The hip prosthesis consists of a specially designed ball that connects to a stem and is inserted into the femur. A prosthetic cup is inserted into the worn socket. The prosthesis has a smooth surface that fits together to allow the ball to move easily and comfortably.
Today, the stem and metal cup portions of most hip implants are made of cobalt/chromium (vitallium)-based alloys or titanium. The ball portion is polished smooth and is made of the cobalt/chromium-based alloys or ceramic materials. The stem portion of the prosthesis may or may not be cemented into place. The surgeon will decide what is best for you. The most commonly used bone cement is an acrylic called polymethylmethacrylate. If bone cement is not used, the implant is covered with a textured coating to allow bone to grow in. The cup portion is not cemented; bone is allowed to grow in and hold it into place, or a screw may also be used. The liner in the cup may be metal, ceramic or durable high performance polyethylene (plastic).
One size doesn't fit all during total hip replacement surgery. Each piece is available in different sizes to accommodate many different body sizes, types and physical needs. Your surgeon will select the implant that best fits your needs. The weight of the implant will vary according to your size but, in general, may weigh one to two pounds. You will not notice the weight in your hip.