Imaging in congenital proximal radioulnar synostosis

A 9-year-old boy with deformity and progressive limitation of right elbow supination was referred for imaging. There was no history of trauma. On examination, there was a right elbow varus deformity [Figure 1a]. Frontal radiographs showed right proximal radioulnar synostosis [Figure 1b-c]. Multidetector computed tomography scan with three-dimensional computed tomography (3DCT) reconstructions showed fused radial and ulnar heads with hypoplastic radial head [Figure 2].

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Figure 1:

(a) Clinical image of a 9-year-old boy showing varus deformity at right elbow; (b and c) frontal radiograph of right (R) elbow joint showing proximal radioulnar joint synostosis with no such abnormality being noted in left (L) elbow joint radiograph.

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Figure 2:

(a) 3D reconstruction; (b) plain computed tomography scan of right elbow showing fusion of radial and ulnar heads with hypoplastic radial head.

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Congenital radioulnar synostosis results from failure of longitudinal separation of radius and ulna in the 7^th gestational week. This condition usually presents bilaterally and is often associated with chromosomal and developmental abnormalities.^[1] 3DCT and multiplanar reconstructions provide a detailed assessment of bony and soft tissue relations for precise surgical planning.^[2]

Congenital proximal radioulnar synostosis (CRUS) should be considered a differential diagnosis in children with limited supination and pronation at the elbow. Our report is a rare case of unilateral CRUS with no other anomaly or family history.