22 THE SUPERIOR EXTREMITY 



rests on the posterior margin of the glenoid cavity, or on the 

 neck of the scapula, or in the infra-spinous fossa. The 

 infra-spinatus is usually stripped up by the head of the bone, 

 and the nature of the rotation of the humerus depends on 

 whether the subscapularis is ruptured or remains intact. 



In all dislocations of the shoulder the normal rounded contour 

 is lost, as the greater tubercle is drawn medially. For the 

 same reason the lateral border of the acromion, now the most 

 lateral bony point in the region, becomes more prominent, and a 

 straight edge can be made to touch both the acromion and the 

 lateral epicondyle of the humerus. In the anterior displacements 

 the head of the humerus produces a rounded elevation, which 

 may occlude the superficial infra-clavicular triangle. This 

 deformity is more pronounced in the sub-clavicular variety. 



Miller's Method of Reduction. The initial steps, which 

 consist of abduction and traction on the arm, draw the head 

 of the humerus free from the scapula, relax the deltoid and 

 supra-spinatus, and stretch the lower part of the capsule and 

 the subscapularis. If the tear involves the anterior part of 

 the ligament, reduction may occur without further manipulation, 

 as in Kocher's method (vide infra). If the tear is confined to 

 the inferior aspect of the capsule, the articular head of the 

 humerus is brought into contact with it by the next step 

 medial rotation. Owing to the continued traction the tendon 

 of the subscapularis is tightly stretched over the head, which it 

 presses through the gap when the traction is lessened. In this 

 method an assistant steadies the patient's chest and scapula 

 throughout, thus exerting counter-extension. 



Kocher's Method of Reduction. In the first instance the 

 patient's elbow is pressed firmly against his side in order to 

 fix the distal end of the humerus, as only by this means can 

 subsequent manipulations exert their full action on the head 

 of the bone. Grasping the patient's wrist with his free hand, 

 the surgeon uses the forearm as a lever to produce lateral 

 rotation of the humerus. This is effected by carrying the fore- 

 arm away from the body till it is nearly in the frontal (coronal) 

 plane, and the movement is performed slowly and steadily in 

 order to overcome the muscular spasm. In this way the 

 anatomical neck is disengaged from the glenoid margin, and 

 the posterior aspect of the greater tubercle comes into contact 

 with the articular surface of the glenoid cavity, from which it is 

 separated by a part of the capsule. 



