Bone Morphology as a Determinative Risk Factor for Type of Ankle Fracture.

Background: We investigated the relationship between ankle radiographic bone morphology and observed fracture type.

Methods: We retrospectively reviewed patients who had visited the emergency department with ankle injuries between June 1, 2012, and July 31, 2018. Patients were treated with open reduction and internal fixation. Patients were grouped by fracture pattern. Group 1 consisted of isolated lateral malleolar fractures, and group 2 comprised bimalleolar fractures. Group 1 was further divided into subgroups A and B based on classification as Weber type B and C fractures, respectively. Four radiographic parameters were measured postoperatively on a standing whole-leg anteroposterior view of the ankle: talocrural angle (TCA), medial malleolar relative length (MMRL), lateral malleolar relative length (LMRL), and distance between the talar dome and distal fibula.

Results: One hundred seventeen patients were included in group 1-A, 89 in group 1-B, and 168 in group 2. The TCA and MMRL were significantly larger in group 2 than in group 1. Lateral to medial malleolar length ratio was also significantly different between the groups. However, there were no significant differences between the groups in terms of LMRL and the distance between the distal fibula tip and talar process. Between subgroups 1-A and 1-B, LMRL (P = .402) and MMRL (P = .592) values were not significantly different. However, there was a significant difference between groups in TCA and the distance between the distal fibula tip and talar process.

Conclusions: The TCA, MMRL, and lateral malleolar length to medial malleolar length ratio were significantly higher in patients with bimalleolar fracture than in patients with isolated lateral malleolar fractures.