肩甲骨関節窩の動的安定化機構としての機能について（第１報）

抄録

The glenoid of the scapula is an essential component of glenohumeral joint and is known to act as a static stabilizer. Meanwhile, the function of the glenoid may be interpreted as a dynamic stabilizer since it upwardly rotates to keep the scapulo-humeral rhythm during shoulder elevation. The purpose of the current study was to analyze the functional aspect of the glenoid comparing the clinical subjects with stable and unstable shoulder. Patients with habitual shoulder dislocation (unstable group: n=11) and with the shoulder lesion without anterior instability such as rotator cuff tendinitis, SLAP lesion and shoulder contusion (control group: n=52) were involved. Two radiographs were taken of each subject (anteroposterior in internal rotation: IR1, zero position). Two straight lines were drawn from superior and inferior tubercle to the center of the humeral head in IR1 image, and the angle of the line was measured (α angle). The difference of the glenoid inclination angles between IR1 and Zero position (β angle) are then measured, and the glenoid extension ratio (α+β/α) was calculated and statistically analyzed with paired T-test. No significant difference was found in α angle between the two groups. The glenoid extension ratio and β angle was significantly lower in the unstable group than in the control group (p< 0.01). The extension ratio may be regarded as an index of "functional glenoid" in shoulder elevation. This result showed that the augmentation of the "functional glenoid" should be emphasized in the treatment of unstable shoulder, as represented by habitual shoulder dislocation. The appropriate physical therapy may be primarily indicated following this concept.