Ulnar variance in children--standard measurements for evaluation of ulnar shortening in juvenile rheumatoid arthritis, hereditary multiple exostosis and other bone or joint disorders in childhood.

Measurements for radioulnar variance in adults cannot be used in children because the epiphyses are not fully ossified. We describe a method of determining ulnar variance in children by using the distance from the distal metaphysis of the radius to the distal metaphysis of the ulna. Standards for this measurement are presented for ages 1.5 to 15.5 years in boys and girls. These measurements change little with age and may be helpful in establishing shortening of the ulna which may been seen in juvenile rheumatoid arthritis, hereditary multiple exostosis, or other bone and joint diseases with childhood onset.