Treatment of avascular necrosis depends on the severity and the age of onset. If the disease is caught early, non-operative treatments, such as crutches to redistribute weight on the femoral head, and range-of-motion (ROM) stretching may be recommended. In most cases, however, surgical intervention is necessary.
Early in the disease process, an outpatient procedure called a Core Decompression can be performed. Through a 1 cm incision on the side of the thigh a small drill is used to create a channel into the necrotic bone. This allows a conduit for new blood vessels to enter the femoral head to speed the resorption and repair phase.
Sometimes a synthesized, highly-concentrated bone morphogenic protein (BMP2) is injected into the necrotic area to further aid in healing. A hip abduction brace is worn full time for 6 weeks after surgery and then at night for several months. The surgery becomes more invasive based on the amount of deformity and symptoms, such as stiffness and pain.
We use the technique of hip joint distraction to treat more advanced stages of avascular necrosis. Technically called hip arthrodiastasis, the procedure involves attaching an external fixator to the pelvis and femur. A core decompression can also be performed, and often stiff, contracted muscles are released through small incisions during this surgery. The fixator is used to acutely push the entire femur, including the femoral head, away from the hip joint by approximately 1 cm. This joint distraction unloads the femoral head to prevent further collapse but allows the hip to move into flexion and extension to prevent stiffness. The fixator is removed after 14 weeks and a brace is used as with the core decompression.
Advanced stages of avascular necrosis can be treated with a more involved surgery called a Safe Surgical Dislocation and Femoral Head Reduction Osteotomy (FHRO). Originally described in Sweden by Dr. Ganz in 2001, this is a complex hip surgery performed routinely at only a few specialized centers in the world. We have modified the original procedure and have been performing it for AVN and Perthes for over a decade with excellent long-term results.
We start with a surgical dislocation of the hip, where the femoral head is removed from the hip joint and visualized. The necrotic bone is then excised and a bone graft applied. We also inserts bone-morphogenic protein (BMP), a growth factor that induces bone to grow. A membrane is then inserted over the bone graft and the BMP, reshaping the femoral head back into a spherical shape. We will then apply an external fixator and distract the hip out of the joint. The external fixator unloads the femoral head, giving it time to heal. The body's weight is supported through the fixator which crosses the hip joint.
Once the femoral head has healed, the external fixator is removed and the femoral head is supported through internal screws. Physical therapy is necessary in order to regain and maximize hip range-of-motion (ROM) and strength.