ABNORMAL CONDITION OF THE ELBOW-JOINT. 



75 



fore-arm, the head of the radius is permitted 

 to pass backwards, somewhat behind its na- 

 tural situation ; but as soon as the effort ceases, 

 the radius resumes its natural position in the 

 lesser sigmoid cavity of the ulna. A true lux- 

 ation in these cases cannot be said to happen, 

 unless the effort of pronation is sufficient to 

 bring the superior extremity of the radius 

 behind the small head of the humerus ; when- 

 ever this has occurred, then the sub-luxation 

 is converted into the complete luxation of the 

 radius backwards, and presents all the cha- 

 racters of this accident, and it cannot be re- 

 placed without the assistance of art. It is 

 known to anatomists that the radio-cubital 

 joint is not advanced much in its development 

 in infants ; that the lesser sigmoid cavity is as 

 yet small and shallow ; and that the coronary 

 ligament of the radius is proportionally longer 

 and more yielding than it is destined to be in 

 after life. This articulation, however, is fully 

 equal, even at this earliest period of life, 

 to sustain any efforts that its own pronator 

 muscles can communicate to it ; but it is 

 by no means constructed so as to be able 

 to resist those forced movements of pronation 

 and stretching we see too frequently given to 

 the fore-arms of infants of a tender age, by 

 their attendants, who in lifting them from the 

 ground usually seize them by the fore-arms, 

 these being at the time in a full state of pro- 

 nation. Thus we find that in delicate children 

 the foundation is laid for that elongation of 

 the coronary ligament, which ends in the con- 

 dition of this joint we have denominated sub- 

 luxation. We have usually observed that the 

 subjects of this affection were delicate from 

 their youth, and that sometimes only one, 

 and that frequently both arms were affected ; 

 that in all cases the extremity was more or less 

 deformed, having a bowed appearance, the 

 convexity being external ; that a very evident 

 protuberance could be seen and felt in the 

 situation of the head of the radius ; and that 

 the patient had nearly perfect use of the arm, 

 although he could neither fully flex nor extend 

 it. When the surgeon places his thumb on 

 the external condyle of the humerus and head 

 of the radius in one of these cases, and at the 

 same time has the fore-arm supinated, the head 

 of the radius is felt to rotate in its proper place, 

 and on its axis, as in its perfect condition ; 

 but if now a forced movement of pronation be 

 given to the head of the radius, the latter will 

 be observed to slip backwards towards the 

 olecranon process : every time the patient him- 

 self fully pronates the fore-arm, the sub-lux- 

 ation occurs, and in supination the radius 

 resumes its place again. This relaxation of 

 the ligaments of the radio-cubital joint, no 

 matter how produced, at all events predisposes 

 those affected with it to the more complete 

 luxation of the radius backwards. 



e. Congenital or original luxation of the 

 superior extremity of the radius backward. 

 Dupuytren is the first pathologist who has 

 spoken of the congenital luxation of the 

 radius; he met with a case of the kind in 



dissection, and described it in his lectures. 

 He found that the superior extremity of each 

 radius had abandoned its natural situation, 

 and was found situated behind the inferior 

 extremity of the humerus, having passed this 

 extremity an inch at least. This disposition 

 being absolutely the same on each side of the 

 body, there existed no difference between these 

 two luxations, which were probably conge- 

 nital. It is also stated that Dupuytren had 

 mentioned that about twenty or twenty-five 

 years before he dissected the case now alluded 

 to, he had seen a case nearly similar, but he 

 was unwilling to speak positively on these 

 cases, as the history was unknown, and acci- 

 dent or disease might have produced similar 

 results. 



Cruveilhier, in his very valuable work on 

 Pathological Anatomy, quotes the above ob- 

 servations from Dupuytren's lectures, and 

 seems to disagree entirely with the celebrated 

 surgeon of the Hotel-Dieu, advancing it as 

 his opinion, that it would be much more na- 

 tural to suppose that the cases described by 

 Dupuytren were not congenital, but rather 

 very old luxations, a long time left unre- 

 duced. 



It is very true that Dupuytren speaks with 

 hesitation about the matter, as he appears to 

 hare met with but two cases, nor can any one 

 speak with certainty on this subject, until ob- 

 servation on the living, and anatomical in- 

 vestigations, shall be combined to elucidate 

 the matter ; but we think that already enough 

 can be adduced to shew, that we have strong 

 grounds for believing that such a congenital 

 defect as luxation of the upper extremity of 

 the radius backwards may be occasionally met 

 with, and this is an opinion we think our- 

 selves authorised to advance, because of the 

 facts and reasons we can adduce to support it. 



In the Museum of the Royal College of Sur- 

 geons in Ireland, there is a specimen, which 

 the writer considers to be one of congenital lux- 

 ation of the upper extremity of the left radius 

 backwards; fig. is a representation of it. 

 The outer condyle of the humerus exists, but 

 in front of it there is no rounded head or 

 capitulum for the radius, or any trace of the 

 usual convex articular surface ever having 

 existed. The coronoid process and great sig- 

 moid cavity of the ulna are unusually large 

 transversely, and stretch almost the whole way 

 across the lower articular extremity of the 

 humerus, which is entirely formed into one 

 single trochlea wider than natural. The head 

 of the radius, which seems never to have been 

 adequately developed, is situated behind the 

 plane of the outer condyle of the humerus. 

 The tubercle of the radius is much enlarged, 

 and leans against the lesser sigmoid cavity of 

 the ulna, while the neck of the radius, directed 

 somewhat back ward, is twice its natural length, 

 and instead of reaching merely to the level of 

 the lesser sigmoid cavity of the ulna, stretches 

 as high up along the ulna as to reach near to 

 the level of the summit of the olecranon pro- 

 cess, while the carpal extremities of the radius 



