Fractures That Do Not Heal: Malunion and Nonunion

Most broken bones heal. Some do not. When a fracture heals in the wrong position it is called a malunion, and when it fails to heal at all it is called a nonunion. Both can be treated, and the sooner they are recognised the simpler that treatment is.

The difference between malunion and nonunion

Malunion means the bone joined, but in the wrong position. It may be bent, twisted, or shortened. The bone is solid, so it can take weight, but the shape is wrong. That changes how force passes through the nearby joints, which is why a malunited fracture can cause problems years later in a joint that was never injured.

Nonunion means the bone has not joined at all. The two ends are still moving against each other. This stays painful, and the limb never feels reliable.

Why some fractures do not heal

Bone healing needs three things: the broken ends held still, a good blood supply, and a body able to do the repair. A problem with any of the three can stop it.

Mechanical reasons

• The broken ends were not held still enough, so new bone kept being disrupted.
• There is a gap between the ends that is too wide to bridge.
• Weight was put on the limb too early.
• A plate, screw or nail has loosened or broken.

Biological reasons

• Poor blood supply to that part of the bone. Some sites are known for this.
• Infection in the bone.
• Smoking, which is one of the strongest risk factors for a fracture failing to heal.
• Diabetes that is not well controlled.
• Poor nutrition, low vitamin D or low calcium.
• Some medicines, including long term steroids and certain anti inflammatory drugs.
• Severe damage to the soft tissue and skin at the time of the injury.

Signs that a fracture is not healing

• Pain at the fracture site that continues long after it should have settled.
• Pain when you put weight on it, months after the injury.
• Swelling or tenderness that will not go.
• A feeling of movement or give at the fracture site.
• The limb looks bent, twisted or shorter than the other side.
• You cannot use the limb normally even though the fracture is old.

Pain that is getting better week by week is normal healing. Pain that has stopped improving, or has started getting worse again, is the sign to have it checked.

Signs of infection in the bone

Infection both causes nonunion and makes it harder to fix, so it has to be ruled out. Sometimes there are clear signs and sometimes there are none at all.

• Redness, warmth or swelling over the fracture.
• Fever or chills.
• Fluid or pus leaking from a wound or an old scar.
• Pain that is worsening rather than settling.
• Feeling generally unwell and tired.

Bone infection can also be silent, showing only as a fracture that refuses to heal. That is why blood tests are usually done alongside the scans.

How it is diagnosed

Diagnosis starts with the history of the injury: how it happened, how it was treated, how long ago, and what has happened since. Other conditions matter too, especially diabetes, smoking and any medicines you take.

Then the bone is imaged.

• X-rays are the first test, and repeat films over time show whether healing is progressing or has stalled.
• CT scan gives a three dimensional view and shows exactly how much bone has bridged the gap. It is the most useful test when the X-ray is unclear.
• MRI shows the soft tissues and is helpful when infection is suspected.
• Blood tests look for signs of infection and for deficiencies that slow healing.

How malunion and nonunion are treated

Treatment depends on which problem it is, where it is, and whether infection is present.

For a nonunion, the usual approach is to make the fracture stable and give it what it needs to heal. That can mean fixing it with a plate, screws or a nail, clearing away the unhealthy tissue at the bone ends, and adding a bone graft to fill the gap and encourage new bone.

For a malunion, the bone has to be cut and realigned, then held in the corrected position while it heals. This is planned carefully beforehand, because the aim is to restore the alignment of the whole limb, not just the bone.

If there is infection, that is treated first. Operating on infected bone without clearing the infection does not work.

Alongside the surgery, the things that stopped the bone healing have to be fixed as well. That means stopping smoking, getting blood sugar under control, and correcting vitamin D and calcium. Surgery alone will not succeed if the reason for the failure is still there.

What you can do to help it heal

• Stop smoking. This is the single biggest thing within your control.
• Follow the weight bearing instructions exactly. Too much too early disrupts healing, and too little for too long weakens the bone.
• Control diabetes.
• Eat enough protein, and correct vitamin D and calcium if they are low.
• Ask before taking anti inflammatory painkillers, as some can slow bone healing.
• Keep your follow up appointments, because a stalling fracture is easier to treat early.

Frequently asked questions

How long before a fracture is called a nonunion?

There is no single number, because different bones heal at different speeds. In general, a fracture that shows no progress on repeat X-rays over several months, and remains painful, is treated as a nonunion. What matters is whether healing has stalled, not the date alone.

Can a nonunion heal without another operation?

Sometimes. If the problem is that the fracture is not held still enough, changing the cast or brace and adjusting weight bearing can be enough. If there is a gap, a poor blood supply or infection, surgery is usually needed.

Does a malunion always need surgery?

No. If the bone healed slightly off but the limb works well and is not painful, it is often left alone. Surgery is considered when the position causes pain, limits function, makes the limb noticeably crooked or short, or is putting a nearby joint at risk.

Why does smoking stop bones healing?

It reduces blood flow to the healing bone and interferes with the cells that build new bone. Fracture healing is measurably worse in smokers. Stopping, even at the point of treatment, improves the chance of success.

Is a nonunion painful forever?

Untreated, it usually stays painful, because the bone ends keep moving against each other. Once the fracture is made stable and heals, the pain generally settles.

Getting a fracture reviewed

If a fracture is still painful months after the injury, or the limb looks bent or short, it is worth having it looked at properly with fresh imaging. Call +91 6355 991 466 or read more about complex fracture management in Surat.

Trusted sources and further reading

This article is general information reviewed by Dr Dev Padia. For more on the conditions and treatments mentioned, see the pages below.

• Complex fracture management — for difficult and non-healing fractures.
• Fracture and trauma surgery — the full range of fracture care.
• OrthoInfo: Nonunions — American Academy of Orthopaedic Surgeons.
• MedlinePlus: Fractures — US National Library of Medicine.

The information on this website is for general guidance and does not replace a personal medical consultation. Please consult a qualified doctor about your own symptoms.