Bilateral symphalangism of the index finger: a case report

Symphalangism is a congenital anomaly of the digits manifested clinically by shortness, which on roentgenographic examination is seen to be due to end to end fusion of the two phalanges, one of which is, in addition, usually short. Symphalangism is uncommon and receives no mention in some radiology texts. Symphalangism is an autosomal dominant trait of whites generally, usually expressed bilaterally in the postaxial (ulnar) fingers. The index finger is involved only when other fingers also are involved, and then the index finger is the least affected. The more common variety of symphalangism, fusion at the proximal interphalangeal joint, is associated with talonavicular fusion and conductive deafness. The authors report here an unusual case of symphalangism which was limited to the proximal interphalangeal joint of the index finger bilaterally. There was no apparent genetic transmission of the anomaly and the patient, who is black, had normal hearing and a normal talonavicular joint.