Measurement of Ulnar Styloid Length and Ulnar Variance in Normal Adults

General information about the ulnar impaction syndrome is scarty and often neglected. The ulnar styloid process and ulnar variance have important roles in this syndrome. The statistical data related to these factors is not enough in Iranian literature. This study measured ulnar styloid length and ulnar variance in a group of healthy adults. In a prospective study، the ulnar styloid length and ulnar variance were measured on the posteroanterior view on 140 of wrist radiographs in a training hospital in Shiraz-Iran. The relative length of the ulnar styloid process and the ulnar impaction potential were assessed with the styloid-capitate ratio (SCR) and ulnar styloid process index (USPI)، respectively. Clinical examination of the wrists for ulnar impaction was also done. The mean ulnar styloid length was 5. 38±1. 45 mm. The average styloid-capitate ratio (SCR) was. 24±. 06 and the average of ulnar styloid process index (USPI) was. 34±. 11. 40. 71% of the radiographic views in SCR، and 56. 42% in USPI were more than average. The ulnar variance showed 19. 3% neutral (23% male، 10% female)، 12. 1% positive (11% male، 15% female) and 68. 6% negative (66% male، 75% female) measurements. It seems a long ulnar styloid process with SCR>. 24±. 06 or an overall styloid length greater than 6 mm is one of the most important cause of pain in ulnar sided wrist pain in our population.