| Osteonecrosis of the Knee |
|
Although the true cause of Osteonecrosis of the knee is often not known, it can be associated with certain conditions and treatments for other diseases. These conditions include obesity, sickle cell anemia, lupus, kidney transplants, and steroid therapy. Steroid-induced osteonecrosis frequently affects multiple joints and is usually seen in young patients.
Signs and symptoms of the disease are similar to other knee problems. They can include:
Regardless of the cause, if the disease is not identified and treated early, it can develop into severe osteoarthritis. Osteonecrosis of the knee can involve the joint surface of the femur or the tibia. The stage of osteonecrosis (how advanced the osteonecrosis is) guides the treatment options available. There are four stages of osteonecrosis of the knee. X-ray, CT (cat scan) and/or MRI are necessary to make the diagnosis and determine the stage.Stage I: Symptoms are most intense in the earliest stage, and may subside in 6 to 8 weeks. Because X-rays are normal, a positive bone scan is needed to make the diagnosis. Treatment for Stage I disease is nonoperative and conservative, focusing on pain relief and protected weight-bearing. Stage II: At this point, X-rays will show some changes to bone under the joint surface. An MRI is needed to diagnose the disease. Stage III: By the time the disease reaches stage III it is clearly visible on X-rays and no other diagnostic tests are needed. The articular cartilage covering the bone begins to loosen as the bone itself begins to die. Operative treatments may be considered at this point. Stage IV: Bone collapse is seen on X-ray in stage IV. Articular cartilage is destroyed, the joint space narrows, and bone spurs may be necessary. Treatment options are determined by the stage of disease, and the person's lifestyle. Surgical treatment options include:
Knee arthoscopy and microfracture drilling is typically indicated for early stage disease. This procedure involves accessing the knee joint using the arthroscope, then drilling the area of osteonecrosis of the knee. The body recognizes the drilling of the bone as an area it needs to heal, bringing blood to the area, and potentially re-establishing a blood supply. The use of a fresh osteochondral graft for treatment of the affected area involves obtaining a matching bone from a bone bank that has been preserved. The graft includes the bone and joint surface. During the surgery the osteonecrotic area is cleared out, and the allograft is prepared to "fit" into the area that has been cleared out. Overtime, the body incorporates the new piece of bone into the joint, providing a new surface for the joint. A total joint replacement involves replacing both the femoral and tibial surfaces of the affected joint. This is usually reserved for late stage disease. |
|
| Last Updated ( Friday, 05 September 2008 ) |
