Which factors influence the decision to perform computed tomography for primary ankle fractures?

E. Harris, S. Bennet, P.W. Robinson, M. Jackson, S.R. Mitchell, J.A. Livingstone

Background: Plain radiographs can underestimate and misrepresent the morphology and severity of primary ankle fractures, whilst the role of CT scanning in the investigation of ankle fractures is poorly defined. The study aimed to identify clinical factors and features of ankle fractures presenting to our unit resulting in investigation with a CT scan.

Methods: A retrospective analysis of primary ankle fractures presenting to a University Teaching Hospital between January 2012 and December 2014 was performed. Following retrieval of demographic and injury data through case notes, the association of high mechanism of injury, ankle joint dislocation on admission, lateral malleolar fracture configuration, and presence of a posterior malleolar fracture with a decision to CT scan was examined. Statistical analysis was performed using chi-square tests.

Results: 366 cases were identified of which 104 received a CT scan. Of patients receiving a CT scan 27 (26%) had a high mechanism of injury (P< 0.05), and 81 (78%) were dislocated on admission (P< 0.05), compared to 41 (16%) and 105 (40%) in patients who did not. Lateral malleolar fracture pattern had no correlation with decision to perform CT. Patients who had a posterior malleolar fracture were likely to receive a CT scan (P< 0.05) versus those without. Overall 67 (74%) of those with a tri-malleolar fracture investigated.

Conclusions: In comparison to existing literature our centre was more proactive in performing CT for malleolar ankle fractures. The presence of a posterior malleolar fracture was strongly associated with decision to perform a CT. High mechanism of injury and ankle joint dislocation were also associated with further CT investigation.

Implications: This study provides an insight into the injury and fracture patterns which can influence a clinician's decision to perform a CT scan in primary ankle fractures.