著者

中村 康雄 林 豊彦 中村 真里 建道 寿教 信原 克哉 菊入 大輔 桐生 慎哉

出版者

バイオメカニズム学会

雑誌

バイオメカニズム (ISSN:13487116)

巻号頁・発行日

vol.17, pp.111-121, 2004 (Released:2005-04-15)

参考文献数

17

被引用文献数

1 1 2

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Diagnosis of a shoulder joint injury, particularly one brought about during sports activities, necessitates measurement of its motion accurately and noninvasively. Conventional measurement of shoulder joint movement, however, deals solely with relative movement between humerus and thorax, neglecting other components of the joint. We have focused on 6-DOF measurement of scapula movement relative to the thorax, a subdominant component of shoulder movement. Such motion data, however, cannot easily be obtained by means of a marker-based motion-capture system, due to the skin mobility relative to the skeleton. The objective of this study was to validate measurement accuracy of scapula movement when measuring markers are attached to the skin above the scapula’s bony landmarks.We employed an open MRI (Magnetom Open, Siemens, Germany) to measure the shoulder joint and markers attached to the subject’s skin. Five and three markers were attached to the skin above the scapula and thorax, respectively. Three volunteers (24.0±2.64 years old), who possessed no distinct kinetic dysfunctions in their shoulders, served as subjects, in this preliminary study. Their shoulder movements were sampled at three humeral elevation angles (0°, 90°, 150°) on a frontal plane by open MRI. In order to reduce the skin mobility, the same movements were recorded, using a more accurate method in which the scapula’s markers were relocated into correct positions, determined through the palpation of an experienced physical therapist, at each humeral elevation. In an attempt to validate the skin mobility, we measured the deviation of the markers from the scapula’s bony landmarks during humeral elevation. Next, the scapula movements were estimated by two different methods as follows: the registration technique using bony shape and the least squares method using the set of markers.The results demonstrated that the deviation of the markers could be reduced into less than or equal to 19.0 mm if the markers were remounted at each elevation angle. Using the remounted markers, we verified the estimated error of position and orientation of the scapula to lie within 10.1° and 6.4 mm, respectively.In conclusion, we validated measurement accuracy of the scapula movement using skin markers above the scapula’s bony landmarks. The results showed that a motion-capture system is capable of quantitatively measuring the static shoulder joint movement with the scapula.