Osteonecrosis of the hip fundamentals
Osteonecrosis (ON) of the hip affects approximately 10,000 to 20,000 new patients annually in the United States. It is a bone disease that causes a break down of the hip joint. Osteonecrosis can also affect other joints, such as the knee and ankle joints.
Children and teenagers can develop Legg-Calve-Perthe’s disease, which is a form of osteonecrosis. With this form of ON, the top of the thighbone (femur) loses circulation, causing the cells in the bone to die. The bone will soften and become vulnerable to collapse when exposed to pressure. Over time, the top of the femur will heal in a collapsed position, which causes the patient stiffness and pain.
What are the causes?
Lack of blood supply to the bone causes osteonecrosis of the hip. Our bones are nourished and supported by a supply of blood. If this blood supply is interrupted, the section of the bone that is not receiving blood dies.
Osteonecrosis can also be caused by bone fractures that interrupt the necessary blood supply to nourish the bone. A traumatic injury, such as a dislocation of the hip, may also cause osteonecrosis. A hip dislocation forces the ball and socket bones out of position, and may put patients at risk for developing the disease. Patients should keep in mind that minor injuries normally do not cause osteonecrosis, and even major traumas rarely cause the disease.
Other diseases may also result in osteonecrosis, due to the deteriorating health of the bone. These diseases include lupus, kidney and liver disease, sickle cell anemia, and blood clotting disorders. High alcohol consumption, long-term use of corticosteroid drugs, local radiotherapy, and high-dosage shots of cortisone may also lead to development of the disease. Approximately 30 percent of patients who develop osteonecrosis have no prior risk for the disease and are otherwise healthy. It is not known why these patients develop the disease.
For patients that develop osteonecrosis of the hip, the symptoms develop over time. The first symptoms are pain and aching in the hip joint, or a throbbing pain in the groin near the hip, or in the buttock. Stiffness in the joints and limping are also typical of the disease. You should contact your physician immediately if you start to feel any of these symptoms.
Your physician will take an X-ray or CAT scan to help in diagnosing osteonecrosis of the hip. An MRI can also detect osteonecrosis by indicating tissue changes.
What are the treatment options?
Treatment for osteonecrosis of the hip depends on whether the disease has gone unprotected for a long time and has progressed to a point where the joint cannot be saved. Since most cases of osteonecrosis of the hip occur in people under 40, the goal of treatment is to preserve the hip joint before turning to total hip replacement surgery. Hip replacement surgery is only conducted when determined absolutely necessary by your doctor. Click here for more information on hip replacement surgery. [link to content]
Conservative treatment, such as protective weightbearing, is usually not an appropriate form of treatment for osteonecrosis of the hip. This form of treatment should only be temporary until your doctor provides a treatment plan.
The course of treatment for osteonecrosis of the hip depends on the condition of the patient and their medical history. Particularly for hip replacement surgery, the decision to have surgery depends on the age of the patient, physical condition, the pain they are experiencing, their response to medication and the stage of the disease.
What are the risks of surgery?
There are possible risks and complications that may happen through hip replacement surgery associated with anesthesia, including respiratory or cardiac malfunction. Other complications include:
- Blood clots
- Injury to nerves and blood vessels
- Stiffness or instability of the joint
- Need for additional surgeries
Patients who are at an increased risk for complications are those with severe rheumatoid arthritis or systemic lupus. In addition, patients with insulin-dependent (type 1) diabetes, malnourishment, hemophilia, or those who have had previous prosthetic joint infections are at higher risk. Make sure to contact your orthopaedic surgeon immediately if you experience any of these problems after surgery.
Joint replacements do not last forever, usually 10-15 years. Hip revision surgery may become necessary when an artificial hip becomes painful. Click here for more information on hip revision surgery.
What happens during surgery?
In addition to hip revision surgery or hip replacement surgery [link to content], there are other surgical treatment options for patients that provide relief for less severe cases. Core decompression is a simple procedure and is used in mild to moderate cases of the disease. This procedure involves removing some of the bone in the hip area by creating a hole in the bone. Patients use crutches after the procedure to ensure the hole in the bone is not fractured. Bone grafting involves removing the dead bone and putting a bone graft in its place. The graft is taken from the patient or a bone bank. Patients may also have a vascularized bone graft, which involves receiving a graft with blood vessels, so a fresh blood supply does not have to be created for the graft. Crutches are then used by the patient for up to a year to promote healing and recovery.
Osteotomy treatment may be recommended in special cases. For this procedure, the bone below the infected area is cut and turned so that another portion of the bone that is not affected is the new weight-bearing area of the joint. Femoral head resurfacing and femoral head replacement are treatments that can slow the progression of the disease. Femoral head preservation has been shown to be extremely successful in cases of non-arthritic hip joints. For femoral head resurfacing, a metal head is attached over the original femoral bone. The femoral head replacement procedure involves replacing the femoral head (top) of the bone and inserting a stem inside the femoral bone.
When the femoral head has collapsed or deteriorated due to arthritis, total hip arthroplasty is recommended. Hip arthroplasty is the procedure of choice for pain relief and to restore hip function. The timing of this procedure will depend on the patient’s age, diagnosis and symptoms.
How frequently should I schedule follow up appointments with my doctor following surgery?
If surgery is the best treatment for you, make sure to schedule your first evaluation within the recommended timeframe indicated by your surgeon. If you have a problem before you schedule your first return appointment after surgery, call your doctor’s physician assistant immediately.
It is important to comply with this schedule and to see your doctor regularly for routine office visits to ensure safe and effective recovery.
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