in the femur what features articulates with the os coxa
The head of the femur articulates with the os coxa (pelvis) at the  acetabulum. The acetabulum is the rounded socket that the head of  the femur fits into. It also allows sl â¦ iding of the pelvic bones and  rotation. This joint is a synovial joint and is an example of a  ball-and-socket joint.