None — Osteonecrosis
Osteonecrosis (also known as avascular necrosis or aseptic necrosis) is the death of an area of bone. Bone is living tissue that needs a blood supply to survive. When the blood supply is disrupted or cut off, the bone in the affected area dies. Eventually, the dead bone tissue may collapse.
A common cause of osteonecrosis is trauma. A fracture, dislocation or other type of injury can damage the blood vessels feeding the area and interfere with circulation to the bone. Other possible causes include: steroid use, excessive consumption of alcohol, past history of radiation or chemotherapy, certain medical conditions, like sickle cell disease, cancer and systemic lupus erythematosus. In many cases, the cause of osteonecrosis is unknown.
The National Osteonecrosis Foundation estimates, annually, about 20,000 Americans develop osteonecrosis. It can occur at any age, but most patients are between 20 and 50 at the time of diagnosis. The most commonly affected bone is the femur (the thigh bone, which forms the hip joint). In the early stages, a patient may be unaware of any damage to the bone. As the bone dies, pain or aching may occur, especially during activity. Eventually, the pain can occur even at rest. Patients may have limited movement and stiffness in the affected joint.
Hip Replacement
When the hip joint is severely damaged by disease or trauma, or when medical treatments don't provide relief from symptoms, a physician may recommend total joint replacement. The diseased parts of the hip (usually the ball of the femur and a part of the hip socket) are removed and replaced with an artificial joint (called a prosthesis).
The American Academy of Orthopaedic Surgeons estimates 193,000 hip replacements are performed in the U.S. annually. Traditionally, surgeons make a 10- to 12-inch incision along the side of the hip. The muscles are separated to access the bones and the hip is dislocated. The joint surfaces are exposed and the damaged sections removed. A cup-shaped socket is secured to the hip and a new femoral head (ball) with a long metal stem is secured into the femur. The incision is then closed.
SuperPATH®
A new method of hip replacement is called, SuperPATH® (also referred to as the "Northern Approach". SuperPATH stands for Supercapsular Percutaneously-Assisted Total Hip. The patient is placed on his/her side and a small (2- to 4-inch) incision is made into the tip of the hip. The diseased portions of the joint are removed. Then, using special instruments and techniques, the new joint is built inside the body. Doctors don't have to dislocate the hip or cut through muscles and tendons.
With the smaller incision and minimal disruption to surrounding tissues, patients have less blood loss during surgery, less post-operative pain and scarring and a faster recovery time. Jimmy Chow, M.D., Surgeon with St. Luke's Medical Center in Phoenix, AZ, says the hip is more stable, even right after surgery. Most patients are out of the hospital in 24 hours. Rehabilitation time is minimal and some patients are able to enjoy leisure activities as soon as three days after surgery.
Chow says SuperPATH can be used for most patients who are candidates for hip replacement, including overweight and elderly patients. The procedure is very new and currently only available through a few surgeons worldwide. However, other surgeons are now learning the technique. For information, you can contact him through his website.
For information about SuperPATH® hip replacement, click here or here
For general information on hip replacement:
American Academy of Orthopaedic Surgeons Arthritis Foundation
For information about osteonecrosis (avascular necrosis) of the hip:
National Institute of Arthritis and Musculoskeletal and Skin Diseases National Osteonecrosis Foundation