Luxations of the inferior extremity of the ulna forwards from the scaphoid cavity of the radius are, according to the opinion also of Dupuytren, excessively rare, at least, " in the course of my long practice," he says, " I have met with but two cases of this accident." One of these cases he gives us a detail of, as follows : — Case. M. Blot, an officer of the gendarmerie, mt. 32, of a sanguine tempera ment and athletic constitution ; while on duty during the night, the horse upon which he was mounted took fright, reared up, and fell back with his rider. The latter was happy enough during the fall to disengage himself nearly from the animal, with the exception that his right arm was placed between the head of the horse and the ground, and thus received a violent shock. M. Blot, considering his fore arm broken, applied to two surgeons, who, each in succession, recognised a dislocation of the ulna at the wrist, and each, also, failed in reducing the dislocation. M. Blot came to Paris, suffering much, and applied at the Hotel Dieu to Dupuytren, on 25th November. He then laboured under the following symp toms :—The forearm was much swollen ; the hand was in a median position betweenpro nation and supination ; the inferior part of the forearm was deformed, rounded or rendered cylindrical near the wrist-joint by the diminu tion of its bilateral diameter—a remarkable saliency existed within and in front, formed by the lower extremity of the ulna thrown forwards towards the palmar aspect—behind, a remarkable depression replaced the ac customed prominency formed by the lower extremity of the ulna (la rualleole Interne); indeed, behind, a depression existed instead of the saliency ordinarily formed by the head of the ulna. If we followed with the fin gers the ulna, from the elbow even to the hand, we perceived that this bone directed itself obliquely forwards and outwards in crossing and passing over the inferior part of the radius. The luxation of the radius forwards became then evident. There was „po crepitation. The movements of pronation and supination were completely lost. Du puytren having failed at the first attempt, he succeeded in reducing the luxation by inclin ing the hand forcibly to the radial side, and pushing with his two thumbs, united the dis placed extremity of the ulna inwards and backwards. By this process the reduction was affected. The patient cried out at once, " I am well." All deformity had disappeared, and the motion of pronation and supination were restored. (Gazette Medical, Malgaigne.) Such cases as these, says Dupuytren, ought to be recorded by every surgeon when he meets with them, in consequence of their rarity and importance.
Luxation of the bones of the carpus. — The bones of the carpus are united to each other so solidly, and their movements are so limited, that without experience, we should be dis posed to pronounce luxation of any of these bones impossible. Nevertheless, the head of the os magnum may be dislocated from the cavity formed for it by the scaphoid and semi lunar bones. The first range of the bones of the carpus is articulated with the bones of the second range in such a manner that slight gliding movements of flexion and extension of the hand are permitted, which augment a little the movements of flexion and extension of the hand upon the forearm, and add some what, as Cruveilhier says, to the grace of the movements of this portion of the upper ex tremity. In flexion, the head of the os mag num, which is somewhat inclined backwards, raises up the thin capsule which surrounds its articulation, and if this movement be carried very far, the capsule and accessory fibres which support the bone posteriorly are broken, and the os magnum escapes from the cavity in which it is naturally placed ; the dis location cannot be called complete, yet the os magnum passes somewhat the level of the posterior surface of the other bones of the carpus.
The accident is more common in women than in men, no doubt because the ligaments are weaker and the bones enjoy greater motion in the former, than in the latter. The luxation backwards .of the os magnum, the only one which can occur, is always the result of a forced and violent flexion of the wrist, such, for example, as a fall on the back of the hand would produce. We recognise the lux ation of the os magnum by the history of the accident, and by the deformity produced. We perceive a hard, circumscribed tumour, which has suddenly appeared on the back of the hand, in the situation which corresponds to the head of the bone. This tumour becomes more prominent when the hand is flexed, and diminishes when it is extended : we can make it disappear entirely by a slight compression. This luxation causes but little inconvenience ; but the head of the os magnum always remains more salient when the hand is flexed, and forms a tumour, more or less marked, accord ing to the extent of the displacement.
We can easily reduce this luxation by tending the hand, or by exercising a slight pressure on the head of the os magnum ; but, although it is easy to make the bone resume its position in the cavity formed for it by the scaphoid and semi-lunar bones, it is very dif ficult to maintain it there, and the incon venience and deformity resulting from the luxation are so trivial, that few persons will submit with to the means usually recommended.
Fractures of the lower extremity of the radius in the immediate vicinity of the wrist-joint. We believe that the first important effort to direct attention to the peculiarities which the fracture of the lower extremity of the radius presents, was made by the late professor of surgery, of the College of Surgeons, in Dublin, Dr. A. Colles, in the year 1814.* Subse quently, we find Sir A. Cooper, in London, and Dupuytren, in Paris, each pointing out the importance, in a practical point of view, of our studying this accident, and distin guishing the case of fracture of the radius with displacement backwards of the carpus, from true dislocation backwards of the hand at the wrist-joint.
Velpeau followed these, concurring with them in the opinion that a transverse frac ture of the lower extremity of the radius was a very common injury, and frequently mistaken for a dislocation. He seemed to be even more positive than his predecessors in maintaining the doctrine that no accidental luxation of the wrist-joint could occur with out a fracture of some of the bony processes, or laceration of the integuments.
This fracture is rarely attributable to any direct cause; it appears, however, that Hub her communicated to the Academy of Medi cine the case of a young girl, who having had the wrist caught between the pole of a car riage and a wall, had gotten a transverse frac ture of the lower extremity of the radius. In this case there was combined with the above mentioned transverse fracture, another vertical one at right angles with it, dividing into two the lower fragment, constituting what in other articulations we have elsewhere in this book (vide KNEE, ELBOW) denominated a T fracture. This species of fracture by direct violence, corresponds much to the cases de scribed by Dupuytren as "Fracture par &rase Fractures of the radius may be caused by falls on the back of the hand, but by far the most frequent sources of the fracture in question are falls on the palm.