backward and became engaged under the tendon, which then held the arm abducted and directed forward and more or less rotated inward. The circumflex vessels and nerves were bruised and sometimes torn. He thought the head of the bone tended always to pass first in front of them and then below and behind them as the arm was lowered. The capsule and the insertions of the rotator muscles were more or less extensively torn. Farabeuf's case is apparently the one mentioned by Poinsot' as Sebilleau's and as having been examined by himself in 1881, The limb was then in slight abduction and inward rotation, the elbow and fingers flexed; movements at the shoulder were almost completely lost. The case is described by Poinsot as one of dislocation backward (sub-acromial or subspinous), and no reference is made by him to Farabeuf's opinion concerning it although he is named among the surgeons who had examined it. Farabeuf maintains that two very similar cases observed by Richet and Bottey and named by the former retro-axillary (see posterior dislocations) were really examples of this variety described by him. The reason for taking this very exceptional form of dislocation out of the group of irregular forms and making of it a class apart is the necessity for emphasizing the route by which the head of the bone has passed to its new position. If in a similar case it should be thought, as was thought in Richet's and Bottey's cases, that the tendon of the triceps lay below the head and that the dislocation was only an exceptional form of the subacromial variety, the attempt to reduce would probably fail, because it would be made according to the method suitable to that variety, whereas it should be made by first transforming the dislocation into a luxatio erecta by raising the elbow to the side of the head, and then reducing by direct traction upward. POSTERIOR DISLOCATIONS. (SUBACROMIAL AND SUBSPINOUS.) Dislocations backward are divided into two classes, the subacromial and the subspinous, according as the head lies under the projecting outer border of the acromion or further back below the spine of the scapula, respectively. A variety of the subacromial, to which the name retroaxillary has been given, has been recently observed and described by Richet and Bottey. Although I think this division into two groups is quite generally accepted by the profession, yet English and American systematic writers upon the subject have, as a rule, refused to adopt it, giving as a reason therefor, the fact that the two differ only in an unimportant feature, the degree of the displacement, and they apply the term subspinous to all. Flower2 justifies the choice of this name in preference to subacromial on the ground that the latter does not express any change from the normal situation of the head of the humerus under the acromion. On the other hand, it may be fairly urged that as in the great majority of cases the 1 Poinsot: Translation of Hamilton's Fract. and Dis., p. 867. head is not displaced so far as to the spine of the scapula, the term subspinous is misleading and improper. I have preferred, in accordance with what I believe to be the general practice of the profession, to retain both terms with the distinction between them established by Malgaigne. Of the two groups the subacromial is much the more frequent, the subspinous being very rare. The actual difference in their frequency is greater than a collation of the reported cases by the titles given them would indicate, for not a few of the former have been described as "subspinous," because the reporters have not discriminated between the two varieties but have applied that term to all. According to Malgaigne, the earliest recorded mention of this dislocation was in 1834, and when he wrote, in 1855, he could collect only 34 cases, of which he had himself observed 3. A very considerable number of cases have been recorded since that time (I found 7 in the Index Medicus for the years 1878 to 1882), and Panas's opinion that many escape recognition, by being mistaken for a sprain or an articular fracture, seems fairly justified, for not only are the diagnostic symptoms sometimes very obscure, but Nélaton said that he had within a short period of time seen three cases that had passed unrecognized by surgeons of merit. In Malgaigne's statistics 26 were men, and 5 women; and in rather more than a quarter of them the cause was muscular action. Bardenheuer quotes Knox, but without giving the reference, as having seen two cases in which the injury was caused by obstetrical manipulations; when seen by him one patient was twenty-one months, the other three years old. Possibly these were examples of dislocation due to paralysis of the muscles of the shoulder, the paralysis itself being the result of obstetrical manipulations. The investigations of Duchenne de Boulogne indicate that this is not an infrequent accident, and that the resulting dislocation is always subacromial. (See Chapter XVIII.) Bardenheuer himself had met with four cases of backward dislocation, in one of which both shoulders had been dislocated by a fall forward upon the elbows. Experiment upon the cadaver shows that the dislocation can be readily produced by forcible internal rotation of the arm, by which the posterior portion of the capsule is torn and the passage backward and outward of the head is made easy. In some of the cases clinically observed also it is plain that this has been the mechanism, and in others it has undoubtedly aided. Thus, Piel, who wrote a thesis on the subject in 1851, saw a woman in whom it had been caused by her husband twisting her arm in a quarrel. In seven of Malgaigne's cases and in several that have since been reported the dislocation occurred during an epileptic fit, presumably by internal rotation of the limb. In other cases the cause has been a blow upon the front of the shoulder (twice a blow with the fist), pressure upon the back of the shoulder while the elbow rested against the ground, an attempt to control the patient in convulsions, once the throwing of a stone by a boy ten years old, and frequently a fall. The anatomical features of the joint, the results of cadaveric experiment, and such histories of cases as are sufficiently complete, indicate that the common mode of production is pressure backward and outward upon the head of the humerus, either directly or through the elbow, combined with adduction. of the limb across the front of the chest and internal rotation. Such a combination is most frequently found in falls forward in which the weight is received upon the elbow, not upon the hand, for in the latter case the arm is usually slightly abducted and the force is received squarely against the surface of the glenoid fossa instead of obliquely outward. It will be remembered that this surface is directed forward and outward, and that as the dislocating force must be exerted obliquely to it it must come from a point that is in front and more or less to the inner side. One of Malgaigne's cases is especially interesting from this point of view, as showing the conditions of the production almost as clearly as an experiment. A woman was trying to take down a box placed high above her head, it slipped suddenly into her extended hand, and the dislocation occurred. In other words, the force was exerted in a suitable direction upon an arm that was elevated, adducted, and rotated inward. In a case observed by Tillaux' the patient, a man twenty-four years old, had his right arm caught in some machinery and was drawn several times about a revolving shaft, receiving a subspinous dislocation, and in addition having the arm almost completely torn away at its middle by being twisted several times upon itself. Autopsies have been made in six recent cases in which death was caused by associated injuries. In Maisonneuve's case (the specimen is pictured in Malgaigne's Atlas, Plate XXII., Figs. 5 and 6) the patient fell from a height of thirty feet. The capsule was torn above, below, and on its outer side; the greater tuberosity was torn off, broken into two pieces, and drawn back below the acromio-clavicular arch by the supra- and infra-spinatus muscles to which it remained attached. The teres minor and subscapularis were still attached to the humerus; the long tendon of the biceps had been torn out of its groove. The circumflex nerve was uninjured. The head of the humerus lay just below the posterior angle of the acromion and was not in contact with either the spine or the neck of the scapula, but rested against the posterior edge of the glenoid cavity. In Laugier's case the subscapularis and supraspinatus were torn from their insertions, and the head of the humerus had passed, as in Maisonneuve's case also, between the infraspinatus and teres minor and was covered only by the deltoid. Two cases were reported by Jössel, one a subacromial, the other a subspinous dislocation. In the first the injury, together with a fracture of skull, was caused by a fall into a cellar. The head of the humerus had torn through the teres minor and lay under the acromion; the limb was so far rotated inward that the articular surface looked directly outward. The supraspinatus and infraspinatus were uninjured. The capsule showed a triangular rent on the outer side just large enough to let the head through. The tendon of the subscapularis was still attached to the humerus, but under it and close by the tendon of the biceps an irregular, movable piece of bone could be felt, the lesser tuberosity, the fracture by which it was separated extending into the bicipital groove; the tubercle was split into two pieces, both adherent to the tendon. 1 Tillaux: Anatomie topographique, p. 536. 2 Laugier: Gaz. des Hôpitaux, 1846, p. 60. 3 Jössel: Deutsche Zeitschrift für Chir., 1874, vol. 4, p. 125. In the second case the patient fell from the height of two stories, dislocated the left shoulder, and sustained a compound fracture of the thigh; he died on the fifth day. The head of the humerus (Fig. 64) had torn FIG. 64. Subspinous dislocation of the shoulder. (JÖSSEL.) through the teres minor and lay under the spine of the scapula, separated from it by the interposed infraspinatus; it was directed backward. The long head of the triceps was almost entirely torn through, and a piece was broken from the axillary border of the scapula just below the glenoid fossa. The subscapularis and the adjoining part of the capsule were torn away from the humerus, bringing with them the lesser tuberosity, the fracture of which was broader than in the preceding case. In the remaining two cases the dislocations were subspinous; in one of them, quoted by Malgaigne' (loc. cit., p. 541), the patient, a man sixty-two years old, fell backward, and the wheel of his wagon, which carried a load of three and a half tons, passed obliquely across the right side of his chest, causing injuries which resulted in his death thirty hours later. Several ribs were fractured, as were also the body of the scapula and the inner portion of its spine. The deltoid, pectoralis major, teres major, and teres minor were torn or crushed, and the capsule was almost entirely detached. When the arm was lowered the head of the humerus lay below the spine of the scapula in the outermost part of the subspinous fossa, the lesser tuberosity corresponding to the edge of the glenoid fossa. In the other, reported by Collins,2 a man sixty years old was knocked down and run over, sustaining, in addition to the dislocation of his right shoulder, fracture of several ribs; he died in a few days of pneumonia. According to Soyez (Thèse de Paris, 1880, No. 179) the case was treated by Denonvilliers, who deposited the specimen in the Musée Dupuytren. It is reported by Malgaigne as if he had himself observed it; hence has arisen the error of supposing that they were different cases. 2 Collins: Dublin Journ. Med. Sci., 1879, ii. p. 166. The capsule was torn on all sides; the supraspinatus and subscapularis were torn away at their insertions, and the long tendon of the biceps was detached from the bicipital groove. The head of the humerus lay between the teres minor and the infraspinatus "immediately beneath the scapular spine." In addition, there is a specimen described by Bouisson, and quoted by Malgaigne, the history of which is so incomplete that it must be treated as an exception; the head of the humerus lay under the acromion, and the inward rotation was so marked that the articular surface looked directly outward, and the greater tuberosity occupied the outer half of the glenoid fossa. In a case described by Küster1 as congenital, but concerning the etiology of which some doubt may be felt, a child fourteen months old had a backward dislocation of both shoulders; the elbows were directed downward and forward, and both arms were rotated inward, the left one very markedly. The patient died in consequence of an operation done upon the left shoulder, and at the autopsy the head of each humerus was found to be normally developed and resting on the posterior border of the abnormally flat and small glenoid fossa. The normal development of the head of the humerus, the fact that the departure from the normal condition of the glenoid fossa was only such as could be accounted for by the changed relations, and the marked internal rotation suggest that the dislocations may have been caused by muscular action, or have been the consequence of local paralysis due to the pressure of the forceps in delivery (see Chapter XVIII.), especially since the report indicates that Küster himself felt there might be a doubt of the supposed congenital character. The important complication of fracture of the anatomical neck has been reported in two cases, one by Delpech, the other by Malgaigne; in each the cause was a fall upon the shoulder. In Delpech's case the fall was due to an apoplexy which soon proved fatal; the head had passed entirely through a large rent in the postero-external part of the capsule, its fractured surface lay against the subspinous fossa, and its articular surface was directed backward and covered by the infraspinatus muscle. The muscular attachments to the humerus were all preserved, and the long tendon of the biceps was intact. Malgaigne's case was not seen by him until eleven months after the receipt of the injury; the head of the humerus could be felt as an immovable, hemispherical body, two inches in diameter, and half an inch below the posterior angle of the acromion. The arm was shortened half an inch, the elbow slightly abducted and not rotated. The upper end of the shaft corresponded to the glenoid cavity. The arm was slightly movable; the head did not share in its movements. The results obtained by experiment upon the cadaver are in harmony with these post-mortem records. In the subacromial variety the head of the humerus is found under the acromion looking backward and inward, with its anatomical neck engaged against the posterior edge of the glenoid fossa, and the lesser tuberosity lying on the latter. The tendon of the 1 Küster: Ein chirurg. Triennium, 1882, p. 256. |