What does a hip prosthesis look like?
A hip prosthesis is an imitation of the normal hip. In the operation, the ball of the hip is removed and the remaining cartilage in the socket is milled out (see Illustration B).
Then the components of the new hip are inserted. The new socket is made of plastic and metal. Then a metal pin with a small head on top will be inserted into the thigh bone. This fits exactly into the plastic socket. This pin is also called the stem or voice.
There are different ways of securing the parts. Our orthopaedists usually clamp the metal socket into the original hip socket. This way, the bone grows into the prosthesis. This growth is achieved after about 6 weeks. Sometimes one or two screws are inserted to ensure extra firmness.
In the metal socket a plastic component is placed that is traditionally made of durable plastic.
The metal stem consists of titanium and can be placed in two ways:
The stem can be fixed in the thighbone with special cement (methyl methacrylate). Here, too, a firm anchoring must be achieved through the growth of bone; as mentioned earlier, this requires about six weeks. On the other hand, the metal stem can be clamped into the femur, without the use of cement. Whether cement is used or not depends on the quality of the bone and the age of the patient.
The lifespan of the hip prosthesis is on average between 15 and 20 years.