The pattern of pain produced by irritation of the acromioclavicular joint and the subacromial space.

To characterize the patterns of pain caused by selective irritation of the acromioclavicular joint and of the subacromial space, hypertonic saline solution was injected 15 times into the acromioclavicular joints of 10 healthy volunteers and 10 times into the subacromial space of 9 healthy volunteers. Irritation of the acromioclavicular joint produced pain directly over the joint, in the antero-lateral neck, in the trapezius-supraspinatus region, and in the anterolateral deltoid. Irritation of the subacromial space produced pain in the region of the lateral acromion, the deltoid muscle, and occasionally in the forearm or the fingers but did not produce pain in the neck or in the trapezius region. Neither acromioclavicular nor subacromial irritation produced pain at the posterior aspect of the shoulder. This information may assist in accurate clinical diagnosis and in the selection of optimal imaging studies for the evaluation of shoulder pain.