The narrowing of the bony pelvic cavity (birth canal) by the different osteotomies of the pelvis.

We measured on pelvic models as well as on female cadaver specimens the narrowing of the bony pelvic cavity after the osteotomies according to Chiari, Salter, Sutherland, Steel, Carlioz and Tönnis. In our own patients the parameters were taken by X-ray and CT examinations as far as possible. The osteotomies according to Chiari, Salter and Sutherland lead to a more or less narrowing of the intertuber-ischial diameter of the pelvic outlet, in addition the Chiari osteotomy leads to a narrowing of the transverse diameter of the pelvic brim. The triple osteotomies according to Steel, Carlioz and Tönnis lead to a narrowing of the middle part of the bony pelvic cavity. It is necessary to inform patients who are operated after the end of growth that a future pregnancy may have to be terminated by a caesarean section.