I was curious if any of you were familiar with knee problems. I knelt down today to do push ups and when I got back up my leg would'nt straighten. Then after about two hours it popped and then was fine. Well about 1/2 hour ago it went out again. Any ideas? I have never seen an ortho about my knees but can hear the cartilage every time I bend them. I'm curious if you all have any similar problems.