1990 年 14 巻 2 号 p. 192-196
It is commonly known that elevation of the arm is combined with rotation. However it is very difficult to measure the rotational angle physiologically. We made a video-computer system for this and measured the angles during elevation in both the frontal and the scapular planes. A special bar (30g) was put on the elbow joint of twenty men and fifteen women.
An X-Y plotter was used to get the positions of the tip a nd the middle point of the bar. Then a personal computer was used to calculate the rotational angle and to analyse the transposition of the instant center of the shoulder joint. From this study we conclude that the rotational angle in the frontal plane that (102.6°) is larger than thar in the scapular plane (65.0°) and that thar of the right shoulder is larger than the left shoulder one. Furthermore, we found that there are two different patterns in the rotational angle.