I injured my left knee when I was younger...I went to the hospital...the doctor said i might have chipped the bone in my knee...anyways...I put it in a brace for about a month...then...took it off and left it alone...when I got in high school...I started lifting weights and playing football, now my knee feels like it is going to explode if I stand for to long, if I walk up stairs...it feels worn out and over worked. When I get done running ...if I run a long ways, my knee gives out on me soon after, and some days it just hurts so bad, I can even walk on it