Definitions & Overview - Broken & Bent
- Nonunion: Fracture fails to unite.
⭐ The FDA defines nonunion as a fracture at least 9 months old with no signs of healing for 3 consecutive months.
- Types:
- Hypertrophic (elephant foot): Vascular, abundant callus, unstable.
- Atrophic: Avascular, no callus, gap present.
- Oligotrophic: Vascular, minimal/no callus; often due to distraction or poor apposition.
- Septic: Infected nonunion.
- Aseptic: Non-infected nonunion.
- Types:
- Malunion: Fracture heals in a non-anatomical/deformed position (e.g., angulation, rotation, shortening).
Etiology & Risk Factors - Why Bones Balk
| Category | Key Risk Factors |
|---|---|
| Patient-Related | Smoking (major!), diabetes mellitus, malnutrition (↓protein, Vit C/D), chronic NSAID/steroid use, systemic infection, advanced age, peripheral vascular disease (PVD). |
| Fracture-Related | Significant instability or gap (e.g., >1mm), compromised blood supply (e.g., scaphoid, talus head), severe soft tissue injury/stripping, substantial bone loss, open fractures (contamination), segmental fractures, intra-articular extension. |
| Surgeon-Related | Inadequate fracture reduction, improper or insufficient fixation (too loose/too rigid), excessive soft tissue stripping during surgery, distraction at fracture site, iatrogenic infection. |
Diagnosis & Classification - Signs & Sorts
- Clinical Features:
- Nonunion: Pain, tenderness, abnormal motion, deformity, pseudoarthrosis.
- Malunion: Deformity, functional limitation, pain, arthritis.
- Investigations:
- X-rays (Serial): Sclerosis, resorption, implant failure, no callus (3-6 months).
- CT Scan: Details anatomy & union.
- Infection: ↑ESR, ↑CRP; Bone/WBC scan.
- Classification of Nonunion (Weber-Cech):
Type Viability Subtype X-ray Feature Hypertrophic Vascular A1: Elephant Foot Abundant callus A2: Horse Hoof Less callus A3: Oligotrophic Minimal/no callus Atrophic Avascular B1: Torsion Wedge Intermediate fragment B2: Comminuted Necrotic fragments B3: Defect Gap, bone loss B4: Atrophic Resorbed ends 
- Paley: For bone defects.
⭐ The 'elephant foot' appearance on X-ray is characteristic of a vascular, hypertrophic nonunion (Weber-Cech Type A1).
Management Principles - Mending Methods
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High‑Yield Points - ⚡ Biggest Takeaways
- Nonunion: Fracture unhealed by 6-9 months. Malunion: Healed with deformity.
- Hypertrophic nonunion ("elephant foot"): good biology, poor stability. Atrophic ("pencil point"): poor biology.
- Key nonunion causes: Infection, avascularity, instability, gap.
- Diamond concept (osteogenic cells, scaffold, growth factors, stability) guides nonunion treatment.
- Common nonunion sites: Scaphoid, tibia (distal), femoral neck.
- Malunion causes functional loss and arthritis; requires corrective osteotomy.
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