# Is my knee supposed to do this? \[slightly TMI\] **URL:** \ **Category:** Factual Questions\ **Created:** [December 10, 2008, 10:25pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626 "2008-12-10T22:25:50Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![KGS](https://avatars.discourse-cdn.com/v4/letter/k/90ced4/32.png) [@KGS](https://boards.straightdope.com/u/KGS)\ **Post date:** [December 10, 2008, 10:25pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/1 "2008-12-10T22:25:50Z")
My kneecaps have a tendency to slide away to the side whenever I bend my knee. It’s been like that as long as I can remember, and I’ve never had any problems until recently. Somehow, last month, I twisted/sprained my knee while sleeping – not sure what happened, except I woke up in SEVERE pain, almost felt like a torn ACL or something. It’s not so painful anymore, just very sore, but the knee brace I bought for it doesn’t fit properly, because my kneecap keeps sliding around when I stand up or sit down. Is this supposed to happen? (My left knee feels fine.) (Note: I’m _not_ asking for medical advice, and yes, I plan to see a doctor if it doesn’t improve by this weekend.) ---
**Author:** ![lisacurl](https://avatars.discourse-cdn.com/v4/letter/l/41988e/32.png) [@lisacurl](https://boards.straightdope.com/u/lisacurl)\ **Post date:** [December 10, 2008, 10:37pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/2 "2008-12-10T22:37:18Z")
I’d go with no. A friend in junior high had surgery for this specific problem. Your kneecaps aren’t supposed to have any ‘play’ to them. ---
**Author:** ![troub](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troub/32/14802_2.png) [@troub](https://boards.straightdope.com/u/troub)\ **Post date:** [December 10, 2008, 10:39pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/3 "2008-12-10T22:39:07Z")
Most definitely not. My wife just had surgery to correct a problem with kneecap tracking, in which her kneecap would grind against the knobby ends of the femur instead of tracking nicely in the groove. It’s supposedly a not uncommon problem in women, because the hip structure sometimes causes the leg muscles to pull the kneecap out of alignment as they grow. She’s had that problem since she was a kid, and had lived with it because her doctor at the time told her there wasn’t much that could be done and she should just avoid running, jumping, etc. She began to have pain again recently, however, and I told her she should finally have someone else look at it. This doctor told her she would be on her way to knee replacement surgery if she didn’t get it fixed soon. They performed an arthroscopic procedure where they cut the “capsule” (basically, as I understand it, the muscle connections, etc.) that hold the kneecap in place, allowing it to be slid into the proper position, followed by physical therapy to rebuild the muscles and stabilize the kneecap in the proper track. ---
**Author:** ![troub](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troub/32/14802_2.png) [@troub](https://boards.straightdope.com/u/troub)\ **Post date:** [December 10, 2008, 10:46pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/4 "2008-12-10T22:46:07Z")
[Chondromalacia patella](http://orthopedics.about.com/cs/patelladisorders/a/chondromalacia.htm) was her diagnosis (took me a while to remember it). Strange, I thought, because she never was really a runner. But apparently it happens to some people (esp. women) anyway. The x-rays and scans taken of her knee showed _serious_ misalignment. The [lateral release](http://orthopedics.about.com/od/kneecappatelladisorders/g/lateralrelease.htm) they mention in that article is at least part of what her surgery was. ---
**Author:** ![KGS](https://avatars.discourse-cdn.com/v4/letter/k/90ced4/32.png) [@KGS](https://boards.straightdope.com/u/KGS)\ **Post date:** [December 10, 2008, 11:24pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/5 "2008-12-10T23:24:39Z")
Holy shit, I seriously had no idea. Looks like I’ll be making that doctor’s appointment after all…dammit, this really sucks. ☹ ---
**Author:** ![liirogue](https://avatars.discourse-cdn.com/v4/letter/l/dbc845/32.png) [@liirogue](https://boards.straightdope.com/u/liirogue)\ **Post date:** [December 11, 2008, 1:59am UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/6 "2008-12-11T01:59:59Z")
> [@lisacurl](#): > > I’d go with no. A friend in junior high had surgery for this specific problem. Your kneecaps aren’t supposed to have any ‘play’ to them. Actually, you should be able to move the kneecap quite a bit when your leg is straightened and relaxed. I had surgery one one of my knees because the kneecap barely moves. As for the OP, no, that isn’t normal. ---
**Author:** ![lisacurl](https://avatars.discourse-cdn.com/v4/letter/l/41988e/32.png) [@lisacurl](https://boards.straightdope.com/u/lisacurl)\ **Post date:** [December 12, 2008, 3:48pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/7 "2008-12-12T15:48:13Z")
> [@liirogue](#): > > Actually, you should be able to move the kneecap quite a bit when your leg is straightened and relaxed. I had surgery one one of my knees because the kneecap barely moves. > > As for the OP, no, that isn’t normal. Your kneecap should glide up and down, sure… it shouldn’t slip off to the side. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [December 12, 2008, 5:17pm UTC](https://boards.straightdope.com/t/is-my-knee-supposed-to-do-this-slightly-tmi/476626/8 "2008-12-12T17:17:12Z")
> [@lisacurl](#): > > Your kneecap should glide up and down, sure… it shouldn’t slip off to the side. Really? When my leg is straight (ie extended, knee not bent) my patella can move in all four directions…laterally, medially, proximally, and distally…did I use those terms right? (left, right, and towards and away from me.) When my knee is flexed, it doesn’t have any “play” in it at all.