Anterior inferior tibiofibular ligament avulsion fractures in operatively treated ankle fractures: a retrospective analysis

BACKGROUND: There is no consensus about the optimal treatment of anterior inferior ligament avulsion fractures of the ankle. The aim of this study is to provide insights regarding the incidence of anterior inferior ligament avulsion fractures, the association with fracture type, and correlation with treatment. METHODS: This study is a retrospective analysis in a level-1 trauma center of adult patients with an ankle fracture operated between the dates 01-01-2009 and 01-09-2017 who had a pre- and postoperative CT-scan. Within the study population, the incidence of AITFL avulsion fracture was defined. Primary outcome was the type of avulsion fracture and related treatment. Secondary outcome was additional surgery in relation to the initial treatment. RESULTS: In total, 65 of 252 (25.8%) patients were diagnosed with an anterior inferior ligament avulsion fracture. Zero patients had a Wagstaffe type 1 fracture, 28 (43.1%) had a type 2, 32 (49.2%) had a type 3, and 5 (7.7%) had a type 4. There was a correlation between Wagstaffe type 2 and Weber B fractures, p < 0.0001, and Wagstaffe type 3 avulsions were correlated with a Weber C fracture, p < 0.0001. Thirty-five of the avulsed fragments (53.8%) were smaller than 5 mm. In 13 (20%) of patients with anterior inferior ligament avulsion fracture, the avulsed fragments were directly fixated during initial surgery. Size and direct fixation of the fragment were significantly correlated (p < 0.0001). Within the anterior inferior ligament avulsion fracture group, only a total of four patients (6.2%) underwent a revision. CONCLUSION: In the current study, an incidence of 25.8% of anterior inferior ligament avulsion fracture in surgically treated ankle fractures is reported. A correlation between the type of Wagstaffe injury and Weber classification was showed. Most fragments smaller than 5 mm were not fixated; however, not all injuries needed syndesmotic screws due to syndesmotic instability. LEVEL OF EVIDENCE: Level IV.