著者

西中 直也 近 良明 Banks Scott A 三原 研一 鈴木 一秀 大田 勝弘 牧内 大輔 松久 孝行 筒井 廣明 杉本 英治 蒲田 和芳

出版者

日本肩関節学会

雑誌

肩関節 (ISSN:09104461)

巻号頁・発行日

vol.32, no.3, pp.509-512, 2008 (Released:2008-11-21)

参考文献数

16

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The glenoid bare spot commonly is observed in the adult shoulder. Carter et al. proposed that cartilage thickness was affected by normal homeostatic loads. The purpose of this study was to measure glenohumeral translation during shoulder abduction in order to explore development of the glenoid bare spot. 10 healthy shoulders (average 31.1 years old) were studied. 3D models of the scapula and humerus were created from CT scans. Motions were recorded with fluoroscopy during active abduction in neutral rotation for unloaded and a 3kg loaded trial. 3D motions were determined using model-based 3D-to-2D registration. Humeral translation was referenced in the superior/inferior direction to the assumed location of the bare spot (center of the circle described by the bony margins of the inferior glenoid). The bare spot location averaged 4.3mm inferior to the superior/inferior midpoint of the glenoid. Glenohumeral contact was 2.6 and 3.1mm superior to the bare spot for unloaded and loaded conditions with the arm at the side. The humeral head moved upward gradually with abduction to 4mm above the bare spot above 70° abduction (p>0.05, 0 vs 3kg). The glenoid surface stabilizes humeral head translation. Carter et al. suggested that cartilage grew thickest with high mechanical demands (compression and sliding) and thinner where demands were low. Humeral translation away from the bare spot with abduction suggests that lower loads were experienced when the humeral head was near the bare spot and larger loads were experienced with humeral translation away from the bare spot. These kinematic observations were consistent with Carter's framework for cartilage growth and provided a plausible explanation for the development of the glenoid bare spot.

著者

鈴木 一秀 南 和延 筒井 廣明 三原 研一 保刈 成 上里 元 内川 友義 菅 直樹 大田 勝弘 牧内 大輔

出版者

Japan Shoulder Society

雑誌

肩関節 (ISSN:09104461)

巻号頁・発行日

vol.23, no.3, pp.373-376, 1999

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[Purpose] The purpose of this study is to analyze the influence of the scapulothoracic joint on the rotator cuff function using integrated electromyography.<BR>[Materials and Methods] Ten shoulders of ten young males who were diagnosed as having dysfunction of scapulothoracic joint with &lceil;Scapula-45&rfloor; radiography and resisted abduction and external rotation test. The activities of the supraspinatus, infraspinatus, deltoid, and biceps were evaluated electromyographically with the loads at 45 degrees elevated position in the scapular plane. Subsequently the activity of these muscles was collected with a manual assist to the scapulothoracic function. The EMG activity was expressed as a percentage of the Max MMT (%MMT).<BR>[Results] The EMG activity increased with the load in all the cases. In 80% of the total cases, the relationship between the supraspinatus and deltoid did not change irrespective of the load (deltoid/supuraspinatus=1 /1.3) without manual assistance. The %MMT of the supraspinatus and deltoid of these cases showed a significant difference between the activity with and that without manual assistance. The tendency was remarkable at 3kg load. In 20% of the total cases, a dysfunction of rotator cuff was noted.<BR>[Conclusion] The results suggest the function of scapulothoracic joint has an effect on the rotator cuff function.