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September 22, 2011 by dailybolusoflr
- Can be misdiagnosed as an ankle sprain
- Can be either of the lateral or the medial tubercle
- The lateral tubercle is the more commonly fractured and serves as the attachment of the posterior talocalcaneal and posterior talofibular ligaments
- Mechanism of injury for lateral tubercle injury is hyper-plantarflexion (compression fractures) or inversion (avulsion fractures) (see image showing avulsion fracture)
- The medial tubercle is the smaller and less commonly injured and serves as the attachment of the posterior third of the deltoid ligament
- Mechanism of injury for medial tubercle injury is dorsiflexion/pronation (similar to deltoid ligament sprains)
- Both injures have pain anterior to the Achilles tendon, but on the respective side, associated with swelling. The lack of malleolar tenderness and typical mechanisms of injury for ankle sprains lead to the lack of diagnosis of this injury.
- An additional finding associated with this injury is pain at the site of injury associated with dosiflexion of the great toe. This is related to the flexor hallucis longus tendon which runs between the two tubercles and that gets compressed by the fracture fragment.
- Treatment involves short leg immobilization for 4-6 weeks.
Image courtesy of L. Regan, MD
Ref: Am Fam Physican 2002 1;66(5): 785-795