Biodynamics of the wrist: radiologic approach to scapholunate instability

A study of 126 normal wrists has allowed us to determine the normal laxity of the scapholunate complex (36 degrees) by measuring and comparing the range of movement of each of these two bones on sagittal views on x-ray films. There was no difference between dominant and nondominant hands. A study of eight cadaver wrists and 13 pathologic wrists has shown greater SL in the presence of scapholunate ligament lesions. The measurement of SL on dynamic sagittal views on x-ray films can detect a pathologic laxity between these two bones. A minimal 15 degrees difference between a normal and a pathologic wrist is reliable.