Kinematics of the scaphoid shift test.

Twenty-five uninjured subjects (50 wrists) were examined clinically and fluoroscopically during performance of the scaphoid shift test. Wrists were placed into 3 groups on the basis of the degree of palpable carpal motion that occurred during the clinical examination. Kinematic parameters of rotation and displacement were calculated from digitized images of the carpals at rest and at maximum displacement. On clinical exam, 36% of normal individuals had positive findings on scaphoid shift test. Dorsal displacement of the scaphoid was not significantly associated with positive scaphoid shift test results in these subjects, while total displacement of the scaphoid (the sum of axial and dorsal displacement) was significantly associated with positive test results. The principle confounding factor appeared to be a high degree of displacement that occurred at the capitolunate joint in some individuals, termed a "midcarpal shift." The data demonstrate that despite a high prevalence of positive scaphoid shifts among uninjured individuals, the ability to accurately detect dorsal displacement of the scaphoid using the scaphoid shift test is limited. On the basis of their findings, the authors recommend that positive test results be confirmed fluoroscopically.