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Hip osteonecrosis, also called avascular necrosis, impairs the blood supply to bone. Hip osteonecrosis occurs when there is an interruption of the blood supply to the head of the femur (the ball, of the ball-and-socket hip joint). The lack of normal blood supply causes a decrease in delivery of oxygen and nutrients to the bone, and the bone subsequently dies. When the bone dies, the strength of the bone is greatly diminished, and the bone is susceptible to collapse.
No one know exactly what causes hip osteonecrosis. When hip osteonecrosis occurs, the bone collapses and the joint surface, the cartilage, looses its smooth shape. Because the cartilage looses the support of the bone underneath itself, the joint surface is quickly worn away, and arthritis quickly progresses.
Most cases of hip osteonecrosis are associated with either alcoholism or steroid use. Other risk factors for developing hip osteonecrosis include sickle cell disease, trauma to the hip (dislocation or fracture), lupus, and some genetic disorders.
Hip osteonecrosis usually has few warning signs. Patients often complain of new onset hip pain and difficulty walking. Common symptoms of hip osteonecrosis include:
The two tests that are most helpful in diagnosing and treating hip osteonecrosis are X-rays and MRIs. The X-ray may be completely normal, or it may show severe damage to the hip joint. If the X-ray is normal, an MRI will be performed to look for early signs of hip osteonecrosis.
Although nonsurgical treatment options like medications or using crutches can relieve pain and slow the progression of the disease, the most successful treatment options are surgical. Patients with osteonecrosis that is caught in the very early stages (prior to femoral head collapse) are good candidates for hip preserving procedures.
This procedure involves drilling one larger hole or several smaller holes into the femoral head to relieve pressure in the bone and create channels for new blood vessels to nourish the affected areas of the hip.
When osteonecrosis of the hip is diagnosed early, core decompression is often successful in preventing collapse of the femoral head and the development of arthritis.
Core decompression is often combined with bone grafting to help regenerate healthy bone and support cartilage at the hip joint. A bone graft is healthy bone tissue that is transplanted to an area of the body where it is needed.
Many bone graft options are available today. The standard technique is to take extra bone from one part of your body (harvest) and move (graft) it to another part of your body. This type of graft is called an autograft.
Many surgeons use bone that is harvested from a donor or cadaver. This type of graft is typically acquired through a bone bank. Like other organs, bone can be donated upon death.
There are also several synthetic bone grafts available today.
Another surgical option is a vascularized fibula graft. This is a more involved procedure in which a segment of bone is taken from the small bone in your leg (fibula) along with its blood supply (an artery and vein). This graft is transplanted into a hole created in the femoral neck and head, and the artery and vein are reattached to help heal the area of osteonecrosis.
If osteonecrosis has advanced to femoral head collapse, the most successful treatment is total hip replacement. This procedure involves replacing the damaged cartilage and bone with artificial implants.
Total hip replacement is successful in relieving pain and restoring function in 90 to 95 percent of patients. It is considered one of the most successful operations in all of medicine.
Woodworth Orthopedics and Sports Medicine will help you decide how to best treat your hip osteonecrosis. Call Dr. Woodworth today at (702) 545-6194 for an appointment.
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