Dislocation is a risk factor for poor outcome after supination external rotation type ankle fractures.

Introduction: Ankle fractures are one of the most common fractures requiring surgical treatment. Ankle fracture-dislocations are significant injuries to the osseous and soft tissue envelope, but studies focused on the effect of dislocation on radiographic and functional outcomes are lacking. The objective of this study was to evaluate the effect of dislocations on postoperative outcomes in SER IV ankle fracture patients.
Materials and Methods: From 2004 through 2010, all operative SER IV ankle fractures treated by a single surgeon were enrolled in a prospective database. SER IV ankle fractures were separated into two groups based on clinical or radiographic evidence of dislocation. The primary and secondary functional outcomes measures were the Foot and Ankle Outcome Score (FAOS) and ankle and subtalar range of motion (ROM) with a minimum of 1-year follow-up, respectively.
Results: 108 patients with SER IV ankle fractures were identified, with 73 in the non-dislocation group (68%) and 35 patients in the dislocation group (32%). Patient demographics and co-morbidities were similar between the two groups. The incidence of open fractures and the application of an external fixator were significantly higher in the dislocation group (p = 0.037 and p = 0.003, respectively). The dislocation group showed a significant decrease in the accuracy of articular reduction (p = 0.003). At a mean follow-up of 21 months, ankle fracture-dislocation patients had increased pain (p = 0.005) and decreased activities of daily living (p = 0.014) on FAOS outcome measures and significantly worse ankle and subtalar ROM.
Conclusions: The results of this study suggest that concurrent dislocation at time of ankle fracture is associated with worse radiographic and functional outcomes, but not an increase in superficial or deep infection. The results from this study may be helpful in counseling patients regarding expected clinical outcomes after ankle fracture-dislocation and in the surgical management of this complex injury.