Malunion (Bone Healed in Poor Position)
When a broken bone heals in the wrong position
Quick Facts
- Type: Bone (orthopedic) complication
- Definition: Fracture healed in poor alignment
- Common causes: Inadequate setting or immobilization, complex breaks
- Main effects: Deformity, stiffness, pain, reduced function
Overview
A malunion happens when a broken bone heals, but in the wrong position. Instead of the bone ends lining up and joining straight, they unite while crooked, angled, twisted, or shortened. Unlike a nonunion, where the bone fails to heal at all, in a malunion the fracture does heal, but the resulting shape and alignment are abnormal.
The effects of a malunion depend on the bone involved and how far off the alignment is. A small amount of misalignment may cause few problems, while a larger deformity can lead to pain, stiffness, weakness, an obvious change in shape, and difficulty using the limb. Some malunions also place extra stress on nearby joints, which can lead to wear over time. Understanding how a bone fracture is set and held during healing helps explain why malunions occur.
Symptoms
Signs of a malunion appear once the fracture has healed in a poor position.
- A visible bend, twist, or angle in the bone or limb
- Shortening of the affected arm or leg
- Ongoing pain, especially with use or weight-bearing
- Stiffness or reduced range of motion in nearby joints
- Weakness or difficulty with normal activities
- Limping or an altered way of walking when a leg is affected
In some cases the change is mainly cosmetic, while in others it causes functional problems and discomfort that interfere with daily life.
Causes
A malunion develops when a fracture heals before it has been brought into proper alignment, or when alignment is lost during healing. Causes include:
- Inadequate setting: The broken bone ends were not lined up well enough when treatment began.
- Loss of position during healing: The bone shifted inside a cast or after surgery before it set.
- Complex or unstable fractures: Breaks that are difficult to hold in good alignment.
- Delayed or missed treatment: A fracture that was not treated promptly and healed on its own in a poor position.
- Severe injuries with bone loss or many fragments.
Children's growing bones can sometimes remodel and correct mild malalignment over time, but adults have far less ability to do so.
Risk Factors
- Severe, unstable, or fragmented fractures
- Fractures that are not treated or set promptly
- Difficulty keeping the bone still during healing
- Injuries near joints or in bones that are hard to immobilize
- Not following weight-bearing and activity instructions during recovery
Diagnosis
A malunion is diagnosed by examining the limb and confirming the abnormal healing with imaging.
- Physical examination: Assessing the shape of the limb, alignment, range of motion, and any difference in length.
- X-rays: The main test, showing the healed bone and the degree and direction of misalignment.
- CT scans: Used for detailed measurement of the deformity, especially before planning surgery.
Doctors consider how much the deformity affects function and comfort, not just how it looks, when deciding whether treatment is needed.
Treatment
Not every malunion needs treatment. Mild misalignment that causes little pain or limitation may simply be monitored. When treatment is needed, options include:
- Observation: For minor deformities that do not affect function.
- Physical therapy: To improve strength, motion, and function, and to manage symptoms.
- Orthotics and aids: Shoe lifts or supports to compensate for length differences or altered alignment.
- Corrective surgery (osteotomy): The bone is cut and realigned, then held with plates, screws, or rods while it heals in the correct position.
- Bone grafting: Sometimes added to support healing after realignment.
The choice depends on how much the malunion affects the person's pain, function, and quality of life, balanced against the demands of surgery and recovery.
Prevention
- Seek prompt medical care for suspected fractures so they can be set correctly
- Follow instructions about casts, braces, weight-bearing, and activity during healing
- Attend follow-up appointments and imaging so any loss of alignment is caught early
- Report new pain or a change in shape during recovery
When to See a Doctor
See a doctor if a healed fracture has left you with a visible deformity, ongoing pain, stiffness, weakness, or difficulty using the limb. It is also worth seeking advice if you notice during recovery that:
- The shape of the limb seems to be changing inside a cast
- New pain or a shift in alignment develops
- You are limping or favoring the limb long after the injury
Early review can sometimes allow correction before the bone fully heals in a poor position.
Frequently Asked Questions
What is the difference between malunion and nonunion?
In a malunion, the broken bone heals but in the wrong position, leaving it crooked, angled, twisted, or shortened. In a nonunion, the bone fails to heal at all and the break does not join. Malunion is a problem of alignment, while nonunion is a problem of failed healing.
Does every malunion need surgery?
No. Mild misalignment that causes little pain or limitation may only be monitored, and physical therapy or supports can help in some cases. Surgery to cut and realign the bone is considered when the deformity causes significant pain, dysfunction, or other problems.
Can a malunion cause problems later?
Yes. A malunion can place extra stress on nearby joints, which may lead to pain, stiffness, and earlier joint wear over time. It can also cause weakness, limping, or difficulty with daily activities, depending on the bone and the degree of misalignment.
How is a malunion corrected?
Corrective surgery, called an osteotomy, involves cutting the bone and realigning it into the proper position, then holding it with plates, screws, or rods while it heals. Bone grafting is sometimes added. Recovery takes additional weeks to months.
Can children's bones correct a malunion on their own?
Children's growing bones can sometimes remodel and partly correct mild malalignment over time. Adults have much less ability to do this, so malunion in adults is more likely to need active treatment if it causes problems.
References
- American Academy of Orthopaedic Surgeons (AAOS). Malunions.
- MedlinePlus, U.S. National Library of Medicine. Fractures.
- Mayo Clinic. Broken bone — Diagnosis and treatment.
- National Institutes of Health (NIH), Musculoskeletal health resources.