Studies have reported a high percentage of ankle fracture dislocations with secondary loss of reduction during primary treatment with a splint or cast. This study aimed to assess the rate of secondary loss of reduction in unimalleolar ankle fracture dislocations treated primarily with a cast or external fixator, identify the potential influence of fracture morphology, and investigate the potential implications. Unimalleolar ankle fracture dislocations with and without posterior malleolar fracture between 2011 and 2020 were included. Patients were categorized into two groups, depending on the method of temporary treatment. Fracture morphology, time to definitive surgery, and soft-tissue complications were compared. Of 102 patients, loss of reduction tended to occur more often in the cast group (17.3%) than in the external fixator group (6.0%). The presence of a posterior malleolar fracture did not have a significant influence on loss of reduction in cast immobilization; however, the fragment proved to be significantly bigger in cases with loss of reduction. No statistically significant differences in soft tissue complications or time to definitive surgery were found. Surgeons should consider the application of interval external fixation in the primary treatment of unimalleolar ankle fracture dislocations with additional posterior malleolar fractures.
Keywords: ankle fracture dislocation; cast; complications; external fixator; loss of reduction; primary management; secondary dislocation.