Anatomy Msk · Year 1 · from Anatomy Msk
Case 1: Weber B Ankle Fracture
Clinical Image
Source: Wikimedia Commons - Ankle Fracture - CC BY-SA 3.0
Case Presentation
A 38-year-old woman presents to the emergency department after twisting her left ankle while walking down stairs in high heels. She reports immediate pain and swelling over the outer aspect of her ankle and was unable to bear weight. Physical examination reveals significant swelling and ecchymosis over the lateral malleolus. There is tenderness over the distal fibula at the level of the ankle joint. The medial side has mild tenderness but no bony tenderness over the medial malleolus. There is no tenderness over the proximal fibula (ruling out Maisonneuve injury). The squeeze test is negative. Neurovascular examination is intact. Radiographs demonstrate an oblique fracture of the distal fibula at the level of the tibial plafond (Weber B classification) with lateral shift of the talus and widening of the medial clear space to 6mm (normal <4mm), indicating deltoid ligament injury. The syndesmosis appears intact on radiographs. Given the unstable injury pattern with talar shift, she undergoes open reduction internal fixation of the fibula with a plate. Intraoperative stress testing confirms syndesmotic stability, and the deltoid ligament is not repaired. She is kept non-weight-bearing for 6 weeks with subsequent progression to full weight bearing.
Key Learning Points
- The ankle mortise is formed by the tibial plafond, medial malleolus, and lateral malleolus
- Weber classification: A (below syndesmosis), B (at syndesmosis), C (above syndesmosis)
- Ankle stability depends on the bony ring and ligamentous support (syndesmosis, deltoid, lateral ligaments)
- Medial clear space widening >4mm indicates deltoid ligament injury and an unstable injury pattern
- Weber B fractures can be stable or unstable; instability requires operative fixation