GRAVITY STRESS RADIOGRAPHS: DOES A POSITIVE RADIOGRAPH MEAN AN UNSTABLE ANKLE?

Assessment of stability in ankle fractures is key in deciding the most appropriate mode of treatment. Stress radiographs have been suggested as a potential method for assessing ankle stability in patients with apparently isolated lateral malleolar fractures. Whilst stress radiographs have been found to be both sensitive and specific in cadaveric experiments, recent clinical studies have suggested that a widened medial clear space (MCS) on stress radiographs may not equate to a functionally unstable ankle. We aimed to assess whether patients with an apparently isolated lateral malleolar fracture on presentation but with a positive gravity stress radiograph (GSR) could be successfully managed non-operatively. A prospective study of all patients with lateral malleolar fractures presenting to our orthopaedic trauma department was undertaken. Patients with an oblique distal fibular fracture pattern and no obvious MCS widening on routine radiographs underwent a GSR. Measurements of the radiographic MCS and superior clear space (SCS) were made and compared with published criteria. 155 patients were included in the study and treated non-operatively fully weight bearing in either a cast or removable boot. Following fracture union all patients had both anatomical alignment of the ankle mortise and good or excellent function. The MCS of 79% of these patients was found to be greater than 4 mm with 19% greater than 6 mm. All of these patients were successfully managed non-operatively. The currently used criteria for measurements on stress radiographs result in high numbers of false positive cases. This may be leading to unnecessary surgery. Further investigation is required in order to identify other clinical or radiographic criteria that may be of use in the assessment of functional ankle stability after fracture.