Fri., 10/5/12 Foot & Ankle, PAPER #39, 10:00 am OTA-2012
Gravity Stress Radiographs: Does a Positive Radiograph Mean an Unstable Ankle?
Kate Ella Bugler; George Smith, FRCS; Timothy O. White, MD, FRCS;
Orthopaedic Trauma Unit, Royal Infirmary Edinburgh, Edinburgh, Scotland, United Kingdom
Background/Purpose: Assessment of stability in ankle fractures is key in deciding the most appropriate mode of treatment. In supination–external rotation (SER) IV fractures where the medial stability is lost due to a ligamentous rather than a bony injury this assessment can be difficult. Stress radiographs have been suggested as a potential method for assessing the competence of the deep deltoid ligament and therefore ankle stability in patients with apparently isolated lateral malleolar fractures. Although 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. These previous studies have used manual stress radiographs and have included an operative arm in which patients were selected for surgical intervention based on empirical clinical criteria. 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 nonoperatively.
Methods: 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; measurement of MCS alone is the most frequently described parameter, with values of 4, 5, and 6 mm variously suggested as cut-off points for diagnosing instability while some previous authors have recommended additional comparison of the MCS with the SCS.
Results: 67 patients underwent GSRs and were treated nonoperatively 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. Radiographic results are shown in the table.
Table. Number (%) of patients with talar shift exceeding the given measurement, ie, false positives on GSRs
Conclusion: The currently used criteria for measurements on stress radiographs result in high numbers of false-positive cases. This may lead 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.
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• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.