Function of the Biceps in Shoulders with Rotator Cuff Tears.

我们发现，在一些肩袖撕裂的肩部，肱二头肌的肌电图活动增加。本研究的目的是确定肩袖撕裂后肱二头肌的稳定功能。我们研究了15个肩袖撕裂和19个正常肩。使用定制设计的支架对二头肌施加1.5 kg的负荷。在肱二头肌负重和不负重的情况下，分别在0度、45度和90度仰角处拍摄正位x线片。使用NIH图像获得肱骨头相对于肩关节的中心。在没有肱二头肌负荷的情况下，袖带撕裂肩部的头部移位更明显：与正常肩部相比，在0度和45度处的头部移位更明显。随着肱二头肌负荷的增加，两组的头部向外移动受到抑制。两组之间的头部位置无显著差异。结果表明，肱二头肌对肩袖撕裂患者的头部稳定有较好的作用。

We found that in some of the shoulders with rotator cuff tears, electromyographic activities of the biceps increased. The purpose of this study was to determine the stabilizing function of the biceps in shoulders with rotator cuff tears. We investigated 15 shoulders with rotator cuff tears and 19 normal shoulders. A custom-designed brace was used to apply 1.5-kg load to the biceps. Anteroposterior roentgenograms were taken at 0, 45, and 90 degrees of elevation with and without biceps loading. The center of the humeral head relative to the glenoid was obtained using an NIH image. Without biceps loading, the head shifted superiorly in cuff-tear shoulders : superior shift was significant at 0 and 45 degrees compared to the normal shoulders. With biceps loading, the superior migration of the head was suppressed in both groups. There were no significant differences in the head position between the groups. The results indicate that the biceps functions to stabilize the head superiorly in shoulders with rotator cuff tears.