@johnbishop: 🙂... not that I’m cheap either, but I was curious. Did sort of the same: compared bend/angle of knees between good one and new one. Then, once in a while, lined up non-tkr knee exactly with angle of tkr knee, took protractor (we’re both old enough to know what that is, and to have one), measured angle of good knee, and calculated from there. Simple question of math and angles. Not perfect, but close enough. Basically, I did it to bolster my ego, and keep me motivated. PT people did focus more on function than ROM in the beginning. Me, being type A personality, needed the pat on the back for doing good.