Last updated: 11/24/2009

Hip replacement surgery is a relatively recent procedure that had to wait for the invention of plastics and other synthetic materials to make reliable prostheses that could withstand years of wear. The first successful total hip replacement was performed...

in 1962 by Sir John Charnley (1911–1982), a British orthopedic surgeon who designed a device that is still known as a Charnley prosthesis. Charnley used a stainless steel ball mounted on a stem that was inserted into the patient's thighbone to replace the femoral head. A high-density polyethylene socket was fitted into the acetabular side of the joint. Both parts of the Charnley prosthesis were secured to their respective sides of the joint with an acrylic polymer cement. More recent developments include the use of cobalt chrome alloys or ceramic materials in place of stainless steel, as well as methods for holding the prosthesis in place without cement.

As of 2003, there are three major types of hip replacement surgery performed in the United States: a standard procedure for hip replacement; a newer technique known as minimally invasive surgery (MIS), pioneered in Chicago in February 2001; and revision surgery, which is done to replace a loosened or damaged prosthesis.

Standard hip replacement surgery

A standard hip replacement operation takes 1-1/2–3 hours. The patient may be given a choice of general, spinal, or epidural anesthesia. An epidural anesthesia, which is injected into the space around the spinal cord to block sensation in the lower body, causes less blood loss and also lowers the risk of blood clots or breathing problems after surgery. After the patient is anesthetized, the surgeon makes an incision 8–12 in (20–30 cm) long down the side of the patient's upper thigh. The surgeon may then choose to enter the joint itself from the side, back, or front. The back approach is the most common. The ligaments and muscles under the skin are then separated.

Once inside the joint, the surgeon separates the head of the femur from the acetabulum and removes the head with a saw. The surgeon uses a power drill and a special reamer to remove the cartilage from the acetabulum and shape it to accept the acetabular part of the prosthesis. This part of the new prosthesis is a curved piece of metal lined with plastic or ceramic.

After selecting the correct size for the patient, the surgeon inserts the acetabular component. If the new joint is to be cemented, the surgeon will attach the component to the bone with a type of epoxy. Otherwise the metal plate will be held in place by screws or by the tightness of the fit itself.

To replace the femoral head, the surgeon first drills a hollow inside the thighbone to accept a stem for the femoral component. The stem may be cemented in place or held in place by the tightness of the fit. A metal or ceramic ball to replace the head of the femur is then attached to the stem.

After the prosthesis is in place, an x ray is taken to verify that it is correctly positioned. The incision is then washed with saline solution as a safeguard against infection. The sutures used to close the deeper layers of tissue are made of a material that the body eventually absorbs, while the uppermost layer of skin is closed with metal surgical staples. The staples are removed 10–14 days after surgery.

Finally, a large triangular pillow known as a Charnley pillow is placed between the patient's ankles to prevent dislocation of the hip during the first few days after surgery.

Minimally invasive hip replacement surgery

Minimally invasive surgery (MIS) is a new technique of hip replacement introduced in 2001. Instead of making one long incision, the surgeon uses two 2-inch (5 cm) incisions or one 3.5-1/2-inch (9 cm) incision. Using newly designed smaller implements, the surgeon removes the damaged bone and inserts the parts of the new prosthesis. MIS hip replacement takes only an hour and a half; there is less bleeding and the patient can leave the hospital the next day. As of 2002, however, obese patients or those with very weak bones are not considered for MIS.

Revision surgery

Revision surgery is most commonly performed to replace a prosthesis that no longer fits or functions well because the bone in which it is implanted has deteriorated with age or disease. Revision surgery is a much more complicated process than first-time hip replacement; it sometimes requires a specialized prosthesis as well as bone grafts from the patient's pelvis, and its results are not usually as good. On the other hand, some patients have had as many as three revision operations with satisfactory results.