Each hip prosthesis is made up of several parts:

	The acetabular component or cup replaces the acetabulum. The acetabular component can either be made of a metal alloy outer shell with a fitted plastic, metal or ceramic liner or it can be made of a one plastic component.
	The femoral component replaces the femoral head. The femoral component can be single or two piece design. The single piece is made of metal alloy. While the two piece design consists of the femoral stem, made of metal alloy and the femoral head that attaches to the stem can be made of either ceramic or metal alloy. This is known as a modular prosthesis. Envelopes of tough ligaments connect the pelvis and femur, covering the joint and stabilizing it. The hip joints movements are initiated and controlled by the thick muscles of the buttock at the back and the thick muscles of the thigh at the front.
A healthy hip joint will allow the leg to move freely within it’s range of motion, while supporting the upper body and absorbing the impact that results from activities such as walking and running.