Predicting Syndesmotic Injury in OTA/AO 44-B2.1 (Danis-Weber B) Fractures

Objective:To establish if preoperative radiographs could predict the rate of syndesmotic injury.Setting:Level 1 trauma center.Design:Retrospective cohort study.Patients/Participants:There were 548 OTA/AO 44-B2.1 fractures that were reviewed, and 287 patients were included in the study.Main Outcome Measurements:Ankle radiographs were used to determine the zone of distal extent of the proximal fracture fragment. Syndesmotic injury was defined as positive intraoperative stress examination that required syndesmotic fixation.Results:There were 191 zone 1 (ending below the plafond) injuries, 57 zone 2 (ending between the physeal scar and the plafond) injuries, and 39 zone 3 (ending above the physeal scar) injuries. Of these, 17% (33 patients) of zone 1, 42% (24) of zone 2, and 74% (29) of zone 3 fractures had syndesmotic injuries. The relative risk of syndesmotic injury of zone 1 compared with zone 2 was 2.4 (P < 0.001), zone 1 to zone 3 was 4.3 (P < 0.001), and zone 2 to zone 3 was 1.8 (P = 0.002). The interobserver and intraobserver reliability was excellent ( = 0.86, 0.94).Conclusion:OTA/AO 44-B2.1 fractures have a varying rate of syndesmotic injury. Weber B fractures that end between the level of the plafond and the physeal scar (zone 2) are 2.4 times more likely to have a syndesmotic injury compared with those that end below the plafond (zone 1). This is magnified in those injuries ending above the scar (zone 3). This simple classification of OTA/AO 44-B2.1 fractures is predictive of syndesmotic injury and may aid in preoperative counseling and planning.Level of Evidence:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.