Reliability of carpal angle determinations.

The radioscaphoid, radiolunate, and radiocapitate angles of nine lateral projections of the wrist (three in flexion, three in extension, and three in neutral position) of three fresh cadaver specimens were measured. Seven orthopedic surgeons (six hand surgeons and one orthopedic surgeon) made the measurements with a standard goniometer using both the axial and tangential methods of angle determination. The overall standard deviation for all measurements was 5.2 degrees, and no significant difference in variability between axial and tangential methods was found. By comparing the same angles from different wrist positions, the amount of flexion-extension motion of the capitate, scaphoid, and lunate with respect to the radius was estimated. To assess the accuracy of such a method of carpal motion determination, a more accurate stereoradiographic method of analysis of carpal kinematics was utilized. The overall estimated error of this standard goniometric method of carpal motion determination averaged 7.4 degrees.