Coracoacromial pressure recordings in a cadaveric model.

A dynamic shoulder model was used to determine the pressure distribution under the acromion, the coracoacromial ligament, and the coracoid process with simulated active glenohumeral joint motion in cadaveric specimens. Computerized regulation of servo-actuator forces initiated controlled cycles of glenohumeral joint motion. Pressures were recorded by using capacitive sensors. Peak pressures averaged 56.6 N/cm2 and were located at the anterolateral border of the acromion in most specimens. Marked pressures were present under the coracoid process. Lack of force of the supraspinatus muscle resulted in an 8% decrease of mean coracoacromial pressures, lack of force on the subscapularis and infraspinatus/teres minor muscles in a significant 61% increase, and lack of force on all rotator cuff muscles in a significant 35% increase. After anterior acromioplasty was performed, mean coracoacromial pressures decreased 5%.