Rainbow Michael J, Crisco Joseph J, Moore Douglas C, Wolfe Scott W
Department of Orthopaedics, The Warren Alpert Medical School of Brown UniversityRhode Island Hospital, 1 Hoppin Street, CORO West, Suite 404, Providence, RI 02903, USA.
J Biomech Eng. 2008 Aug;130(4):041003. doi: 10.1115/1.2913332.
Previous studies have found gender differences in carpal kinematics, and there are discrepancies in the literature on the location of the flexionextension and radio-ulnar deviation rotation axes of the wrist. It has been postulated that these differences are due to carpal bone size differences rather than gender and that they may be resolved by normalizing the kinematics by carpal size. The purpose of this study was to determine if differences in radio-capitate kinematics are a function of size or gender. We also sought to determine if a best-fit pivot point (PvP) describes the radio-capitate joint as a ball-and-socket articulation. By using an in vivo markerless bone registration technique applied to computed tomography scans of 26 male and 28 female wrists, we applied scaling derived from capitate length to radio-capitate kinematics, characterized by a best-fit PvP. We determined if radio-capitate kinematics behave as a ball-and-socket articulation by examining the error in the best-fit PvP. Scaling PvP location completely removed gender differences (P=0.3). This verifies that differences in radio-capitate kinematics are due to size and not gender. The radio-capitate joint did not behave as a perfect ball and socket because helical axes representing anatomical motions such as flexion-extension, radio-ulnar deviation, dart throwers, and antidart throwers, were located at distances up to 4.5 mm from the PvP. Although the best-fit PvP did not yield a single center of rotation, it was still consistently found within the proximal pole of the capitate, and rms errors of the best-fit PvP calculation were on the order of 2 mm. Therefore, the ball-and-socket model of the wrist joint center using the best-fit PvP is appropriate when considering gross motion of the hand with respect to the forearm such as in optical motion capture models. However, the ball-and-socket model of the wrist is an insufficient description of the complex motion of the capitate with respect to the radius. These findings may aid in the design of wrist external fixation and orthotics.
先前的研究发现腕关节运动学存在性别差异，并且关于腕关节屈伸和桡尺偏斜旋转轴位置的文献存在差异。据推测，这些差异是由于腕骨大小不同而非性别导致的，并且通过按腕骨大小对运动学进行归一化处理可能会消除这些差异。本研究的目的是确定桡头关节运动学差异是大小还是性别的函数。我们还试图确定最佳拟合枢轴点（PvP）是否将桡头关节描述为球窝关节。通过将一种体内无标记骨配准技术应用于26名男性和28名女性腕部的计算机断层扫描，我们将从头状骨长度得出的缩放比例应用于以最佳拟合PvP为特征的桡头关节运动学。我们通过检查最佳拟合PvP中的误差来确定桡头关节运动学是否表现为球窝关节。缩放PvP位置完全消除了性别差异（P = 0.3）。这证实了桡头关节运动学差异是由于大小而非性别。桡头关节并非表现为完美的球窝关节，因为代表诸如屈伸、桡尺偏斜、掷镖者动作和反掷镖者动作等解剖运动的螺旋轴距离PvP最远可达4.5毫米。尽管最佳拟合PvP并未产生单个旋转中心，但它仍始终位于头状骨的近端极内，并且最佳拟合PvP计算的均方根误差约为2毫米。因此，在考虑手部相对于前臂的总体运动时，例如在光学运动捕捉模型中，使用最佳拟合PvP的腕关节中心球窝模型是合适的。然而，腕关节的球窝模型对于头状骨相对于桡骨的复杂运动描述不足。这些发现可能有助于腕关节外固定器和矫形器设计。
