Deltoid ligament injuries: anatomy, biomechanics, and clinical implications

Abstract

Ankle joint stability is crucial for weight-bearing and movement in human locomotion, provided by the articulating bony structures and ligamentous support. The deltoid ligament is a fan-shaped, complex medial structure of the ankle joint, consisting of two layers—superficial and deep. It extends from the medial malleolus and inserts into the medial aspect of the talus, navicular, and calcaneus. The primary function of the deltoid ligament is to restrain abduction and external rotation forces, with specific parts of the ligament being affected depending on the mechanism of injury. Common injury mechanisms include excessive dorsiflexion, abduction, or external rotation, which can result in ligament rupture or avulsion fractures. While lateral ankle ligaments are more frequently injured, studied, and treated, medial ankle injuries account for approximately 5.0% - 15.0% of cases and are often associated with more severe conditions, such as ankle fractures or syndesmotic injuries. If left untreated or mismanaged, complications such as chronic ankle instability and post-traumatic osteoarthritis may develop. Given the lack of consensus regarding diagnosis and management, this review comprehensively examines the anatomy, biomechanics, mechanisms, and pathology of the deltoid ligament injury, drawing upon existing literature to enhance evidence-based treatment decisions and optimize long-term patient outcomes.