An Unusual Case of Hyperphalangism Associated With Forearm and Elbow Anomalies

Abstract

Hyperphalangism is characterized by an extra phalanx between the phalanges of a finger, usually excluding the thumb. This abnormality is distinguished from Polydactyly and polyphalangism in that the hand has more phalanges in the fingers and no extra fingers. Because the digits are small and short, a better term to describe this abnormality would be "brachyhyperphalangism", 7 but the term is cumbersome and unpopular.We have reviewed the world literature up to the present time and have never seen reported elbow abnormalities associated with hyperphalangism. CASE REPORTThis 8-year-old boy has been followed by us in our office for two years. He first presented to us at age six. Since birth he has had elbow problems with no history of trauma. X-rays of the hands are very similar bilaterally. He has a shortened metacarpal with four phalanges in the long finger. The index, ring and little fingers appear to be normal. The ring finger appears long when compared to the abnormal long finger (Fig. 1). There was no family history of similar anomalies. At age seven-and-a-half, the child returned to the office complaining of difficulty in extending the forearm. His range of motion of supination, pronation and flexion was essentially normal and full. He lacked 25° of full extension bilaterally. The left ulna was short with a significant radial bow (Fig. 2). The right arm showed a short ulna with a posterior dislocation of the radial head (Fig. 3). In the future the Ilizarov technique could be used to lengthen both ulnar bones and straighten the radius in each arm.