Sternoclavicular Joint

STERNOCLAVICULAR JOINT, represents a very strong connection between the sternum and the end of the clavicle. Between the clavicle and the notch of the sternum is located a thick and strong cartilaginous plate - the articular disc. Thanks to the disc, the joint is divided into two chambers, with the sternal end of the clavicle articulating only with the disc, which has the shape and size of the articular surface of the clavicle (see figure, p. 134). The articular disc, or meniscus, has a coarse-fibrous structure and is firmly connected above with the edge of the clavicle, and below it is attached to the cartilage of the first rib. In origin, this is a rudiment of the episternum, which clearly appears in reptiles and later together with the clavicle serves to connect the limb with the chest cage. The considerable strength of the joint is ensured by a strong ligamentous apparatus. In front and behind, the capsule is strengthened by means of short and strong sternoclavicular ligaments. Between the sternal ends of both clavicles run fibers of the interclavicular ligament; part of them are woven into the articular disc. The less strong costoclavicular ligament extends from the clavicular end of the first rib upward and outward, to the lower surface of the clavicle. The unique structure of the joint and the wide capsule allow for a considerable range of motion in all directions, making this joint mechanically similar to the ball-and-socket type. The blood supply to the joint occurs through branches of the internal mammary artery. With various movements of the arm, there is coordination of movements in all three joints connecting the upper limb and shoulder girdle with the trunk. When raising the arm upward to the horizontal, both joints articulating with the clavicle participate along with the shoulder joint. - Due to the superficial location of the clavicle and the role it plays as an intermediate link between the shoulder girdle and the trunk, the clavicle itself and its joints are often subjected to severe trauma - fracture of the clavicle or dislocation in the sternoclavicular or acromioclavicular joints. According to Stimson's data, dislocation of the sternal end of the clavicle occurs five times less frequently than the acromial. Most often, there occurs an anterior dislocation of the clavicle - luxatio claviculae praesternalis, resulting from forced movement of the shoulder girdle backward or simultaneously downward and backward. In this case, only the anterior sternoclavicular ligament may rupture, as a result of which the end of the clavicle is set in a position of subluxation. A more severe injury causes rupture of all ligaments and a complete anterior dislocation of the clavicle, which is easily recognized clinically. Functional disturbances occur only in the first days, then work capacity is restored almost completely. More significant disturbances are caused by habitual dislocation in the sternoclavicular joint. Posterior dislocation of the sternal end of the clavicle also occurs - lux. claviculae retrosternalis. The mechanism of occurrence of this dislocation: direct application of force from front to back or indirect, by compression of the shoulder girdle forward and inward. The end of the clavicle is displaced inward or downward and inward, more often located between the sternothyroid muscle and the sternum (Stimson); according to other authors - between the trachea and the sternohyoid and sternothyroid muscles. The end of the clavicle, pressing on the trachea or esophagus, can cause dyspnea or dysphagia. Of 16 cases collected by Polaillon, dyspnea was observed 6 times, dysphagia - 3 times. A depression at the site of the sternal end of the clavicle, tense forward inclination of the shoulder and shoulder girdle, disturbance of movements of the entire shoulder girdle, severe pain, and finally the mechanism of trauma confirm the diagnosis of posterior dislocation of the clavicle. Disturbance of breathing is observed in approximately one-third of all cases. Dislocation of the sternal end upward (lux. claviculae suprasternalis) differs from anterior dislocation by the displacement of the clavicle backward from the sternal process of the sternocleidomastoid muscle (see Vol. VI, p. 41, figs. 22 and 23). In the literature, 20 cases of upward dislocation of the clavicle have been collected; of these, two cases were established at autopsy. By applying direct force to the shoulder and the acromial end of the clavicle, the ligamentous apparatus and the upper part of the capsule rupture. With further action of the force, the end of the clavicle is displaced inward and upward. By palpation, the end of the clavicle is determined behind the sternal process of the sternocleidomastoid muscle. Approaching of the shoulder girdle to the chest, local tenderness, less frequently - dyspnea or dysphagia, limitation of movement of the arm and head are noted. Treatment. In fresh cases - immediate reduction of the dislocation (by performing manipulations opposite to the action of the force that caused the dislocation). In anterior dislocation, the shoulder girdle is pulled outward and slightly backward, applying constant pressure on the sternal end from front to back. In posterior dislocation, reduction is achieved by pulling the shoulder girdle outward and backward, with the application of greater force. In upward dislocation of the clavicle, reduction is obtained by pulling the arm outward, applying direct pressure on the sternal end of the clavicle downward and outward. To prevent subsequent subluxation and recurrence, careful and rational fixation is necessary. In habitual dislocation, Stimson achieved good results by injecting alcohol into the area of the sternoclavicular joint. In more severe and irreducible cases, surgical intervention is indicated. - Inflammatory diseases of the articulatio sternoclavicularis are observed extremely rarely. Individual cases of tuberculous abscesses and fistulas in the area of this joint may have their source in the retrosternal lymph glands or the first rib, secondarily involving the sternoclavicular joint. Conservative therapy is preferable here. Chaklin observed a metastatic abscess with purulent destruction of the joint during septicopyemia. During typhoid epidemics, in rare cases, involvement of the sternoclavicular joint was noted along with other complications; the disease of the joint in these cases should probably be considered as metastatic infection in paratyphoid complications. Surgical intervention in such arthritis should be palliative. - Tumors of the sternal or sternal end of the clavicle sometimes require wide resection or extirpation of the clavicle, however, this does not significantly disrupt the function of the shoulder girdle. V. Chaklin.