BONE, PATHOLOGICAL CONDITIONS OF. 



441 



they receive more blood. The periosteum has 

 undergone analogous changes. The chemical 

 composition is not the same throughout. Thus, 

 on the one hand, there is notalways the same rela- 

 tion between the respective proportions of phos- 

 phoric acid and lime sometimes too much, 

 sometimes too little of the acid : on the other, 

 the proportion between the animal and earthy 

 substance varies considerably. Sometimes the 

 quantity of animal matter is greatly increased, 

 so that the relation is 74 : 26, or even 75,8 : 24,2, 

 or so far as 79,54 : 20,6. Often it is the same 

 as that met with in the healthy condition, or it is 

 even less, as 25,5 : 74,5,* although the bones are 

 spongy. These differences depend probably 

 on the intensity, and, more particularly, on the 

 period of the disease ; but they prove, at least, 

 that the essence of rickets does not consist in 

 an original deficiency of earthy material. 



It is unnecessary to quote any farther autho- 

 rities to shew that no universality of opinion 

 prevails as to the pathology of this important 

 disease, and that it still requires careful and 

 accurate investigation. It seems, however, to 

 be agreed on, that when the patient begins to 

 recover, a great activity may be observed in the 

 deposition of the earthy material, and that it is 

 principally deposited where it is most wanted, 

 viz. on the concave surfaces of the curves. 



Fragilitas. We have classed a brittle con- 

 dition of the bones under the head of a dispro- 

 portionate abundance of the earthy substance, 

 rather in compliance with a doctrine that was 

 once universally believed, and perhaps is still 

 pretty generally admitted, than as the statement 

 of a fact that may be supported by evidence. 

 It was supposed that the presence of a greater 

 quantity of phosphate of lime rendered the 

 bone short-grained and dry, and therefore 

 more liable to snap across ; and this condition 

 of bone, as peculiarly appertaining to old age, 

 has been placed by Boyer among the predis- 

 posing causes of fracture.f The opinions of 

 Ilibes on this subject, and the doubt cast by 

 chemical analysis on the ordinary explanations 

 of a softened condition of bone on the one 

 hand, and of its fragility on the other, have 

 been already noticed, and, notwithstanding some 

 attention to the subject, we are obliged to leave 

 it without even attempting a solution of the 

 difficulty ; the results even of several series of 

 experiments, which were instituted in the years 

 1831 and 1832, with a view to the elucidation 

 of this difficult question, scarcely deserve to be 

 stated, as they were in every respect unsatis- 

 factory. We compared the respective thick- 

 ness of the thigh-bone in the adult and the 

 aged, the section being made exactly in the 

 middle : we weighed equal lengths of similar 

 bones we softened equal lengths and equal 

 weights by means of dilute muriatic acid 

 and we burned equal portions and weights 

 also, with a view of comparing them under 

 these different circumstances, but could never 



* These chemical results are quoted by Meckel 

 from Monro's Outlines of Anatomy. 



t Traite des Maladies Chirurgicales, torn. iii. p. 

 22. 



arrive at any fixed or certain conclusions. In 

 one remarkable instance the bone of a wo- 

 man, who must have been seventy or eighty 

 years of age, was thicker, stronger, and con- 

 tained more both of the animal and earthy 

 materials than any adult bone with which it 

 was compared. We were, therefore, obliged 

 to adopt M. Kibes' theory of " a change of 

 action," just as we see the muscle of an old 

 man incompetent to such a display of strength 

 as would be easy to that of a younger person, 

 although the latter may be smaller, and pos- 

 sessed apparently of less toughness of fibre. 



Fragility seems to exist under two different 

 conditions, one derived from, or having rela- 

 tion to, some defect or imperfection in the 

 bone itself; the other being rather a symptom 

 of some other disease than a disease itself, and 

 arising from some vice or taint in the constitu- 

 tion. The former of these is exhibited in the 

 fragility occasionally observed in the bones of 

 some young persons, and more constantly in 

 those of the old ; but it may be remarked that 

 the causes that produce this fragility (whatever 

 they are) do not interfere with the restorative 

 powers of the part. True, a fractured bone is 

 tedious in uniting, and is frequently followed 

 by unpleasant consequences in aged persons, 

 but in such all the vital powers exhibit evi- 

 dence of sluggishness and debility; whilst in 

 youth, so far from fragility interfering with the 

 process of union, fractured bones have been 

 observed to be consolidated in even less than 

 the usual period. But when any particular 

 condition of constitution or any disease seems 

 to be the exciting cause of fragility, it may 

 also be regarded as a cause of subsequent non- 

 union. Of these, cancer, fungus haematodes, 

 and sea-scurvy, seem to furnish the most nu- 

 merous and best authenticated instances ; sy- 

 philis has been added, probably from the fact 

 of some fractures remaining disunited until 

 the patients had been subjected to a course of 

 mercury; its influence, however, is question- 

 able, unless where it had previously produced 

 caries. A state of pregnancy or of lactation 

 has been mentioned as predisposing to fracture, 

 and impeding or delaying the process of re- 

 union ; but however the observation might 

 have been occasioned by a few solitary cases, 

 it is not borne out by general experience. 



In the fragility of early youth, and where 

 union would take place quickly and kindly, it 

 is not to be expected that the bone (if there 

 was an opportunity of examining it) should 

 present any morbid appearances unless the 

 evidences of its physical weakness in the small- 

 ness of its diameter and the thinness of its 

 walls should be so considered. In the aged, 

 as all persons are not afflicted with this fragility, 

 so are there some whose bones cannot be dis- 

 tinguished from those of the healthy adult. 

 As to the ordinary characters of the hones of 

 old persons, Mr. Wilson remarks they are 

 never found so friable and fragile as to crumble 

 like a calcined bone, but, on the contrary, they 

 contain a large quantity of oil ; and when 

 dried after death, they are so greasy as to be 

 unfit to be preserved as preparations. Their 



