What Causes Protruded Knee Post Replacement Surgery?

I had knee replacement Dec 15 At this time my knee is sticking out at least an inch further than the other one. It will not extend and after intense therapy and doing excercises three times a day it is still at 4 degrees. And painful doing the stretching excercises. I think a tendon may have been displaced two weeks after surgery when the knee got twisted in the blankets getting into bed. do I keep on doing therapy or should I rest it? I also walk at least 2 miles a day and ride a stationary bike 3 times a week. YYYY@YYYY