Non-union and mal-union fractures

What is a non-union or mal-union fracture?

A non-union fracture is when a broken bone fails to join back together, even though it has had enough time to heal. A mal-union fracture is when a broken bone does heal, but in the wrong position, for example, bent, twisted or shorter than it was before.

What are the symptoms of a non-union or mal-union fracture?

With a mal-union fracture, you might notice:

• the bone looks crooked, bent, twisted or rotated
• the bone is shorter than it used to be
• pain, swelling or a limp when you use the affected bone
• pain elsewhere in your body, if the misaligned bone puts extra strain on nearby joints
• numbness, tingling, muscle weakness or nerve pain, if the bone is pressing on a nearby nerve

With a non-union fracture, you might have:

• a deep, persistent pain right where the bone broke
• lasting weakness or reduced movement
• a visible bump or gap where the bone should have joined
• swelling, fever or chills, if the area has become infected

What causes a non-union or mal-union fracture, and who is at risk?

Around 10 to 15% of surgically treated fractures go on to develop a non-union. Most broken bones heal well with the right care, and when they do not, it is usually down to a mechanical problem, a biological one, or a mix of both.

A mechanical problem means the broken pieces have not been held together firmly enough while healing. A biological problem means your body has not had what it needs to heal the bone, often because of a poor blood supply to the area.

A number of factors can raise your risk of a non-union or mal-union, including:

• the type of break, such as a spiral fracture (caused by a twisting injury) or a comminuted fracture (where the bone breaks into several pieces)
• an injury that damages the blood supply to the bone
• treatment that starts too late, or a cast or brace removed too soon
• going back to using the bone before it has fully healed
• smoking or using nicotine products
• older age, poor nutrition, or conditions such as diabetes or thyroid disease
• carrying significantly more body weight than recommended
• some medicines, including chemotherapy drugs, blood thinners, opioids, anti-inflammatory painkillers and steroids
• a break in a bone with a naturally limited blood supply, such as the scaphoid (a small wrist bone), the shin bone near the ankle, or a small bone at the base of the little toe
• infection at the fracture site.

Are there different types of non-union?

Doctors often describe non-unions by how the bone looks on an X-ray:

• Hypertrophic non-union: the bone is producing new tissue at the fracture site, but the pieces still are not meeting. This usually points to a stability problem rather than a healing problem and it often improves once the bone is held more firmly in place.
• Atrophic non-union: there is little or no new bone growth, usually because of a poor blood supply. If infection is also present, this is known as a septic non-union.
• Oligotrophic non-union: some new bone has formed, but the broken ends are not lined up correctly, often because they were not set accurately or shifted afterwards.

How is a non-union or mal-union fracture diagnosed?

Your doctor will start by asking about your original injury, any previous treatment, and your general health. They will examine the bone, checking for visible deformity and gently testing how it moves and feels. Depending on which bone is affected, they may watch you walk or measure the length of the limb.

You will usually have imaging to confirm the diagnosis, such as an X-ray, a CT scan or an MRI scan. A mal-union is diagnosed when the bone has healed in the wrong position.

A non-union is diagnosed when the bone has not started, or has not finished, healing within a reasonable time. This is usually six, nine or 12 months, depending on the bone involved and your general health.

Blood tests may also be used to check for infection and to look for underlying causes, such as low vitamin D, which is found in 60 to 70% of people with a non-union in some studies.

How is a non-union or mal-union fracture treated?

Non-surgical treatment

For a mal-union, this might include:

• a brace to help hold the bone in a better position
• an orthotic shoe insert, if one leg has become a different length to the other
• physiotherapy, to strengthen the muscles around the bone and take some of the strain off it
• over-the-counter anti-inflammatory painkillers, for occasional discomfort.

For a non-union, this might include:

• treating an underlying cause, such as an infection or poor nutrition
• a brace, splint or cast to keep the bone still while it heals
• a bone stimulator, a device that uses ultrasound or electromagnetic waves to encourage healing
• injections such as stem cells or platelet-rich plasma to help stimulate new bone growth.

Surgical treatment

For a mal-union, this might include:

• an osteotomy, where the surgeon cuts the bone to correct its position, shortening, lengthening or realigning it as needed
• limb lengthening surgery, where a device is attached to gradually lengthen a bone that is too short.

For a non-union, this might include:

• debridement, where the surgeon removes any dead tissue from the bone
• vascular surgery, to restore blood flow to the area
• a bone graft, where a piece of bone from elsewhere in your body, or from a donor, gives new bone growth a fresh start
• open reduction and internal fixation (ORIF), where the surgeon repositions the bone pieces and holds them with screws, plates or nails
• replacing existing metalwork or adding an external frame, to give the bone more stability while it heals.

Both non-surgical and surgical treatments have good success rates, though healing and rehabilitation can take time. For example, one review of frame surgery for infected non-unions found healing rates of 76 to 100%, depending on the case. You may need a cane or walker for a period, alongside a course of physiotherapy.

When should I see a doctor?

See a doctor if you think you might have broken a bone, even if you are not sure. Fractures heal best when they are treated early.

If you have already been treated for a fracture but you still have pain, swelling, deformity or difficulty using the bone weeks or months later, it is worth getting this checked. Fever or chills alongside bone pain could mean an infection, and need prompt medical attention.