PELVIS. 



203 



Extremes of dif- 

 ference between 

 the two sides. 



1 . From the sciatic tuberosity of | f rom j to 



one side to the posterior su- > if j nc j ieSt 

 perior iliac spine of the other J 



2. From the anterior superior iliac 1 from 10 



spine of one side to the pos- J- lines to 1 

 terior superior of the other J in. 1 1 lin. 



3. From the spine of the last lum- "I from 8 



bar vertebra to the anterior j- lines to 1 

 superior iliac spine J in. 4 lines. 



4. From the trochanter major of! from 1 in. 



one side to the posterior su- j- to I in. 

 perior iliac spine of the other J 7 lines. 



5. From the lower border of the "I from 7 



pubic symphysis to the pos- 1- lines to 1 

 terior superior iliac spine J inch. 



In these measurements it is to be remarked, 

 that the first presents the mosl marked dif- 

 ferences on the two sides. This results from 

 the fact that the sciatic tuberosity of the an- 

 kylosed side is placed more posteriorly than 

 the '^opposite one, while the posterior supe- 

 rior iliac spine is lower on the side free from 

 ankylosis. Hence it results that the ankylosis 

 is always found on that side of which the sciatic 

 tuberostty is nearer to the opposite posterior su- 

 perior iliac spine. These two points on a lean 

 subject are easily to be distinguished. On the 

 fat subject, there is, in the position of the iliac 

 spine, a depression caused by the firmer attach- 

 ment of the integuments to the bone at that 

 place. 



Another test of the presence of the ob- 

 lique deformity practised by Naegele was, 

 to place the patient upright with the back 

 against an even wall, so that the shoulders and 

 nates should equally touch it, and then drop- 

 ping two plumb-lines, one from the spine of 

 the first sacral or last lumbar vertebra, and the 

 other from the centre of the lower border of 

 the pubic symphysis. In the well-formed pel- 

 vis, the plane in which these two lines fall, 

 forms two right angles with the plane of the 

 wall, but in the pelvis obliquely deformed, it 

 is an obtuse angle on the ankylosed side, and 

 an acute angle on the side opposite ; the dif- 

 ference between these two angles marking the 

 degree of distortion. 



Cause of the obliquely deformed pelvis. 

 Dr. Naegele was inclined to the opinion that 

 the cause of this peculiar condition of the 

 pelvis was, an arrest of development of one 

 side of the sacrum and the corresponding in- 

 nominate bone ; with ossification of the joint 

 instead of its normal development. The 

 following reasons led him to this conclusion. 

 The intimate and complete fusion of the 

 bones into one piece ; and the absence of any 

 mark or cicatrix indicating a former separa- 

 tion, except a scarcely perceptible line on the 

 upper aspect of the place of junction ; a 

 section of the ankylosis exhibiting an uniform 

 areolar texture in the internal structure. The 

 defective development, in its whole length, of 

 the ankylosed side and lateral mass of the 



sacrum, as well as of the innominate bone 

 in breadth, as particularly exhibited in the 

 narrowing of the sciatic notch ; and the 

 analogy herein drawn, from the defective de- 

 velopment and fusion of other bones, especi- 

 ally those of the cranium. The great re- 

 semblance between the several pelves affected 

 by this disease, which argues identity of cause ; 

 original deficiency of development being more 

 likely to produce similarity of results than the 

 accidental and subsequent inflammation. And 

 lastly, the presence of the distortion from the 

 earliest period, together with the youth of 

 the individuals affected, and the total absence 

 of any symptoms whatever, indicating an ex- 

 ternal cause for the distortion, in the whole 

 course of their history. 



In two of the cases of this deformity, there 

 had been present disease of the hip joint, 

 which in one had led to the formation of a 

 false acetabulum ; but this was not, in the 

 opinion of the above-named author, the cause 

 of the oblique distortion. He had never seen 

 the distortion coincident with rickets, though 

 he suggests the possibility of such a compli- 

 cation. 



Rokitansky also considers this deformity 

 to be a congenital malformation, and not a 

 consequence of foetal intra-uterine disease. 



Dr. Knox adopts the theory that the 

 arrest of development having taken place 

 while the ossification of the sacrum was in- 

 complete, the whole of that side of die pelvis 

 remains thereafter stationary in its foetal or 

 brute transitional form, while the other ad- 

 vances to complete development ; and thus 

 one side is perfect, while the opposite is 

 simply that of an undeveloped pelvis magnified. 

 This anatomist also states, that in the mu- 

 seum of Dr. Outrepont there is a female pelvis 

 presenting the oblique deformity on both 

 sides, producing a superior opening of a very 

 elongated shape, with its broadest part towards 

 the sacrum. 



The lateral epiphysial sacral pieces, which 

 form the auricular surface, appear in the ob- 

 lique deformity to have failed in establishing a 

 separate identity, though the presence of the 

 sacral holes and transverse lines and grooves 

 lead to the supposition that the number of the 

 primary ossific points has been normal. Un- 

 der this supposition, the coalescence of the 

 sacrum and ilium would, probably, take place 

 between the sixth and ninth months of intra- 

 uterine life, (at which time the characteristic 

 ossific points of the three first sacral vertebrae 

 begin to appear,) by the prolongation into 

 them of the ossifying process from the ilium 

 or " pleurapophysis," already considerably ad- 

 vanced in its bony development. 



Another hypothesis as to the cause of the 

 ankylosis. is found in the occurrence of in- 

 flammatory disorganisation, after the com- 

 plete formation of the sacro-iliac joint, and, 

 as a consequence, oblique deformity of the 

 bones. Dr. Rigby inclines to this theory, and 

 thinks that ulcerative absorption must have 

 existed in the joint, though probably in early- 

 life. 



