Part 29

8. I have already said, that without a fracture of the olecranon, no luxation forward can occur (5). But what cause can act with sufficient power on the parts to produce both accidents at the same time? It would be necessary that a fall which had produced a fracture should be succeeded by another fall; but in such a case, the fore-arm would be half-bent, and it is in a state of extension alone (7) that the luxation can take place.

9. Lateral luxations, that is, luxations at the sides have been divided into complete, when the two articular ranges of the arm and fore-arm, have lost their connexion entirely, and incomplete, when only one bone or one part of a bone has been separated from its natural connexion with the humerus. But what cause can act with sufficient force to produce the first kind of luxation, namely, that which is complete? In such an accident so great would be the extent of the wreck and ruin of the part, that without doubt amputation would be the only resource.

10. The second kind of lateral displacement is the result of a stroke which forces violently the extremity of the fore-arm outward or inward. A footman, says Petit, in falling from a carriage, had his arm entangled between the spokes of the wheel, and suffered in consequence a luxation outwards. Another produced one inwardly, by being thrown from his horse, and falling with his arm under him, on rough ground. Strokes of this kind may, as that author remarks, vary in a singular manner. But, in general, in all of them, the fore-arm must represent a lever of the first kind, where the power acts on the end next the hand; the resistance being in the joint, and the fulcrum in the middle.

§ III.

OF THE SIGNS.

11. To form an idea of the signs or appearances of a luxation backwards, let us examine, for a moment, the natural situation of the olecranon, and the condyls of the humerus. As these eminences are easily felt under the skin, a knowledge and recollection of their situation will serve as a standard of comparison, to judge of the changes they experience in a luxation. When the fore-arm is extended, the olecranon is on a level with the internal condyl, and a little above the external one. In a state of flexion, it descends below this level, and is then farther below the internal than the external condyl. In either situation, it is nearer to the first than to the second, the radius separating it from the latter.

12. But, when a luxation has taken place, this apophysis, still remaining on a level with the two condyls, even although the fore-arm be half-bent, is oftentimes separated from the internal one, and driven towards the other: a preternatural protuberance announces this change of position of the olecranon. The coronoid apophysis, whose posterior surface glides in the large groove of the humerus, corresponds to this groove now only with its anterior surface: sometimes the olecranon cavity receives its extremity. The radius passes backward over the small head of the humerus. At the fold of the arm, a transverse protuberance, more perceptible on the internal side, announces the presence of the displaced articular extremity of the os humeri. Over this extremity are reflected the biceps and the brachialis muscles in a state of violent distension. These muscles, greatly irritated by such distension, continue in a state of habitual contraction, in consequence of which, they keep the fore-arm half-bent. Nor can the anconeus muscle, which is necessarily relaxed, act so as to prevent this semiflection. Severe pains would be the consequence of attempts to extend the fore-arm; the limb is in a state of pronation; yet I find among the cases collected by Desault, several examples where supination existed; this state is explained by the relaxed condition of the pronator muscles. At the level of or opposite to the coronoid cavity is a depression or hollow manifesting the absence of the apophysis of that name.

That deep depression in the os humeri, which, in a natural state of the parts, receives the upper end of the olecranon process. TRANS.

13. Should chance give rise to a luxation forward, an anterior projection of the two bones of the forearm, and above all, of the coronoid eminence, a depression corresponding to the olecranon cavity, the extremity of the humerus carried backward and downward, the rigid extension of the fore-arm, a protuberance behind formed by the fractured olecranon (5), and severe pains, necessarily resulting from attempts to bend the limb, &c. would constitute the principal characteristic signs of the displacement.

14. In lateral luxations, a protuberance at the internal or external side of the articulation, always shows of what kind it is. If the displacement be to the internal side, the olecranon is then situated behind the small tuberosity: the middle protuberance of the os humeri bears on the radius, which is sometimes placed even behind the internal articular eminence of that bone, which then rests on the external depression of the great sigmoid cavity. Hence, as Petit judiciously observes, arises the direction of the fore-arm outward, the above eminence presenting a manifest obliquity in that direction. In this luxation, the ulna has been known to lose entirely its connexion with the humerus, and the radius to be brought into contact with the internal condyl of that bone. This is what some authors call a complete luxation. Others reserve that name for cases where, the two articular ranges have lost their correspondence or apposition entirely.

15. In a luxation outwards, the olecranon corresponds to the external condyl; the middle projection of the humerus, to the internal depression of the great sigmoid cavity; the small head of this bone, to the external depression; the radius projects outwards; and the humerus makes a protuberance inwardly.

16. After all, these changes of situation vary remarkably, and it belongs to theory rather than practice, to trace their history, with precision. In general, luxations outwardly happen more frequently than those inwardly, a circumstance which is fully explained by the structure of the joint. In both, the lateral ligaments are almost always lacerated.

A swelling more or less considerable accompanies all the different kinds of luxation, and is sometimes carried so far as to involve the diagnosis in great uncertainty, particularly when the displacement is not very great. This phenomenon (the swelling), seems, in general, to correspond, in a direct ratio, to the force with which the articulation resists. Indeed the violence, and consequently the irritation, are always in proportion to the resistance of the parts.

§ IV.

OF THE REDUCTION.

17. The means of reduction vary according to the different kinds of displacement. They are all, however, founded on nearly the same principles, and it will be easy to form proper ideas of them, when we shall have given an account of the means necessary to be employed in luxations backward, of which the others are only modifications.

Here genius seems to have been as prodigal of resources, as nature has been of obstacles. Indeed, to accomplish the reduction, we sometimes see the surgeon placing his elbow in the fold of the affected arm, interlocking his fingers with those of the same limb, and, then, bending with his whole force, both his own fore-arm, and that of the patient, to effect at the same time extension, counter-extension, and reduction or conformation: at another time we see him fixing the fold of the injured arm against some resisting body, such as a bed-post; and while an assistant, then, pushes the displaced olecranon against this body, he himself, pressing on the shoulder with one hand, and grasping the fore-arm with the other, bends it forcibly, in order, by that means, to produce a replacement: again, a body of some size, being placed in the fold of the arm, serves as a fulcrum, on which the fore-arm, being suddenly flexed, moves and acts like a lever of the first kind, of which the power, being applied at the extremity next the hand, draws it backward and upward, and by that means pushes in a contrary direction its luxated end, where the resistance is made. On some occasions, the fore-arm of the diseased side, bent at a right angle, is placed on a horizontal table, and, while the lower extremity of the humerus is thus resting on the table, the surgeon pushes it backward with one hand, and with the other, taking hold of the extremity of the fore-arm, draws it in a contrary direction.

18. The ancients employed the three first modes. Pare has had engravings of them made: Scultel has also given figures of them as practised by Hippocrates. The Arabians knew of no other modes, nor did their descendants, who were only compilers from them. The practitioners of our own day still continue their use. But, in general, they are chargeable with the numerous inconveniences and faults of producing intense pain, of not being completely under the direction of the surgeon, of bringing the point of luxation too near to the place on which counter-extension is made, and of bruising and doing violence to the parts: nor do they disengage, by means of previous extension, the luxated ends of the bones, to facilitate their replacement in their natural situations.

This last charge is not applicable to the last of the processes proposed by Petit. But, here, the extending forces are most commonly insufficient; the surgeon, having both his hands engaged, is not able to act on the joint to assist in the replacement: and the counter-extension made is too near to the point of luxation.

19. In common cases, Desault employed a method as simple and more efficacious, which few writers have recommended, and none have described with accuracy.

The patient is, indifferently, either seated or standing. The fore-arm being half-bent, an assistant takes hold of the extremity next the hand, to make extension; another, to make counter-extension, takes hold of the humerus a little below its middle, with both hands, the fingers crossing before, and the thumbs behind. The extension is made gradually, and when it begins to move the olecranon, and draw it from the place it accidentally occupies, the surgeon, to aid in the reduction, grasps the lower end of the humerus with both hands, crosses his fingers in the fold of the arm, applies his thumbs to the olecranon, and drawing the first backward, pushes at the same time the latter forward; thus, he favours, on the one hand extension, and on the other counter-extension, and in that way finishes the reduction.

20. This method is most commonly practised with success, in recent luxations, where we have oftentimes seen the reduction effected at the Hotel-Dieu, by the simple process of pushing, as just mentioned, the olecranon forward, the humerus being held backward, without any previous extension, while the fore-arm was merely supported by the assistants.

21. But the luxation being oftentimes of long standing, presents very great difficulties. What means must then be employed? It is an established principle, that the force with which a power acts, is in direct proportion to its distance from the point of resistance. Augment this distance, and the extending forces, being doubled and even trebled, will more easily dislodge the luxated extremity. But this indication is fulfilled, by two long straps, formed each of a towel folded several times, one of which is fixed above the wrist, and the other round the humerus a little below its middle. Extension is then made at their extremities, and is almost always sufficient, when aided by skilful efforts of the surgeon (19), to accomplish the reduction. The application of a strap round the humerus is never necessary, unless when the resistance is very great; because, in counter-extension, it is requisite only to withstand or bear against the efforts of extension, but not to act in a contrary direction.

22. But in cases of this kind, the strap, placed, as we have directed, round the lower part of the humerus, has sometimes the disadvantage of compressing too much the brachialis and the biceps muscles, and thus preventing them from acting; this inconvenience is particularly felt in old luxations, where great force is employed; for, the more active then the contraction of these muscles is, the more it will aid the surgeon in his efforts to draw the bones into their natural situation, when once disengaged by extension, from that which they had accidentally occupied. If, in such a case, we impede the contraction of these muscles, how can they fulfil this office?

23. It was this which, in certain cases, induced Desault to place his counter-extension under the armpit, by means of a strap passing, as in the luxation of the humerus, over a ball previously fixed in this hollow, and crossing, not on the top of the opposite shoulder, but behind that of the diseased side. By this contrivance the humerus was drawn or rather held back, by a force acting perfectly in the line of its direction. But is not this force situated too near to the centre of motion? The strap for making extension, fastened at the wrist, answers very well, as has been already mentioned (21).

24. Should the luxation be forward, the extension must be directed according to the state and position in which the fore-arm is found, which is always extended. The hands of assistants alone (19), or straps (21), may then serve to make the extension, which the surgeon must aid, by grasping, in a direction the reverse of that in the preceding case, the lower extremity of the humerus, that is, by crossing his fingers behind, and placing his thumbs on the coronoid apophysis, to push it downward and backward.

25. The strap for counter-extension, would in such a case, always afford the greatest advantage, by being placed exactly as in luxations of the humerus, that is, by running to, and crossing on, the opposite shoulder; the direction or course of the fore-arm, which is necessarily in a state of extension, sufficiently explains this; finally, the reduction of the luxation must be succeeded by the reduction of the olecranon (5), and by the application of a proper apparatus to retain the whole.

26. The reduction of lateral luxations, differs but little from that of luxations backwards. The displaced extremities must be first dislodged by previous extension (19). The surgeon, then, taking hold of the lower part of the arm, places his fingers before, and with his thumbs, crossed on the olecranon, pushes that apophysis forward and inward, if the displacement be outwardly, but forward and outward if it be inwardly. Does the case prove very difficult, recourse must be had to the other means (21 and 23). The hands of the surgeon must still, according to the direction of the displacement, assist the extension made by the straps.