454 



BONE, PATHOLOGICAL CONDITIONS OF. 



limited period of our existence, or why even 

 amongst young persons it may occur in one 

 individual and not in another, form questions 

 to which, in the present state of our knowledge, 

 we can give no answer. We are not even 

 agreed on the different steps of the process or 

 on the structure principally engaged. 



It has been observed that the portion of the 

 bone which is to die, and for some space above 

 and below it, is surrounded by a dense thick- 

 ened mass, of rather a gelatinous character ; 

 that this mass, after a very short time, becomes 

 opaque in detached spots, and that depositions 

 of osseous material are found within it, so that 

 a case of bone may be constructed around the 

 original one before it actually dies, and thus 

 the limb never be entirely deprived of support.* 

 As soon as the dead bone separates from this 

 surrounding mass, the internal surface of this 

 new material becomes, under some circum- 

 stances, covered with a layer of lymph, and 

 under others with regular ossific granulations, 

 which gradually increase until a new bone is 

 formed, nearly as serviceable, though not so 

 symmetrical or so beautiful as the old one. It 

 next becomes a question, what is this gelatinous 

 mass, and whence is it derived ? It has been 

 supposed that it was the periosteum of the old 

 bone swelled and thickened, and at the same 

 time softened in consistence ; and this opinion 

 has been strengthened by Dr. Macartney ,f the 

 present Professor of Anatomy in the University 

 of Dublin, who stated that he had opportunities 

 of watching the progress of the disease from its 

 earliest periods Sapwards. According to this 

 gentleman, " the first and most important cir- 

 cumstance is the change that takes place in the 

 organization of the periosteum : this membrane 

 acquires the highest degree of vascularity, be- 

 comes considerably thickened, soft, spongy, and 

 loosely adherent to the bone ; the cellular sub- 

 stance, also, which is immediately connected 

 with the periosteum, suffers a similar alteration : 

 it puts on the appearance of being inflamed, its 

 vessels enlarge, lymph is shed into its inter- 

 stices, and it becomes consolidated with the 

 periosteum." Next, " the newly organized pe- 

 riosteum, which, for the sake of distinction, one 

 might call the vascular sheath or investment, 

 separates entirely from the bone, after which it 

 begins to remove the latter by absorption, and 

 during the time that this process is carrying on, 

 the surface of the vascular investment, which is 

 applied to the bone, becomes covered with 

 little eminences, exactly similar to the granula- 

 tions of a common ulcer." To this doctrine 

 Mr. Russell, of Edinburgh, strongly objected. 

 He stated that if the osseous matter was depo- 

 sited between the layers of periosteum, both the 

 external and internal surfaces of the new de- 

 posit ought to be perfectly smooth, whereas the 

 contrary is observed they are rough, irregular, 

 and one of them is covered with granulations. 

 He instanced cases of fracture in which, one 

 fragment overlapping the other, and being thus 



" See Russell on Necrosis. 



t See Crowther on White Swelling. Edition 

 1808, p. 183. 



permanently entangled, the periosteum between 

 the two can have no share in the reproduction, 

 and yet the whole is united by a cylindrical 

 shell of bone, on the principle of reproduction 

 in necrosis. It is also known that compound 

 fractures, where the fragments have been exten- 

 sively stripped of periosteum, have united in 

 the same way, and the regeneration of bone, in 

 these instances, could not be attributed to peri- 

 osteum, inasmuch as that had been destroyed. 

 It must be owned that tin's is a very unusual 

 occurrence in compound fractures, but one sin- 

 gle example will be sufficient to prove that the 

 reproduction can take place independently of 

 the periosteum. And again, in cases where 

 disease has caused the sloughing and destruc- 

 tion of the periosteum, as for instance in deeply 

 seated paronychia, still reproduction is some- 

 times accomplished by a process resembling 

 necrosis. These arguments seem to be very 

 decisive in overturning the doctrine of the sur- 

 rounding shell being formed by the periosteum, 

 and accordingly Russell supposed that a depo- 

 sition takes place from all the surrounding 

 structures ; that it is at first gelatinous ; that it 

 soon assumes the appearance of cartilage ; and 

 that at the end of twenty-four days bony specks 

 may be discovered within it. The external 

 surface of this deposit is rough, and attached to 

 the surrounding parts : its thickness is quite 

 unequal, being greater in proportion to the du- 

 ration of the disease, and always more so than 

 the bone it is destined to replace. The internal 

 surface, or that next the old bone, is more 

 smooth, and covered either with lymph or gra- 

 nulations. Boyer, Meckel, Weidmann, and 

 other continental surgeons, attribute the process 

 nearly altogether to the periosteum, and there- 

 fore their opinions need not be particularly dis- 

 cussed ; but it is proper to mention that all the 

 very accurate descriptions we read, of the pro- 

 gress from gelatine to cartilage and from carti- 

 lage to bone, must be received with the utmost 

 caution. It is by no means usual to meet with 

 cases exemplifying these descriptions ; and 

 amongst a considerable number of dissections 

 of necrosis, it will perhaps be difficult to find 

 one in which the existence of cartilage can be 

 separately and distinctly shown. 



Such is an outline of the chief opinions en- 

 tertained on this interesting subject, and it is 

 probable that, to a certain extent, they are all 

 correct. When the periosteum has not been 

 removed or spoiled, there can be no doubt that 

 it is deeply and even principally engaged in the 

 process of reproduction. In the museum at 

 Park-street, the specimens exhibiting the earliest 

 period of the disease show the periosteum as 

 slightly thickened, smooth on its internal, but 

 more rough and flocculent on its external sur- 

 face, detached from the bone, the surface of 

 which is smooth, and scarcely appears changed 

 from its natural and healthy condition. At a 

 more advanced period, the periosteum is still 

 thicker, but is not softened ; on the contrary, 

 it has nearly the firmness of ligament, and 

 there are small osseous depositions within it ; 

 the bone then being rough and uneven on its 

 surface and evidently having lost its vitality. 



