Nonunion
Non-Union
Definition
- No clinical or radiographic evidence of healing for 3 months beyond the expected healing time of a given bone, with no signs that the bone will continue towards union.
Risk Factors
| Category | Risk Factors |
|---|---|
| Patient | Smoking, alcoholism, radiotherapy, non-compliance, malnutrition, older age |
| Fracture | High energy fractures, bone loss, pathological fractures, compound fractures, specific bone involvement, avascular necrosis (AVN) |
| Fixation | Distracted fractures, periosteal stripping, inadequate stability |
Classification
| Type | Description |
|---|---|
| Hypertrophic | Adequate biology but inadequate mechanics. X-ray shows callus but incomplete bridging. |
| Atrophic | Inadequate biology. X-ray shows no callus and faded bone ends. Often caused by excessively rigid stabilization with inadequate fracture compression. |
| Synovial | A synovial joint (pseudoarthrosis) forms around the fracture. X-ray shows sclerotic bone ends, no callus formation. |
| Infected | May present with any radiographic appearance and may or may not show clinical signs of infection. |
Diagnosis
- High index of suspicion based on risk factors for a given patient.
Clinical Union Indicators
- Pain-free under physiological loading.
- Non-mobile fracture.
X-ray Indicators of Non-Union
- Persistent fracture gap.
- Sclerotic, rounded, or faded bone ends.
- Metalware failure or loosening.
- New deformity.
X-ray Indicators of Union
- Bridging callus and restoration of cortical congruity.
- Obliteration of fracture gaps.
- Bridging trabeculae on 3 out of 4 cortices.
- The most reliable method is the number of cortices bridged.
Additional Diagnostic Tools
- CT Scan: Useful for complex periarticular non-unions.
- Bone Scan: Generally not very useful; may show cold areas in atrophic or synovial non-unions.
- MRI: Good for diagnosing and quantifying infection and for pre-operative planning.
Treatment of Non-Union
- The treatment depends on the type of non-union.
Hypertrophic Non-Union
- Improve the strain environment by lowering strain through interfragmentary compression and rigid fixation.
Infected Non-Union
- The infection must be eradicated before healing can proceed.
- Debride the non-union site back to clean, bleeding bone ends.
- A staged protocol may be required.
- Use external fixation if possible or techniques such as distraction osteogenesis.
Atrophic Non-Union
- Problem due to biology or inadequate compression with rigid, low-strain fixation.
- Debride the non-union site.
- Drill the canals until bone bleeds.
- Use bone grafting.
- Fix rigidly with compression or use techniques such as exchange nailing with grafting.
- The key is to create bleeding surfaces at the non-union site and use bone grafts to promote healing.