NORMAL KINEMATICS OF CARPAL BONES - A 3-DIMENSIONAL ANALYSIS OF CARPAL BONE MOTION RELATIVE TO THE RADIUS

Normal carpal kinematics were studied in 22 cadaver specimens using a biplanar radiography method. The kinematics of the trapezium, capitate , hamate, scaphoid, lunate, and triquetrum were determined during wris t motion in sagittal and coronal planes. The results were expressed us ing the concept of the screw displacement axis and converted to descri be the magnitude of rotation about and translation along three axes (X -axis: pronation-supination axis, Y-axis: flexion-extension axis, and Z-axis: radial-ulnar deviation axis) commonly used for the wrist. The orientation of these axes is expressed relative to the radius. Within the proximal carpal row, considerable differences of carpal behavior a round the Y-axis were observed during sagittal plane motion of the wri st. The scaphoid exhibited the greatest magnitude of rotation, and the lunate the least. The magnitude of rotation of the carpal bones aroun d the X-axis during sagittal plane motion of the wrist was small. The proximal carpal bones exhibited some ulnar deviation in 60 degrees of wrist flexion. During coronal plane motion of the wrist, the magnitude of radial-ulnar deviation of the distal carpal bones was mutually sim ilar and generally of a greater magnitude than that oi the proximal ca rpal bones. The proximal carpal bones experienced some flexion during radial deviation of the wrist and extension during ulnar deviation of the wrist. Translation was generally minimal in all carpal bones throu ghout wrist motion. This study reports results from the largest cadave r wrist kinematics study completed to date. The accuracy of the curren t method was improved when compared to previous studies. A sufficient number of specimens to allow statistical comparison was used and minim al interspecimen variability was noted. This study enabled a precise d escription of quantitative analyses of normal carpal kinematics relati ve to the radius. (C) 1997 Elsevier Science Ltd.