CafeDoor

This is the upper femur minus the hip capsule showing head (covered in yellow cartilage) & neck (bone, though in the babies the top of neck is still cartilage). The red cap, on the head, like a yarmulke, is the acetabulum (red indicating bone in continuum with the pelvis). It has cartilage on its inner surface which you see peeking out a wee bit. A normal femoral head is NOT fully covered by the socket. The more horizontal the socket, the more stable it is to STANDING. Not more stable. More stable to standing . Standing badly, upright & adducted, uncovers the femoral head more at the top. Being “uncovered” by hip adduction does not equate with being a bad hip joint; though a bad posture to be in. A hip socket needs some depth. It needs reasonable coverage of the top of the femoral head. But, most of all, the center of the cup, a sphere, should coincide with the center of the femoral head. If THAT isn't exact, then the socket wall was damaged.