Osteonecrosis (Avascular Necrosis) is classified in stages referring to how far the disease has progressed. There are the Ficat and the Steinberg Classification systems. Most orthopedic doctors use the Ficat classification system to determine at what stage your disease is. The stages are as follows:
- X-Ray: ON (AVN) is not detectable.
- MRI: there might appear slight bone marrow edema or joint effusion. Joint effusion most commonly appears in the knees.
- Bone Scan: evidence of increased uptake. Increased uptake is mainly due to increased activity of osteoblasts (cells responsible for bone formation) associated with new bone formation, and to a lesser degree by increased blood flow to bone. Increased uptake is an indication that there might be a tumor, fracture or infection.
- X-Ray: mixed osteopenia, a condition where bone mineral density is lower than normal, or evidence of sclerosis.
- MRI: evidence of lesion; an abnormality in bone tissue.
- Bone Scan: increased uptake (see note above).
- X-ray & MRI: bone collapse of joint appears imminent.
- X-ray & MRI: collapse of joint.
To learn more click here: Ficat Classification and Steinberg Classification
A lot of websites, talking about Ficat Classification, refer to the level of pain at each stage of the disease. One indication of early ON (AVN) in the hips is pain in the groin. However, it appears to me that the pain differs from one ON (AVN) sufferer to another. My ON (AVN) is in my distal femurs and the first time I felt pain was in my knee caps. As the disease worsened the pain ran like hot rods up and down my thighs.Take into account that every body is different.