The sense of joint position is called proprioception. Research shows that proprioception is altered with osteoarthritis. The more severe the patient's symptoms, the longer it takes for the knee to register its position.
Scientists aren't sure if the arthritic changes cause the change in joint position sense or the other way around. There could be other causes for your problem such as loss of joint motion and muscle weakness. It might be a good idea to have this checked out before a misstep causes a serious problem.