Cause?

My feet pronate and are very flat. When I try and point them forward with my feet apart it makes my butt stick out but when my feet are together it is no problem. When I make an L with my feet with, my left foot pointing forward, my left hip goes to the left and my right foot rolls in until my three smallest toes are off the ground. When I stand like this it is impossible for someone to push my knee back so that my toes touch the ground again. I can't bend my knees and keep them over my toes even if someone is holding my legs. When I'm standing and want to extend my left leg out in front of me (kicking) I first have to adjust my hip until it pops but when I'm laying down I don't have to adjust. My legs are still strong though. I can leg press a 240 pound man with my knees starting at my chest without a problem. I would like to know if this a tendon, muscle, or bone problem. I would also like to know what joint is the problem. I ask because I have undiagnosed knee problems and it is affecting me in karate.
I have also noticed that when I extend my arms in front of me and try and roll them over (palms up) I can only rotate them 90 degrees or like I'm clapping. When I put my fists on my hips knuckles up I can't pull my elbows in almost like I have wings. Nobody can turn my hands over or push my elbows in. What might cause this? Thank you and sorry about the long post.

[Michael L Gross, MD]

Its really hard to tell from your description exactly why the problem is.  I suggest evaluation b a physiatrist (a specialist in physical medicine and rehabilitation)