Besides, the gait was weird, like I was deliberately landing on the ball of my right foot, or trying to come down flat, rather than on the heel. So my right foot and leg were held stiff, giving me a rocking-back-and-forth gait, rather than the standard inverted-pendulum movement of normal walking. When I consciously tried to walk normally, it worked fine.
I had some discomfort in my right heel. Perhaps I'm trying to compensate for that pain, not the knee.