Background: Some of the Mason type I fractures cannot be detected on early radiographic images. These occult fractures are considered as a diagnostic challenge for physicians. Our aim was to determine the value of bedside ultrasonography for the detection of Mason I radial head fractures that are non-visible in early X-ray's.
Methods: A prospective blind single-center diagnostic study was conducted (from June 2012 till May 2013) concerning 23 patients who were clinically suspicious of having a radial head fracture. These patients were evaluated with a bedside high frequency ultrasound in the Emergency Room (E.R.). The two sonographic criteria that were considered to be diagnostic for fracture were: a. effusion besides the radial head-neck and b. cortical discontinuity of the radial head or neck. All patients also underwent a Computed Tomography (CT) as the gold standard imaging modality for diagnosis of occult radial head fractures.
Results: Fifteen out of 23 patients were diagnosed with radial head fracture using both ultrasound and CT. On the other hand, there were three patients with negative ultrasound and positive CT, in addition two patients were found positive in the ultrasonographic exam, while this result was not confirmed by the CT scan. In comparison with CT, ultrasound exam appeared to have 83.3% sensitivity, 60% specificity, 88.2% positive prognostic value and 50% negative prognostic value (when at least one diagnostic sonographic criterion was positive). The accuracy of the sonographic study for the diagnosis of the aforementioned fractures was 78.2%. Effusion in contact with the radial neck was the most sensitive sonographic sign (14/15 of the true positive radial head ultrasounds).
Conclusion: Bedside ultrasound in the E.R. was proven to be a sensitive tool for early (day-1) diagnosis of the occult radial head fractures. It could be used as an adjacent imaging modality in patients suspicious for radial head fracture, when the initial X-rays are negative.
Level of evidence: II.
Keywords: Computed tomography; Early diagnosis; Elbow diagnostic ultrasound; Occult radial head fracture; Ultrasound.