1. Luxation of both bones of the fore-arm backwards.—This luxation is the most frequent of all those to which the elbow-joint is liable; it is usually produced by a Fall on the palm of the hand, the fore-arm being at the time ex tended on the arm, and carried forwards, as when a person falling forwards puts out his hand to save himself.
The patient suffers at the moment of the acci dent an acute pain in the elbow-joint,and is often conscious of something having given way in the joint. The fore-arm inclines to a state of supina tion (fig.41); the whole extremity is manifestly shortened ; the olecranon process rises very much above the level of the tuberosities; or, to speak more correctly, with reference to the po sition of the limb, which is always presented to us for examination more or less flexed, this process is placed much behind and somewhat below the plane of the condyles of the humerus. The tendon of the triceps carried back with the olecranon stands out in relief, as the tendo Achillis does from the malleoli. This part or the triceps thus standing out can be seized through the integuments by the fingers, and we perceive in front an interval between it and the back part of the humerus. Anteriorly, in the fold of the arm, through the thickness of the soft parts, we can feel a hard tumour, situated obliquely from without inwards and back wards, formed by the lower articular extremity of the humerus. The rounded head of the radius can be seen prominent below the exter nal condyle, and we can occasionally even sink the end of the thumb into the hollow of its cup-like extremity, and if now a movement of pronation and supination be communicated to it, the nature of the case becomes very evi dent.
The patient himself feels the arm powerless, and we find we can communicate to it but little motion. When we make the attempt to rotate or Ilex the arm on the fore-arm, we find our efforts resisted, and that we give the patient pain ; a little extclis:on of the elbow-joint is allowed; and we have invariably found that a lateral movement of abduction and adduction could be given to the fore-arm, motions this joint does not enjoy in the natural state, but which we can account for being now permitted, when we recollect the complete laceration the lateral ligaments must suffer in this injury.
The transverse fracture of the lower extremity of the humerus, or a forcible separation of its lower epiphysis, are accidents most liable to be confounded with luxation of both bones backwards; but although the elbow projects much backwards, and there is a marked prominence in front, still the relative position of the condyles of the humerus and the olecra non process is not altered in the fracture, as they have already been described to be, in the lux ation. Add to this, that in the fracture the sur
geon can flex the patient's fore-arm on his arm, a movement which, in the luxation, the patient can neither himself fully perform, nor can it be communicated.
In the case of the transverse fracture also, notwithstanding the apparent similitude at first with the luxation, when a steady extension is made by pulling the hand forwards, while the arm is fixed, all the marks of luxation disap pear, to return again very shortly, when the extending force is relaxed. In fracture, too, a characteristic crepitus may be felt just above the elbow-joint, by rotating the fore-arm on the humerus. It is very true that, in some cases of luxation, the dislocated bones are very rea dily restored to their place, and on the other hand, that a transverse fracture of the humerus may, after it is reduced, remain so for a little time, and thus we may perhaps account for the fact, that these accidents have been confounded with each other, and the mistake is a serious one. To guard against error in our diagnosis, it would be well, after the bones have been re duced, to try the experiment of pushing the fore-arm backwards, while the arm is steadily pressed forwards ; if the accident has been a luxation, no change occurs, but if there has been a transverse fracture of the humerus, or of the coronoid process of the ulna, all appear ances which erroneously induced a suspicion that the accident was one of luxation, are re newed, but not so the error of attributing these appearances to a luxation, for now the exist ence of a fracture can no longer be doubted. Lastly, after the bones, in a case of luxation, are apparently restored, it will be prudent to examine the head of the radius, and it will be right to be satisfied that this bone has also been replaced as well as the ulna, for, in the luxa tion of both bones backwards, the connexion of the radius with the ulna by means of the coronary and oblique ligaments, may have suffered, and under such circumstances, if care be not taken, the restoration of the radius to the lesser sig moid cavity of the ulna and capitulum of the humerus may have been forgotten, as we have known to have happened in one instance.