Objective To investigate changes in collateral ligament length during flexion and extension of the metacarpophalangeal joint (MCJ) of the four fingers. Methods Spiral CT scans of the MCJ of the index, middle, ring and little fingers were obtained from 6 volunteers. Images from the mid-metacarpal to midproximal phalanx were acquired while the MCJ moved from 0° of flexion to 90° of flexion with 30° inerements.Changes in length of the collateral ligament of MCJ of each individual finger during MCJ movement were analyzed by software processing after three-dimensional image reconstruction of bone structures were obtained. Results During flexion of the MCJ the dorsal bundle of the ulnar and radial collateral ligaments lengthened, while the volar bundle shortened. The length of the middle bundle did not change significantly. Conclusion During MCJ flexion and extension, the collateral ligaments are in a state of tension. However tension in different portions of the ligament varies. There are two main relative movements during MCJ flexion: lengthening of the dorsal bundle of the collateral ligament results in increased tension and shortening of the volar bundle results in decreased tension. The middle bundle always maintains proper tension, restricting and regulating the movement of the joint.%目的 研究在体示、中、环、小指掌指关节屈伸运动时尺桡侧侧副韧带的长度变化.方法 以螺旋CT扫描6例志愿者的示、中、环、小指的掌指关节,分别获得各掌指关节在0°至屈曲90°内每隔30°的运动范围内掌骨中段以远至近节指骨中段的图像,三维重建骨结构图像后经软件处理得到在各掌指关节屈伸运动时尺桡侧侧副韧带的长度变化.结果 掌指关节屈曲时,尺桡侧侧副韧带的背侧束逐渐伸长,而掌侧束相对缩短,中间束长度无明显的变化规律.结论 掌指关节屈伸活动时侧副韧带都处于紧张状态,只是韧带内部相对紧张、松弛的部位及程度不同.它屈曲时主要存在2种相对的运动:侧副韧带的背侧束伸长,紧张性增大;掌侧束缩短,紧张性相对减小;而中间束始终保持了合适的紧张度,共同限制和调节关节的运动.
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