A Method of Roentgenologic Examination of the Shoulder

Abstract

Calcifications in the soft tissues are often seen in roentgenograms of the shoulder girdle. Fractures with separation of small cortical spicules of bone are not infrequent findings. Tendon injuries, as rupture of the supraspinatus tendon and dislocation of the long head of the biceps brachii, are also known to occur. On occasion, the roentgenologist may be called on to localize accurately such particles and other abnormalities. Stimulated by necessity, the authors early became aware that the usual roentgenograms of the shoulder, namely anteroposterior views with the hand in supination and pronation, are insufficient, even if taken in stereoscopic pairs. The great freedom of motion of the humeral head on the surface of the glenoid fossa actually adds to the difficulty of the exact localization of a lesion. Anatomically the freedom of motion of the humerus is favored by a relatively loosely enveloping joint capsule, which attaches to the glenoid rim above and to the anatomical neck of the humerus below. This joint capsule extends in a tubular sheath enveloping the long head of the biceps brachii in its passage through the bicipital groove. Two layers of muscle overlie the shoulder girdle: the outer group, passing over the shoulder to insert into the upper humeral shaft, consists of the deltoid, pectoralis major, latissimus dorsi, and teres major; the inner group, the so-called short rotators of the shoulder, include the supraspinatus, infraspinatus and teres minor inserting into the greater tuberosity, and the subscapularis, inserting into the lesser tuberosity. The subacromial bursa, somewhat smaller than the palm in a given individual, fits like a skullcap over the lateral aspect of the shoulder between these outer and inner muscle planes, obviously so located to prevent friction from contrasting movements (Codman, 1). Because small calcifications so frequently appear within the short rotator tendons and periosteal proliferation may occur at the site of their insertion into the humerus, and because small bone fragments may actually be separated from these insertions, it is important to elaborate. The short rotator tendon insertions are broad and flat, measuring about an inch in length. They fuse into a continuous band or, better, interdigitate with one another. Fibers of this tendinous cuff are incorporated with the joint capsule proximal to their insertion. The greater tuberosity of the humerus forms an arc from before back, with its anterior margin bulging externally and sloping downward and forward for the insertion of the supraspinatus muscle; in the mid sector of this greater tuberosity a flat cortical plate of fingernail size slopes caudad externally and forms the facet for the infraspinatus insertion; and the less prominent posterior slope of the greater tuberosity marks the site for the insertion of the teres minor. The lesser tuberosity anteriorly (for the subscapularis) is a prominent “nubbin”-like projection.