No. 79.

VOL. IV.

LECTURES

ON THE

PRINCIPLES, PRACTICE, & OPE

RATIONS OF SURGERY,
BY PROFESSOR SAMUEl cooper.

Delivered at the University of London,
Session 1832-1833.

LECTURE XLVIL, delivered FEB. 4, 1833. GENTLEMEN, It is scarcely necessary for me to say, that a dislocation cannot happen without a great deal of injury being done to the joint, and parts connected with it. Thus, it is evident, that the ligaments must be ruptured, which naturally keep the head of a bone from being thrown into the particular direction of the displacement; and, if those ligaments had been capable of adequate resistance, the bone could not have been moved out of its right situation. But, gentlemen, besides the capsular and other ligaments, the tendons and muscles may be torn. Thus, in the shoulder-joint, there is sometimes a rupture of the bicipital tendon; and when the head of the humerus is thrown into the axilla, the tendon of the subscapularis is torn. However, I wish you to remember, that the tendon of the biceps is not invariably broken; for, in Sir Astley Cooper's valuable work on Dislocations, you may find the particulars of the dissection of dislocated shoulders, proving that the bicipital tendon may neither be displaced from its groove, nor ruptured. In dislocations of the head of the thigh-bone, there will sometimes be a laceration of certain muscles, as of the adductor brevis and the pectinalis; and when the alteration in the length of the limb is considerable, several of the muscles will either be very much stretched, or preternaturally relaxed, in consequence of the distance between their origins and insertions being materially changed.

Let me now, gentlemen, offer a few general observations on the symptoms of dislocations. In the first place I may remark, that an acci

VOL. IV.

dent of this kind must produce a complete interruption of the functions of the joint. Ther, the limb will either be shortened, lengthened, or distorted, one of these changes invariably taki place. When the limb is elongated, this symptom is of itself enough to convince you that the case cannot be a fracture; and this view will be confirmed, when you find that no crepitus can be felt. Another circumstance particularly meriting your notice is, that, in a dislocation, the axis of the bone is no longer natural. Thus, when the shoulder is dislocated, the axis of the humerus will not tend towards the glenoid cavity of the scapula, but towards whatever point the head of the bone may occupy, while its lower end will incline outwards, backwards, or forwards accordingly. You will also observe, that in dislocations, the natural prominences of the bones in the neighbourhood of the joint will be rendered either more conspicuous, or be more hidden than usual. Thus, in a dislocation of the shoulder-joint, the acromion will become, or will seem, more prominent, in consequence of the cushion of the shoulder being flattened by the stretched state of the deltoid muscle, and by the removal of the head of the bone from its situation. On the other hand, when the dislocation is of the hip, the projection of the trochanter major will be diminished. In some dislocations you will be able to feel plainly the head of the bone in the unnatural situation which it occupies; and if you attempt to rotate the limb, you will distinctly perceive that part of the bone moving in a place away from the articular cavity. Another common symptom of a dislocation is a hollowness in the situation of the joint, the head of the bone does not fill the articular cavity, and there is a remarkable depression, where none ought to exist: thus, when the head of the humerus is out of its place, you may always feel such depression under the acromion.

There is another symptom, gentlemen, which particularly claims your attention, which is, that the dislocated bone cannot be moved with the same facility as if it were fractured; and hence there is a considerable rigidity about the

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