The hip joint is a ball and socket joint, where the head of the thigh bone (femur) articulates with the cavity (acetabulum) of the pelvic bone.
Avascular necrosis is a condition of decreased blood supply to the bone causing death of bone tissue. Causes include bone fractures affecting the blood vessels, alcohol abuse, long-term steroid use, cancer treatments, and conditions such as sickle cell anemia and lupus.
Avascular necrosis commonly affects the head of the femur but can affect any bone. Necrosis leads to tiny cracks on the bone which finally causes the head of the femur to collapse. The condition causes pain due to increased pressure in the blood vessels of the bone marrow at the region of the necrosis.
Early stages of avascular necrosis can be treated by core decompression surgery, which reduces pressure, promotes blood flow, and encourages healing of the bone.
Core decompression is indicated in the early stages of avascular necrosis when the surface of the head is still smooth and round. It is done to prevent total hip replacement surgery, which is indicated for severe cases of avascular necrosis and involves the replacement of the hip joint with an artificial device or prosthesis.
Core decompression is done under spinal or general anesthesia. The patient is placed on their back in the supine position. Live X-ray imaging or fluoroscopy is used to guide your surgeon during the procedure.
A small incision is made on your hip and a guidewire is passed from the incision through the neck of the femoral bone to the necrotic area in the femoral head. A hole is then drilled along the wire. The necrotic bone is then removed. This reduces the pressure immediately and creates space for the new blood vessels to grow and nourish the existing bone.
The cavity that is left behind in the bone is sometimes filled with bone graft taken either from another part of your body or a deceased donor. Sometimes synthetic bone graft material is used. The incision is then closed with sutures. Another variation of the same surgery involves drilling very small diameter holes from a single point. The surgical wound, in this case, is very small and may require only a single suture.
After the operation, crutches are to be used for 6 to 12 weeks to prevent weight bearing at the hip joint until the femur bone heals completely. You will be able to resume your regular activities 3 months after the surgery.
The advantages of core decompression include the following:
- Prevents complications of collapse of the femoral head
- Preserves bone of the femur
- Delays the need for total hip replacement where the diseased femur head is replaced with an artificial prosthesis.
Risks and Complications
As with all surgeries, core decompression may be associated with certain complications such as:
- Fracture along the core track
- Perforations in the femoral head
- Deep vein thrombosis
Core decompression is a prophylactic surgery indicated to treat avascular necrosis at its initial stages. It is a relatively safe procedure and can be performed on both hips during the same surgery if needed.