著者

中村 真里 中村 康雄 林 豊彦 福田 登 駒井 正彦 橋本 淳 信原 克哉 Chao Edmund Y.

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

no.16, pp.13-25, 2002-06-25

被引用文献数

9 4

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Baseball pitching involves a complicated and rapid movement that has been investigated to prevent injuries and to improve the pitching performance. It is difficult to assess the pitching motion with high accuracy and a high sampling rate, due to the limitations of preexistent camera systems. The current camera system, however, has enough capacity to measure pitching motions with high accuracy and a high sampling rate. We have been diagnosing shoulder joint injuries caused by pitching. The patients (N=939) felt pain during the pitching sequence as follows: top position (32.5%), maximum external rotation (27.2%), and ball release (14.5%). Hence the top position is one of the most important postures to investigate the mechanisms of shoulder joint injury in pitchers. There have been no studies that focused on the top position, however. The main purpose of this study was to develop a system to assess the pitching motion accurately. Another purpose was to estimate the instant of the top position and evaluate the kinematics of the shoulder and elbow joints. Pitching movement was assessed using a motion capture system (ProReflex MCU500, Qualisys Inc., Sweden) in a studio that has an official pitcher's mound and home base. This system can record the positions of reflective markers at 500 Hz using seven CCD cameras. Thirty-two markers were mounted on the joints and body landmarks of each subject. Two markers were mounted on the ball. The pitching motions of eleven subjects were assessed, after a period for warm up. Kinematics parameters were calculated using three-axis gyroscopic Euler angle. The instant of the top position was observed for all subjects before the lead foot touched the ground. The interval from the top position to ball release was 0.242±0.0438 [s] (n=11). The subjects were divided into two groups by the type of posture at the instant of the top position, as follows: internal rotation group (n=5), 11.8±6.08 degrees, and external rotation group (n=6), 38.1±19.97. Other kinematics parameters at the top position were adduction of the shoulder at 74.2±19.84 degrees, horizontal adduction of the shoulder at 37.3±14.10 degrees, and extension of the elbow at 92.1±21.63 degrees. The timing and posture of the estimated top position were almost the same as those of the conventional top position. From the top position to lead foot contact on the pitching sequence, there were three patterns of elbow leading. The three patterns did not depend upon experience. We interpreted them as individual variations.

著者

建道 寿教 橋本 淳 橋本 卓 駒井 正彦 中村 真里 信原 克哉 中村 康雄

出版者

Japan Shoulder Society

雑誌

肩関節 (ISSN:09104461)

巻号頁・発行日

vol.28, no.3, pp.427-431, 2004

被引用文献数

2

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The Purpose of this study was to analyze the articular contact pattern of the normal glenohumeral joint. There are few previous papers concerning the dynamic contact patterns, although the studies of using the cadaver or the tracking device have been reported. The subjects consisted of 10 normal volunteers. The subjects were fixed on a tilted stand with free motion around the scapula.3D MRI images were extracted at the scapular plane at every 30° between 30° and 150° in the supine position. The images obtained at each position were transmitted to a personal computer and the description of the bony frame by digitizing methods using the analyzing software were developed. Three dimensional reconstruction of the glenohumeral joint were performed. The items of measurement were the following (1)The contact area; the distances between the humeral head and the glenoid surface were calculated and the distribution set at the distances were considered to be the contact area. The shortest distance was regarded as the proximity of the joint. The change of the center of the distribution was investigated. (2)The center of the humeral head (3) Kinematics of the humerus; (from the aspect of the scapula) Results: (1)In the contact area; the minimum contact area had shifted superiorly up to 90 or 120° elevation, but after 120° it shifted inferiorly. Concerning the antero-posterior direction of the glenoid, it shifted antero-inferiorly at the elevated position compared to that of the 30Thlevation. (2)In the center of the humeral head; it shifted superiorly at 120° or 150° compaired to the 30° elevation. Its change was within 3mm. (3)In the Kinematics of the humerus; although the glenohumeral movement was totally 66°, it was only 17' after 90° elevation. We conclude that although the contact area shifted superior until 90°, it shifted to the central part of the glenoid over 120°, because the centripetal force might have worked at the elevated position. The distribution of the contact area was assumed to be reflected as a result of seeking a good congruity of the humeral head and the glenoid.

著者

中溝 寛之 橋本 淳 中村 真里 金谷 整亮 信原 克哉 中村 康雄

出版者

日本肩関節学会

雑誌

肩関節 (ISSN:09104461)

巻号頁・発行日

vol.28, no.2, pp.355-358, 2004-08-30 (Released:2012-11-20)

参考文献数

5

被引用文献数

1

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The purpose of this study was to investigate the characteristics of baseball pitching motion in young pitchers. Sixty-five asymptomatic pitchers were analyzed with a motion capture system. The subjects were classified into two groups according to their age: A: 34cases (10-15 years old), B: 3lcases (19-34 years old). Kinematic and kinetic parameters were used to compare the differences between the two groups. Abduction and horizontal adduction angles of the upper arm were smaller in group A at ball release. The trunk was less flexed and twisted, but was bent much more toward the non-throwing side in the group A. There were no significant differences between the two groups with regard to the elbow angles, the wrist angles and the interval from arm-cocking phase to ball release. Our results showed that the young pitchers tend to put their pitch arm behind their trunk at ball release. That position is not close to “Zero Position”. It causes stretching the anterior structure of the shoulder. Furthermore, the shoulder is overloaded by the rotational stress from the end of armcocking phase to ball release. Repetition of this stress might cause epiphyseal damage for young pitchers. The young pitchers should be taught proper pitching mechanics. Limitation on pitches might be able to reduce the risk of epiphyseal damage in young pitchers.

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.