Hip Replacement

Hip replacement, or arthroplasty of the hip, is a surgical procedure in which the damaged or diseased parts of the hip joint are removed and replaced with new, artificial parts or hardware. Hip replacement is usually done to relieve refractory pain, to increase mobility or to correct a fracture or deformity. The procedure, primarily reserved for those over the age of 60 in the past, is becoming more prevalent among younger, more active people.

Other Names

• Hip arthroplasty
• Total hip replacement
• Hip hemiarthroplasty

Description

The hip joint is a ball and socket joint. The ball is the femoral head, and is part of the femur (upper leg or thigh bone). The socket is the acetabulum, part of the pelvic bone. The femoral head (ball) fits into the acetabulum (socket) and is lubricated by the synovial fluid, which helps with joint movement. In a healthy hip, the surfaces of the ball and socket are smooth and move easily past each other. Arthritis or other conditions make the surfaces rough and cause pain as the hip joint moves.

Why Hip Replacement Is Done

The main indications for hip replacement surgery are pain unrelieved by medicine, loss of motion or deformity of the hip joint.

Some other indications for hip replacement are:

• Pain severe enough to cause lack of sleep
• No relief or incomplete relief from pain medicine
• Difficulty walking up and down stairs
• Difficulty standing
• Inability to mantain an active lifestyle because of pain

Common causes for deterioration of the hip joint are:

• Osteoarthritis
• Traumatic hip injury
• Rheumatoid Arthritis
• Osteonecrosis
• Tumors of the bone

Hip replacement surgery may also be necessary to repair a broken hip. The need for hip replacement instead of surgical pinning of the patient's own hip joint depends on the exact location of the break. If the break is close to the head of the thigh bone (femur), typically hip replacement surgery is indicated. A partial hip replacement called hemiarthroplasty (hemi from the Greek for half) is performed for certain fractures of head and neck of the femur.

Types

There are several different types of hip replacement surgeries:

Conventional

Conventional hip replacement surgery exposes the muscles overlying the hip joint during surgery. The muscles are repaired at the end of the procedure. The hip joint is usually replaced with a metal (usually chrome or titanium) ball and plastic (polyethylene) socket which may have a metal shell. The new joint is either cemented in place, fixed with screws, or bone is encouraged to grow and fix the new joint in place. The incision size is tailored to the size of the patient and is generally between 6 and 12 inches. This type of surgery has become more efficient (quicker and with a smaller incision) over the past few years.

Mini incision

In this procedure, a smaller (three or four inch) incision is made on the side of the hip. The muscles on the side of the hip tend to heal easier than those on the back and front on the hip, thus decreasing blood loss, procedure time, and recovery time.

Two incision (MIS 2)

In this procedure, two small incisions are made, one on the anterior (front) of the hip and used to place the socket of the hip joint, the other incision on the posterior (back) part of the hip and used to place the ball part of the joint. Typically, the muscles are moved aside during the procedure rather than being cut as in conventional hip replacement surgery. This procedure involves less pain, less cutting, quicker recovery time but is not used in patients who are obese, have significant hip deformity, or have osteoporosis. Surgeons are required to have additional training to perform this procedure.

Preparation for Hip Replacement

Some things that may make the hip replacement and recovery go more smoothly:

• Requesting information such as pamphlets and contact phone numbers and web sites to learn as much about the procedure and recovery as possible
• Strengthening the upper body to make crutches or a walker easier to maneuver
• Arranging for home care and placing things within reach on the first floor will decrease pain and joint dislocation caused by excessive movement.
• Losing weight prior to the procedure will decrease the load on the new joint
• Quitting smoking will decrease healing time
• Non-steroidal anti-inflammatory medicines are generally stopped one week prior to surgery

A thorough medical examination is done to assess any potentially complicating problems. In addition, a dental examination is done to rule out any sources of infection that may complicate recovery.

How Hip Replacement Is Done

Hip replacement surgery is performed by an orthopedic surgeon who has specialized training in surgery of the bones.

During a traditional hip replacement, which is a one to two hour procedure, the surgeon makes an incision over the hip through the muscles and removes the diseased bone tissue and cartilage from the hip joint, while leaving the healthy parts of the joint intact. Then the surgeon replaces the head of the femur and acetabulum with new, artificial replacement parts. The new hip is made of materials that allow a natural gliding motion of the joint. Usually the new hip is made of a metal ball and a very high density plastic head,sincethese have been proved to last the longest. In recent years, some surgeons have begun performing mini incision and two incision hip replacement, which require smaller incisions and a shorter recovery time than traditional hip replacement. Candidates for this type of surgery are usually age 50 or younger, of normal weight based on body mass index, and healthier compared to candidates for traditional surgery. Joint resurfacing is also being used as an alternative to hip replacment.

There are two types of hip prostheses (replacement parts):

Cemented

Cemented parts are fastened to existing, healthy bone with a special glue or cement. Hip replacement using these parts is referred to as a cemented procedure. Cemented replacements are more frequently used for older, less active people and people with weak bones, such as those who have osteoporosis, while uncemented replacements are more frequently used for younger, more active people.

Uncemented

Uncemented parts rely on a process called biologic fixation, where a porous surface is created that allows new bone to grow into the pores and hold the parts in place. The primary disadvantage of an uncemented prosthesis is a somewhat longer recovery period. Because it takes longer for the bone to grow into the prosthesis, a person with an uncemented replacement may have to limit weightbearing for up to six weeks to protect the hip joint (depending on surgeon preference).

Sometimes a combination of cemented and uncemented parts are used; this combination is referred to as a hybrid replacement. Typically a cemented stem and uncemented cup are used in this type of procedure.

Studies show that cemented and uncemented prostheses have comparable rates of success. Studies also indicate that if additional hip replacement, or revision, is needed, the rates of success for cemented and uncemented prostheses are comparable. However, more long-term data are available in the United States for hip replacements with cemented prostheses, because doctors have been using them here since the late 1960s, whereas uncemented prostheses were not introduced until the late 1970s.

Benefits

For the majority of people who have hip replacement surgery, the procedure results in:

• Decreased pain
• Increased mobility
• Improvements in activities of daily living
• Improved quality of life.

Risks

According to the American Academy of Orthopaedic Surgeons, more than 193,000 total hip replacements are performed each year in the United States and more than 90% of these do not require revision.

New technology and advances in surgical techniques have greatly reduced the risks involved with hip replacements.

Complications

• The most common hip problem that may arise soon after hip replacement surgery is hip dislocation. Because the replacement ball and socket are smaller than the normal ones, the ball can become dislodged from the socket if the hip is placed in certain positions. The most dangerous position usually is with the knees pulled up to the chest.
• The most common later complication of hip replacement surgery is an inflammatory reaction to tiny particles that gradually wear off of the artificial joint surfaces and are absorbed by the surrounding tissues. The inflammation may trigger the action of special cells that may cause destruction of some of the bone, causing the implant to loosen. To treat this complication, the doctor may use anti-inflammatory medications or recommend revision surgery (a subsequent surgery to replace an artificial joint). Medical scientists are experimenting with new materials that last longer and cause less inflammation.
• Heterotopic bone formation (bone growth beyond the normal edges of bone). Studies are also looking at the use of bisphosphonates, ciprofloxacin, pentoxifylline, and other medications to prevent this bone resorption around the implants.
• Leg length discrepancy which may be caused by the prosthesis or by weakness in the muscles of the hip
• Breakage of the prosthesis which may require an additional surgery for replacement
• Wound infection, which often can be treated with antibiotics but rarely requires removal of the prosthesis

Other (systemic) complications include:

• Blood clots in the deep veins of the leg (deep vein thrombosis or DVT) that can move to the lung and cause pulmonary embolism (PE)
• Urinary infection or difficulty with urination
• Pneumonia that may result from difficulty taking deep breaths and coughing after anesthesia

Related problems

Hip replacement is one of the most successful orthopaedic surgeries performed. Studies have shown that more than 90% of people who have hip replacement surgery will never need to replace an artificial joint. However, because more people are having hip replacements at a younger age, and wearing away of the joint surface becomes a problem after 15 to 20 years, replacement of an artificial joint, which is also known as revision surgery, is becoming more common. It is more difficult than first-time hip replacement surgery, and the outcome is generally not as good, so it is important to explore all available options before having additional surgery.

Doctors consider revision surgery for two reasons: if medication and lifestyle changes do not relieve pain and disability, or if x rays of the hip show damage to the bone around the artificial hip that must be corrected before it is too late for a successful revision. This surgery is usually considered only when bone loss, wearing of the joint surfaces, or joint loosening shows up on an x ray. Other possible reasons for revision surgery include fracture, dislocation of the artificial hardware, and infection.

Effectiveness

In the past, doctors reserved hip replacement surgery primarily for people over 60 years of age. The thinking was that older people typically are less active and put less stress on the artificial hip than do younger people. In more recent years, however, doctors have found that hip replacement surgery can be very successful in younger people as well. New technology has improved the artificial parts, allowing them to withstand more stress and strain and last longer.

Today, a person's overall health and activity level are more important than age in predicting a hip replacement's success. Hip replacement may be problematic for people with some health problems, regardless of their age. For example, people who have chronic disorders such as Parkinson's disease, or conditions that result in severe muscle weakness, are more likely than people without chronic diseases to damage or dislocate an artificial hip. People who are at high risk for infections or in poor health are less likely to recover successfully. Therefore they may not be good candidates for this surgery. Recent studies also suggest that people who elect to have surgery before advanced joint deterioration occurs tend to recover more easily and have better outcomes.

Recovery

Immediately after surgery

Immediately after hip replacement surgery, the patient rest to allow the cut made by the surgeon to heal and the body to recover from the anesthetic. During this time, pillows or special devices are usually used to brace the hip in the correct position. Intravenous antibioitics are usually given to prevent infection of the new hip and fluids may also be given to replace fluids lost during surgery. Often blood transfusions may also be required. There also may be a tube located near the incision to drain fluid and prevent infection around the joint. A type of tube called a catheter may be placed into the bladder to drain urine until the patient is able to use the bathroom. The doctor will prescribe medicine for pain or discomfort. Usually medicines are also given to prevent blood clots, which are not uncommon after hip replacement surgery and can be serious. This may include heparin or low molecular weight heparin which thin the blood and are given by injections into the stomach, or warfarin which is given as a tablet. Blood tests are usually taken every day or so after the surgery to make sure that no blood transfusion is necessary and to make sure the body is recovering well from surgery.

On the day after surgery or sometimes on the day of surgery, therapists begin to teach patients exercises to improve recovery. Since pneumonia is a severe complication in patients who have undergone major surgery, respiratory therapists may be involved, and ask patients to breathe deeply, cough, or blow into a simple device that measures lung capacity. This is called an incentive spirometer. These exercises reduce the collection of fluid in the lungs after surgery and to prevent lung collapse (atelectasis).

As early as one to two days after surgery, patients may be able to sit on the edge of the bed, stand, and even walk with assistance. Patients are often amazed by how quickly this is possible, but it is vital to the recovery of a patient to start the process of physical therapy as early as possible.

While still in the hospital, physical therapists may teach patients exercises such as contracting and relaxing certain muscles, which can strengthen the hip. Because the new, artificial hip has a more limited range of movement than a natural, healthy hip, the physical therapist also will instruct on the proper techniques for simple activities of daily living, such as bending and sitting, to prevent injury to the new hip.

Recovery and rehabilitation

Usually, people do not spend more than three to five days in the hospital after hip replacement surgery. Occasionally there is a need for futher care in a skilled nursing facility or rehabiliation hospital. Most people with hip replacement will require two to three months of physical therapy to improve motion, strength, balance, endurance and function. General recovery from the surgery takes about three to six months, depending on the type of surgery, a patient's overall health condition, and the success of rehabilitation. Full recovery can take up to year at times.

Physical therapy and exercise after hip replacement

Proper exercise can reduce stiffness and increase flexibility and muscle strength. This includes range-of-motion activities and muscle-strengthening exercises. The doctor or therapist are usually instrumental in deciding when a patient can move on to more demanding activities. Many doctors recommend avoiding high-impact activities, such as basketball, jogging, and tennis at least temporarily if not permanently. These activities can damage the new hip or cause loosening of its parts. Some recommended exercises are walking, stationary bicycling, swimming, and cross-country skiing. These exercises can increase muscle strength and cardiovascular fitness without injuring the new hip.

Alternatives to Hip Replacement

Before considering a total hip replacement, the doctor may try other methods of treatment, such as exercise, walking aids, and medication. In young patients, doctors will often try hard to delay hip replacement since their prosthesis may not last, and revision surgery may become necessary at a later time.

Excercise and motility aids

• An exercise program can strengthen the muscles around the hip joint.
• Walking aids such as canes and walkers may alleviate some of the stress from painful, damaged hips and help patients to avoid or delay surgery.

For hip pain without inflammation, doctors usually recommend the analgesic medication acetminophen (Tylenol).

Medication

• For hip pain with inflammation, treatment usually consists of nonsteroidal anti-inflammatory drugs, or NSAIDs. Some common NSAIDs are aspirin and ibuprofen (Motrin, Advil). NSAIDs on a long-term basis should only be used under a doctor's supervision as they can have side effects in the kidney and stomach. When neither NSAIDs nor analgesics are sufficient to relieve pain, doctors sometimes recommend combining the two. Again, this should be done only under a doctor's supervision.
• In some cases, a stronger analgesic medication such as tramadol or a product containing both acetaminophen and a narcotic analgesic such as codeine may be necessary to control pain.
• Topical analgesic products such as capsaicin and methylsalicylate may provide additional relief. Some people find that the nutritional supplement combination of glucosamine and chondroitin helps ease pain. People taking nutritional supplements, herbs, and other complementary and alternative medicines should inform their doctors to avoid harmful drug interactions.
• In a small number of cases, doctors may prescribe corticosteroid medications, such as prednisone or cortisone, if NSAIDs do not relieve pain. Corticosteroids reduce joint inflammation and are frequently used to treat rheumatic diseases such as rheumatoid arthritis. The downside of corticosteroids is that they can cause further damage to the bones in the joint. Also, they carry the risk of side effects such as increased appetite, weight gain, and lower resistance to infections. A doctor must prescribe and monitor corticosteroid treatment. Because corticosteroids alter the body's natural hormone production, which is essential for the body to function, their ingestion should not be stopped suddenly, but in consultation with a doctor.
• Sometimes, corticosteroids are injected into the hip joint. A joint lubricant such as Hyaluronan may also be injected into the hip joint to relieve pain.

Other procedures

• If exercise and medication do not relieve pain and improve joint function, the doctor may suggest a less complex corrective surgery before proceeding to hip replacement. One common alternative to hip replacement is an osteotomy. This procedure involves cutting and realigning bone, to shift the weight from a damaged and painful bone surface to a healthier one. Recovery from an osteotomy takes 6 to 12 months. Afterward, the function of the hip joint may continue to worsen and additional treatment may be needed. The length of time before another surgery is needed varies greatly and depends on the condition of the joint before the procedure.
• Hip resurfacing involves reshaping the damaged bone and capping the head of the femur (ball) with a metal prosthesis. The socket (acetabulum) may also be resurfaced with metal. The procedure was developed in the 1960s but fell out of favor because the early material used (Teflon) had a high rate of failure. Hip resurfacing is popular in Europe, but was only FDA approved in the United States in 2006. ^[1] Benefits include maintaining more original bone and forming a larger hip ball (thus decreasing the risk of dislocation). Risks include the possibility of small fragments of metal shearing from the joint and entering the bloodstream. The particles are removed by the kidneys, so this procedure is also not recommended if the patient has diabetes or kidney disease. Osteoporosis is also a contraindication since the risk of fracture is increased in this condition.

Experts on Hip Replacement

The Hip Society has a search engine to find orthopedic surgeons who perform hip replacement.

The American Academy of Orthopaedic Surgeons also has a search engine.

Research

To increase the chance of surgical success and decrease the risk of complications and prosthesis failure, researchers are working to develop new surgical techniques, more stress-resistant materials, and improved prosthesis designs. They are also studying ways to reduce the body's inflammatory response to the artificial joint components.

Researchers are also studying gender and ethnic discrepancies in those who have the procedure, and characteristics that make some people more likely to have successful surgery.

Other areas of research address issues of recovery and rehabilitation, such as appropriate postsurgical analgesia for older people, and home-health and outpatient programs.

Joseph Zuckerman, professor & chair of the Department of Orthopaedic Surgery at NYU's Hospital for Joint Diseases, discusses how innovations in materials used for joint replacement allow formerly crippled patients to live pain-free:

Clinical Trials

There are many ongoing clinical trials related to hip replacement surgery. A list is available here

References

1. ↑ U.S. Food and Drug Administration, Center for Devices and Radiological Health. New Device Approval: Birmingham Hip Resurfacing (BHR) System - P040033. Full Text

External Links

American Academy of Orthopaedic Surgeons (AAOS)

American Physical Therapy Association

Arthritis Foundation

The Hip Society

Hip Replacement.com