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

To establish if preoperative radiographs could predict the rate of syndesmotic injury.

Level 1 trauma center.

Retrospective cohort study.

There were 548 OTA/AO 44-B2.1 fractures that were reviewed, and 287 patients were included in the study.

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.

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 (κ = 0.86, 0.94).

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.

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.