A Treatise on Fractures, Luxations, and Other Affections of the Bones

by P.-J. Desault

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.