Core Decompression is used for young patients with initial stages of osteonecrosis of the hip, before the head collapses.
The patients is usually on crutches for 6 – 24 weeks. The results depend on the size of the osteonecrosis. In small size damages, the core decompression has up to 80% successful results. In advanced stages, the results can be less than 30% successful.
This is the most used operation to treat the osteonecrosis of the hip. It is called "decompression operation" because the operations is based on the idea that the blood pressure in the bone tissue around the death bone focus is increased.
Opening the area of the dead bone from outside will attain three objectives:
lower – decompress the blood pressure
restore the blood circulation to the dead bone tissue
The surgeon hopes that a new, healthy bone tissue will grow into the necrotic (dead) bone and rebuild it successively. To help the replacement process, the surgeon may remove the dead bone and replace it with healthy bone chips taken from the patient’s skeleton.
The operation is carried out under fluoroscopic (X-ray) guidance.
The surgeon puts first a guide wire through the neck of the femoral bone from the outside of the hip joint (trochanter) into the area of dead bone. (There are other ways how to access the necrotic bone area in the femoral head that are more difficult). On this wire the surgeon then puts a drill head that makes a canal through the femoral neck to open the area of the necrotic bone.
After opening ( "decompressing") the necrotic bone area, the surgeon may stop there.
Many surgeons, however, remove the dead bone tissue and replace it with patient’s own small "fresh" bone chips. The cells in the "fresh" crushed bone tissue are of course dead but the "fresh" bone tissue contains hormones (bone morphogenetic protein hormones) that entice formation of the new healthy bone tissue that successively rebuilds the inlaid bone chips.
The patient must use protective weight bearing at least 6 weeks or longer if the decompression canal was larger. The results depend on the stage of the disease. In early stages, before the femoral head collapses, there are up to 80 % successful results with healed necrosis. In later stages of the disease, when the surface femoral head already was damaged, there are less than 30% successful results.