What is a hip replacement?

Indications and Procedures

The most common reason for hip replacement
surgery is the decline in efficiency of the hip joint that often results from osteoarthritis. Osteoarthritis is a common form of arthritis
that causes joint and bone deterioration, which may lead to the wearing down of cartilage and cause the underlying bones to rub against each other. This may result in severe pain
and stiffness in the affected areas. Other conditions that may lead to the need for hip replacement include rheumatoid arthritis
(a chronic inflammation of the joints), avascular necrosis (loss of bone caused by insufficient blood supply), and
injury.

Generally, physicians may be more inclined to choose less invasive techniques such as physical therapy, medication, or walking
aids before resorting to surgery. In some cases, exercise programs may help reduce hip pain. In addition, if preliminary treatment does not improve the patient’s condition, doctors may use corrective surgery that is not as invasive as hip replacement.

Typically, a candidate for total hip replacement surgery (THR) possesses a hip that has worn out from arthritis, falls, or other conditions. The hip consists of a ball-and-socket joint wherein the head of the femur (thigh bone) fits into the hip socket, or acetabulum. In a normal hip, this arrangement provides for a relatively wide range of motion. For some older adults, however, deterioration caused by arthritis and other conditions reduces the effectiveness of this arrangement, compromising the integrity of the hip socket or the femoral head. This state can lead to extreme discomfort.

Total hip replacement may provide the best long-term relief for these symptoms. Total hip replacement involves the removal of diseased bone tissue and the replacement of that tissue with prostheses (artificial devices used to replace missing body parts). Usually, both the femoral head and the hip socket are replaced. The femoral head is replaced with a metal ball that is attached to a metal stem and placed into the hollow marrow space of the femur. The hip socket is lined with a plastic socket. Other materials have also been used effectively as hip replacements.

In some cases, the surgeon will use cement to bond the artificial parts of the new hip to the bone tissue. This approach has been the traditional method of ensuring that the artificial parts hold. One problem with this method is that over time, cemented hip replacements may lose their bond with the bone tissue. This may result in the need for an additional surgery. However, a cementless hip replacement has been developed. This approach includes a prosthesis that is porous so that bone tissue may grow into the metal pores and keep the prosthesis in place.

Both procedures have strengths and weaknesses. In general, recovery time may be shorter with cemented prostheses, since one does not have to wait for bone growth to attach to the artificial prostheses. However, the potential for long-term deterioration of the replaced hip must be considered. A cemented hip generally lasts about fifteen years. With this in mind, physicians may be more likely to use a cemented prosthesis for patients over the age of seventy. Cementless hip replacement may be more advisable for younger and more active patients. Some physicians have used a combination of approaches, known as a “hybrid” or “mixed” hip. This combination relies on an uncemented socket and a cemented femoral head.

Uses and Complications

Total hip replacements are generally quite successful, with about 98 percent of surgeries proceeding without serious complications. In rare instances, however, complications occur, including blood clots and infections during surgery and hip dislocation or bone fracture after surgery. In addition, in some cases, bone grafts may be used to assist in the restoration of bone defects. In these instances, bone may be obtained from the pelvis or the discarded head of the femur. Other postoperative complications may include some pain and stiffness.

Patients recovering from total hip replacement usually remain in the hospital up to ten days if there are no complications. However, physical therapists may initiate therapy as soon as the day after surgery. Physical therapy involves the use of exercises that will improve recovery. Many patients are able to sit on the edge of their bed, stand, and even walk with assistance as early as two days after surgery. Patients must remember that their artificial hip may not provide the same full range of motion as an undiseased hip. Physical therapists teach patients how to perform daily activities without placing an undue burden on their new hips. This may require learning a new method of sitting, standing, and performing other activities.

While many factors may affect recovery time, full recovery from surgery may take up to six months. At that point, many patients enjoy such activities as walking and swimming. Doctors and physical therapists may discourage patients from participating in such high-impact activities as jogging or playing tennis, which may burden the new hip. Despite these restrictions, many patients are able to perform normal activities without pain and discomfort. Nonetheless, people who have undergone hip replacement surgery are advised to consult with their doctors about proper exercise and activity levels.

Perspective and Prospects

Total hip replacement is one of the most common surgical interventions that older adults face. The American Academy of Orthopedic Surgeons estimates that more than 285,000 hip replacement surgeries are performed in the United States each year. The majority of hip replacements are performed on individuals over the age of sixty-five. One of the reasons for this is that the activity level of older adults is lower than that of younger adults, therefore reducing the concern that the new hip will wear out or fail. However, technological advances have improved the quality of the artificial hip, making hip replacement surgery a more likely intervention for younger adults as well.

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