Steve - I'm experiencing the same thing with the knee cap moving. I don't know what it is either. My PT wants me to come in and take a look at it, but can't get in for an appt until April 1. I've completed the walk/jog program and the PT said he would also start another more sport oriented program with lateral and agility movements included. He also wanted me to do some of the jogging on a track or something in addition to the treadmill. I find the treadmill easier. The first set doesn't feel as good as the second and third. Once everything gets warmed up the leg seems to feel alright. Until then though it feels like I'm running on a rod, no shock absorption. Anyway, I have made several 18 minute jogs. It doesn't feel "normal" yet, but I plod along. On the treadmill I was jogging at 6.2-6.5 mph on the track I've been jogging at a 9 minute mile pace. I'm curious with what others are experiencing with the knee cap moving too.