vascular events. Following a fracture, a hematoma forms which provides the building blocks for healing. Subsequently, reabsorption occurs of the 1 to 2 mm of bone at the fracture edges that have lost their blood supply. It is this bone reabsorption that makes fracture lines become radiographically distinct 5 to 10 days after injury. Next, multipotent cells are transformed into osteoprogenitor cells, which begin to form new bone.