J9S 



PELVIS. 



consequently the greatest share of supporting 

 the weight of the body, falls nearer the left leg 

 and the left side of the pelvis. The effect is 

 such as to produce great similarity in the form 

 of all these pelves, which vary only in the de- 

 gree of distortion. The sacral promontory is 

 directed to the left side, while the sacral con- 

 cavity is more or less twisted so as to face 

 the left acetabulum. The innominate bone 

 of the left side is placed lower and more ver- 

 tical than that of the right side, which appears 

 longer and less bent ; so that the left ischial 

 tuberosity projects lower and more vertically 

 than the right, which is everted and directed 

 outwards. The left acetabulum is brought 

 nearer to, and more directly under, the sacral 

 promontory, the cotylo-sacral arch being more 

 curved than the right ; while the right sacro- 

 iliac joint and lateral sacral mass are higher, 

 the cotylo-sacral curve more open, the 

 iliac wing more spread, and directed, .like the 

 acetabulum, more forwards, and the ischio- 

 pubic ramus placed more obliquely, than those 

 on the left side. 



In the female Hunterian skeleton, the ob- 

 liquity of the spine and pelvis are so great, 

 that the upper dorsal vertebrae are placed 

 above the right sacro-iliac joint. The femora 

 are shortened, and curved forwards and out- 

 wards, and the leg bones forwards and inwards, 

 in compensating curves. The left knee, how- 

 ever, is more under the line of gravity than the 

 right. A tendency to a somewhat similar 

 twist is seen in an adult hydrocephalic ske- 

 leton in the same collection. 



These pelves present, at first sight, some re- 

 semblance to the very different " obliquely 

 ovate" pelvis of Naegele. The most charac- 

 teristic differences are, the presence of other 

 rickety appearances, and the want of the co- 

 incidence of lateral deviation of the pubic 

 symphysis with the sacro-iliac ankylosis and 

 malformation of the latter. 



Rokitansky includes all the pelves which 

 present a want of symmetry at the sides under 

 the general term of oblique pelves, after Osian- 

 der's classification, in which he comprehends 

 by far the greatest number of pelvic deformi- 

 ties of all kinds. He gives, as a characteristic 

 of this class, approximation of the sacral 

 promontory to the pectineal eminence on one 

 side, which side has also a higher level and a 

 less pelvic inclination than the opposite one, 

 originating in a lateral curve and torsion of 

 the sacrum towards the contracted side, and 

 straightening out of the linea innominata on 

 the opposite side, between the sacro-iliac joint 

 and the acetabulum. It includes the frequent 

 pelvic deviations resulting from lateral curva- 

 ture of the spine, but most frequently arises 

 from rickets, or displacement of the femur 

 by hip-joint disease or violence. 



To a rickety child, who rarely begins to 

 walk till after the usual age, by far the most 

 frequent positions are thr two which we have 

 just considered, and the mechanism of these 

 positions, in my own estimation, is quite suf- 

 ficient to account for the first impression of 

 the most frequent deformity of the rickety 



pelvis, the ovate, as well as for the not un- 

 common angular infantile distortion. 



In standing and walking the supporting pres- 

 sure on the pelvic structures is sustained, 

 either divided or alternately undivided, be- 

 tween the cotyloid cavities and the sacrum. 

 From the peculiar disposition of the cotyloid 

 articulation, the pressure of the head of the 

 femur is exerted in two directions, 1st, upward 

 and backwards along the cotylo-sacral rib, 

 which is the principal line of pressure, and, 2nd, 

 inwards on the lateral pelvic arch. In the up- 

 right position the softened cotylo-sacral rib 

 yields in the direction of its C curve, which 

 becomes more acute as the sacrum sinks. An 

 increased obliquity of the pelvic inclination, 

 such as has been stated to be generally conse- 

 quent upon the advance of the sacral promon- 

 tory and increased lumbar curve in the ellipti- 

 cal deformity, will bring the line of gravity, 

 both of the trunk and whole body, in front of 

 the acetabular supports, which will cause them 

 to increase the backward curve when pressure 

 is exerted upon them (see Jig. 122. E, a b.), 

 But that such a condition is produced by a 

 greater obliquity of the normal infant pelvis 

 than that of the adult, or that this alone is 

 sufficient to account for the elliptical defor- 

 mity taking place usually in the infant pelvis, 

 by causing divergence of the acetabula under 

 pressure during the upright posture, as asserted 

 by Dr. Murphy, is a conclusion which the re- 

 sults of the observations given in a former 

 section, as well as those of Weber, therein 

 stated, will not at all admit of ; for, as was 

 there seen, the obliquity of the normal infant 

 pelvis is not at all ^greater, if as great, as that 

 of the adult. 



But if the acetabula are already separated 

 by the elliptical deformity, or if the leg bones 

 yield inwards, so that the pressure on the aceta- 

 bular articular surface at its upper vaulted part 

 is directed upwards and outwards, as seen in the 

 accompanying diagram (fig. 122. B, a, 6), then 

 the pressure inwards of the heads of the fe- 

 murs upon the lateral pelvic arches is taken 

 off, there is traction instead of pressure on 

 the pubic tie, the acetabula become still more 

 widely separated, and the elliptical deformity 

 increased. In such specimens of ovate pel- 

 vic deformity as have the leg bones attached, 

 I have found the tibiae and fibulas bent much 

 inwards, or the leg bones so disposed by an 

 inward knee-bend as to take off the inward 

 pressure at the acetabula, and even sometimes 

 by extreme adduction of the femurs, so as to 

 exercise a strain upon the round ligaments of 

 the hip joint and rotator muscles, and thus pro- 

 duce a direct outward traction. In this posi- 

 tion of the bones, the action of the adult 

 muscles which support the erect posture viz., 

 the great glutei and psoae, will be such as to 

 increase the deformity (seeder. 122. E, c d), as 

 well as those before mentioned which sustain 

 the spine erect. 



If the angular deformity have been already 

 impressed upon the infant pelvis by the 

 bending of the cartilaginous junction, while 

 the bones of the legs, and in some degree those 



