E2915. Adult Avulsion Injuries of the Ankle and Hindfoot: Looking Beyond the Malleoli
  1. Kimia Kani; University of Maryland School of Medicine
  2. Stephanie Jo ; University of Maryland School of Medicine
  3. Jack Porrino ; Yale School of Medicine
  4. Hyojeong Mulcahy ; Yale School of Medicine
  5. Felix Chew ; University of Washington
Avulsions injures (AIs) occur at level of soft-tissue (i.e., capsuloligamentous, myotendinous, and retinacular) attachments to bone. Accurate recognition of the true spectrum of these injuries on imaging requires familiarly with pertinent anatomy and underlying injury mechanism. The purpose of this exhibit is to review the relevant anatomy, mechanisms of injury, typical imaging findings, and potential complications of the spectrum of ankle and hindfoot AIs.

Educational Goals / Teaching Points
The goals of this article are to recognize and describe the imaging features of common and uncommon AIs at the level of the ankle and hindfoot; describe the relevant anatomy and mechanisms of each injury; familiarize with the commonly used eponyms for these fractures; describe potential complications; briefly outline management options.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The calcaneus is the only osseous structure (with the exception of a small slip from the posterior tibialis that attached to the talus) that provides tendinous attachments at the level of ankle and hindfoot. Posterior calcaneal tuberosity avulsion fractures at level of Achilles tendon insertion may be post-traumatic or occur as insufficiency fractures in the context of diabetes mellitus or renal osteodystrophy. Such fractures are classified according to the Lee classification. Calcaneal avulsion fractures may also occur at sites of smaller tendinous attachments, especially the extensor digitorum brevis. Capsuloligamentous avulsions fractures, especially lateral talar and anterior calcaneal process fractures have the potential to be easily missed on radiographs. Therefore, targeted search for such fractures is recommended on every post-traumatic ankle radiographs. On CT imaging, in the presence of retinacular avulsion fractures, the position of their respective contained tendons should be specifically evaluated for potential subluxation or dislocation.

Familiarity with the true spectrum of avulsion fractures at the level of the ankle and hindfoot, and development of a search pattern that targets some of the more easily missed fractures is necessary for accurate interpretation of post-traumatic ankle examinations.