The Hip JointThe hip joint is where the pelvis and femur (thigh bone) meet and consists of a ball and socket type joint. The socket, called the acetabulum, is a part of the pelvis and accepts the ball, called the head of the femur (femoral head), which is the end of the femur closest to the body. The femoral head and acetabulum are both covered by a thick layer of articular cartilage that allows the head pivot inside the acetabulum in a nearly frictionless and pain free manner. The rim of the acetabulum is lined with a different and thicker type of cartilage called the labrum and this serves to make the socket deeper and to reduce the stresses across the hip joint
Hip ArthritisAs in any other joint, the articular cartilage that allows for smooth and pain-free motion of the hip joint can erode, leaving the exposed bone of the head of the femur and the exposed bone of the acetabulum to rub against one another. This process can result in significant pain and stiffness. Many patients with arthritis of the hip complain of pain in the front of the hip (groin area), back of the hip (buttock), or on the side. An additional complaint is stiffness of the hip joint making such activities as donning shoes and socks quite difficult.
Treatment of Hip ArthritisThe treatment of arthritis of the hip is usually divided into non-operative and operative treatments. In most cases, non-operative treatments are exhausted before operative measures are considered.
Non-operativeNon-operative treatments for arthritis of the hip include physical therapy, weight-loss, changing one’s activities, using assistive devices, such as a cane, and taking anti-inflammatory medicines. Activity modifications include reducing high-impact and repetitive activities that place increased stresses on the hip joint. The use of a cane, usually in the hand opposite the affected hip, can reduce the stress across the hip joint. Anti-inflammatory medicines, such as ibuprofen and naprosyn, can reduce the inflammation around the hip joint that is caused by the arthritis and provide significant pain relief.
OperativeIf all non-operative treatments fail, surgery is the next best option. The specific type of surgery to best treat each person can vary, and is a decision that is to be made in consultation with your orthopaedic surgeon. For most cases of advanced arthritis, a hip replacement is the treatment of choice for eliminating pain and restoring function to the hip joint.
The two most common types of replacement surgery are hip resurfacing and total hip replacement. Hip resurfacing involves placing a metal cup in the diseased acetabulum and a metal cap on the head of the femur. This type of hip replacement is only indicated in a small minority of patients with hip arthritis.
Total hip replacement is a highly successful and reproducible surgical procedure to treat advanced arthritis of the hip. The pioneering work of this procedure began in the early 1960’s with significant advancements made by our physicians and researchers at the Massachusetts General Hospital.
The surgery involves a small incision on the side of the hip to gain access to the hip joint. The diseased femoral head is removed. Both sides of the ball and socket joint are replaced with metal and plastic in a two step procedure. First, the acetabulum, or socket, is prepared to accept a hemispherical cup, usually made of metal (titanium or cobalt-chrome). The cup is positioned into the pelvis and is often held in place by friction (‘press-fit’) and occasionally by screws into the bone of the pelvis. A liner (plastic polymer, metal, or ceramic) is then attached to the inside of the cup. The back of the cup is designed so that the patient’s own bone will grow into the small holes in the metal, which allows for the metal cup to be permanently attached to the bone of the pelvis. Second, the femur is machined to accept the stem. The stem, or femoral component, is inserted into the middle of the bone. The stem is also usually made of titanium or cobalt-chrome. Over time, the bone in the femur will grow into the microscopic holes in the metal of the stem to permanently fix the stem to the femur. Occasionally, bone cement may be used to fix any of these components. A metal or ceramic ball is placed at the top of the stem. The ball on the stem is then placed inside the lining of the cup, reproducing the ball and socket joint of the native hip.