My dad, my dads dad, and my dads brother all have serious knee problems. They all have had them replaced - my dad is about to. He was a runner, ballroom dancer, and tennis player; always very active. He started having really bad problems and gets cortisone shots in his knees every so often so that he can move around a little without excruciating pain. I ve always had weaker knees than my friends -even when I was in elementary school my knees would randomly give out. Lately I ve been starting to get some more knee pain and discomfort. I did some squats on the leg press machine which usually doesn t bother me, but ever since then it s hurt to walk a little or go up stairs. I m only 18, but have had shin splints because of flat feet (which I hear doesn t help knee problems). I was wondering if I should get this checked out or simply stop doing some things. If there s any advice you have to help my knees last a little longer than 40, that would be amazing. Thanks!