I have osteoarthritis in my knee, i will wake up in the middle of the night with pain coming from my knee, as if i'm "stuck" and the more i try to straighten my leg or move to stop the pain the pain gets more severe. what could be doing this?

Inflammation : Inflammation causes heat, redness, swelling and pain. Your knee OA can be treated in several non surgical ways including topicals (Voltaren gel), off loading bracing, steroid or visco elastic supplement injections, nerve injections at the knee, and so,forth. Sometimes a fragment gets loose in the joint and can aggravate the joint. See your Ortho or pain doc.to,determine best treatment for YOU.