Adaptive kinematics of the proximal carpal row

Objective To analyze the in vivo three-dimensional kinematics of the proximal carpal row by magnetic resonance imaging (MRI) and to delineate the characteristics of the adaptive kinematics of the proximal carpal row in different movement patterns. Methods We studied the in vivo three-dimensional kinematics of the proximal carpal row with a markerless bone registration technique. Magnetic resonance images of 12 healthy volunteers' wrist were acquired during motion patterns of dart throwing motion (DTM), extension-flexion motion (EFM), and radioulnar deviation (RUD). A total of 15 different wrist positions were performed and recorded from each volunteer. Image data were entered into the software designated for carpal kinematics measurement. The respective motions of the scaphoid and triquetrum relative to the lunate in cross-sectional, sagittal and coronal planes were analyzed. Results In DTM, rotation of the scaphoid relative to the lunate was 0 ° in the cross-sectional plane, 23° in the sagittal plane, and 0° in the coronal plane. In cross-sectional and coronal planes, the range of rotation was not statistically significant (t=-0.039, P=0.970; t=0.163, P=0.873), whereas rotation in the sagittal plane was significant (t=-4.521, P=0.001). In EFM, rotation of the scaphoid relative to the lunate was 2 ° in the cross-sectional plane, 48° in the sagittal plane and 15 °in the coronal plane. In the cross-sectional plane, the movement was not significant (t=0.312, P=0.761), whereas rotation in the sagittal and coronal planes showed statistically significant differences (t=-9.206, P=0.000; t=5.697, P=0.000). In RUD, rotation of the scaphoid relative to the lunate was 7° in the cross-sectional plane, 15° in the sagittal plane and 6° in the coronal plane. Data in the cross-sectional and coronal planes were not significant (t=-1.402, P=0.188; t=-1.410, P=0.186), whereas rotation in the sagittal plane showed statistically significant difference (t=3.180, P=0.009). In DTM, rotation of the triquetrum relative to the lunate was 8° in the cross-sectional plane, 8° in the sagittal plane and 8 ° in the coronal plane. Data in the cross-sectional plane were not significant (t= 2.128, P=0.057), whereas rotation in the sagittal and coronal planes showed statistically significant difference (t=-4.439, P=0.001; t=-3.078, P=0.011). In EFM, rotation of the triquetrum relative to the lunate was 2 ° in the cross-sectional plane, 15° in the sagittal plane and 3 ° in the coronal plane. Data in cross-sectional and coronal planes were not significant (t=0.487, P=0.636; t=-1.455, P=0.174), whereas rotation in the sagittal plane showed significant difference (t=-3.547, P=0.005). In RUD, rotation of the triquetrum relative to the lunate was 4 ° in cross-sectional plane, 4° in the sagittal plane and 7° in the coronal plane. Data in the cross-sectional and sagittal planes were not significant (t=1.006, P=0.336; t=1.015, P=0.332), whereas rotation in the coronal plane showed significant differences (t=-2.236, P=0.047). Conclusion In different movement patterns, the proximal carpal row adapts accordingly. The adaptive motion in the sagittal plane is the most significant, yet the intercarpal motion of proximal carpal row in the cross-sectional and coronal planes are synchronous. Adaptive range of motion between the scaphoid and lunate is much more than that between the lunate and triquetrum. Adaptive range of motion in the EFM is greater than that in the DTM and RUD. The adaptive motion of the proximal carpal row maintains the overall harmonious motion of the wrist. Key words: Carpal bones; Magnetic resonance imaging; Imaging,three-dimensional; Kinematics