KINEMATICS OF THE SCAPHOID SHIFT TEST

Twenty-five uninjured subjects (50 wrists) were examined clinically an d fluoroscopically during performance of the scaphoid shift test. Wris ts were placed into 3 groups on the basis of the degree of palpable ca rpal motion that occurred during the clinical examination. Kinematic p arameters 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 shi ft lest. Dorsal displacement of the scaphoid was not significantly ass ociated with positive scaphoid shift test results in these subjects, w hile total displacement of the scaphoid (the sum of axial and dorsal d isplacement) was significantly associated with positive test results. The principle confounding factor appeared to be a high degree of displ acement that occurred at the capitolunate joint in some individuals, t ermed a ''midcarpal shift.'' The data demonstrate that despite a high prevalence of positive scaphoid shifts among uninjured individuals, th e ability to accurately detect dorsal displacement of the scaphoid usi ng the scaphoid shift test is limited. On the basis of their findings, the authors recommend that positive test results be confirmed fluoros copically.