A broken bone usually improves in a predictable direction: pain settles, the fracture becomes more stable, and follow-up X-rays show new bone bridging the break. But sometimes the process stalls.
If you are months out from a fracture and still asking, “Why is my fracture not healing?”, the answer is not always that something went wrong. Some fractures simply heal more slowly than others. In other cases, the bone may have developed a delayed union or a nonunion, meaning healing is taking much longer than expected or has stopped progressing enough to require a new plan.
The important point is that a slow-healing fracture deserves a diagnosis before it deserves a treatment. The problem may be mechanical, biological, infectious, or a combination of those factors.
At Pacific Bone & Joint, fracture-reconstruction evaluation focuses on three questions: Is the bone actually progressing toward union? Is the fracture mechanically stable? Is there a biological or medical reason healing is being held back?
The hero image above is a representative two-view radiograph of tibia and fibula pseudarthrosis, cropped for presentation from Jmarchn / Wikimedia Commons under CC BY-SA 3.0. It is not a Pacific Bone & Joint patient or a treatment result.
What do delayed union and nonunion mean?
Bone healing takes time, and the expected timeline depends on the bone involved, fracture pattern, blood supply, soft-tissue injury, treatment method, age, medical conditions, and many other factors. There is no single number of weeks that defines normal healing for every fracture.
A delayed union means the fracture is healing more slowly than expected, but there may still be evidence of progress.
A nonunion means the fracture has failed to heal adequately and is no longer showing the expected progression toward solid union. The American Academy of Orthopaedic Surgeons describes nonunion as a fracture that fails to heal, while delayed union refers to a fracture that takes longer than usual to heal. AAOS: Nonunions.
That distinction matters because a delayed union may still heal with time and careful management, while an established symptomatic nonunion often requires a more targeted intervention.
How does a fracture normally heal?
Bone is living tissue. After a fracture, the body creates a healing environment around the break, builds new tissue, mineralizes it, and gradually remodels the area into stronger bone.
For that process to succeed, three broad ingredients matter:
- Stability: The fracture needs enough mechanical stability for new bone to bridge the gap.
- Blood supply and healing biology: Living bone and surrounding soft tissues need adequate circulation and viable cells.
- A healthy overall environment: Nutrition, metabolic health, infection status, medications, nicotine exposure, and other medical factors can influence healing.
AAOS emphasizes stability, blood supply, and adequate nutrition as central requirements for fracture healing. AAOS: Nonunions.
A fracture can struggle because one of these elements is missing, or because several smaller problems add up.
What are signs that a fracture may not be healing?
Persistent pain alone does not prove a nonunion. Many fractures remain sore for months, especially with activity. But certain patterns should prompt reassessment.
Common reasons to return for orthopedic evaluation include:
- Pain that remains centered at the fracture site long after the expected early recovery period
- Pain that improves very little over several follow-up visits
- A feeling of motion, instability, or giving way at the old fracture
- Difficulty progressing weight bearing despite appropriate rehabilitation
- X-rays that continue to show a persistent fracture line without convincing bridging
- Hardware that appears loose, bent, or broken
- New deformity, shortening, or abnormal rotation
- Recurrent swelling, redness, drainage, or other concern for infection
AAOS notes that persistent pain and lack of progressive healing on imaging are common clues. Serial X-rays are especially useful because the trend over time can be more informative than one image on one day. AAOS: Nonunions.
Why do some fractures fail to heal?
There is rarely one universal explanation. In fracture reconstruction, it is useful to think about mechanics, biology, and infection.
1. The fracture may not be stable enough
Bone needs some controlled mechanical loading to heal, but excessive motion across a fracture can prevent bridging. This can happen after a difficult fracture pattern, loss of reduction, inadequate fixation, hardware failure, or repeated stress before the bone is ready.
When instability is the dominant problem, simply waiting longer may not solve it. The mechanical environment may need to be changed.
2. The blood supply may be limited
High-energy injuries can damage the soft tissues and blood vessels around a fracture. Open fractures, severe comminution, bone loss, and prior surgeries may all affect local biology.
The AAOS notes that open fractures can involve damage to blood supply and carry greater risk of infection and healing complications. AAOS: Open Fractures.
3. Infection may be present
A fracture can fail to heal because of infection, sometimes even without dramatic fever or severe redness. Infection is especially important to consider after open injury or previous fracture surgery.
An infected nonunion is treated differently from a purely mechanical or biological nonunion, which is why laboratory testing, cultures, and careful surgical planning may be necessary when infection is suspected.
4. Nicotine can interfere with healing
Smoking and other nicotine exposure are important modifiable risk factors in bone healing. Nicotine and tobacco use can impair blood flow and cellular activity needed for bone repair.
For a patient facing a delayed union or nonunion, stopping nicotine is not a cosmetic recommendation. It can be an important part of improving the biological environment for healing.
5. Medical and nutritional factors can matter
Poorly controlled diabetes, significant anemia, nutritional deficiency, severe vitamin or mineral abnormalities, osteoporosis, and other metabolic or endocrine problems may contribute in selected patients.
This does not mean every person with a slow fracture needs an enormous laboratory panel. Testing should be guided by the fracture pattern, history, symptoms, and clinical suspicion.
6. Some fractures are simply difficult fractures
Certain bones and fracture patterns have limited blood supply or experience high mechanical stress. Some injuries start with substantial bone loss or soft-tissue damage. Even with appropriate initial care, these fractures can be harder to heal.
A nonunion therefore does not automatically mean the original treatment was incorrect. The next step is to identify what is preventing union now.
How is a possible nonunion evaluated?
The evaluation begins with the story of the fracture.
Important questions include how the injury occurred, whether it was open or closed, what treatment was performed, how weight bearing progressed, whether pain ever improved, whether there has been drainage or infection, nicotine exposure, medications, medical conditions, and whether the limb feels unstable.
The physical examination looks for tenderness at the fracture, motion or deformity, skin and wound condition, limb alignment, joint stiffness, muscle weakness, circulation, and nerve function.
X-rays
Serial X-rays are usually the starting point. They can show whether bridging bone is increasing, whether the fracture line is changing, and whether implants remain stable.
CT scan
A CT scan may be useful when standard X-rays cannot clearly show how much of the fracture has bridged, especially around complex anatomy or hardware.
Laboratory testing
When infection or a systemic healing problem is a concern, blood tests may be appropriate. AAOS notes that laboratory testing may help identify infection or medical factors such as anemia or diabetes in selected patients. AAOS: Nonunions.
The goal is not simply to label the fracture “nonunion.” It is to determine why it is not healing.
Does every slow-healing fracture need surgery?
No. This is one of the most important distinctions for patients.
A fracture that is healing slowly but still showing progression may simply need more time, protection, and optimization of contributing factors. The correct plan depends on symptoms, fracture stability, imaging progression, and the consequences of continued waiting.
Nonsurgical management may include:
- Continued protection or modification of weight bearing
- Bracing or immobilization in selected situations
- Correction of nutritional or medical issues when identified
- Nicotine cessation
- Review of medications and overall bone health
- A prescription bone-growth stimulator in selected cases
The U.S. Food and Drug Administration classifies non-invasive bone-growth stimulators that use electrical, magnetic, or ultrasonic fields for treatment of established nonunions or certain failed fusions. These devices are prescription treatments, not a substitute for diagnosing instability or infection. FDA product classification.
A stimulator cannot make an unstable construct mechanically stable, and it cannot eradicate an infection. Patient selection matters.
When does nonunion surgery become reasonable?
Surgery may be considered when a symptomatic fracture has clearly stopped progressing, when instability or deformity is present, when hardware has failed, when bone loss is substantial, or when infection requires operative treatment.
The exact operation depends on the cause.
Revision fixation
If the fracture lacks stability, plates, nails, screws, or another fixation strategy may need to be revised so the bone has a better mechanical environment for healing.
Bone grafting
Bone graft can add biological support to a fracture that has stalled. Depending on the situation, graft may come from the patient’s own bone, donor tissue, or a bone-graft substitute.
Removing nonviable tissue
Some established nonunions contain scar tissue or unhealthy bone at the fracture site. Surgery may involve preparing the bone ends and restoring a healthier healing surface.
Treating infection
When infection is present, treatment may require cultures, removal of infected or nonviable tissue, antibiotics, staged reconstruction, and sometimes changes in fixation strategy.
Correcting alignment
If a fracture has healed or is healing in a poor position, treatment may overlap with malunion reconstruction. Restoring alignment can matter because a crooked or shortened limb may overload nearby joints even if the fracture itself eventually unites.
Pacific Bone & Joint evaluates these problems through its malunion and nonunion reconstruction service. The plan is individualized, and not every patient needs the same operation.
What can you do to help a fracture heal?
Patients often ask whether there is something they can take or do to “make the bone heal.” There is no single supplement or exercise that overrides poor mechanics, infection, or major bone loss. But several practical steps can improve the overall healing environment.
- Avoid nicotine. Cigarettes, vaping products containing nicotine, and other nicotine sources can impair healing.
- Follow weight-bearing instructions. Too much load too early can be harmful in some fractures, while unnecessary prolonged unloading can also have downsides. Follow the plan for your specific fracture.
- Eat enough protein and overall calories. Healing requires energy and building blocks.
- Manage medical conditions. Diabetes, anemia, osteoporosis, and other conditions should be addressed when relevant.
- Keep follow-up appointments. Serial imaging is how your team determines whether healing is actually progressing.
- Do not stop prescription medicines on your own. If a medication may affect bone health, discuss it with the prescribing clinician rather than discontinuing it abruptly.
If a fracture is not healing, the most useful intervention is often finding the limiting factor rather than adding another supplement.
Where does physical therapy fit?
Physical therapy is important, but timing matters.
After a fracture, PT can help restore joint motion, muscle strength, gait, balance, and confidence. It can also help patients safely progress activity once the fracture is stable enough for rehabilitation.
But physical therapy cannot mechanically stabilize an unstable nonunion or treat an infected fracture. If pain remains sharply localized to the fracture site or progress repeatedly stalls, the underlying bone problem should be reassessed before simply pushing harder in therapy.
For a new fracture that is following a normal course, our fracture care service explains how evaluation, protection, imaging, and rehabilitation fit together.
When should you seek urgent care?
A delayed union is usually not an emergency, but some symptoms need prompt attention.
Seek urgent medical evaluation for:
- Increasing redness, warmth, drainage, or fever around a previous fracture or surgical incision
- A sudden new deformity or a clear change in alignment
- New inability to bear weight after a period of improvement
- New numbness, severe weakness, a cold foot or hand, or major color change
- A new open wound over hardware or bone
- Sudden severe pain after a new injury to the healing limb
If you are unsure whether symptoms represent an emergency, it is safer to have the limb assessed.
What should you bring to a nonunion consultation?
A good reconstruction visit is much more useful when the full timeline is available.
If possible, bring or arrange access to:
- Original injury X-rays and CT scans
- Operative reports from previous fracture surgery
- Follow-up imaging showing the progression over time
- Any prior culture results or infection records
- A current medication list
- Details about nicotine use, diabetes, osteoporosis, or other health conditions
Seeing the sequence of images can reveal whether the fracture was improving and then stalled, never progressed, or changed mechanically over time.
The practical takeaway
A fracture that still hurts months later is not automatically a nonunion, and a nonunion does not automatically mean a major reconstruction is required.
The useful questions are more specific:
- Is the fracture truly progressing toward union?
- Is it stable enough to heal?
- Is the blood supply and biology adequate?
- Could infection or a medical factor be interfering?
- Would more time help, or has the situation reached the point where intervention offers a better path?
That framework helps separate a slow fracture that needs patience from a stalled fracture that needs a different strategy.
If a fracture has remained painful, unstable, or unchanged on imaging, request an orthopedic fracture-reconstruction evaluation with Pacific Bone & Joint so the cause of delayed healing can be identified and the options reviewed with you.
Sources and further reading
- American Academy of Orthopaedic Surgeons: Nonunions
- American Academy of Orthopaedic Surgeons: Open Fractures
- U.S. Food and Drug Administration: Non-invasive bone growth stimulator classification
This article is for patient education and does not replace an individual examination, diagnosis, or treatment plan.
