Mechanical evaluation of the scaphoid shift test.

Manipulative examination of the carpal bones is an important facet of the examination of the wrist. Abnormal translation of portions of the carpus in response to applied force is a commonly used clinical indicator of ligament injury. Unilateral scaphoid hypermobility during the so-called scaphoid shift test is felt to represent traumatic instability, especially in the context of wrist injury. The test, however, is subjective, and requires considerable experience to correlate the degree of scaphoid mobility with pathologic significance. We used an instrument that quantifies the load-displacement behavior of the scaphoid and its supporting ligaments during application of a dorsally directed load at the scaphoid tubercle. We evaluated 18 uninjured (normal) wrists with clinical ligament examination and with mechanical testing. Subjects who exhibited a positive scaphoid shift had significantly increased displacement and significantly decreased stiffness when compared with subjects who did not have a shift.