The clinical features common to all dislocations are prominent, although Dugas' symptom is not constant.
Fig. 19.—Sub-coracoid Dislocation of Humerus.
(Sir H. J. Stiles' case. Radiogram by Dr. Edmund Price.)
Treatment.—The guiding principle in the reduction of these dislocations is to make the head of the bone retrace the course it took in leaving the socket. The main obstacles to reduction being muscular contraction and the entanglement of the head with tendons, ligaments, or bony points, appropriate means must be taken to counteract each of these factors.
A general anæsthetic is an invaluable aid to reduction, and should be given unless there is some reason for withholding it. It is specially indicated in strong muscular subjects, and in nervous patients who do not bear pain well, and particularly when the dislocation has existed for a day or two. In quite recent cases, however, the surgeon may succeed in replacing the bone by taking advantage of a temporary faintness, or by engaging the patient's attention with other matters while he carries out the appropriate manipulations.
When an anæsthetic is employed, the patient should be laid on a mattress on the floor, or on a narrow, firm table; otherwise he should be seated on a chair.
Kocher's method is suitable for the great majority of cases of sub-coracoid dislocation. (1) The elbow is firmly pressed against the side, and the forearm flexed to a right angle. The surgeon grasps the wrist and elbow and firmly rotates the humerus away from the middle line ([Fig. 20]) till distinct resistance is felt and the deltoid becomes more prominent. In this way the rent in the lower part of the capsule is made to gape, and the head of the humerus rolls away from the middle line till it lies opposite the opening, rotation taking place about the fixed point formed by the contact of the anatomical neck of the humerus with the anterior lip of the glenoid cavity (D. Waterston). (2) The elbow is next carried forward, upward, and towards the middle line ([Fig. 21]); the humerus acting as the long arm of a lever on the fulcrum furnished by the muscles inserted in the region of the surgical neck, the head, which forms the short arm of the lever, is carried backward, downward, and laterally, and is thus directed towards the socket. (3) The humerus is now rotated towards the middle line by carrying the hand across the chest towards the opposite shoulder ([Fig. 22]). The anatomical neck of the humerus is thus disengaged from the edge of the glenoid, and the head is pulled into the socket by the tension of the surrounding muscles.
