Mri report said knee necrosis. Suggest!

One year back My right knee was suddenly swelling and unable to walk.so i consulted an orthopedic and he has given antibiotics and later i have taken arthritis treatment for 15days .During the treatment no pain but once stop again getting pain.So i took an MRI and got report as bone infarcts.i consult some other orthopedic he has done arthroscopy and later said get the treatment for arthritis.after 1year i got swelling in left knee.i took the MRI for left knee got the report as osteonecrosis.i consult orthopedic doctor.he said no problem continue the arthritis treatment. But I am worried about the necrosis.present i don't have pain.just have little swelling in left knee due to effusion. What I need to do.please suggest