Hip replacement surgery is a procedure in which the doctor removes the painful hip joint and replaces it with an artificial joint often made from plastic and metal components. Usually, it is done when all other treatment options have failed to provide pain relief to the patient.
Why is Hip replacement surgery done?
Some conditions can damage the hip joint and create the need for hip replacement surgery.
Osteoarthritis: It is commonly known as wear-and-tear arthritis. It damages the slick cartilage that covers the ends of bones and is helpful in moving the joints smoothly.
Rheumatoid arthritis: An overactive immune system causes rheumatoid arthritis. It produces a type of inflammation that can erode slick cartilage and occasionally underlying bone, resulting in deformed and damaged joints.
Osteonecrosis: If there is an inadequate blood supply to the ball portion of the hip joint, the bone may collapse and deform.
A hip replacement is considered if the patient is experiencing hip pain:
- Despite the pain medication, the pain persists
- Worsens with walking, even with a walker or cane
- Interferes with your sleep
- Affects your ability to climb stairs
- Difficult to rise from a seated position
Tests and Diagnosis for Hip Replacement
A medical history and physical examination of the patient are done.
An X-ray is done to diagnose the characteristic features such as spurring of the joint margins and narrowing of the joint.
Hip Replacement Surgery Procedure
Hip replacement surgery can be performed traditionally or by using a minimally-invasive technique. The only difference between the two procedures is the size of the incision made to perform surgery.
During the Procedure
The hip replacement surgery procedure takes a few hours & is performed under general anaesthesia. In the surgery, a damaged bone and cartilage are removed and then new plastic, ceramic or metal implants are used to restore the alignment and function of the hip.
- An incision is made along the side of the hip and muscles are moved to connect them to the top of the thigh bone that exposes the hip joint.
- Then, the ball portion of the hip joint is removed by cutting the thigh bone with a saw.
- After this, an artificial joint made with metal, plastic or ceramic is attached to the thigh bone using cement or any other special material that allows the remaining bone to attach to the new joint.
- The surface of the hipbone is prepared by removing any damaged cartilage and the replacement socket part is attached to the hipbone.
- The new ball is then inserted into the socket part of the hip. The doctor then reconnects the muscles and closes the incision.
Most of the hip replacement surgeries today are performed using the standard technique that includes one 8-10 inch cut along the side of the hip. In recent years, doctors are also using a minimally-invasive technique wherein doctor makes one to two cuts of 2 to 5 inches long.
However, both surgeries are performed with the same procedure.
The small cuts are thought to ease pain following surgery, lessen blood loss, shorter hospital stays, speed healing and reduce scar appearance.
After the Surgery
- The patient is likely to stay in the hospital for 4-6 days and a wedge-shaped cushion will likely be placed between the legs of the patient to keep the new hip joint in place.
- A drainage tube will likely be placed in the bladder for urination.
- Physical therapy begins the day after surgery and within days, the patient can walk with a cane, walker or crutches.
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 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.
The doctor may also order one or more specialized tests, depending on the known or suspected causes of the pain:
- Aspiration. Aspiration is a procedure in which fluid is withdrawn from the joint by a needle and sent to a laboratory for analysis. It is done to check for infection in the joint.
- Arthrogram. An arthrogram is a special type of x ray in which a contrast dye is injected into the hip to outline the cavity surrounding the joint.
- Magnetic resonance imaging (MRI). An MRI uses a large magnet, radio waves, and a computer to generate images of the head and back. It is helpful in diagnosing avascular necrosis.
- Computed tomography (CAT) scan. A CAT scan is another specialized type of x ray that uses computers to generate three-dimensional images of the hip joint. It is most often used to evaluate the severity of avascular necrosis and to obtain a more accurate picture of malformed or unusually shaped joints.
Bone densitometry test. This test measures the density or strength of the patient's bones. It does not require injections; the patient lies flat on a padded table while an imager passes overhead. This test is most often given to patients at risk for osteoporosis or other disorders that affect bone density.
Aftercare following hip replacement surgery begins while the patient is still in the hospital. Most patients will remain there for five to 10 days after the operation. During this period, the patient will be given fluids and antibiotic medications intravenously to prevent infection. Medications for pain will be given every three to four hours, or through a device known as a PCA (patient-controlled anesthesia). The PCA is a small pump that delivers a dose of medication into the IV when the patient pushes a button. To get the lungs back to normal functioning, a respiratory therapist will ask the patient to cough several times a day or breathe into blow bottles.
Aftercare during the hospital stay is also intended to lower the risk of a venous thromboembolism (VTE), or blood clot in the deep veins of the leg. Prevention of VTE involves medications to thin the blood; exercises for the feet and ankles while lying in bed; and wearing thromboembolic deterrent (TED) or deep vein thrombosis (DVT) stockings. TED stockings are made of nylon (usually white) and may be knee-length or thigh-length; they help to reduce the risk of a blood clot forming in the leg vein by putting mild pressure on the veins. TED stockings are worn for two to six weeks after surgery.
Physical therapy is also begun during the patient's hospital stay, often on the second day after the operation. The physical therapist will introduce the patient to using a walker or crutches and explain how to manage such activities as getting out of bed or showering without dislocating the new prosthesis. In addition to increasing the patient's level of physical activity each day, the physical therapist will help the patient select special equipment for recovery at home. Commonly recommended devices include a reacher for picking up objects without bending too far; a sock cone and special shoehorn; and bathing equipment.
Following discharge from the hospital , the patient may go to a skilled nursing facility, rehabilitation center, or directly home. Ongoing physical therapy is the most important part of recovery for the first The physical therapist will monitor the patient's progress, as well as suggest specific exercises to improve strength and range of motion. After the home visits, the patient is encouraged to take up other forms of physical activity in addition to the exercises; swimming, walking, and pedaling a stationary bicycle are all good ways to speed recovery. The patient may take a mild medication for pain (usually aspirin or ibuprofen) 30–45 minutes before an exercise session if needed.
Most patients can start driving six to eight weeks after the operation and return to work full time after eight to 10 weeks, depending on the amount and type of physical exertion their jobs requires. Some patients arrange to work on a part-time basis until their normal level of energy returns.
Hip replacement surgery involves both short- and long-term risks.
The most common risks associated with hip replacement are as follows:
- Dislocation of the new prosthesis. Dislocation is most likely to occur in the first 10–12 weeks after surgery. It is a risk because the ball and socket in the prosthesis are smaller than the parts of the natural joint, and can move out of place if the patient places the hip in certain positions. The three major rules for avoiding dislocation are: Do not cross the legs when lying, sitting, or standing; never lean forward past a 90-degree angle at the waist; do not roll the legs inward toward each other—keep the feet pointed forward or turned slightly outward.
- Deep vein thrombosis (DVT). There is some risk (about 1.5% in the United States) of a clot developing in the deep vein of the leg after hip replacement surgery because the blood supply to the leg is cut off by a tourniquet during the operation. The blood-thinning medications and TED stockings used after surgery are intended to minimize the risk of DVT.
- Infection. The risk of infection is minimized by storing autologous blood for transfusion and administering intravenous antibiotics after surgery. Infections occur in fewer than 1% of hip replacement operations.
- Injury to the nerves that govern sensation in the leg. This problem usually resolves over time.
The long-term risks of hip replacement surgery include:
- Inflammation related to wear and tear on the prosthesis. Tiny particles of debris from the prosthesis can cause inflammation in the hip joint and lead eventually to dissolution and loss of bone. This condition is known as osteolysis.
- Heterotopic bone. Heterotopic bone is bone that develops in the space between the femur and the pelvis after hip replacement surgery. It can cause stiffness and pain, and may have to be removed surgically. The cause is not completely understood as of 2002 but is thought to be a reaction to the trauma of the operation. In the United States, patients are usually given indomethacin (Indocin) to prevent this process; in Germany, surgeons are using postoperative radiation treatments together with Indocin.
- Changed length of leg. Some patients find that the operated leg remains slightly longer than the other leg even after recovery. This problem does not interfere with mobility and can usually be helped by an orthotic shoe insert.
Loosening or damage to the prosthesis itself. This development is treated with revision surgery.