LAUSR

OBJECTIVE We present a series of 20 cases of a sleeve-type injury of the distal tibia characterized by traumatic periosteal stripping caused by a high ankle sprain. We characterize the magnetic resonance imaging findings associated with this injury and highlight its association with distal tibial osteonecrosis. MATERIALS AND METHODS We collected 20 cases of high ankle sprains with periosteal stripping of the distal tibia through teaching files and a search through our PACS database. We recorded the presence and pattern of syndesmotic ligamentous injury and the presence or absence of syndesmotic widening in patients with periosteal stripping. The presence or absence of associated fractures and osteonecrosis was noted and characterized by location. RESULTS The most commonly torn ligament was the anterior inferior tibiofibular ligament. 25% (5/20) of the patients in our series developed osteonecrosis. Osteonecrosis developed as early as 3-4 weeks following the initial injury. Of the patients with osteonecrosis, 40% (2/5) had fractures of the posterior malleolus. All patients with osteonecrosis had widening of the syndesmosis. Two of the five patients with osteonecrosis were in the pediatric age group. CONCLUSION In contrast to conventional syndesmotic and interosseous ligamentous tearing, high ankle injuries with tibial periosteal stripping may result in avulsion of the extra-osseous vasculature supplied by the periosteum, leading to osteonecrosis. This pattern of injury has not been emphasized in the literature. Our findings underscore the importance of the integrity of the periosteum for maintaining adequate vascularity of the distal tibia.