Bone marrow pressure in osteonecrosis of the femoral condyle (Ahlbäck's disease).

Concerning the clinical, radiographic, and scintigraphic aspects of Ahlbäck's disease, there are similarities with avascular necrosis of the femoral head. In 1980, therefore, we introduced a method of measuring bone marrow pressure which had been used in cases of osteoarthritis and pain in the knee. The measurement is done in the medial and lateral femoral condyle and in the medial part of the tibial head. Our findings were increased values in all stages of the disease, indicating that early (preradiographic) diagnosis and a differential diagnosis between osteoarthritis and osteonecrosis are possible using this method alone. We treat the earliest stages by core biopsy only (the bone cylinder is sent for histological classification) and have had very good results to date.