The hip is a large joint made up of the femur and pelvic bone. The ends of these bones are covered in cartilage that acts like wax to protect the bones and allow smooth movement. Damage to this cartilage can lead to osteoarthritis and stiffness or pain. The labrum absorbs shock from movement and its damage can cause pain in the bottom, groin or lower back. The hip is surrounded by important muscles like the gluteus medius, hip flexors, piriformis, and hamstrings that help with walking, running, and other movements.