Fractures, or broken bones, are common injuries that orthopaedists treat. The healing process is generally the same for all fractures; through a series of stages, new bone forms and fills in the fractured area. If the fracture is severe, problems that slow the healing process can occur.

How does a fracture heal?
Stage 1: Inflammation
Bleeding from the fractured bone and surrounding tissue causes the fractured area to swell. This stage begins the day you fracture the bone and lasts about 2 to 3 weeks.

Stage 2: Soft callus
Between 2 and 3 weeks after the injury, the pain and swelling will decrease. At this point, the site of the fracture stiffens and new bone begins to form (see figure). The new bone cannot be seen on x-rays. This stage usually lasts until 4 to 8 weeks after the injury.

Stage 3: Hard callus
Between 4 and 8 weeks, the new bone begins to bridge the fracture. This bony bridge can be seen on xrays. By 8 to 12 weeks after the injury, new bone has filled the fracture.

Stage 4: Bone remodeling
Beginning about 8 to 1 2 weeks after the injury, the fracture site remodels itself, correcting any deformities that may remain as a result of the injury. This final stage of fracture healing can last up to several years.

The rate of healing and the ability to remodel a fractured bone vary tremendously for each person and depend on your age, your health, the kind of fracture, and the bone involved. For example, children are able to heal and remodel their fractures much faster than adults.

Problems
Fractures heal without problems in most people. However, when they occur, fracture problems are almost always a result of a severe injury. Compartment syndrome: Severe swelling after a fracture can put so much pressure on the blood vessels that not enough blood can get to the muscles around the fracture. The decreased blood supply can cause the muscles around the fracture to die, which can lead to long-term disability. Compartment syndrome usually occurs only after a severe injury.

Neurovascular injury: Some fractures are so severe that the arteries and nerves around the injury site are damaged.
Infection: Open fractures can become infected when the jagged bone ends are exposed to the air where they have torn through the skin.
Post-traumatic arthritis: Fractures that extend into the joints (intra-articular fractures) or fractures that cause the bones to meet at an abnormal angle in the joint can cause premature arthritis of a joint.
Growth abnormalities: A fracture in the open physis, or growth plate, in a child, can cause many problems. Two of these problems are premature partial or complete closure of the physis. This means that one side of a bone or the whole bone stops growing before it naturally would. If one side of a bone stops growing before the other side, the bone will grow at an abnormal angle. If the whole bone, such as a thigh bone, stops growing prematurely, it will be shorter than the other thigh bone, making one leg shorter than the other.
Delayed union: A fracture that takes longer to heal than expected is a delayed union.
Nonunion: A fracture that fails to heal in a reasonable amount of time is called a nonunion.
Malunion: A fracture that does not heal in a normal alignment is called a malunion.

These problems and complications do not often occur. When they do occur, orthopaedists have methods for managing them.

Richard Johnston III, M.D.
Atlanta, Georgia