MEMOIR X.
ON THE LUXATIONS OF THE RADIUS OVER THE ULNA.
1st, Most authors who have written on the luxations of the fore-arm, have omitted considering separately those confined to the radius alone. Some detached observations may be found here and there, on the luxations of the upper extremity of this bone, which Duverney alone has treated at some length. Those of its lower extremity, though more frequent, and more easily produced, appear to have almost entirely escaped the attention of the French practitioners, who have transmitted nothing to us on that point, owing, no doubt, to their having had no knowledge of it from experience. But since, at the present day, a sufficient number of facts are collected on the subject, some account of these displacements cannot be a matter of indifference to the art, and it may be traced with as much precision as the accounts of other similar accidents.
§ I.
OF THE DIFFERENCES IN POINT OF STRUCTURE BETWEEN THE TWO ARTICULATIONS OF THE RADIUS WITH THE ULNA.
2. The radius, the moveable agent in pronation and supination, rolls on the ulna its fixed basis or abutment, by means of two small articulating surfaces, the one at its upper end, slightly convex, broad within, and narrow without, corresponding to the small sigmoid cavity, in which it is lodged; and the other at its lower end, concave, semicircular, and fitted to the convex edge of the ulna, which it receives. Hence two kinds of articulation different from each other, with respect to their motions, the connexion of their surfaces, and the ligaments which strengthen them. Let us specify these differences; they will serve to shed light on those that exist between the displacements of the two extremities of the radius.
3. At its upper end, the radius, in performing pronation and supination, moves only on its own axis; at its lower end, it rolls round the axis of the ulna: therefore, being farther removed from their centre, its motions must have both a greater range and greater force, in the latter case than in the former. The head of the radius, turning on itself within the annular ligament, cannot distend it in any direction or part. The cellular membrane attached to this ligament is alone slightly stretched, but being loose and elastic, it yields without resistance. At its lower end, on the contrary, the radius, turning from without inwards during pronation, keeps the capsule posteriorly in a state of tension, and draws it against the immoveable head of the ulna, which tends to pass through it, if the motion be forcible. The same phenomenon occurs in a contrary direction, during supination; the radius is directed backward, and the ulna inward. Being in this case distended before, and relaxed behind, the capsule is disposed to laceration anteriorly.
4. In addition to this disposition, the ligaments of the two articulations are disproportioned in their strength. Thin and weak at the lower articulation, thick and firm at the upper one, they are in this respect strikingly different. The head of the radius, resting against the small but firmly fixed head of the humerus, finds there, in most of its movements, an obstacle to displacement. On the contrary, its lower end, drawing along with it in its movements, the bones of the carpus which are connected with it, derives from them no solid support.
§ II.
DIFFERENCES IN THE LUXATIONS OF THE RADIUS; DIFFICULTIES OF THAT AT ITS UPPER END.
5. It follows from what has been said (3 and 4), 1st, that the lower articulation of the radius is not only exposed to the action of more causes of displacement, but possesses fewer means of resisting those causes, and that, from the threefold consideration of its motions, the ligaments which connect its articulating surfaces, and their relation to each other, it must be frequently subject to luxations: 2dly, that for reasons the very reverse of these, its upper articulation must be very seldom subject to luxation.
6. Indeed, what cause is there to produce luxation in this latter joint. Is it from a forcible exertion of pronation or supination that this accident can occur? Surely not: for, on the one hand, as the lower articulation offers less resistance than the upper one, it is evident that, in either state of motion, it being the weakest, will be displaced first, and the motion being thus checked, can no longer operate to the displacement of the other. On the other hand, however forcible the motion may be, there will be in the upper articulation, nothing but a rotation of the bone on its own axis (3). How, then, without being carried forward, backward, &c. can the head be displaced? Indeed, it would be necessary that all the fastenings or bonds of attachment muscular and ligamentous, should be first broken. But these are too strong, and the motion is too weak. Can the displacement be produced by a blow impressed on the radius from below upwards? By no means: because the head of the humerus making, in this case, a solid resistance will not permit it to escape from the capsule (4). Can it arise from a violent extension or flexion of the fore-arm? No. This effort being altogether confined to the ulna, affects the radius in but a very faint degree.
7. It appears from hence, that the accidental luxation of the upper end of the radius, suddenly produced by external causes, must, if it ever occur, be extremely rare. But it is not so with respect to luxations which take place slowly in this joint, particularly in children, where, in consequence of repeated efforts, the ligaments become relaxed. But this kind of displacement, being almost always complicated with a swelling of the joint, and sometimes not to be reduced by the expedients of art, cannot be comprised in my present plan.
9. But experience would seem to have at times exposed the fallacy of these considerations and reasonings, founded merely on the structure of the parts. Duverney relates some instances of luxations of the head of the radius, produced suddenly by external causes. Two other practitioners are also of opinion that they have witnessed similar displacements. But did they examine the subject with all that attention which it required? A similar case was reported to the Academy of Surgery, by one of its associates; but doubts were entertained with regard to its reality: and, ultimately, there were so few facts in its favour, and such strong presumptions against it, that Desault was induced to deny the luxation altogether, till its reality should, by new proofs, be more certainly established.
After all, if it should occur, the same signs which announce the luxation, when the ligaments, in consequence of being gradually relaxed or in some way distended, permit the head of the radius to be insensibly displaced, would then appear as the sudden effect of external violence.
LUXATION OF THE LOWER EXTREMITY OF THE RADIUS.
§ III.
OF THE KINDS OF DISPLACEMENT.
9. The causes which produce the displacement of the lower end of the radius, are the same with those that give rise to other similar affections. 1st, The convulsive action of the pronator and supinator muscles, is doubtless a rare cause of the accident, since Desault never met with an instance of it. 2dly, The action of external bodies, which, by forcibly and suddenly producing the motions of pronation, rupture the posterior portion of the capsule, or, by those of supination, lacerate its anterior portion.
10. Hence two kinds of displacement, the one forward, the other backward. The first is somewhat frequent; the second is much less so. The latter was never seen by Desault but once, and that was in the corpse of a man who had had both his arms luxated, but respecting the circumstances of which he could receive no information. The other kind occurred frequently in his practice, of which five examples have been already published. The difference no doubt arises from this circumstance, that the greater part of our powerful motions are performed only in the direction of pronation. This appears to be proven by the following circumstances.
11. If, in several dead bodies, we lay bare the bones of the fore-arm, still united by their ligaments, and push the extremity of the radius forcibly backwards, that is, in the direction of supination, a laceration will as readily occur in the anterior part of the capsule, as it will in its posterior part, when, by forcibly pushing the same extremity forward, the motion of pronation is performed. Hence the difference does not arise from the structure, but from the direction of the motions impressed on the limb.
§ IV.
OF THE SIGNS.
12. The signs which characterize a luxation of the radius forward, are, 1st, The constant pronation of the limb: 2dly, An inability in it to assume the state of supination, and even severe pains arising from attempting it: 3dly, A protuberance larger than common, formed behind, by the small head of the ulna passing through the capsule: 4thly, The end of the radius being situated more anteriorly than natural: 5thly, The constant adduction, and almost constant extension of the wrist: 6thly, The semiflexion of the fore-arm, and very often of the fingers: this position is generally assumed by the fore-arm, in affections of the bones that form it, and, in the present case, cannot be changed without considerable pain: 7thly, A swelling more or less extensive, which sometimes appears around the articulation, at the moment of the accident, and which never fails to occur afterwards, unless the reduction be immediately effected. This occurrence may conceal the state of the articulation, and make the accident be considered, at first sight, as a sprain, as Desault witnessed in certain cases, where the disease had been mistaken by the surgeons who were first called to the persons injured. It is easy to conceive of the sad consequences of this mistake, which, by preventing any effort at reduction, gives the articular surfaces time to form adhesions, and thus oftentimes renders the mischief irreparable.
13. If to these signs be added, the severe pains experienced by the patient, the circumstances of the fall, in which the fore-arm is violently drawn into a state of pronation, we will have a view of every thing that can here aid the practitioner in his diagnosis.
14. Most of the foregoing signs, taken in the opposite sense, would characterize a luxation of the radius backward, should it occur: such, for example, as a forced supination of the limb, an inability as to pronation, the pains that would result from this movement if performed by force, the tumour formed anteriorly by the extremity of the ulna, the posterior situation of the large head of the radius, and the abduction of the wrist.
15. The dead body, in which Desault observed this kind of displacement (9), being dissected with care, exhibited in the articular parts, the following diseased state. The tendons of the flexor muscles, pushed outwards, adhered to one another and to the skin; a substance of a cellular texture filled up the sigmoid cavity of the radius, and occupied the place of the cartilage which naturally invests it: the inter-articular ligament, which passes between the ulna and the os pyramidalis, scarcely touched the head of the ulna, having followed the radius backwards; and the head of the ulna, situated before the sigmoid cavity of the radius, rested on one of the ossa sesamoidea, to which it was attached by a capsular ligament.
§ V.
OF THE REDUCTION.
16. Extension so important in the reduction of other luxations, renders scarcely any service in this: impulsion alone answers the purpose. If the displacement be forward, it is reduced in the following manner: The patient sits or stands indifferently; the latter position, however, has sometimes this advantage over the former, that by placing the part to be operated on more on a level with the hands of the surgeon, it gives him both more readiness and more force in his motions: one assistant supporting the elbow, separates the arm a little from the body; while another taking hold of the hand and fingers, gives them also an equable support.
17. The surgeon grasps the extremity of the fore-arm, with both hands, one placed on its internal, and the other on its external side, so that his two thumbs may meet before, between the ulna and the radius, and the fingers behind. He then exerts himself to separate the two bones from each other, by pushing the radius backward and outward, and retaining the ulna in its place; in the mean time the assistant who supports the hand, endeavours to move it in the direction of supination, and consequently to draw the radius, with which it is connected, into the same state. Being thus pushed in a direction opposite to that of its displacement, by two forces, the one exerted directly on it, and the other acting indirectly, the radius is forced outwards, and the ulna, returning through the opening in the capsule, is replaced in the sigmoid cavity.
18. Should a luxation of the radius backwards ever occur, the same process executed in an inverse direction, would serve the purposes of reduction. The surgeon with his fingers would have to press the extremity of the radius forward and inward, while a forcible pronatory movement impressed by the assistant on the hand intrusted to him, would favour the effort and finish the reduction.
19. The disappearance of the signs (12...14) of the luxation bespeak its reduction. In general the pain is entirely removed; sometimes a perceptible sound, or report, caused by the passage of the bone through the opening in the capsule, announces the replacement.
20. When the luxation is of long standing, it is always attended with more or less difficulty, occasioned by the adhesions of the surrounding soft parts to the articulating surfaces, by the thickening of the capsule, which diminishes the size of its opening, by the rigidity contracted by the whole part, &c. It is, in such cases, useful to employ emollient applications for some time previously to attempting the reduction, in order to produce such a relaxation, and diminution of the congestion, as may favour the efforts of the surgeon.
21. The first patient whom Desault visited at the Hotel-Dieu in quality of surgeon in chief, had a luxation forward, of more than two months standing, in which the use of these means facilitated the reduction: but they are sometimes insufficient, and then the radius remains immoveable, and the forearm performs its motions but partially.
22. It would seem as if nature, always industrious to provide, amid the disorders of our organs, some resources for the exercise of their functions, has been desirous of preventing here, the inconvenience attendant on a failure of reduction, by rendering luxations backward much more difficult than those forward. Indeed if the fore-arm be kept constantly in a state of supination, it will be much less useful, than if it were always in a state of pronation, the situation in which most of the motions necessary to our existence are performed.
§ VI.
OF THE SUBSEQUENT TREATMENT.
23. When the reduction is finished, the articulating surfaces have sometimes a great tendency to be displaced, by the different movements of the fore-arm, a tendency of which we may easily form an idea, if we observe, that in a state of pronation, the head of the ulna presses against the back part of the strained capsule, and consequently against its opening, when the luxation has been forward: a contrary state of things occurs in a luxation backward. Whence it is always prudent to avoid, for some time, the motions of pronation and supination, according to the direction of the displacement.
24. Should the tendency to displacement be very great, it will be necessary to adopt the simple method pointed out in a case already published by Desault.
Case I. The case was a luxation forward, which was easily reduced. But the easier the reduction, the more difficult was it to retain the replaced parts. This was at length accomplished, by fixing the fore-arm in a state of supination, and applying one thick compress behind the ulna, while the radius was pushed backward by another compress, placed on its anterior part, both secured by a common roller. This apparatus was continued for the space of a month, after which the reduced bones remained in their natural situation. The patient began, at first, to perform gentle motions of the wrist, avoiding those of pronation, on which he afterwards ventured by degrees, and with great caution.
25. These gentle motions frequently repeated, when a displacement is no longer to be apprehended, remove that unavoidable rigidity which, for some time, occupies the parts around the joint. It is advisable, for some time, to apply on the hand and extremity of the fore-arm, compresses wet with some discutient liquor, to prevent the swelling resulting perhaps from the inactivity and sprain of the parts. This was the practice of Desault.
I will close this memoir by two cases, extracted from the Journal of Surgery, in order to confirm, by experience, what has been already settled in theory.
Case I. Desault was called to visit a child five years old, supposed to be labouring under a fracture of the arm. He learnt from the parents of the child, that, as it was lying in a very low bed, a young man who was playing with it, had taken hold of its fore-arm, and drawn it towards him, twisting it forcibly at the same time in the direction of pronation; that the effort had been accompanied by a report, and the child had immediately experienced an acute pain throughout the whole limb, but more particularly along the posterior part of the fore-arm.
When Desault saw the patient, no swelling had as yet supervened; the arm was removed from the body, and carried a little forward, while the fore-arm, half-bent, was kept in a state between pronation and supination. There existed, at its lower and back part, a preternatural tumour, formed by the head of the ulna carried behind the sigmoid cavity of the radius. The hand was a little extended, and in a state of adduction. The patient carefully preserved that position, and, as soon as it was changed, or the part affected touched, manifested signs of the most acute pain.
From these appearances, Desault discovered immediately a luxation of the radius forward, which was reduced in the manner already mentioned (16 and 17). By this process, the bones, being a little separated from each other, were replaced with facility. The suffering of the patient was immediately at an end; the limb resumed its natural state, and performed its functions as freely as before; lest some congestion might be the consequence, the injured parts were covered by compresses wet with camphorated spirits; these were secured by a bandage moderately tight, and no accident whatever supervened.
Case II. On the 29th of January, 1789, Madeleine Fuser, a washer-woman, thirty-four years of age, had the lower extremity of the radius luxated forward.
Just as she had finished wringing a sheet, another washer-woman, who was assisting her to wring it, giving it a forcible jerk, did violence to her left arm, which was at the time in a state of strong pronation.
The woman experienced immediately a severe pain, accompanied by a sensation as if something had been torn. The sheet dropt from her hand, and she fell on the ground. Believing that she had received only a sprain, she neglected to apply for aid, and did not enter the Hotel-Dieu till the sixth day after the accident.
There was then a little swelling at the lower part of the fore-arm and at the wrist: the latter was extended and in a state of adduction; the fingers were bent. This woman suffered but little, when her hand was supported and kept still; but the pains became severe, when she attempted to move it. It was plainly perceived that the radius was placed before the ulna, and that the bones overlapped each other.
Process of reduction the same as in the preceding case. It was accompanied by a kind of report, and its completion was clearly announced by the restoration of the natural shape of the limb, and by the freedom of its motions. Compresses wet with vegeto-mineral water were applied to the wrist.
This patient remained fifteen days in the hospital, at the end of which, she performed with ease the motions of the wrist and hand.