Patterns of Anterior Inferior Tibiofibular Ligament Avulsion Fracture Accompanied by Ankle Fracture

Abstract

Category: Ankle; Trauma Introduction/Purpose: The anterior inferior tibiofibular ligament (AITFL) avulsion fracture accompanying an ankle fracture cause compromising ankle stability, and requires accurate evaluation and clarifies pathophysiology. The aim of this study was to investigate the correlation between AITFL avulsion fracture and Lauge–Hansen, Wagstaffe classification. Methods: 128 patients (70 males and 58 females) operated at the present institution between January 2013 and July 2017 were included. AITFL avulsion fractures occurred in 68 patients. Fracture was diagnosed based on the preoperative simple radiographs obtained of the ankle joint in the anteroposterior, lateral and mortise views. In cases wherein diagnosis was difficult using radiographs alone, CT was additionally used. AITFL avulsion fractures were classified based on the fracture site according to the Wagstaffe classification system. The anteroposterior and horizontal lengths as well as the height of the avulsed bone fragment were measured using CT scans in the coronal, sagittal and axial views. Thereafter, the relationship between the Lauge-Hansen classification of ankle fractures and the characteristics of AITFL fracture was statistically analysed using the Fisher exact test. Results: Type II of the modified Wagstaffe classification system was 39 examples, followed by type III (9 examples) and type IV (8 examples). Out of 7 pronation-abduction fractures, 3 were those of AITFL avulsion fracture, while out of the 21 pronation- external rotation fracture examples, 9 were those of AITFL avulsion fracture. Out of the 95 examples of supination-external rotation fracture, there were 56 examples (59%) of AITFL avulsion fracture. Of the pronation fractures, 0% was a fibular avulsion fracture and 43% were a tibial avulsion fracture. Of the supination fractures, 44% were a fibular avulsion fracture and 16% were a tibial avulsion fracture. The difference in the ratio of fibular and tibial avulsion fractures between the pronation and supination fractures was significant. (p < 0.0001) Conclusion: Some of the AITFL avulsion fractures examined in this study may have been caused by collisions with the talus rather than the traction of the AITFL. Although Wagstaffe fractures accompanied by a supination–external rotation-type fracture results from the traction of the AITFL, a tibial avulsion fracture in a patient with a modified Wagstaffe type 4 fracture and a supination fracture appears to result from a continuous external rotation and repeated collisions of the talus with the anterolateral corner of the distal tibia.