Ligamentous Injuries in Stable Ankle Fractures

Category: Ankle; Trauma Introduction/Purpose: When considering ankle fractures requiring fixation, it has been shown that stability is the key determinant. Lauge-Hansen supination external rotation (SER) 2 injuries are by definition stable and has been shown to be successfully managed non-operatively. SER 3 and SER 4 ankle fractures are unstable with complete syndesmosis disruption and the majority are managed operatively. We hypothesise that a percentage of radiologically stable injuries involve more structures than previously thought. The primary aim is to determine the prevalence of SER3 and SER4 ankle injuries amongst radiographically SER 2 injuries. Methods: This cross-sectional study uses baseline data from a longitudinal study at Gold Coast University Hospital and Health Service (GCHHS). Patients attending the GCHHS fracture clinic were invited to participate provided they had a radiographically stable SER 2 fracture. Those meeting the eligibility criteria were referred for ankle magnetic resonance imaging (MRI) to assess the integrity of the syndesmotic and ankle ligaments. Results: To date, this study has recruited 33 participants. Following MRI, 23 were determined to have true SER 2 injuries. Nine participants were however reclassified as SER 3 and one participant was reclassified as having an SER 4 injury. Of the SER 3 injuries six included a non-displaced posterior malleolus fracture, while the remaining three were purely ligamentous. Conclusion: This study demonstrates that a portion of radiographically stable ankle injuries involve more structures than previously thought. When radiographic SER 2 injuries were further evaluated with MRI, nearly half were reclassified as SER 3 and 4 injuries. This may suggest that some SER 3 and 4 injuries are functionally stable and can be managed successfully non-operatively.