5. Luxations of the upper extremity of the radius from the humerus and ulna.—When we look into the best books we possess for infor mation on this subject, we must be struck with the remarkable discrepancy of the opinions we find expressed by the authors. Thus, upon the subject of luxation forwards of the radius, we find the celebrated Boyer stating that he doubts such a luxation can occur without being complicated with a fracture. Sanson states that this luxation forwards has never been observed, and moreover advances what he considers as anatomical and physiological explanations, to show the impossibility of such an occurrence. Sir A. Cooper, on the contrary, gives six examples of the luxation of the upper extre mity of the radius forwards. The French writers state of the luxation of this extremity of the radius backwards, that although it is rare it has been many times witnessed, while Sir A. Cooper, alluding to this luxation back wards, says, " this is an accident which I have never seen in the living," but he gives an anatomical account of the appearances found in a subject, the history of which was unknown, brought into St. Thomas's Hospital for dissec tion. Having thus stated the different opinions of authors upon this subject, we shall proceed to give an account of—a, the luxation of the upper extremity of the radius forwards; b, of its luxation laterally and upwards ; c, of its luxation backwards; d, of its sub-luxation ; e, of its congenital luxation backwards.
a. Lusatian of the radius at the elbow-joint forwards.—The symptoms of this accident are as follows : the fore-arm is slightly bent, but cannot be brought to a right angle with the arm, nor can it be completely extended ; when it is suddenly bent, the head of the radius strikes against the fore part of the humerus, and pro duces so sudden a stop to its motion as at once to convince the surgeon that one bone strikes against the other. The hand is placed in a prone position ; but neither its pronation nor its supination can be completely performed, although its pronation may be nearly complete. The head of the radius may be felt on the front and upper part of the elbow-joint, and if rota tion of the hand be attempted, the bone will be perceived to roll ; this last circumstance and the sudden stop to the bending of the arm are the best diagnostic marks of this injury. In the dissection of this case, the head of the radius is found resting in the hollow above the external condyle of the os humeri. The ulna is in its natural position. The coronary and part of the capsular ligaments as well as the oblique and a portion of the interosseous liga ments nre torn through. The laceration of the latter ligament allows of the separation of the two bones. The biceps muscle is shortened (fig. 43).
We have known an instance in which this accident was produced in the following man ner: the patient in endeavouring to protect his head from a blow aimed at him by a man who with both hands wielded a spade, received the force and weight of the spade on the edge of the ulna, which, at the same time that it pro duced a compound fracture of this bone, also dislocated the radius forwards. This latter complication not having been discovered in time, remained ever afterwards unreduced.
b. Lateral dislocation of the upper extremity of the radius.—This is an accident we find alluded to for the first time by Sir A. Cooper, in the appendix to the edition of his work on luxations. Ile does not adduce any recent case of it, but states that Mr. Freeman brought to his house a gentleman, aged twenty-live, whose pony having run away with him when he was twelve years old, he had struck his elbow against a tree, while his arm was bent and advanced before his head, in consequence of which the olecranon was broken, and the radius luxated upwards and outwards above the external condyle. When the arm was bent, the head of the radius passed the os humeri ; he had a useful motion of the limb, but neither the flexion nor the extension was complete.
As the case here stated is the only one we are acquainted with on record of luxation of the radius upwards and outwards, we may be perhaps excused for exceeiing our ordinary limits by relating the following case of this accident ; the subject of it was a very intelligent medical student, about twenty-three years old, and we shall give the case nearly in his own words :— Ile writes as follows : " When I was very young, a blow was aimed at my head by a person having a heavy boat-pole in his hands.
I endeavoured to save my head by parrying the blow with my left arm. I received the pole on the middle and back part of the fore-arm with a force which knocked me down, and caused a wide lacerated wound where the pole came in contact with it. Whether a luxation of the radius occurred at this time or not was not known, but ever since the accident the arm has been weak, and about seven years ago the weakness increased, and it became liable to partial luxations forwards upon the slightest causes, which luxations I reduced myself by making extension with my right arm, until at length I got a severe fall, which dislocated it to such an extent, forwards and outwards, as to defy my attempts to restore it The arm was locked in the flexed position, and the head of the radius was to be felt high up, and pro jecting slightly outside the external condyle of the humerus. The biceps muscle was con tracted, and its tendon was very prominent, hard, and tense, like a bowstring. The hand was supinated. I suffered little pain, except when extension was attempted, when it became intense. Sir A. Cooper remarks, in his cases of luxation of the radius forwards, that the fore-arm is slightly bent, but cannot be bent to a right angle, nor completely extended. My arm was bent to an acute angle, and could not admit of the slightest extension. The luxation was reduced by extension, and in six weeks passive motion was begun ; but I found it painful to use it, and the head of the radius would often catch in the ridge above the ex ternal condyle, but on extending the arm it returned with a noise into its place. A month, however, did not pass before I was one morn ing awakened in making some awkward move ment in my bed, and my arm became luxated worse than ever. On this occasion the surgeon who heretofore had easily replaced the bone found it impracticable to effect it, and called in Mr. Colles to his assistance ; but although much force was used it was in vain. From this time the bead of the radius never was returned back to its proper situation, but habi tually remained dislocated completely forwards in front of the external condyle. The liga ments seemed to have been so lacerated, and the joint felt so weak, that I was in constant terror lest the bone should be further luxated as formerly, and that it should again slip over the external condylc of the humerus. I could extend my arm, but not fully, and could rotate it, but could not flex it sufficiently to use my fork at dinner. In this state I remained for six years, and in the winter of 1834-5 the radius was again luxated laterally over the external condyle of the humerus by a fall from my bed. Now the difficulty experienced in bringing the bone back to the situation it had so long occu pied in front of the external condyle, was ex treme. I went to the hospital, and two sur geons, assisted by six of my brother pupils, could not, with all their force, reduce the bone. The pulleys were also nowused,but without suc cess. Dr. O'Beirne and the late Dr. M'Dowel were called into consultation; they placed me sitting on my bed, and fixing the hollow angle at the bend of the elbow against one of the bed-posts, they used great force to straighten it, in which they succeeded ; that is to say, they replaced the bone, not into its original berth, but back to the new socket, which had been formed for it in front of the external con dyle, where it had been lodged for six years previously to the last accident, and where it now remains. At this moment it presents all the characters assigned to the luxation of the radius forwards ; the rounded head of this bone is quite prominent in front of the external con dyle of the humerus, in which situation it seems to have worked for itself a socket, and behind the head of the radius a deep depres sion exists. The arm has a rounded appear ance, and the fore-arm is much wasted." This case seems to us important as proving three circumstances : 1. that a partial luxation forwards of the radius can exist from relaxation or elongation of ligaments ; 2. that this partial luxation or weakness of the joint is readily convertible into the true luxation forwards ; and, 3. that in the case of unreduced luxation of the radius forwards the patient is still in danger of further luxation of this bone laterally, or above the capitulum and outer condyle of the humerus.