Three-dimensional alignment changes of the shoulder girdle between the supine and standing positions
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(2020) 15:411
RESEARCH ARTICLE
Open Access
Three-dimensional alignment changes of the shoulder girdle between the supine and standing positions Noboru Matsumura1*, Yoshitake Yamada2* , Satoshi Oki1, Yuki Yoshida1, Yoichi Yokoyama2, Minoru Yamada2, Takeo Nagura1 and Masahiro Jinzaki2
Abstract Background: Although humans spend most of their day in a standing or sitting position, it is difficult to accurately evaluate the alignment of the shoulder girdle during daily activity, and its alignment changes between positions. The purpose of this study was to evaluate the 3-dimensional alignment of the shoulder girdle in the supine and standing positions by computed tomography (CT) and to assess the alignment changes of the shoulder girdle between these two positions. Methods: CT scans of both shoulders of 100 healthy volunteers were prospectively taken in both supine and standing positions on the same day. The local 3-dimensional coordinate systems of the thorax, clavicle, and scapula were defined from the specific bony landmarks, and 3-dimensional angular rotations and positions of the clavicle and scapula were calculated. Differences in rotations and positions of the clavicle and scapula were evaluated between the supine and standing positions. Results: Compared with the supine position, the clavicle showed significantly less elevation and greater retraction, and the scapula showed significantly less upward rotation, anterior tilting, and internal rotation in the standing position. Compared with the supine position, the clavicle center was located more inferiorly, posteriorly, and laterally, and the scapula center was located more inferiorly, posteriorly, and medially in the standing position. Conclusions: The present study showed that angular rotations and positions of the clavicle and scapula change significantly with position due to the effect of gravity. Keywords: Shoulder girdle, Upright computed tomography, Shoulder girdle alignment, Clavicle rotation, Scapula rotation, Scapulothoracic joint
Introduction Humans perform their activities of daily living mainly in a standing or sitting position, but it is difficult to accurately evaluate the alignment of the shoulder girdle during daily activities. Plain radiographs can be taken in an * Correspondence: [email protected]; [email protected] 1 Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan 2 Department of Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
upright position, but 3-dimensional anatomical alignment cannot be assessed on 2-dimensional projection images [1]. On the other hand, computed tomography (CT) scans have the advantage of assessing bones and joints three dimensionally, and they are now widely used to evaluate joint pathologies, but CT scans are usually taken in the supine position. Direct measurement [2] and measurement using electromagnetic tracking devices [3–6] require palpation for identification of the bony landm
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