" The forearm was semi-flexed as well as the hand. The bony plane represented by the metacarpus and the carpus was almost parallel to that of the forearm. The hand was neither adducted nor abduced, but had suffered a dis placement "de totalite" towards the internal side. At the posterior and inferior part of the forearm there was a saliency formed by the displaced carpus. A line drawn from the summit of this saliency to the phalangeal ex tremity of the metacarpal bone to the middle ,finger, measured three inches and seven lines, the same length which the uninjured carpus and metacarpus of the opposite side presented. At the inferior and anterior part of the forearm A, there existed a transverse eminence, situ ated about eight lines nearer to the extreme point of the angers, than the posterior sali ency B, while it projected anteriorly beyond the plane of the palmar surface of the hand, fully seven lines. The radii on both sides measured alike. The skin was abraded, and a wound about an inch long existed on the dorsal surface of the radius near the wrist, at about the level of the superior border of the pronator quadrates.
Ligaments.— The external lateral ligament and the posterior ligament were lacerated ; the anterior completely torn from the border of the radius. Some remnants of this struc ture lay on the front of the carpus. The in ternal lateral ligament was not torn, hut the styloid process of the ulna, maintained by this ligament, and at the same time by the attach ment of the sheath of the flexor carpi ulnaris, had been detached from the body of the bone. Thus all the means of union of the articu lations had been completely severed, and the bones of the forearm were only held to the carpus by some bundles of fibres, which passed posteriorly from the triangular ligament to the internal side of the carpus.
radius did not present any trace of fracture ; the body of the ulna was also unbroken, but its styloid process was torn from the rest of the bone, although still held by ligament and tendon, as above men tioned. In the new position which the bones of the forearm had accidentally assumed, re latively to the carpus, they concealed and lay in front of the whole first range of carpal bones, end had been arrested in their descent only by the true annular ligament, and the tendons of those flexor muscles which pass behind this ligament."* Let us suppose now a transverse fracture of the radius, situated near to the wrist-joint, with the displacement backwards of the in ferior fragment. This kind of accident will most simulate a luxation of the wrist, such as the foregoing case, in consequence of the size of the two eminences, the one placed anteriorly, the other posteriorly ; but in frac ture the anterior and posterior saliency, in general, are not very conspicuous ; while in luxation the posterior formed by the carpus, and the anterior by the bones of the forearm, have each a thickness of more than half an inch.
It is very true that we have seen cases (seefig. 933., for example) of fractures through the junction of the lower epiphyses of the radius, with fracture also of the ulna, which even in this amount of saliency of the anterior and posterior prominency, much resembled the case of a dislocation ; but the saliency pos teriorly in the case of the dislocation is formed only by the rounded summit of the carpus, and the measurement from this point to the ulti mate extremity of the middle finger gives only the normal length of the hand; whereas, if the deformity at the back of the forearm resulted from a fracture of the radius with displacement backwards of the lower frag ment surmounting the carpus, a measurement taken from the summit of the dorsal pro minence to the end of the middle finger would show an increase of at least half an inch over the normal length of the whole hand, because to the summit of the carpus in the case of fracture with displacement is superadded the amount of the depth of the lower fragment of the radius. By this test of measurement, therefore, we might settle our diagnosis be tween these two accidents which so much resemble each other.
The styloid process, too, of the radius can be felt still holding its normal relation to the carpus in cases of fracture, and to move with the hand when any motion is communi cated to it ; whereas, in the rare dislocation of the wrist-joint, which we are here consi dering, the, lower extremity of the radius and ulna will be found placed in front of the carpus, and here, too, form an abrupt swell ing, just above the superior margin of the annular ligament of the wrist.
Dislocation of the bones of the forearm back wards with displacement forwards of the carpus.
— It is said that this dislocation, which is the reverse of the foregoing case of Voillemier, may occur as the result of accident.* Upon this head all we have to say is, that this dis location of the bones of the forearm back wards at the wrist-joint, as the result of acci dent, must be exceedingly rare ; but that, on the other hand, this is the very displacement of the bones which so usually exists in almost all cases of congenital dislocation of the wrist joint (figs. 924. and 925.).