I am unable to extend my knee. When I woke up this am I tried to stand and had a sharp pain in the back of my right knee and unable to bear weight at all. Yes, I am morbidly obese, and I have a family history of Degenerative Joint Disease. I am 64 years old, approx. 5 3 , and around 210. No health insurance, will be getting paid tomorrow n plan to see a doc at the health clinic.