A 4-Year-Old Child Who Could Not Supinate Her Forearm

Sanjeev Tuli, MD; Maria Kelly, MD; Kathleen Ryan, MD; Sonal Tuli, MD; Beverly P. Giordano, MS, RN, CPNP, PMHS


J Pediatr Health Care. 2014;28(4):357-360. 

In This Article

Differential Diagnosis and Diagnostic Testing

Although congenital radioulnar synostosis (RUS) was the most likely cause of the child's inability to supinate her forearm, consideration of other potential causes was necessary. Congenital subluxation of the radial head is the condition most commonly confused with RUS; both conditions may be found in affected individuals. Acquired radial head subluxation (also known as nursemaid's elbow) presents with flexion and pronation of the affected arm. However, children with acquired radial head subluxation are in pain and present with a history of having the outstretched arm pulled vigorously. Greenstick fractures of the humerus, Monteggia fractures of the ulna, and hypoplastic radial heads may present with signs and symptoms similar to RUS. These diagnoses can be differentiated by a careful history and radiologic studies.

Radiographs showed synostosis of the proximal radioulnar joint of the right arm (Figure 2, narrow arrows). The radius was bowed and shorter than in the unaffected left arm. No subluxation of the radial head was observed. The unaffected left arm had a normal radioulnar joint (Figure 2, wide arrows). A clinical diagnosis of congenital RUS was made. The child had no evidence of syndromes sometimes associated with this skeletal deformity (e.g., acrocephalosyndactyly, Apert syndrome, Carpenter syndrome, arthrogryposis, mandibular dysostosis, Williams syndrome, Klinefelter syndrome, Holt-Oram syndrome, microcephaly, multiple exostoses, and fetal alcohol syndrome; Wurapa, 2012). She had learned to compensate well by using her left arm. Her mother was not interested in having the child evaluated for surgical intervention (e.g., takedown of the synostosis) and declined a referral to an orthopedic specialist.

Figure 2.

Synostosis of the right proximal radioulnar joint (narrow arrows). The radius was bowed and shorter than that of child's unaffected left arm. The unaffected left arm had a normal radioulnar joint (wide arrows). AP = anteroposterior.