Recently I noticed a cracking noise when I extend my right knee out and at full extension it will pop. I had a MRI done on my right knee which showed a chronic tear of my medial meniscus. My doctor told me that chronic means its been torn for awhile. I am training to do the chicago marathon which is oct. 10. My doctor told me to go ahead with my activities including running as long as there is no pain. I have tightness at times and I do ice my knee after my runs. Am I ok to continue to run? Is surgery needed for the tear?