The idea that a transverse section of the head of the metacarpal bone presents an outline of a cuneiform figure with the narrowest part of the wedge towards the palm, or forwards, was first advanced by Mr. Hey, and has subsequently been adopted with too little reflection by many writers: for our part we do not think that the head of the metacarpal bone does present this form assigned to it by hey. But even al though it be conceded that it has occasionally a form which would answer to the description given by Mr. Hey, and that its cuneiform figure would facilitate its gliding between the lateral ligaments and forbid its return, surely such an obstacle to the return of the bone would suppose a state of integrity of both lateral ligaments. In our experiments on the dead subject, we found one of these lateral ligaments invariably torn whenever a complete luxation was effected; but with the theory of Hey, which seems to us quite unsupported by the normal anatomy of the bone or the anatomy of the accident, how can we reconcile the observation, that when the first phalanx of the thumb is dislocated to the palmar instead of the dorsal aspect of the metacarpal bone, equal difficulty of reducing the luxation has been experienced by very eminent surgeons ! For example, Velpeau says, " we have seen but once the first phalanx of the thumb pass in front of the first metacarpal bone. The sub ject of this accident was a woman aged forty five years; the bone had been out for three days, there was no inflammation." I thought, says Velpcau, " that it was owing to some want of skill in myself that I could not succeed in reducing the luxation ; but M. Professor Bou gon also made fruitless efforts to effect it; finally, M. Roux, with his well-known address and ingenuity, was not more successful, and the bone remained ever afterwards core duced."* Upon the whole it would appear to us that in the case of the dislocation of the first pha lanx of the thumb on the dorsum of the meta carpal bone, the cause of the difficulty we ex perience in reducing it will not be found either in the mechanical resistance of the lateral liga ments or in the interposition of muscular or fibrous parts between the extremities of the dislocated bones, but that, whether the luso tion be the common one backwards or the more unusual one forwards, the vital contraction of numerous muscles on a small and yielding bone (whose ligaments have been lacerated) will be the principal opposing force we have to contend with. Most of these muscles will be found to be favourably circumstanced for the opposition, for they are either inserted into or attached very close to the bones of the first phalanx of the thumb: they are six in number; some of them are of considerable length, and the aggregate force of both long and short muscles constitutes a very powerful means of maintaining displaced the first phalanx of the thumb ; nor should it be forgotten, in estimat ing their force, that the very large supply of blood vessels and nerves which these muscles receive, must add much more to the energy of their contraction than the size and number of their composing fibres would lead us to suppose.
If such a view of the abnormal condition of the different structures which compose this articulation be correct, we should derive from it the important practical precept, that when we have one of those difficult cases to contend with, our first effort should be to reduce, as much as practicable, the irritability and vital force of the muscles which act on the dis located bone before any of our mechanical appliances be resorted to. When the general system of the patient has been under the de pressing influence of the usual means, viz. tartarized antimony, &c., and under these fa vourable circumstances the surgeon has with patience and perseverance used all the force that he deems expedient or justifiable, and has not succeeded in replacing the bone, our expe rience would induce us to recommend that in such a case no further measures should be had recourse to. We have, in the museum of the
Richmond Hospital, a cast of the hand of a man who had suffered this luxation sixteen years before the cast was taken. The history he gave the writer was briefly that he consulted an eminent surgeon, who used all the means in his power to reduce the dislocation, but could not succeed; that the surgeon then proposed to the man an operation which he explained, and which from the patient's description of it we may conclude consisted in laying bare the head of the metacarpal bone and removing it, as had been about that time recommended by Mr. Evans, of Henley near Wellington; the man, however, refused to consent to the pro posal, and had good reason to be content with his own determination, as he can now oppose the point of the thumb to the other fingers, and can follow his business, which is that of a plas terer, with very little inconvenience, affording us a proof that the advice given by Sir A. Cooper relative to irreducible dislocations of the metacarpal bone, may be well extended to the common dislocation backwards of the first phalanx, viz. " that if the bone cannot be re duced by simple extension, it is best to leave the case to that degree of recovery which nature will in time produce, rather than divide the muscles or run any risk of injuring the nerves or the bloodvessels." The first phalanges of any of the other fin gers may be luxated backwards. The little finger appears to us, after the thumb, the most liable to this accident ; it is sometimes difficult to reduce. Mr. Romer, a pppil of the mond Hospital, lately brought to the writer a patient who was the subject of luxation of the first phalanx of the little finger on the back of its metacarpal bone. This patient was a female about thirty-five years of age ; the bone had been only a few hours luxated, and some inef fectual attempts had been previously made to reduce it. The reduction was effected with some little difficulty by at first increasing the extension, and then by forcibly flexing the last phalanx. In this case the long extensor tendon of the little finger was displaced from its sheath and groove, and lay on the ulnar side of the metacarpal bone and luxated phalanx, and never afterwards could be maintained in its proper place. This accident is very easily re cognized, yet it has been occasionally left un reduced.
It has been stated already that luxation of the .rst phalanx of the thumb forwards may occasionally happen, and we have also good authority for supposing that a similar luxation may occur to the phalanx of the index finger. These accidents, however, are very rare ; the middle, ring, and little fingers have never been seen thus displaced ; indeed, Boyer seems to think such an accident in these last, impossible from the nature of their articulation with their metacarpal bones.
Lusation of the second, and third or distal phalanges.—The articulations of these pha langes being only covered by the skin and the tendons of the flexor and extensor muscles, their luxations are also very easily recognized. In the luxation backwards, the only one which we have had occasion to observe, the luxated phalanx is turned to the side of extension, and forms with the phalanx above it an angle more or less open. \\ hen it is the second phalanx which is luxated, the third is flexed by the elongation of the tendon of the deep flexor, and it is impossible to extend it or flex the second. The reduction of these luxations is generally easy if time be not allowed to elapse between the occurrence of the luxation and the period of attempting its reduction.