Nakagaki K, Ozaki J, Tomita Y, Tamai S
Department of Orthopaedic Surgery, Gojo Prefectural Hospital, Nara, Japan.
Clin Orthop Relat Res. 1995 Sep(318):144-51.
An estimation of the residual function of the supraspinatus muscle after rotator cuff tear is useful to select the best operative method for repair of the torn cuff and to evaluate prognosis after surgery. The residual function of the supraspinatus muscle was studied by magnetic resonance imaging with motor unit potential amplitudes on electromyograms. Forty-three normal shoulders and 41 shoulders in patients with cuff tears were scanned by magnetic resonance imaging parallel to the long axis of the supraspinatus muscle. The ratio of the largest width of the supraspinatus muscle belly to the distance from the greater tubercle to the proximal end of the supraspinatus muscle was termed the supraspinatus muscle belly ratio. The linear bands of the supraspinatus muscle and the variation in the muscular signal intensity were classified into 3 grades. With a reduction in the motor unit potential amplitude, the supraspinatus muscle belly ratio became lower than 0.15. Additionally, the degree of appearance of the linear bands in the supraspinatus muscle belly increased, and the signal intensity became less uniform. The residual function of the supraspinatus muscle decreased when such morphologic changes were shown by magnetic resonance images. By analyzing these images, the best operative method for repairing a rotator cuff tear can be selected and the prognosis can be evaluated.
评估肩袖撕裂后冈上肌的残余功能，有助于选择修复撕裂肩袖的最佳手术方法，并评估术后预后。通过磁共振成像结合肌电图上的运动单位电位幅度来研究冈上肌的残余功能。对43例正常肩部和41例肩袖撕裂患者的肩部进行了与冈上肌长轴平行的磁共振成像扫描。将冈上肌肌腹的最大宽度与大结节到冈上肌近端距离的比值称为冈上肌肌腹比值。将冈上肌的线性带和肌肉信号强度的变化分为3级。随着运动单位电位幅度的降低，冈上肌肌腹比值低于0.15。此外，冈上肌肌腹内线性带的出现程度增加，信号强度变得更不均匀。当磁共振图像显示出这种形态学变化时，冈上肌的残余功能下降。通过分析这些图像，可以选择修复肩袖撕裂的最佳手术方法并评估预后。
