腱板断裂症例における肩内外旋位での肩外転筋力の検討

抄録

In a recent anatomic study, it was reported that the supraspinatus tendon inserted into the anteriormost area of the highest impression on the greater tuberosity, while the infraspinatus tendon extended to the anterolateral area of it. It was thought that the infraspinatus works as the abductor at the internal rotation (IR) position and the supraspinatus works as the abductor at the external rotation (ER) position in the previous study. We measured the shoulder abduction strength at IR and ER positions in rotator cuff tear to prove this hypothesis. We examined 69 cases of rotator cuff tear in MRI. Tears of 11 cases were located at the anterior part of the highest impression (HIa). Tears of 19 cases were located at the posterior part of the highest impression (HIp). Tears of 13 cases were located at the anterior part of the middle impression (MIa). Tears of 19 cases were located at the posterior part of the middle impression (MIp). We measured shoulder abduction strength at 40 and 90 degrees' scaption between IR and ER position. The device of measurement used was MicroFET. We compared the rate of affected / unaffected side in abduction strength at IR with ER. In HIa, 40 degrees test was IR: 81.3%, ER: 70.8% (NS), 90 degrees test was IR: 76.5%, ER: 65.5% (p<0.05). In HIp, 40 degrees test was IR: 71.6%, ER: 70.1% (NS), 90 degrees test was IR: 66.7%, ER: 64.1% (NS). In MIa, 40 degrees test was IR: 73.5%, ER: 72.0% (NS), 90 degrees test was IR: 68.3%, ER: 66.3% (NS). In MIp, 40 degrees test was IR: 55.7%, ER: 56.9% (NS), 90 degrees test was IR: 62.7%, ER: 67.4% (NS). When rotator cuff tear was located at HI-a, the abduction strength at ER was statistically less than at IR. We should think that the supraspinatus works as abductor at ER position and the infraspinatus works as abductor at IR position.