Diagnosis

Your physician will take your medical history and perform a physical exam, which will aid in making the proper diagnosis. Osteonecrosis of the knee develops through four stages, which can be identified by symptoms and through X-ray analysis.

Stage I: Symptoms of osteonecrosis are most intense in the earliest stage and may continue for 6 to 8 week period before they subside. X-rays will appear normal making a positive bone scan necessary to make the diagnosis.

Stage II: It may take several months for the disease to progress to this stage of osteonecrosis. It will become possible to see on the X-rays that the distal femoral condyles (lowest part of the upper leg). An MRI, bone scan or CT scan may be used to diagnose the disease.

Stage III: Three to 6 months after the onset of osteonecrosis the disease will be clearly visible on X-rays. The articular cartilage will begin to loosen and pull away from the dead bone. Operative treatments may be considered at this point.

Stage IV: The bone will have clearly collapsed and the articular cartilage will be destroyed. The joint space will have narrowed (distance separating the upper and lower leg and bone spurs may form). Severe osteoarthritis results and joint replacement surgery may be necessary.