Radio-ulnar synostosis (or synosteosis) is generally considered a rare, congenital abnormality, manifested by marked impairment in supination of the forearm due to fusion of the upper end of the radius with that of the ulna. Males are affected about twice as frequently as females, and in approximately 50 per cent of the cases the condition is bilateral.
In 1932 Fahlstrom1 collected reports of 185 cases from the literature (including that of his own case). The condition was apparently first described by Sandifort,2 in 1793. Salisachs3 in 1934 reviewed 195 published reports of cases. Since that time, 5 additional cases4 have been reported, making a grand total of 200. An analysis shows that 113 males and 64 females were affected; in 23 cases the sex was not mentioned. The condition was bilateral in 113 patients and unilateral in 83. The left forearm was involved in 43 and