With modern treatment methods, most broken bones (fractures) heal without any problems. After a broken bone is treated, new bone tissue begins to form and connect the broken pieces.
Some broken bones do not heal even when they get the best surgical or nonsurgical treatment. In some cases, certain risk factors make it more likely that a bone will fail to heal. When a broken bone fails to heal it is called a "nonunion." A "delayed union" is when a fracture takes longer than usual to heal.
How do broken bones heal?
For bone healing to happen, the bone needs adequate stability and blood supply. Good nutrition also plays a role in bone healing.
Stability. All treatment of broken bones follows one basic rule: the broken pieces must be put back into position and prevented from moving out of place until they heal. Some fractures can be held in position with a cast. Some fractures require surgical fixation with devices like screws, plates, rods and frames.
Blood supply. Blood delivers the components required for healing to the fracture site. These include oxygen, healing cells, and the body's own chemicals necessary for healing (growth factors). The blood supply to the injured bone usually comes back on its own during the healing period.
Nutrition. A broken bone also needs adequate nutrition to heal. Eating a healthy and well-balanced diet that includes protein, calcium, vitamin C, and vitamin D is the best way to ensure adequate nutrition; dietary supplements that go beyond the daily requirements are not effective. (The rare exception is the severely malnourished patient with many injured organs. In this case, the doctor will discuss dietary guidelines and make recommendations for adding dietary supplements.)
What causes bones to not heal?
Nonunions happen when the bone lacks adequate stability, blood flow, or both. They also are more likely if the bone breaks from a high-energy injury, such as from a car wreck, because severe injuries often impair blood supply to the broken bone.
What are some risk factors that may prevent bones from healing?
Several factors increase the risk of nonunion.
- Use of tobacco or nicotine in any form (smoking, chewing tobacco, and use of nicotine gum or patches) inhibits bone healing and increase the chance of a nonunion
- Older age
- Severe anemia
- A low vitamin D level
- Poor nutrition
- Medications including anti-inflammatory drugs such as aspirin, ibuprofen, and prednisone. The physician and patient should always discuss the risks and benefits of using these medications during fracture healing
- A complicated break that is open or compound
- Blood Supply
Nonunions are more likely to happen if the injured bone has a limited blood supply.
- Some bones, such as toe bones, have inherent stability and excellent blood supply. They can be expected to heal with minimal treatment.
- Some bones, such as the upper thighbone (femoral head and neck) and small wrist bone (scaphoid), have a limited blood supply. The blood supply can be destroyed when these bones are broken.
- Some bones, such as the shinbone (tibia), have a moderate blood supply, however, an injury can disrupt it. For example, a high-energy injury can damage the skin and muscle over the bone and destroy the external blood supply. In addition, the injury can destroy the internal blood supply found in the marrow at the center of the bone.
What are symptoms of a bone failing to heal?
Patients with nonunions usually feel pain at the site of the break long after the initial pain of the fracture disappears. This pain may last months, or even years. It may be constant, or it may occur only when the broken arm or leg is used.