Dull, Dull, Dull

The knee exercises continue.  I'm well aware that this isn't exactly what's happening, but the pain / sensation is that my kneecap shifts out of place.  It jolts me to a stop, and it takes several seconds before I'm able to move again.  Although this is a different condition from what led to knee surgery on my right side many years ago, the exercises are largely the same: working the tendons and ligaments to hold everything in place.  Bor,  Ring.