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Purpose: To measure the scapholunate distance in normal wrists in a child population., Material and Methods: In 79 children with unilateral wrist trauma boths wrists were radiographed in p.a. and lateral views., Results: The median scapholunate distance ranged from 9 mm in the 7-year-old to 3 mm in the 15-year-old children. Baseline values are presented.

It has been proposed that negative ulnar variance is a predisposing factor to development of posttraumatic carpal ligamentous instability. However, this implies that no correlation exists between ulnar variance and carpal bone angles in the normal wrist. Carpal bone angles on lateral wrist radiographs and ulnar variance were measured in a series of 75 normal wrists. The mean ulnar variance was -0.03 mm (SD 1.56, range -5 to 5). The correlation coefficients were 0.06, -0.11, and -0.05 between the ulnar variance, and radiolunate, radioscaphoid, and scapholunate angles, respectively. A correlation between the carpal angles on lateral wrist radiographs, and ulnar variance in normal wrists could not be demonstrated, suggesting that the presence of negative ulnar variance may serve as an impartial clue to the presence of ligamentous instability.

A number of methods exist for determination of carpal bone angles on lateral wrist radiographs. However, there is no general or precise definition of the angles measured. In this study the positioning of the wrist is emphasized and a device used to obtain standardized radiographs is presented. An analysis of variance of two series of patients revealed no radiological difference between the contralateral wrists in the same person. We conclude that the asymptomatic wrist can be used as normal reference in the assessment of carpal bone angles in the pathological wrist and a difference between the carpal bone angles in the two wrists in the same person exceeding 5 degrees can be considered significant.