WRIST-JOINT (ABNORMAL ANATOMY). 



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extremity was destitute of the rounded head, 

 which in the normal state is received into the 

 concavity of the radius, and was carried for- 

 wards outwards and upwards (see fg. 927.). 

 About half an inch above the level of its 

 lower extremity it was in contact with the 

 rail ins by a very small surface which was 

 destitute of cartilage. An anterior and pos- 

 terior ligament connected the two bones in 

 this situation, and permitted a very slight, 

 degree of motion between them. The lower 

 extremity of the radius was totally destitute 

 of articulating surface, and was represented 

 by a rounded and blunt margin. 



The surface for articulation with the carpus 

 was placed altogether on the anterior aspect 

 of the bone. It consisted of a deep excava- 

 tion of an oblong form, and its longest diame- 

 ter running somewhat transversely ; it was 

 tolerably smooth, though not invested with 

 cartilage. 



The radius and ulna were not only remark- 

 ably short, but likewise atrophied, both as to 

 breadth and thickness. 



Their superior extremities, with the excep- 

 tion of being unusually small, presented no 

 abnormal appearance. 



The bones of the first row of the carpus 

 were in a state of atrophy, especially the 

 semi-lunar bone. When the hand was flexed 

 at a right angle with the forearm, the lower 

 end of the ulna formed a most conspicuous 

 projection, while during extension, two pro- 

 minences were seen ; one, in front, caused 

 by the carpus, the other posteriorly, mark- 

 ing the position of the lower extremities of 

 the bones of the forearm. The hand was 

 inclined to the radial side of the forearm ; 

 it admitted of being flexed to a right angle, 

 and could be extended perfectly. The ex- 

 tensor tendons in their passage from the 

 forearm to the hand were lodged in deep and 

 narrow grooves, or channels, formed on the 

 dorsal aspect of the radius. 



Upon the left side the deformity was equally 

 remarkable, although the reverse of that no- 

 ticed on the right side. The carpus was re- 

 ceived into a socket formed for it by the 

 radius and ulna. This socket was not at the 



lowest extremity of the bones of the forearm 

 but near to it, and on the dorsal aspect of 

 the bones, and it presented somewhat a 

 glenoid shape, the longest diameter of which 

 was directed obliquely downwards and in- 

 wards. With respect to the carpus, there was 

 neither a scaphoid nor semi-lunar bone. The 

 hand placed in the state of extension formed 

 a right angle with the forearm, but the patient 

 had the power of bringing it to a straight 

 line with the latter, in which position two 

 prominences were seen; but, contrary to what 

 was observed on the opposite side, the dorsal 

 projection was here formed by the carpus, 

 the extremities of the radius ami ulna con- 

 stituting the palmar eminences (see Jig. 927.). 

 In this left extremity, the carpus and forearm, 

 including the elbow joint, were malformed, 

 as well as the wrist-joint, but the rest of the 

 skeleton, with the exception of the right 

 wrist-joint and forearm, was quite normal. 



CASE III. Case of congenital luxation of 

 the wrist-joint of both bones of the left fore- 

 arm backwards. 



The writer exhibited to a meeting of the 

 Surgical Society of Dublin, on March 20ch, 

 184-7, the cast of the left forearm of an adult 

 female, who had been born with a luxation of 

 the carpal extremity of both the bones of 

 the left forearm backwards. The lower ex- 

 tremities of the radius and ulna were placed 

 completely on the dorsum of the carpus, 

 while the hand was, consequently, situated in 

 the front of these bones. 



This remarkable cast of congenital luxa- 

 tion of the wrist-joint was sent across the 

 Atlantic by Dr. 11. MacDonnell, now holding, 

 as a surgeon of the Montreal Hospital, a 

 distinguished place in British America. 



We observe that in the casts ( figs. 928. and 

 929., the representations of Dr. R. MacDon- 

 nell's case), the hand is well formed, but that 

 the forearm is much shorter than it should be, 

 being very little longer than the hand ; the 

 whole length of the forearm is not eight inches, 

 while that of the hand, measured in its greatest 

 length, amounts to six inches and one half. 

 The forearm in its upper part is round and 

 muscular; as we examine it towards the hand, 



Fig. 928. 



. 



Congenital dislocation of both Bones of the Forearm backwards. 



it assumes a well marked quadrilateral form, having passe;!, by fully an inch, the carpal ex- 



and we observe a projection on the dorsum of tremity of the radius. 



the carpus posteriorly, obviously formed by When we place the forearm on its palmar 



the lower extremities of the radius and ulna, aspect, as on a table, and view the uluar side 



which are dislocated backwards. The lower of it, we notice that the ulna rules conspi- 



extremity of the forearm at the wrist here cnously on the back of the carpus, bein^ 



exhibits a very oblique termination, the ulna above its level about an inch ; and at the 



