I tore my lateral and medial meniscus. Not sure how much, but I'm in pain all the time. I got this knee brace because I believed the hinges would help my knee not go left/right (a.k.a, the wrong way) when walking. It doesn't happen very often, but it's extremely painful and something I would rather not experience. Anyway, I measured my knee and it just happened to be in the "small" size range. I decided to get a medium because I had read reviews in which people had said to get one size up. I'm glad I got the medium, but the bottom part is tight on my leg (below the kneecap) as is. I don't think the small would have fit at all. I'm 6ft 3, and I weigh about 180 pounds. So, I'm rather tall and skinny. I've only had this product about a day, but when I put it on it feels absolutely amazing. My only problem with it is since it helps keep my knee somewhat straight when walking, I find it feels a little odd. I don't walk like a normal person...more like a penguin (or so I'm told). But, I've been pain free all day and I'm going to keep using it and see how it goes. I'm not going to give it 5-stars yet until I've had more time with it, however. (But, right now, I love it!) EDIT 12/7/2011: I've been using this brace for about a week, and I can tell you it's STILL amazing. I've found myself thinking about not wearing it because there's no way it hurts so much without it. Seriously. But, I still wear it because after a long day, my knee will start aching a little. Not enough to make me worried, but enough to remind me. And, of course, it doesn't help with the stiffness I get when I sit for too long. But, overall I would recommend this to anyone with meniscus problems. I can't recommend this product for ACL, PCL, or MCL problems, as mine are fine...as far as I can tell. EDIT 9/7/2013: I've had this brace for just shy of 2 years and it's been wonderful. Unfortunately, it's time to get another. I wore mine almost every day, 8+ hours a day while at work, so I've managed to wear it out. I work in a store, so I'm walking around constantly. It DOES squeak, but I've never had anyone ask me why I'm squeaky, lol. If you wear it every day, make sure to wash it. The material will stretch after several days, and washing it will not only clean it, but make the material go back to the original snugnesss. Although, you may want to take out the hinges before you wash it, as I've noticed after about a year that the hinges will fall out (especially if you lose the cover piece that goes directly over the hinge). I've read a few reviews where people did not like this brace and recommended others. The braces recommended by others are heavy duty and may not fit under one's pants, so if you're looking for one that you can conceal under your clothes, this has been the best choice I've found. In all, 2 years later, the Mueller Hg80 Hinged Knee Brace is still my #1 choice, however I've recently been looking at theShock Doctor Ultra Knee Supporter with Bilateral Hinges (Black) , as well.