CHAPTER III.

DISLOCATIONS OF THE SHOULDER.

THESE accidents usually occur in middle-life, and are rarely met with in early childhood or in old age. After escaping from the capsule, the head of the bone may pass forwards, backwards, or downwards-the particular form of the dislocation being determined mainly by the direction of the force and the position of the arm at the time of the injury. The primary displacement may also be modified subsequently by muscular action or by further violence; this especially applies to the downward dislocation. The violence which generally produces the injury is a fall or blow upon the hand or the elbow, with the arm abducted and rotated outwards. The result is that the head of the bone is thrust violently against the anterior inferior part of the capsule which gives way, and allows the head of the bone to pass downwards below the glenoid cavity.

VARIETIES.-In all the forms of dislocation the primary displacement is sub-glenoid. As the head of the bone passes downwards it comes into contact with the anterior edge of the long head of the triceps, and, unless the direction of the force be such as to drive the head backwards, the result of contact with this structure is displacement forwards; the head then lies below the coracoid process-the so-called sub-caracoid dislocation which is the most common dislocation of the shoulder.

When the violence is more severe, the head of the bone may be thrust beyond the coracoid process until it lies beneath the clavicle the form spoken of as sub-clavicular dislocation Still more rarely the head of the bone travels backwards; this is the result either of a fall with the hand fully outstretched, or of direct violence applied to the front of the shoulder. Here also the lower part of the capsule is torn, but generally somewhat more posteriorly than in the former instances, and the head of the bone is carried backwards and lodges in the infra-spinous fossa-the sub-spinous dislocation.

Among the rarer forms are the sub-acromial dislocation, in which the head of the bone passes upwards into contact with the acromion, and

the supra-acromial dislocation, in which it lodges actually above it. These two forms are excessively rare, and, as the treatment is practically the same as for the other varieties, we need not refer to them further.

DISPLACEMENT.-Sub-coracoid Dislocation.-The upper arm is directed somewhat backwards and outwards so that the elbow is away from the side. The forearm is supinated, there is marked flattening of the shoulder, and the head of the bone can be made out in its new situation.

Sub-clavicular Dislocation.-The signs of this variety are usually those of the preceding one in an exaggerated degree; not uncommonly the coracoid process is fractured by the head of the humerus as it passes upwards towards the clavicle.

Sub-glenoid Dislocation. Here there is generally much pain from the pressure of the head of the bone upon the nerves; the elbow projects markedly from the side, the arm is slightly elongated, and the head of the bone can be felt in the axilla. There may be absence of pulse at the wrist from pressure on the axillary artery, or a rapid oedema of the hand from pressure on the vein.

Sub-spinous Dislocation. The arm is generally rotated inwards, is nearer to the side than in the other forms, and the long axis of the humerus is directed slightly forwards.

TREATMENT OF SIMPLE DISLOCATIONS.

Immediate reduction should be effected, and means must then be taken to retain the head of the humerus in the glenoid cavity.

REDUCTION.-Reduction may be effected either by manipulations, having for their object relaxation of the capsule and the muscles and the re-introduction of the head of the bone through the rent in the capsule by which it left the joint; or by traction, which brings the head of the bone down to the rent in the capsule.

The patient should be placed under a general anæsthetic. The pain of a dislocation is generally very severe, and the powerful muscles around the joint are kept in a state of such violent contraction that they offer great resistance to reduction; when, however, the patient is anæsthetised, manipulations often suffice to replace the head of the bone with the greatest ease. Indeed, in the ordinary sub-coracoid cases, it is not at all uncommon to find that, by the time the patient is fully anæsthetised, the dislocation has reduced itself. When, however, no anæsthetic is at hand, the pain that the patient suffers may be so severe as to demand immediate reduction without waiting. The best method of reduction for dislocation downwards or forwards is by the manipulations introduced by Kocher and usually called by his name. It is performed as follows:

Kocher's Method. When the patient is not under an anæsthetic he sits bolt upright in a chair, and an assistant steadies the trunk and fixes

the scapula. It is essential that the entire trunk should be steadied during the manipulations, as otherwise the patient may defeat them entirely by swaying the body about. A good plan is to fasten the trunk to the back of a strong chair by means of a stout jack-towel. The surgeon stands or kneels a little in front of the patient on the affected side, and first flexes the forearm to a right angle and then steadily approximates the elbow to the side (see Fig. 4). This stretches the upper part of the

FIG. 4.-KOCHER'S METHOD OF REDUCING DISLOCATIONS OF THE SHOULDER. First Stage. The trunk is fixed by a stout towel passed round the back of a chair and held by an assistant. The elbow is then flexed to a right angle and approximated to the chest-wall.

capsule and causes the head of the bone to hitch against the edge of the glenoid cavity (see Fig. 9). The arm is then rotated outwards until the rotation can be carried no farther (see Fig. 5). This carries the head of the bone outwards from the coracoid process to beneath the acromion, and relaxes the outer and posterior portion of the capsule, which has been unduly on the stretch (see Fig. 10). The whole arm is now brought forwards and upwards, full outward rotation of the humerus being still maintained, until the limb is almost at a right angle to the body (see Fig. 6). This relaxes the front and upper part of the capsule so that the gap in it

is freely open, while at the same time the head of the bone comes down almost to its normal position (see Fig. 10). The last step in the manipulations is to rotate the arm inwards, and carry the elbow forwards across the front of the chest, making the fingers touch the opposite shoulder (see Fig. 7). This brings the head of the bone back through the rent in the capsule (see Fig II); and at this point it generally slips into position almost imperceptibly. The arm is finally brought down to

Second

FIG. 5.-KOCHER'S METHOD OF REDUCING DISLOCATIONS OF THE SHOULDER.
Stage. The forearm is rotated outwards as far as it will go while the elbow is kept at a
right angle and firmly pressed to the side.

the side (see Fig. 8) to which it is fastened after being supported in a large elbow-sling. Although these manipulations have been described in stages for the sake of clearness, the process is continuous in practice and should be carried out rapidly and forcibly.

In some cases the re-position of the bone is not noticeable, and it is not until after the manipulation has been completed that an examination of the shoulder shows that it has been successful; in other cases there is a distinct jerk when it slips in. There should be no difficulty in ascertaining whether the dislocation has been reduced. The

roundness of the shoulder, due to the prominence of the greater tuberosity in its proper place beneath the deltoid, at once denotes success. Moreover the hand can be brought to the opposite shoulder, and a ruler laid flat upon the outer aspect of the arm can no longer be made to touch both the external condyle and the acromion as it did when dislocation was present.

Traction Methods. In muscular subjects without an anesthetic

Third

FIG. 6.-KOCHER'S METHOD OF REDUCING DISLOCATIONS OF THE SHOULDER.
Stage. While full outward rotation is maintained, the arm is carried upwards parallel to
the antero-posterior plane of the body until it is almost horizontal.

Kocher's method is not always successful; should it fail, some form of traction must be resorted to.

Outward Traction. The method that seems to combine the most satisfactory results with the least pain to the patient and bruising of the parts is the following: The patient is laid flat upon the back on the ground or on a low couch, and the surgeon sits or kneels beside him; the forearm is flexed to a right angle, and the arm is drawn gradually from the side until it is at right angles to the trunk. An assistant, if available,