Excision Of The Scapula

The removal of the scapula necessitates the division of a large number of muscles, for which see pages 226 and 227. The subscapular artery at the anterior border, about 2. 5 cm. (1 in.) below the head or glenoid process, and the suprascapular at the suprascapular notch, are to be ligated before removing the bone. Skirting the posterior edge is the posterior scapular, the continuation of the transverse cervical artery; it is to be avoided when detaching the muscles. The acromial branches of the acromial thoracic artery ramify over the acromion process; they are not so large as those already mentioned.

Mr. Jacobson suggests that if safety permits one should allow the acromion process to remain, as it preserves the point of the shoulder and to some extent, the functions of the trapezius muscle.

Excision Of The Head Of The Humerus

The incision for the removal of the head of the humerus should be commenced just outside of the coracoid process and be carried 10 cm. (4 in.) downward in a direction toward the middle of the humerus, where the deltoid inserts. This incision may be made while the arm is somewhat abducted but it does not go in the groove between the deltoid and pectoralis major muscles. This groove contains the cephalic vein and the humeral branch of the acromial thoracic artery, and hence is to the inner side of the coracoid process and as the incision is to the outer side, it passes through the deltoid near its anterior edge (Fig. 265).

The incision goes through the muscle and exposes the capsule of the joint. The sides of the wound are to be retracted and, if the long head of the biceps muscle is not recognized by sight, the finger is inserted and the arm rotated. The bicipital groove can be felt and the tendon identified.

The capsule is to be incised along the outer edge of the long tendon of the biceps and as the arm is rotated inward the supraspinatus, infraspinatus, and teres minor muscles are to be detached from the greater (posterior) tuberosity. The biceps tendon is again brought into view by rotating the arm outward and its sheath (transverse ligament) slit up and the tendon luxated inward.

The attachment of the capsule and subscapularis muscle to the lesser (anterior) tuberosity is then divided while the arm is rotated outward. The biceps tendon lies in the bicipital groove between the two tuberosities. When the arm is lying with the palm upward, in a supine position, the bicipital groove looks directly anteriorly in a longitudinal line passing midway between the two condyles of the lower end. The position of the head and groove can be told by observing the position of the condyles.

The head is directly above the internal condyle and the groove is on the anterior surface above a point midway between the condyles. After the capsule has been opened and the attachments of the muscles to the greater and lesser tuberosities divided and the tendon of the biceps luxated inward, the head is thrust directly upward and out of the wound and sawed off as low as desired.

Immediately below the lower edge of the tuberosities is the surgical neck. On it anteriorly winds the anterior circumflex artery, and posteriorly the circumflex (axillary) nerve and posterior circumflex artery. These should not be disturbed, for the artery will bleed and injury of the nerve will cause paralysis of the deltoid muscle.

Posterior and transverse incisions have been suggested for this operation but they are not to be advised. The circumflex nerve and posterior circumflex artery are almost certain to be injured and the functions of the deltoid are liable to be seriously impaired or altogether lost.

If more access is desired than can be obtained by a straight incision as directed, the deltoid can be detached from its origin along the outer end of the clavicle and acromion process and turned down. This does not interfere with its nerve supply. The circumflex nerve going to the muscle crosses the humerus at about the junction of the upper and middle thirds of the deltoid or a finger's breadth above its middle. After resection of the bone the deltoid can again be brought up and sewed to its previous attachment.

Fig. 265.   Resection of the shoulder joint. The arm has been rotated outward so as to put the tendon of the subscapularis on the stretch. The long tendon of the biceps has been dislocated from the bicipital groove and is held to the inner side by a hook.

Fig. 265. - Resection of the shoulder-joint. The arm has been rotated outward so as to put the tendon of the subscapularis on the stretch. The long tendon of the biceps has been dislocated from the bicipital groove and is held to the inner side by a hook.

The character of the operation depends on the nature and extent of the disease. The operator should be familiar with the epiphyseal line, which runs from the inside upward and outward in the line of the anatomical neck as far as the middle of the bone, and then slopes slightly downward and outward to reach the surface almost on a level with the lower (inner) edge of the articular surface. As this is the site of most active growth of the humerus in young subjects this epiphyseal cartilage should be spared as much as possible.

The disability arising from a free resection is so great, owing to the loss of movements resulting from the detachment of muscles and interference with the epiphyseal cartilage, that formal resections are rarely performed, but, instead, the diseased parts are simply gouged away and as much allowed to remain as possible.

It is to be remembered that rotation inward is mostly performed by the sub-scapularis and outward rotation by the infraspinatus and teres minor. The supra-spinatus aids abduction. A too free excision is liable to be followed by a flail-joint, in which case the limb hangs helplessly by the side with the dorsum pointing forward.

The axillary fold muscles insert on the anterior surface of the bone and hence turn the arm inward and draw it in toward the body, they do not compensate for the loss of the muscles attached to the tuberosities.

The bleeding in the operation will be mainly from the acromial branches of the acromial thoracic artery and the bicipital branch of the anterior circumflex artery, which runs in the bicipital groove.