Ankle Syndesmosis Injuries: Anatomy, Biomechanics, Mechanism of Injury, and Clinical Guidelines for Diagnosis and Intervention

Abstract

Syndesmosis injuries are rare, but very debilitating and frequently misdiagnosed. The purpose of this clinical commentary is to review the mechanisms of syndesmotic injuries, clinical examination methods, diagnosis, and management of the injuries. Cadaveric studies of the syndesmosis and deltoid ligaments are also reviewed for further understanding of stress transmission and the roles of different structures in stabilizing the distal syndesmosis. External rotation and excessive dorsiflexion of the foot on the leg have been reported as the most common mechanisms of injury. The injury is most often incurred by individuals who participate in skiing, football, soccer, and other sport activities played on turf. The external rotation and squeeze tests are reliable tests to detect this injury. The ability of imaging studies to assist in an accurate diagnosis may depend on the severity of the injury. The results of cadaveric studies indicate the importance of the deltoid ligament in maintaining stability of the distal tibiofibular syndesmosis and the congruency of the ankle mortise. Intervention programs with early rigid immobilization and pain relief strategies, followed by strengthening and balance training are recommended. Heel lift and posterior splint intervention can be used to avoid separation of the distal syndesmosis induced by excessive dorsiflexion of the ankle joint. Application of a rigid external device should be used with caution to prevent medial-lateral compression of the leg superior to the ankle mortise, thereby inducing separation of the distal syndesmosis articulation. Surgical intervention is an option when a complete tear of the syndesmotic ligaments is present or when fractures are observed.

Morphometric Study and Anatomical Variations of the Medial Ligament of the Talocrural Joint

“…Of all ankle sprains, medial (or deltoid) ligament injury may occur in up to 18% (Lin et al, 2006). 20-40% of ankle injuries will lead to a chronic instability and disability (Renstrom, 1994).…”

Suture Button Fixation for Syndesmosis Injuries: Review of the Literature

“…Pain and tenderness on the anterior aspect of syndesmosis are the most common findings [22]. In pure ligamentous injuries, squeeze test (Hopkins test) and external rotation under stress test (Kleiger test) may be useful [1,3,9,10,22]. External rotation stress test found more reliable than squeeze test [1].…”

“…Deep portion provides 33% and superficial portion provides 9% of ankle stability. Failure of two of these ligaments leads to mechanical laxity of syndesmosis [2,3,8,10,11]. Syndesmosis widens 1.5 mm physiologically while ankle dorsiflexion [8].…”

“…Different from lateral ankle sprains, mechanism of injury mostly involves external rotation, eversion and excessive dorsiflexion [1,3]. Less commonly seen mechanisms are dorsiflexion with axial loading, eversion, inversion, plantar flexion, pronation and internal rotation [4,7,[13][14][15][16][17].…”

“…Because of high levels of missed injuries the real prevalence of syndesmosis injuries is underestimated [1]. It is less frequently seen than lateral ankle injuries [3]. The incidence differs between 1% to 18% in different studies [4][5][6][7][8][9].…”