Mr. Key, in his account of another case of dislocation of the os humeri backward on the dorsum of the scapula, writes as follows : I found a very stout man sitting up in bed in sreat pam, and complaining more than patients commonly do under dislocation, and I concluded it to be some fracture about the cervix, especially as at first view nothing could be seen of a hollow under the deltoid muscle, the joint appearing round as usual. On pass ing to the man's side to examine the limb, the deformity of the shoulder became visible, the forepart appeared flattened, and the back of the joint fuller than natural : the head of the bone could be seen as well as felt, resting on the posterior part of the cervix scapulee. The elbow could be brought to the side, or raised on a level, with the acromion. Rotation out wards was entirely impeded, in consequence of the subscapularis being stretched, all motions of the limb giving him extreme pain, which was referred to the lower part of the deltoid muscle, in the direction of the articular nerves, which were probably injured by the pressure of the head of the bone." The dislocation of the head of the hu merus backwards on the dorsum of the scapula is said to be very easily recognised, yet the writer has seen two examples of it which had been overlooked at the moment of the accident, and he has heard of two others. When the svvelling, the result of the lacera tion of parts, has subsided, the nature of the injury becomes very evident indeed. A gentle man, Mr. A. F., aged about 35 years, called upon the writer four years ago to examine his shoulder. He stated that he was thrown off a jaunting car about three months previously', and injured his shoulder, and that ever since he had had but very imperfect use of his arm. The patient had been educated as a medical man, had practised surgery, but did not him self suspect the nature of the injury, when, about ten weeks after the accident, he called upon the writer. The nature of the injury was very manifest. The arm was placed close to the side, was neither lengthened nor short ened; he had no pain in the shoulder joint, but had very imperfect use of the limb. The shoulder had not the flat appearance externally surmounted by the prominent angle formed by the acromion, which characterises the ax illary dislocation ; nor had he the fulness be neath the clavicle and in front of the acromion which are noticed in the dislocation forwards ; on the contrary, a deficiency was observed in front beneath the acromion ; and here the fingers could be sunk into a deep fossa, which seemed to extend even to the unoccupied glenoid cavity ; while behind the posterior angle of the acromion a tumor as large as an orange could be seen and felt (fig. 440.). This rounded prominence moved with the shaft of the humerus ; a well-marked vertical groove showed the distinction between the convexity which belonged to the head of the dislocated humerus behind and that which formed the posterior angle of the acromion (fig. 440.).
An energetic attempt was made at the Richmond Hospital to reduce the dislocation in this case three months after the accident had occurred, but without success.
Diagnosis between fractures of the superior extremity of the humerus and dislocations of the we have already pointed out the symptoms which are peculiar to each of the forrns of scapulo-humeral dislocations, we may here direct attention to the fact, that these symptoms are very similar to those which belong to fracture of the upper extre mity of the humerus: so that in many cases the difficulty of distinguishing between these different injuries is such as to lead not un commonly to a false diagnosis. Every person labouring under either a fracture or luxation of the superior extremity of the humerus, informs us that he has fallen on that side of the body on which the injury exists ; but the position of the arm at the moment of the accident will be found to have been different in the case of fracture and dislocation : so that if we know how the limb was placed at the moment of the fall, we may be led to con jecture from this alone the nature of the ac cident which has occurred. If, for example, when the patient is falling, his arm is se parated from his body directed forwards, or outwards, as it were instinctively to break the fall, and save the upper part of the body, if under these circumstances displacernent of the upper part of the humerus occurs, the existing deformity will be found to be the result of dislocation ; but if, on the contrary, the fall takes place when the arm is by the side, as, for instance, in the breeches pocket, and no effort is made by the patient, at the moment of the fall, to raise the arm, the momentum and weight of the body have been received on the point of the shoulder, the resulting injury has been most probably a fracture of the head and upper part of the humerus. In both cases the pain expe
rienced at the shoulder is severe, and gives rise to the impression, on the patient's mind, that he fell on that part ; but if the patient has met with a dislocation, it will be found that in reality he has fallen on the palm of the hand, evidences of which the surgeon will be better able to discover in the ex coriations which the palm has suffered, than by any report which the patient himself may be enabled to make. When the patient has met with a fracture, we shall, on inquiry, discover that the fall has taken place on the outside of the shoulder ; there is, in this case, no abrasion of the palm of the hand, while con siderable tumefaction and extensive ecchy mosis, the effects of contusion, are observable along the outer side of the arrn. When called to the patient immediately after the accident, we notice those circurnstances as to the hand and clothes which will instruct us as to the probability, whether the patient had fallen forwards on the palm of the hand, or com pletely outwards on the stump of the shoulder. In case of fracture, moreover, there is exten sive ecehymosis; in simple dislocation, little, if any ; but if it should exist, it is rather on the anterior and internal part of the limb, than on the outside, as in fracture. In both fracture and luxation the acromion is salient, and the deltoid flattened ; but as the dis placement is more complete in luxation than in fracture, the prominence of the acromion and the depression beneath it are more marked in the former than in the case of fracture. When there is a luxation, and we wish to impart movements to the limb, the humerus often moves in connection with the scapula, as if the two bones made but one body. If there is a fracture, there is abnormal mobility at one point in the upper part of the humerus. This mobility is ordinarily accompanied by a crepitus which is best eli cited by seiz:ng the inferior extremity of the humerus at the elbow and rotating it on its long axis.
Finally, great efforts are frequently neces sary to effect a reduction of the dislocated humerus ; but once replaced, the bone remains in its proper articular cavity, and the de formity of the shoulder does not recur ; but in fracture, although the bone may be replaced with comparative facility, yet, if it be left un supported, the deformity will almost imme diately recur. In the case in which it is not easy to distinguish a fracture from a luxation, Dupuytren gives the precept —" Rendez au membre, par des rnanceuvres convenables, sa forme et sa longueur naturelles ; retournez aupres du malade sept ou huit heures apres si vous trouvez l'epaule deformee, soyez as sure que vous avez a faire une fracture." # Malgaigne has made the observation, that in all luxations of the head of the hu merus, the head of the bone inust descend below its ordinary level, and consequently that, no matter which of the three disloca tions has occurred, the dislocated arm must be longer than the other. This appears to us to be a point, by attention to which we may be assisted in our endeavours to establish the diagnostic marks between dislocation and fracture, because, in fracture of the humerus, we have almost invariably found, whether from some overlapping of the bones, or im paction of one of the fragments into the other, that some shortening of the arm exists. If there be dislocation, the arm is sometimes abnormally lengthened, and never shortened. In the measurement of the injured limb we have therefore a simple means to resort to, which will no doubt assist us much in making our diagnosis.