600 



ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 



been formed for the reception of the enlarged 

 heads of the humeri behind the glenoid cavi- 

 ties, and partly beneath the bases of the spines 

 of the scapulae just where the head of the 

 humerus has been found to rest in the ordi- 

 nary dislocation backwards from accident ; 

 but in this case, although the history was 

 unknown, that these appearances were not 

 the result of accident is almost certain, 

 as similar abnormal appearances are ob- 

 servable on each side. The notice of this 

 preparation in the catalogue of the museum 

 is as follows (p. 10832.) : " The bones of 

 both the shoulder joints of an adult. In each 

 joint there has been ' ulceration,' or such 

 absorption as occurs in chronic rheumatism 

 of the articular surface of the head of the 

 humerus, and the glenoid cavity. The heads 

 of the humeri are flattened and enlarged by 

 growths of bone around their borders; and the 

 glenoid cavities, enlarged in a corresponding 

 degree, and deepened, extend backwards 

 and inwards to the bases of the spines of the 

 scapulae. The articular surfaces, thus en- 

 larged, are mutually adapted, and are har- 

 dened, perforated, and in some parts polished 

 and ivory-like. The changes of structure 

 are symmetrical, except in that the articular 

 surfaces of the right shoulder joint are more 

 extensively polished than those of the left." 



SECTION II. Accident. The principal 

 accidents the shoulder joint and the bones in 

 its immediate vicinity are liable to, are frac- 

 tures and luxations. 



FRACTURES. A fracture may traverse the 

 acromion, the coracoid process, or detach 

 the glenoid articular portion of the scapula 

 from the body of this bone by passing directly 

 across the neck of the scapula. 



A. Fracture of the aci-omion process. A 

 fracture of the acromion process may be caused 

 by the fall of a heavy body on the superior 

 surface of the acromion; but this accident 

 most usually occurs in consequence of falls 

 in which the patient is thrown from a height 

 on the point of the shoulder. The fracture 

 of the acromion will be generally found to 

 have taken place at a point behind, and within, 

 the junction of the clavicle with this bony 

 process ; its direction we always observe to 

 be in the original line of the junction of the 

 epiphysis with the rest of the bone. In this 

 accident, if the distance be measured from 

 the sternal end of the clavicle to the extre- 

 mity of the shoulder, it will be found lessened 

 on the injured side. Considerable ecchymosis 

 of the shoulder may be expected soon to suc- 

 ceed the injury, and the patient will be unable 

 to elevate the arm. Sometimes the perios- 

 teum of the acromion is not torn, and then, 

 although the fracture of the bone has been 

 complete, there is no displacement of the 

 fragments. If, however, this fibrous invest- 

 ment of the acromion, above and below, be 

 completely torn across, the acromion process 

 will be found to be depressed, because it will 

 be pulled down by the weight of the extremity 

 and contraction of the deltoid muscle. The 

 portion of the acromion thus detached is 



generally very moveable, following the clavicle 

 whenever the arm is moved. This accident 

 is best recognised by the surgeon first taking 

 hold of the elbow of the affected side, and 

 elevating the whole arm perpendicularly. 

 " Having thus restored the figure of the part, 

 he places his hand upon the acromion, and 

 rotates the arm, when a crepitus can be dis- 

 tinctly perceived at the point of the spine of 

 the scapula." * 



Fractures of the acromion unite by bone, 

 sometimes with much deformity, arising from 

 ossific depositions, which however do not, 

 after a time, interfere much with the motions 

 of the arm. This union has sometimes been 

 known to take place in forty-eight days, and 

 in other cases in a much shorter time. The 

 union, however, is frequently only ligamentous. 

 Sir A. Cooper speaks of a false joint being 

 occasionally the result of a fracture. Mal- 

 gaigne, alluding to a case in which a false 

 joint was the consequence of a fracture of 

 the acromion, says that the fractured surfaces 

 presented a polished appearance, and were 

 covered with an ivory deposit, the effects of 

 friction. He adds, that the union was not 

 simply a ligamentous connexion, but that an 

 arthrodial false joint had been formed. In 

 all the specimens of this fracture examined by 

 Malgaigne, the superior border of the fracture 

 was surmounted with small bony crests of 

 new formation, of which the more consider- 

 able number grew from the scapular portion 

 of the acromion, while those produced from 

 the detached extremity of this process were 

 but few, no doubt in consequence of its lesser 

 degree of vitality. This remark of Malgaigne 

 coincides with the observations to be found 

 in Sir Astley Cooper's Work, that the dis- 

 position to ossific union is very weak in the 

 detached acromion. Malgaigne, however, re- 

 fers to a preparation in the Museum of Du- 

 puytren, in which the external fragment pos- 

 sessed a thickness almost double that of the 

 portion of bone from which it had been de- 

 tached. This thickness the writer of the 

 Catalogue of the Museum thought was caused 

 by an overlapping of the fragments of the 

 broken portions of the acromion ; but Malgaigne 

 supposes it to have arisen from simple hyper- 

 trophy of the detached fragments. 



B. Fracture of the coracoid process is a 

 rare accident, and when it does occur, it is 

 generally the result of a severe injury, in 

 which the fracture of the bone is the least of 

 the evils attendant on the compound injury. 

 ThusBoyerf gives us the account of a fracture 

 of the coracoid process produced by the blow 

 of a carriage pole ; the patient died in a few 

 days afterwards, in consequence of the severe 

 contusion he suffered at the moment of the 

 accident. The coracoid process, when frac- 

 tured at its basis, is pulled downwards and 

 forwards by the lesser pectoral coraco-bra- 

 chialis and short portion of the biceps muscle. 

 We are told]; that if the contusion accom- 

 panying this accident be slight, we can seize 



* Sir A. Cooper. 



f Maladies Chirurgicales. 



Sanson. 



