A System of Midwifery

by Edward Rigby

“If the superior strait does not constantly present the same figure in deformed pelvis; if it is sometimes larger on one side than the other; if one of the acetabula is nearer to the sacrum, while the other approaches less; if the symphysis of the pubes is removed in many cases from a line which would divide the body into two equal parts, it is because the rickets has not equally affected all the bones of the pelvis, nor equally hurt all their junctions; and because the attitude which the child takes in walking or sitting may change a little the direction of the compressing power, which I have just mentioned.” (Baudelocque, translated by Heath, vol. i. p. 60.) Nor is it necessary that the degree with which the disease affects the different parts of the pelvis should vary in order to produce these inequalities of distortion, for there is no reason to suppose that the promontory of the sacrum would approach the symphysis pubis in a straight line, even where the softening of the bones was uniform throughout; the attitude of the child, as above-mentioned, and the manner in which it supports itself, will have no inconsiderable influence in determining the direction in which the distortion takes place.

In those instances where the promontory is forced low down into the pelvic cavity, the sacrum becomes bent upon itself, the upper part of it forming a sharp curve backwards, while its lower portion together with the coccyx being confined by their attachments, and more or less compressed by sitting, are directed forwards. This is not seen where the projection of the promontory is but slight; the curve of the sacrum so far from being increased is rather lessened; the sacrum is straighter and flatter than usual, so that, although the brim of the pelvis is contracted, we not unfrequently find the outlet even larger than natural: in other cases, where the softening of the bones has gone to a considerable extent, the outlet is diminished, from the tubera ischii having been forced inwards.

The degree to which the promontory projects, of course, varies considerably. The distortion is occasionally so great as not even to leave an inch of antero-posterior diameter. This excessive deformity, however, is more frequently the result of mollities ossium coming on after puberty, for we seldom find children live through this critical period where it has been the result of rickets. The brim of a deformed pelvis varies considerably in shape: “sometimes it has the form of a kidney, or that of the figure eight (∞); sometimes it is triangular or heart-shaped, the sides being curved inwards, from the acetabula having been pressed backwards or inwards, the ossa pubis are bent forwards and outwards, and form at their symphysis a sort of beak-like process, which is the apex of the heart: in this species of deformed pelvis, which is usually the result of mollities ossium, the outlet also is usually much distorted: this arises from the tubera ischii being forced nearer to each other, thus contracting the pubic arch.” (Naegelé’s Lehrbuch, 2te Ausgabe, p. 247.)

From Naegelé.

Malacosteon, or mollities ossium. An arthritic, rheumatic, or gouty diathesis is a morbid state, in which softening of the bones may take place at a much later period of life, and to a most extraordinary extent. In almost all the cases of extreme pelvic deformity which have been recorded, the distortion has been owing to this disease, and not to rickets in early life: in a pathological point of view there is a considerable analogy between these two diseases. From a variety of causes there is a superabundant formation of acid in the system, which its excreting organs are unable to throw off. The effects of this condition will vary according to circumstances; among them the softened state of the bones from a deficiency of insoluble bone earth is not the least remarkable. Mollities ossium seldom attacks women who have had no children: sometimes it begins shortly after delivery, and very frequently during pregnancy, during the progress of which it continues to increase. Hence, it occasionally happens, that a woman has given birth to several healthy living children without any unusual difficulty in her labours, and where, after this, the pelvis has gradually become so deformed from mollities ossium, as to render delivery impossible by the natural passages, and, therefore, to require the Cæsarean operation. Pelves of this sort, may be easily distinguished from those which have been deformed in early life by rickets; they have evidently attained their full adult growth before the process of softening had commenced: the ilia, for instance, are of the natural size, but bent across, as if they had been folded like wet pasteboard; whereas, the bones of the ricketty pelvis have not attained their full development, they are stunted in growth as well as distorted in shape, the two processes, viz. of growth and distortion, having evidently, co-existed.

The form of the pelvis in mollities ossium necessarily varies with the peculiar circumstances under which the individual is placed: thus, if her strength allows her to sit up, or even to get about, as is generally the case more or less, the promontory and the pubic bones are gradually pressed towards each other, so that the antero-posterior diameter is greatly diminished:[123] if, however, she is confined entirely to bed for a considerable period, the distortion takes a different and much rarer form. From her lying first on one side and then on the other, the pelvis is laterally compressed; the transverse diameter becomes even shorter than the antero-posterior; and if the disease continues long enough, the pelvis is at length so altered and mis-shapen, that nearly all its original configuration is obliterated. The weight of such a pelvis varies considerably: where the disease has ceased some time before death, and bone earth has been again deposited, there will be little difference in this respect from a natural healthy pelvis; but if the patient has died with the disease in full activity, its weight will be greatly diminished, amounting sometimes only to a few ounces.

Mollities ossium, to a slight extent, we believe, is not very uncommon, although cases of extreme deformity from this cause are of rare occurrence. Mr. Barlow states, that “eight cases of this species of progressive deformity have fallen under my notice, in one of which the projection of the last lumbar vertebra at its union with the angle of the sacrum was so much bent forwards into the cavity of the pelvis, that on the introduction of the fore-finger up the vagina, a protuberance was presented to the touch very much resembling the head of the fœtus pretty far advanced into its cavity. On carrying the finger a little anteriorly past the projection, I could with difficulty ascertain the head of the child: but on moving it around, the distortion appeared so great, that the whole circumference did not exceed that of a half-crown piece. This occurrence was on the 29th of April, 1792, at which time I delivered the woman with the crotchet, and the bones of the pelvis receded considerably to the impulsive efforts during the extraction of the head of the fœtus; yet, notwithstanding, the flexibility of the bones of the pelvis, and the debilitated state of her constitution, she recovered speedily and without interruption.” On the 2d February, 1794, being in the neighbourhood, and learning that she was still alive, Mr. Barlow visited her and requested an examination. “I found her unable to walk without assistance, and as she sat, her breast and knees were almost in contact with each other. The superior aperture was nearly in the same state as when I delivered her with the crotchet, but the outlet appeared more contracted, the rami of the pubes overreached, leaving a small opening under the symphysis barely sufficient to admit the finger to pass into the vagina by that passage, and another aperture below, but rather larger, and parallel with the junction of the tuberosities of the ossa ischii. From what I learned afterwards respecting this decrepit female, she survived this period about two years, at which time she was become still more distorted in the spine; and after her death it was with difficulty she could be put into her coffin; this woman bore nine children, and died in the thirty-ninth year of her age.” (Barlow’s Essays, p. 329.)

Mollities ossium may be feared when, in addition to the general breaking up of the health and strength, the patient suffers from arthritic pains and swellings of the limbs, the urine is generally loaded with lithic secretion: and most of all, where distinct shortening and gradual distortion of the skeleton is taking place. Where the deformity has been the result of rickets in early life, a little careful observation of the patient’s external appearance will quickly lead the experienced eye to suspect the nature of the case.