Pathoanatomy and Injury Mechanism of Typical Maisonneuve Fracture.

Objective: Maisonneuve fracture is a special type of injury which are rare in clinic. The manifestation of such fractures is variable. The aim of this study is to describe the pathoanatomical features of typical Maisonneuve fracture on the basis of radiographs, computed tomography (CT) scans, magnetic resonance imaging (MRI), and intraoperative exploration findings, and to investigate the injury mechanism of this variety.

Methods: The data of 41 patients with Maisonneuve fracture from April 2014 to September 2019 were retrospectively analyzed. There were 32 males and nine females, the average age was 37.9 years (range, 18 to 61 years), the fractures occurred on the left side in 20 patients and on the right side in 21 patients. The cause of injuries were traffic accident in five patients, sprain injury in 20 patients, and falling injury from height in 16 patients. All patients underwent posteroanterior and lateral X-ray examinations of the ankle and calf. CT scan of the ankle was performed in 38 patients, including three-dimensional reconstruction in 33 patients. MRI examination of the ankle and calf was performed in 28 and five patients, respectively. Forty patients were treated with open reduction and internal fixation. The features of proximal fibular fracture, injuries of the medial and posterior structures of the ankle, injuries of the anterior inferior tibiofibular ligament and the interosseous membrane were recorded and analyzed.

Results: Forty-one patients had proximal one-third fractures of the fibula including six patients with fracture involving the fibular neck, 30 with proximal one-third fractures of the fibular shaft, and five with proximal-medial one-third junction fracture of the fibular shaft. Thirty-five patients (35/41, 85.37%) with injury of posterior structures, 34 patients had posterior malleolar fracture (34/41, 82.93%), and one patient had posterior inferior tibiofibular ligament rupture (1/41, 2.44%). There were 20 patients with type I fracture, four patients with type II fracture, and 10 patients with type III fracture according to the Haraguchi classification of posterior malleolus fracture. The fracture of the medial malleolus was in 30 patients (30/41, 73.17%), rupture of the deltoid ligament was in 10 patients (10/41, 24.39%), and medial structures intact were in one patient (1/41, 2.44%). All 41 patients had injury of the anterior inferior tibiofibular ligament.

Conclusions: Maisonneuve fracture is characterized by fractures of the proximal fibula and the complete rupture of the anterior inferior tibiofibular ligament. Pronation-external rotation is the main injury mechanism. The manifestations of typical Maisonneuve fracture including that the fibular fracture located in proximal one-third diaphysis and the fracture line was from anterosuperior to posteroinferior.