<s>[INST] Hello...I just got results of MRI of knee and I am worried about osteonecrosis and marrow anemia as I am not sure how they correlate to osteoarthritis of knee.  I also has loss of cartalidge in two areas of my knee. Pain is constant and I also have a tilted patella. Am I looking at surgery.? [/INST] Hello,Osteonecrosis and marrow damage would have shown up on the MRI. They are not caused by osteoarthritis. Osteoarthrits is damage to the cartilage early in the disease and then later you can get bone spurs. It depends upon the extent of the cartilage loss whether or not it is time for a knee surgery. The orthopedic doctor can give you the best advice.Regards </s>