AB213. SOH25_AB_013. Onion skin type lesions of the deltoid ligament

Background: Ankle ligament injuries are prevalent in sports, with deltoid ligament injuries constituting a rare 5% of ankle sprains. Deltoid ligament injuries are often difficult to discern, due to its anatomic variation, and consensus regarding diagnosis and management are yet to be established.

Methods: This paper aims to provide a comprehensive understanding and novel description of deltoid ligament injuries we have termed the onion skin lesion of the deltoid ligament, that can be observed clinically, radiologically and arthroscopically.

Results: Magnetic resonance imaging findings of deltoid ligament injuries demonstrate increased fluid between the superficial ligamentous fibres and the lateral side of the medial malleolus, with arthroscopic examination correlating a bare periosteal layer on the anterior medial malleolus and peeling of the deltoid ligament both posteriorly and proximally on the lateral side of the medial malleolus. The peeling mechanism compares to peeling layers of an onion skin. Despite this, deltoid ligaments often appear intact on open examination, further contributing to difficulties in diagnosis and delay in surgical interventions.

Conclusions: The onion skin lesion of the deltoid ligament, a novel description of deltoid ligament injuries, provides a valuable framework for establishing clinical and radiological diagnostic criteria. Further research is required to establish treatment protocols and outcomes of deltoid ligament repair.

Keywords: Ankle sprains; arthroscopy; deltoid ligament; magnetic resonance imaging; medial ankle instability