Itoi E, Motzkin N E, Morrey B F, An K N
Biomechanics Laboratory, the Department of Orthopedics, Mayo Clinic/Mayo Foundation, Rochester, Minn.
J Shoulder Elbow Surg. 1992 May;1(3):131-9. doi: 10.1016/1058-2746(92)90090-P. Epub 2009 Feb 25.
Eleven fresh-frozen cadaver shoulders were studied to examine the influence of scapular inclination on inferior stability of the glenohumeral joint. All muscles except the rotator cuff were removed, and the capsule was vented. Inferior stability tests in the hanging position (sulcus test) and in 90° abduction (abduction inferior stability [ABIS] test) were simulated by the application of a 1.5 kg load with the scapula inclined at - 15°, 0°, 15°, and 30° in the sulcus test and at 15°, 30°, 45°, and 60° in the ABIS test. An electromagnetic tracking device was used to record the position of the humerus in relation to the glenoid. In the sulcus test all of the shoulders dislocated when the scapula was inclined at - 15°. However, when the scapula was inclined at 30°, no shoulder dislocated before loading, and one shoulder dislocated after loading. As a result both the loaded and unloaded positions of the humeral head shifted significantly to the superior direction as the scapular inclination increased (p < 0.0001). In the ABIS test, however, the positions of the humeral head shifted interiorly with an increase in scapular inclination (p < 0.0001), although none of the shoulders dislocated in any of the inclination angles. We conclude that scapular inclination contributes significantly to inferior stability of the glenohumeral joint. Increased scapular inclination prevents inferior displacement of the humeral head, probably because of a bony cam effect that causes tightening of the superior capsule.
对11个新鲜冷冻尸体肩部进行研究，以检验肩胛倾斜度对盂肱关节下方稳定性的影响。除肩袖肌外，所有肌肉均被切除，关节囊被切开。通过在肩胛倾斜度为-15°、0°、15°和30°时施加1.5 kg负荷来模拟悬吊位（沟试验）和90°外展位（外展下方稳定性[ABIS]试验）的下方稳定性测试，在ABIS试验中肩胛倾斜度为15°、30°、45°和60°。使用电磁跟踪装置记录肱骨相对于关节盂的位置。在沟试验中，当肩胛倾斜度为-15°时，所有肩部均发生脱位。然而，当肩胛倾斜度为30°时，无肩部在加载前脱位，1个肩部在加载后脱位。结果，随着肩胛倾斜度增加，肱骨头的加载和未加载位置均显著向上方移位（p<0.0001）。然而，在ABIS试验中，尽管在任何倾斜角度下均无肩部脱位，但随着肩胛倾斜度增加，肱骨头位置向内侧移位（p<0.0001）。我们得出结论，肩胛倾斜度对盂肱关节下方稳定性有显著贡献。肩胛倾斜度增加可防止肱骨头向下移位，可能是由于骨凸轮效应导致上方关节囊收紧。
