Thanks very much for sharing your story, we can all learn from each other.
I agree that you very likely have a genetic predisposition to scarring, given that you have Dupuytrens contracture. This is a fibroproliferative disorder of the connective tissue that involves myofibroblast proliferation, and the two are essentially the same process except arthrofibrosis affects a joint.
I also agree that you most likely overdid the rehab exercises, this is very common unfortunately, due to the misunderstanding of surgeons and physios. I suspect that many people who end up with AF do so because they are highly motivated people who do everything they can to recover well, and do as they’re told after advice to “push hard” while exercising.
The CPM should have helped so long as it was gentle, but 24 hours isn’t long enough, it needs to be used every day long term until the inflammation settles.
I’m not a clinician, but in my opinion redoing the TKR would be very unwise. In fact, for you any more surgery could well lead to increased problems, but especially major surgery like a TKR that will cause major inflammation. In my experience surgeons will often suggest a replacement TKR to treat AF even when there is no indication that there is anything at all wrong with the existing prosthesis (such as a broken or loose component), not because there is evidence that it helps, but because it is something to do. And, of course, surgeons do surgery, that is their job.
The fact that you’re a fast healer suggests that your healing response is where the problem lies, fibrosis is an overly enthusiastic healing response.
If you’re able to hire or buy a second hand CPM and use it gently every day that may help with your ROM. You’re probably aware that stretching every day is one of the leading therapies for Dupuytrens. Other than that, try to do as many things as you can on the “Key Points” list and consider the diagram “drivers of arthrofibrosis”.
All the best,