Overview
what it is and why it mattersMost fractures heal on a predictable schedule. When they do not, the result is either a non-union or a mal-union, two distinct problems that require different thinking. A non-union is a fracture that has failed to heal: well past the time the bone should have knitted back together (generally 6 to 9 months for most bones in the limbs), the X-ray still shows a gap or a persistent fracture line rather than the new bone that signals healing. Non-unions happen for different reasons. Sometimes the bone is still trying to heal but the fracture moved too much for the ends to join. Sometimes the bone has stopped trying to heal at all. And sometimes an infection at the fracture site has shut healing down and has to be cleared first. The reason matters because each one calls for a different surgical plan.
A mal-union is a different problem: the bone has healed, but in the wrong position. The limb may be shortened, angled to one side, or rotated relative to the other limb. Minor mal-alignment is often well tolerated, but when the deformity is significant, it changes how load passes through the adjacent joints, accelerating cartilage wear over the years. A tibial mal-union that loads the inner side of the knee harder than the outer side will, over time, grind down the cartilage on that side and produce premature knee arthritis.
Risk factors for non-union include smoking (which reduces blood flow to healing bone), poorly controlled diabetes, low vitamin D, certain medications, high-energy fractures with bone loss, and inadequate fixation of an unstable pattern. Identifying and correcting any underlying factors is part of the treatment plan before surgery.
Symptoms
what you may notice- Persistent fracture-site pain, ongoing pain at the original break well beyond the expected healing window, usually several months
- Abnormal motion at the fracture, the bone moves where it shouldn't (non-union), sometimes with a grinding or shifting sensation
- Visible deformity, the limb looks shortened, angled, or twisted compared to the other side (mal-union)
- Compensatory problems, limping, altered gait, or pain in the joints above or below the healed-but-crooked bone
Diagnosis
exam first, imaging secondSequential X-rays over time tell the story: healing should show progressive bridging bone forming across the fracture line. A CT scan is the most sensitive test for confirming non-union; it clearly shows whether bone has bridged the gap. Blood work checks for infection and for metabolic problems that could be slowing healing (vitamin D deficiency, thyroid issues, low calcium). A nuclear medicine bone scan can show whether the bone is still biologically active at the fracture site.
How We Treat It
what we try first, in orderCare starts with the things that give bone its best chance to heal on its own before any operation is planned. The steps below are introduced in the order we usually reach for them.
1
Fix the Reasons Healing Stalled
Several things slow a fracture down: smoking (which reduces blood flow to healing bone), poorly controlled diabetes, low vitamin D, certain medications, high-energy fractures with bone loss, and inadequate fixation of an unstable pattern. Identifying and correcting any underlying factors is part of the treatment plan before surgery.
2
Bone Stimulator (Low-Intensity Pulsed Ultrasound / LIPUS)
An FDA-cleared external device that delivers low-intensity ultrasound waves through the skin to stimulate bone healing. It is worn at home for a set period each day on the schedule your surgeon prescribes. The evidence is strongest for non-unions of the wrist and tibia.
Surgical Options
if non-operative care isn't enoughMost established non-unions, and any mal-union that is causing meaningful pain or functional problems, need surgery. The procedure typically combines two things: replacing or revising the fixation hardware to provide better stability, and adding bone graft to provide fresh biology at the fracture site. For mal-unions, an osteotomy (a controlled surgical re-break) is sometimes done first to put the bone back into proper alignment.
Providers Who Treat Non-Union & Mal-Union
fracture care team
Frequently Asked
questions we hear in clinicWhen is a fracture called a non-union?
When it has failed to heal well past the time the bone should have knitted back together, generally 6 to 9 months for most bones in the limbs. At that point the X-ray still shows a gap or a persistent fracture line rather than the bridging bone callus that signals healing.
What is the difference between a non-union and a mal-union?
A non-union is a fracture that has failed to heal. A mal-union is a fracture that has healed, but in the wrong position, so the limb may be shortened, angled to one side, or rotated relative to the other limb.
Does a mal-union cause problems down the road?
Minor mal-alignment is often well tolerated. When the deformity is significant, it changes how load passes through the adjacent joints, which accelerates cartilage wear over the years. A tibial mal-union that loads the inner side of the knee harder than the outer side can, over time, grind down that cartilage and produce premature knee arthritis.
Can a non-union heal without surgery?
Care starts with correcting the underlying factors that stalled healing and, in some cases, a bone stimulator (LIPUS), an FDA-cleared external device worn at home on a daily schedule your surgeon prescribes. That said, most established non-unions, and any mal-union that is causing meaningful pain or functional problems, need surgery.
What does the surgery involve?
The procedure typically combines two things: replacing or revising the fixation hardware to provide better stability, and adding bone graft to provide fresh biology at the fracture site. For mal-unions, an osteotomy (a controlled surgical re-break) is sometimes done first to put the bone back into proper alignment.
What raises my risk of a non-union?
Smoking (which reduces blood flow to healing bone), poorly controlled diabetes, low vitamin D, certain medications, high-energy fractures with bone loss, and inadequate fixation of an unstable pattern. Identifying and correcting any underlying factors is part of the treatment plan before surgery.
Further Reading
authoritative sourcesExternal patient-education references and related OSI pages for additional background: