4. We have heretofore adverted only to the ordinary symptoms and anatomical characters belongine to the three dislocations which the head of die humerus is liable to ; but practical surgeons have, however, noticed that a dis location of the head of the humerus is times conzbined with a fracture of this bone.
In this case the fracture 'may sometimes en gage merely the tuberosities, sometimes the anatomical, and sometimes the surgical neck of this bone. It has been long ago noticed by Thompson *, that when the head of the humerus is dislocated into the axilla, the greater tuberosity of this bone, which gives attachment to the three posterior capsular muscles, is torn off from the shaft of the hu merus, and left attached to these muscles. This observation of Thompson has since been repeated by others, from amongst whom we have already quoted a case adduced by Sir Philip Crampton, of an axillary dislocation, in the dissection of which it was found that the tuberosities were detached. Such a com plication with a dislocation of the humerus would no doubt facilitate the reduction of the dislocated bone, but its subsequent main tenance in its place would be thereby rendered very difficult.
We have reason to believe that a fracture, completely detaching the greater tuberosity of the humerus, may be combined with a dislo cation forwards ; and in this case, although the dislocation may be reduced, the head of the humerus cannot be maintained in the glenoid cavity. We have for some time con sidered this to be the explanation of the spe cimen contained in the Richmond -Hospital Museum, an account of which we find given by Dr. R. Smith, and from which we abstract the following :—" Upon removing the soft parts, the head of the bone presented itself, lying partly beneath, and partly internal to the coracoid process. The greater tuberosity, together with a very small portion of the outer part of the head of the bone, had been completely separated from the shaft of the .humerus. This portion of the bone occu pied the glenoid cavity, the head of the hu merus having been drawn inwards, so as to project upon the inner side of the coracoid process ; it was still contained within the capsular ligament, which was thickened and •enlarged, and bone had been deposited in its tissue. A new and shallow socket had been
formed upon the costal surface of the neck of the scapula, below the root of the coracoid process, and the inner edge of the glenoid cavity, the tuberosity was united to the shaft only by ligament. The injury had occurred many years before the death of the patient, but the history of the case was not precisely known." But fracture of the greater tuberosity may also occur, as a consequence of falls on the outer side of the shoulder, or otherwise, with out any dislocation following.
Fracture of the lesser tuberosity of the humerus may, we suppose, be an accident likely to attend on dislocations of the head of this bone, and would, we imagine, be at tended with consequences similar to those which followed the laceration of the tendon of the subscapularis muscle in a case of dis location on the dorsum of the scapula, no ticed by Sir A. Cooper and Mr. Key.
Dislocation of the head of the humerus, ac companied with a fracture of the neck of the humerus. — Sometimes the luxation or the humerus is complicated with a fracture of the anatomical or surgical neck of this bone ; we have then one of those rare lesions to deal with, for which nature and art can do but little. In such a case it is plain that the dis location has first occurred. When there is both a dislocation and fracture, Sir A. Cooper says, the symptoms resemble those which usually accompany the dislocation into the axilla, the head of the bone being there felt ; but there is somewhat less of the hollow to be observed below the acromion, and the del toid muscle does not seem much depressed, because the broken extremity of the shaft quits the head and lodges in the glenoid cavity of the scapula. Upon rotating the arm, the broken shaft of the bone can be perceived to move under the acromion ; there is but little power of motion ; and considerable pain is felt not only in the shoulder, but in the arm and hand. The head of the os humeri can be felt when the arm is raised, and the sur geon's fingers are introduced into the axilla ; but when the arm is rotated at the elbow, the head of the bone remains entirely unmoved, or very little obedient to the motions of the elbow. In some cases, but not always, a dis tinct crepitus can be perceived.