The pubic bone, the ischium and the ilium make up the pelvic girdle, fused together as one unit.

http://en.wikipedia.org/wiki/Pelvic_fracture

The pubic bone, the ischium and the ilium make up the pelvic girdle, fused together as one unit. They attach to both sides of the spine and circle around to create a ring and sockets to place hip joints. Attachment to the spine is important to direct force into the trunk from the legs as movement occurs, extending to one’s back.