Nonunion (Failed Bone Healing)

Overview

When a bone breaks, the body normally repairs it by forming new bone that bridges the gap and gradually restores strength. A nonunion is when this healing process fails, so the broken ends do not join together even after enough time has passed for healing to be expected. The fracture remains unhealed, often causing ongoing pain and difficulty using the affected limb.

Nonunion is different from a delayed union, where a fracture heals more slowly than usual but is still progressing. In a true nonunion, healing has stalled and is unlikely to complete without further treatment. Many factors influence whether a bone fracture heals normally, including the blood supply to the bone, how well the break is held still, the person's general health, and whether infection is present.

Symptoms

A nonunion is suspected when a fracture that should have healed continues to cause problems.

• Persistent pain at the fracture site, often worse with movement or weight-bearing
• Swelling, tenderness, or warmth over the break
• A feeling of movement, clicking, or instability where the bone should be solid
• Difficulty using the limb or bearing weight long after the injury
• Visible deformity in some cases

Pain and tenderness that continue well beyond the usual healing time are the main clues. Sometimes a nonunion is discovered on follow-up X-rays even when symptoms are mild.

Causes

A fracture may fail to heal when one or more conditions needed for healing are missing. Common contributing factors include:

• Poor blood supply: Bone needs a good blood supply to heal; certain bones and severe injuries are prone to limited blood flow.
• Movement at the fracture: If the broken ends are not held still enough, new bone cannot bridge the gap.
• Infection: Infection in the bone (osteomyelitis) interferes with healing.
• Gap between the bone ends: If the pieces are too far apart or soft tissue is caught between them.
• Severe or complex fractures: Including those with significant bone loss.

Health and lifestyle factors such as smoking, diabetes, poor nutrition, and certain medications also reduce the body's ability to heal bone.

Risk Factors

• Smoking, which strongly impairs bone healing
• Diabetes and poor circulation
• Poor nutrition or low vitamin D and calcium
• Open fractures and high-energy injuries
• Infection at the fracture site
• Older age and conditions such as osteoporosis
• Certain medications, including some anti-inflammatory and steroid drugs

Diagnosis

Nonunion is diagnosed by combining symptoms with imaging that shows the fracture has not healed.

• X-rays: Repeated over time to see whether new bone is bridging the break; a nonunion shows no progress toward healing.
• CT scan: Gives a detailed view to confirm whether the bone ends have joined.
• Blood tests: To look for infection or underlying problems affecting healing.
• Bone scans: Occasionally used to assess bone activity and rule out infection.

Doctors also review factors that may be preventing healing, such as smoking, nutrition, infection, and the stability of any fixation already in place.

Treatment

Treatment aims to create the conditions a fracture needs to heal, and is tailored to the cause. Options include:

• Addressing underlying factors: Stopping smoking, improving nutrition and vitamin D, and controlling diabetes.
• Better immobilization: Improved casting, bracing, or surgical fixation to hold the bone ends still.
• Surgery: Often needed, and may involve internal fixation with plates, rods, or screws to stabilize the bone.
• Bone grafting: Adding bone, often taken from elsewhere in the body, to fill gaps and stimulate healing.
• Treating infection: Clearing any infected bone before healing can occur.
• Bone stimulation: Devices using electrical or ultrasound signals are sometimes used to encourage healing.

With the right treatment, many nonunions eventually heal, though recovery can take additional months.

Prevention

• Stop smoking, which greatly improves bone healing
• Eat a balanced diet with adequate protein, calcium, and vitamin D
• Follow weight-bearing and activity instructions after a fracture
• Keep follow-up appointments so slow healing is caught early
• Control diabetes and other conditions that affect circulation and healing

When to See a Doctor

See your doctor if a fracture continues to hurt, feels unstable, or fails to improve as expected over the weeks and months after injury. Contact your care team promptly if you notice:

• Persistent or worsening pain at an old fracture site
• Increasing swelling, redness, warmth, or fever, which may signal infection
• A new sense of movement or grinding where the bone should be solid
• Difficulty using or bearing weight on the limb long after the break

Related Topics

Frequently Asked Questions

References

1. American Academy of Orthopaedic Surgeons (AAOS). Nonunions.
2. MedlinePlus, U.S. National Library of Medicine. Fractures.
3. Mayo Clinic. Broken bone — Diagnosis and treatment.
4. National Institutes of Health (NIH), Bone health resources.