Hip joint replacement is surgery to replace all or part of the hip joint with an artificial device (a prosthesis).

The hip is a ball and socket joint, linking the "ball" at the head of the thigh bone (femur) with the cup-shaped "socket" in the pelvic bone. A total hip prosthesis is surgically implanted to replace the damaged bone within the hip joint.

The total hip prosthesis consists of three parts:

• A cup that replaces your hip socket. The cup is usually plastic, although some centers are trying other materials like ceramic and metal.
• A metal or ceramic ball that will replace the fractured head of the thigh bone.
• A metal stem that is attached to the shaft of the bone to add stability to the prosthesis.

If the surgery is a "hemi-arthroplasty," the only bone replaced with a prosthetic device is the head of the femur.

You will receive an extensive preoperative evaluation of your hip to determine if you are a candidate for a hip replacement procedure. Your health care provider will assess the degree of disability, impact on your lifestyle, and pre-existing medical conditions. The health care provider will also evaluate your heart and lung function.

The surgery will be performed using general or spinal anesthesia. The orthopedic surgeon makes an surgical cut, often over the buttocks, to expose the hip joint. The head of the thigh bone is removed and removed. Then, the hip socket is cleaned out and a tool called a reamer removes all of the remaining cartilage and arthritic bone.

The new socket is implanted, after which the metal stem is inserted into the thigh bone. The artificial components are fixed in place, sometimes with a special cement. The muscles and tendons are then replaced against the bones and the surgical cut is closed.

You will return from surgery with a large dressing on the hip area. A small drainage tube will be placed during surgery to help drain excess fluids from the joint area. Many surgeons also place a knee immobilizer or special pillow between the legs in the operating room to prevent the hip from dislocating.

You will have moderate to severe pain after surgery. However, you will receive painkillers for the first day or more after surgery. Painkillers may be given through a vein ( intravenously, or IV) through the spinal cord (an epidural), or by way of a special patient-controlled analgesia (PCA) device.

The pain should gradually decrease, and by the third day after surgery, painkillersk, taken by mouth, may be sufficient to control your pain. Try to schedule your pain medications about 30 minutes before walking or changing position.

You will also return from surgery with several IV lines in place to provide fluids and nutrition. The IV will remain in place until you are drinking adequate amounts of fluids.

If the procedure is elective (planned in advance rather than in response to an injury), you can donate blood several weeks prior to surgery to replace any blood lost during the procedure.

Sometimes, the blood that is drained from the wound during surgery is collected in a special sterile container to be reinfused through an IV after surgery.

You will also return from surgery wearing special stockings or inflatable compression stockings, which are used to reduce your risk of developing blood clots . Blood clots are more common after leg surgery.

Start moving and walking early after surgery. On the first day after surgery, you should get out of bed to a chair. When in bed, perform ankle exercises frequently to prevent development of blood clots.

You may be instructed on how to use a device called a spirometer, which shows how much air you breathe in at one time. You'll be shown how to gradually increase the depth of each breath you take, and to perform deep breathing and cough procedures to prevent pneumonia.

A Foley catheter may be inserted during surgery to monitor your kidney function and fluid level. It will be removed after surgery. You will be encouraged to try to walk to the bathroom with assistance.

Hip joint replacement is primarily done in people age 60 and older. The operation is usually not recommended for younger people because of the strain they can put on the artificial hip, causing it to fail prematurely.

The reasons for replacing the hip joint include:

• Fractures in the elderly of the neck of the femur (usually requires a hemi-arthroplasty)
• Hip joint tumors
• Severe arthritis pain that limits a person's ability to do the things they want to do

This surgery is usually not recommended for:

• Current hip infection
• Extreme obesity (weight over 300 pounds)
• Nerve disease affecting the hip
• Paralyzed quadriceps muscles
• People with poor skin coverage around the hip
• Serious physical disease (terminal disease, such as metastatic cancer)
• Those with severely limiting mental dysfunction
• Very young patients

• Blood clots in the legs (deep vein thrombosis), which can break free and move to the lungs (pulmonary embolus)
• Dislocation of the artificial hip
• Extra bone growth that can cause stiffness
• Infection that requires removal of the artificial hip
• Pneumonia

The results are usually excellent. The operation relieves pain and stiffness, and most patients need no help walking.

With time -- sometimes as long as 20 years -- the artificial joint will loosen and revision surgery will become necessary. Younger people may wear out the lining of their new cup and need it replaced before the artificial hip loosens.

You will remain in the hospital for 3 to 5 days after surgery. However, some people may need to stay temporarily at a rehabilitation unit or long-tern care center until mobility has improved and they are safely able to live independently. These centers will provide intensive physical therapy to assist you in regaining muscle strength and flexibility in the joint.

Be careful after surgery that you don't dislocate the artificial hip. The new hip will not have the same range of movement of the original joint, although you should eventually be able to return to your previous level of activity. While you should avoid vigorous sports such skiing or contact sports, many people go on to play tennis and golf quite successfully.

The use of crutches or a walker may be necessary for as long as 3 months, although most people who did not use them before are able to walk without them in several weeks.

Many surgeons place their patients on blood thinners for several weeks after surgery to help prevent blood clots. These may be taken in the form of pills (either Coumadin or aspirin) or injections.

SPECIAL PRECAUTIONS

The new joint has a limited range of movement. You will need to take special precautions to avoid displacing the joint, including:

• Avoid crossing your legs or ankles even when sitting, standing, or lying.
• When sitting, keep you feet about 6 inches apart.
• When sitting, keep your knees below the level of your hips. Avoid chairs that are too low. You may sit on a pillow to keep your hips higher than your knees.
• When getting up from a chair, slide toward the edge of the chair and then use your walker or crutches for support.
• Avoid bending over at the waist. You may consider purchasing a long-handled shoehorn or a sock aid to help you put on and take off your shoes and socks without bending over. Also, an extension reacher or grabber may be helpful for picking up objects that are too low for you to reach.
• When lying in bed, place a pillow between your legs to keep the joint in proper alignment.
• A special pillow or splint may be used to keep the hip in correct alignment.
• An elevated toilet seat may be necessary to keep the knees lower than the hips when sitting on the toilet.

Harkess JW. Arthroplasty of the hip. In: Canale ST, Beatty JH, eds. Campbell's Operative Orthopaedics. 11th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 7.

St Clair SF. Hip and knee arthroplasty in the geriatric population. Clin Geriatr Med. Aug 2006; 22(3): 515-33.

Jones CA. Total joint arthroplasties: current concepts of patient outcomes after surgery. Rheum Dis Clin North Am. Feb 2007; 33(1): 71-86.