I don't have arthritis, and you'd probably get an answer that fits your circumstnaces better from someone who does, but I do have a touchy knee, and I found the plyo moves in Plyo X (the most high-impact of the workouts) to be quite knee friendly (vs the cheerleader-high jumps or pivoty moves in some of Cathe's workouts). There are only two moves in PlyoX that I took to the rebounder or modified for impact, which is easy to do. Tony himself has a bad knee, and often shows modifications of lower body moves, like not going so deep into squats.