What to do if i had an mri of my knees showing reactive edema and bone signal is homogeneous what is that?

It depends: Reactive edema basically translates to inflammation. Inflammation can be caused by multiple things including but not limited to acute trauma, repetitive micro trauma, arthritis, and/or even an autoimmune disorder such as rheumatoid arthritis. I would recommend discussing the findings with your orthopaedic surgeon as clinical correlation is necessary.