A common foot injury we see after a motor vehicle accident is a talar neck fracture. Excessive dorsiflexion that occurs after slamming on the breaks commonly fractures the neck of the talus. The talus is a bone, which makes up part of the ankle joint. Three main arteries supply blood to the talus, the posterior tibial artery, the anterior tibial artery and the peroneal artery. When two of the three is disrupted avascular necrosis (AVN) occurs and upon weight bearing, the talus can collapse. If lucency is seen on x-rays 6-8 weeks after the injury this is known as the Hawkins sign, and is indicative of revascularization and viability of the talus. The most widely used classification of talar neck fractures is the Hawkins classification. There are four stages describing the severity of dislocation of the talus and its surrounding joints, and each stage predicts the severity of AVN.
- Stage 1:minimal displacement of talus, 7-15% chance of AVN
- Stage 2: subtalar joint subluxation, 35-50% chance of AVN
- Stage 3: ankle joint dislocation, 85% AVN
- Stage 4: subtalar joint, ankle joint and talonavicular joint dislocation, 100% chance of AVN
- Cast immobilization and non-weight bearing
- Fusion of the joints
If you have suffered from an ankle injury for a motor vehicle accident, come see us at Foot & Ankle Doctors, Inc.