Bulk Effect of Rotator Cuff on Inferior Glenohumeral Stability as Function of Scapular Inclination Angle: A Cadaver Study

ITOI, E., MOTZKIN, N.E., MORREY, B.F. and AN, K.-N. Bulk Effect of Rotator Cuff on Inferior Glenohumeral Stability as Function of Scapular Inclination Angle: A Cadaver Study. Tohoku J. Exp. Med., 1993, 171(4), 267-276-Eleven fresh cadaver shoulders were studied to determine the static contribution (bulk effect) of the rotator cuff on inferior glenohumeral stability provided by scapular inclination. All musculature, including the rotator cuff, was removed. The position of the humerus relative to the scapula was recorded using an electromagnetic tracking device under conditions of no force and 1.5kg of inferior translation force applied to the humerus, with the arm in the hanging position (sulcus test) and then in 90° abduction (Abduction-Inferior Stability test=ABIS test), with the scapula inclined referable to the vertical line at -15°, 0°, 15° and 30° in the sulcus test and at 15°, 30°, 45° and 60° in the ABIS test. In the sulcus test without load, all shoulders dislocated at scapular inclination angles of -15° and 0°, whereas no shoulders dislocated at 30°. The angle of scapular inclination had a significant effect on humeral head positions (p