602 



ABNORMAL CONDITIONS OF THE SHOULDER JOINT. 



fully examined. The arm was slightly short- 

 ened. The contour of the shoulder was not 

 as full nor as round as that of its fellow, and 

 the acromion process was more prominent 

 than natural. Upon opening the capsular 

 ligament, the head of the humerus was found 

 to have been driven into the cancellated tis- 

 sue of the shaft, between the tuberosities, so 

 deeply as to be below the level of the summit 

 of the great tubercle ; this process had been 

 split and displaced outwards; it formed an ob- 

 tuse angle with the outer surface of the shaft 

 of the bone. The distance to which the su- 

 perior fragments had penetrated into the shaft 

 is well seen in the wood-cut (_/?g.432.) 



Fig. 432. 



The head of the humerus impacted. 



Nelaton and Smith* have alluded to cases 

 of intra-capsular fractures of the head of the 

 humerus, in which the detached head of the 

 bone became inverted on itself, and was thus 

 impacted into the shaft of the humerus. Nela- 

 ton observes : "Dr. Dubled showed me a 

 specimen, in which the cap which the summit 

 of the head of the humerus forms had been 

 broken from the shaft, and afterwards in- 

 verted on itself, so that the broken surface of 

 the upper fragments looked upwards and in- 

 wards, while the smooth polished articular 

 part looked downwards, and in this position 

 was buried into the shaft or inferior fragment. 

 Notwithstanding this displacement, consoli- 

 dation had taken place." The superior frag- 

 ment was enveloped by stalactiform produc- 



tions, which had sprung up from the shaft of 

 the humerus. 



In the year 1843, Dr. Robert Smith laid 

 before a meeting of the Pathological Society 

 of Dublin, a remarkable specimen of a frac- 

 ture of the neck of the humerus, in which the 

 head of this bone was driven into the shaft, 

 splitting asunder the bone in the situation of 

 the tuberosities. The subject of the observa- 

 tion was a woman, set. 40, who, many years 

 before her death, had met with the accident. 

 On proceeding to make the post-mortem ex- 

 amination of this case, it was remarked that 

 the acromion process was prominent ; the del- 

 toid flattened ; the arm was shortened ; the 

 glenoid cavity could not be felt ; the shaft of 

 the humerus was drawn upwards and inwards, 

 so as to be almost in contact with the cora- 

 coid process ; the motions of the joint were 

 limited ; and the capsular muscles atrophied. 



Dissection. When the soft parts were re- 

 moved, and the capsular ligament was opened, 

 the traces of a fracture having long ago passed 

 through the anatomical neck of the humerus 

 were obvious. The head of the humerus was 

 solidly united to the shaft. But, upon ex- 

 amining further, what struck Dr. Smith as 

 very remarkable was, that the head of the 

 humerus was found reversed, or turned up- 

 side down, in the articulation ; or, in other 

 words, the fractured surface was turned up- 

 wards towards the glenoid cavity, and the 

 cartilaginous articulating surface turned down- 

 wards, as in Nelaton's case, towards the shaft. 

 The only explanation of this circumstance 

 which can be given is, that the. head of the 

 bone, at the time of the accident, had been 

 completely separated from the shaft by a frac- 

 ture through the anatomical neck ; that thus 

 rendered free in the interior of the joint, the 

 head of the bone became inverted on itself, 

 and was thus subsequently driven into the 

 cancellated structure, between the tubercles. 



It appears that in the Museum of the Col- 

 lege of Surgeons of Dublin, a third specimen 

 of th's complete inversion of the upper frag- 

 ment of the brok n humerus is to be found.* 



2. Extra- capsular fracture through the tuber- 

 cles. The fracture may be extra-capsular ; 

 passing through the tuberosities beneath the 

 anatomical neck of the humerus, yet above 

 the line of the junction of the epiphysis, with 

 the shaft of the bone. 



This fracture is usually the consequence of 

 severe falls on the outside of the shoulder ; it 

 may occur at all ages, but is most frequently 

 met with in elderly persons. The line of the 

 lesion may be transverse, but usually the 

 bone is broken into many fragments. There 

 is some shortening of the arm, but very little 

 if any transverse displacement of the bony 

 fragments The long tendon of the biceps, 

 in front, and the strong fibres proceeding from 

 the bony attachment of the capsular ligament 

 and capsular muscles, will retain the fragments 

 in their place. The shortening is the result 

 of the mutual impaction into each other of 



* Dr. R. Smith's work on Fractures. 



* See Dr. R. Smith's work on Fractures. 



