Abstract
Introduction
The involvement of the posterior malleolus (PM) in dislocated bimalleolar ankle fractures is associated with inferior clinical outcomes. There is no consensus on whether and when a computed tomography (CT) scan should be performed in the case of an inconspicuous X-ray of the PM. How high is the risk of missing a posterior malleolus fracture (PMF) without a CT scan? The aim of this study was hence to analyze the rate of correctly performed assessments of the PM in bimalleolar ankle fractures based on X-rays and to correlate this with surgical therapy.
Materials and Methods
In total, 100 bimalleolar ankle fractures, 50% with and 50% without PMF visible on the basis of a CT scan, were analyzed by 4 observers at 2 different time points 30 days apart (d1 and d2). The observers had to decide on the basis of X-rays whether a PMF was present or not. This was followed by a correlation with the operative treatment.
Results
Analyzing each observer independently, the correct diagnoses of a present PMF were made in an average of 83% of cases, with no significant difference between seniors and residents. In 22 of 50 cases (44%) with a PMF confirmed on a CT scan, it was missed by at least one of the observers based on plain radiographs. For those PMF that required fixation (24 of the 50 PMF), in 25% of cases, at least 2 observers missed the diagnosis of a PMF.
Conclusions
Based on our results, there are deficits in the detection of PMF in bimalleolar ankle fractures only on the basis of X-rays, even in PMF that were later fixed surgically. This study aids the awareness that PMF can be easily missed on X-rays and raises the question of whether a CT scan might become mandatory in distal fibula fractures that involve the upper ankle joint.
Levels of Evidence:
Level III: Retrospective study
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