Fracture of the lateral process of the talus with associated deltoid ligament injury: a report of 2 cases

BACKGROUND: Fractures of the lateral process of the talus (LTPF) are rare and only rarely are associated ligamentous injuries. The injury mechanism is commonly considered to be similar with ankle sprains, where excessive varus of the hindfoot leads to avulsion fractures of the lateral process of the talus. However, previous cadaveric studies have suggested that LTPF was more likely to be caused by eversion or external rotation force with dorsiflexion of the ankle. But no clinical evidence has been provided. CASE PRESENTATION: Two patients presented to the emergency department with ankle pain after ankle eversion or external rotation. Physical examination revealed tenderness and swelling on both medial and lateral sides of the ankles. Plain radiographs and computed tomography revealed LTPF and medial soft tissue swelling, and magnetic resonance imaging confirmed a discontinuity of the deltoid ligament in Case 1. Surgical exploration revealed rupture of the superficial layer of the deltoid ligaments with intact deep layer in both patients. Treatment included fixation of the lateral process of the talus with headless compression screws and repair of deltoid ligaments. Both patients achieved excellent clinical outcomes 1 year post injury. CONCLUSION: There are many possibilities of the injury mechanism of LTPF. These two cases provided clinical evidence that eversion or external rotation force, in addition to inversion, was also an important mechanism of LTPF. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12893-022-01781-y.