Local pressures in the subacromial space.

We recorded pressures in the subacromial space with various degrees of humeral abduction. The recordings were made during open surgery and under general anaesthesia using a 2-mm-thick piezo-electric pressure transducer. The pressures were recorded in 14 patients with shoulder impingement syndrome (Neer's stage II) and in eight patients with acromioclavicular dislocation serving as controls. The pressures were higher in the impingement group than in the control group. In both groups the highest pressures were recorded antero-laterally under acromion. In patients with impingement syndrome, the pressures increased significantly with abduction.