Distal Fibula Fracture Classification and Treatment
Distal fibula fractures are most effectively classified using the Danis-Weber system, with treatment decisions based primarily on fracture stability and the integrity of the ankle mortise, rather than fracture pattern alone. 1
Classification Systems
Danis-Weber Classification
This is the most widely used classification system for distal fibula fractures:
- Type A: Fracture below the level of the syndesmosis (infrasyndesmotic) 2
- Type B: Fracture at the level of the syndesmosis (most common type) 1, 3
- Type C: Fracture above the level of the syndesmosis (suprasyndesmotic) 2
Lauge-Hansen Classification
Based on mechanism of injury and position of the foot at the time of injury:
- Supination-External Rotation (SER): Most common mechanism (corresponds to Weber B) 4
- Pronation-External Rotation (PER): Corresponds to Weber C fractures 2
- Supination-Adduction (SA): Corresponds to Weber A fractures 2
- Pronation-Abduction (PA): Less common mechanism 4
Diagnostic Approach
Initial Assessment
- Standard radiographic protocols should include three views: anteroposterior, lateral, and mortise views 5
- Weight-bearing radiographs provide important information for fractures of uncertain stability 5
- Medial clear space of <4 mm confirms stability 5
Advanced Imaging
- Stress radiographs may be necessary to detect associated mortise instability 2
- The gravity stress view is more reliable than manual stress views in supination-external rotation injuries with suspected deltoid ligament disruption 5
- CT may be indicated for complex fracture patterns or when intra-articular involvement is suspected 5
Treatment Algorithm
1. Stable Fractures (Non-displaced or minimally displaced)
- Non-operative management is recommended for: 3, 4
- Isolated fibula fractures with medial clear space ≤6 mm
- No evidence of ankle mortise instability
- Treatment consists of immobilization with a cast or ankle orthosis for 6 weeks 2
2. Unstable Fractures
- Surgical management is indicated for: 1, 2
- Displacement >2mm
- Ankle mortise instability (medial clear space >4mm)
- Bi- or tri-malleolar fractures
- Open fractures
- High-energy injuries
3. Surgical Options
- Plate fixation: Traditional lateral plating provides good stability but has higher wound complication rates 6
- Antiglide plate fixation: Particularly beneficial for Weber Type B fractures and in older patients with osteoporotic bone 1
- Intramedullary nailing: Minimally invasive option with lower wound healing complications (97.4-100% union rates) 6
- Syndesmotic fixation: Required when syndesmotic instability persists after fracture fixation 6
Post-Treatment Management
Non-operative Protocol
- Immobilization for 6 weeks 2
- Protected weight-bearing as tolerated 4
- Regular radiographic follow-up to ensure maintenance of reduction 3
Post-surgical Protocol
- Rest, elevation, and local cooling of the injured leg 6
- Partial weight bearing (15-20 kg) in an ankle foot orthosis or cast for 6 weeks 6
- Implant removal may be necessary in approximately 33% of surgically treated patients due to persistent pain 3
Outcomes and Complications
Outcomes
- Long-term functional outcomes are comparable between operative and non-operative treatment for stable isolated distal fibula fractures 3
- Olerud-Molander scores show good to excellent results in 89% of non-operatively treated stable fractures versus 71% in operatively treated cases 4
Complications
- Surgical complications: Wound infections (3%), hardware irritation requiring removal (33%) 3
- Non-operative complications: Deep venous thrombosis, malunion, delayed union 3, 2
- Risk factors for worse outcomes: Female gender, older age, unstable fracture pattern, and co-morbidities 4
Special Considerations
- In elderly or medically compromised patients, non-operative treatment may be preferred even for some unstable fractures 2
- Displacement of the distal fibula after non-operative treatment does not necessarily affect functional scores or pain 4
- The quality of reduction and functional outcome is comparable between nail fixation and plate fixation, but nail fixation has lower wound complication rates 6