@bland9 , as someone who also has severe arthrofibrosis, I can really sympathize with your OH.
Some of the top people in the US that work on cases such as these (Peter Millet at the Steadman Clinic in Vail, CO for example) say that revisions for people with arthrofibrosis will only generate more scar tissue, due to the trauma and inflammation that result. Instead they recommend arthroscopic lysis of adhesions, because it is so much less traumatic.
I had a revision (which filled up with scar tissue), then an arthroscopic lysis of adhesions (which did really well at first and then resulted in severe pain) and then a second revision (which has been very successful in terms of eliminating the pain, but my range of motion is still limited by scar tissue.)
It turns out that I caught an infection during the first revision which was not caught and acted on (though the post-op bloodwork showed it present) and this infection was present and untreated for the recovery from the 1st revision and throughout the surgery and recovery from the arthroscopic LOA. I believe this ruined the results from the first revision and the arthroscopic LOA. It was caught during pre-op for the second revision (which was not optional as the prosthesis had come loose and my leg was in danger of breaking) and treated with tons of IV anitbiotics. I had to infuse myself at home with antibiotics through a PICC line for six weeks.
If we knew more about your OH we could give better suggestions. Lacking that, I would say:
1. I assume he has had an x-ray to make sure that his existing TKR parts have not come loose or are misaligned. If this were true, then a revision to fix this (with a new surgeon) may very well fix the problem.
2. Have him get a metals sensitivity test (if he is allergic to nickel for example, this has to be addressed, and nothing else you do will matter).
3. Have him get a least a blood test to check for indicators of innflammation and infection. Aspirating fluid from the knee and culturing it to test for infection would be great too but the docs hesitate to do this for fear of infection (and rightly so - trust me, infections are no fun at all.) If there is an infection this has to be fixed, or nothing else you do will matter.
4. Consider an arthroscopic lysis of adhesions. You will need to find a specialist - these are difficult procedures and not every OS can do them.
5. Consider a revision with a specialist. I don't know how things work in the UK, but there are specialists in the US for example that deal with the most difficult cases. If you were in the US you could for example go to the HSS in New York City. The UK must some equivalents but whether or not your insurance covers it is a question.
The most important takeaway is that a patient with severe arthrofibrosis needs the very best specialist surgeon. Seeking out one of the best surgeons in the country is really the thing to consider.
One thing to keep in mind - what one surgeon says is impossible, a different specialist will do with ease. The first surgeon will speak in absolutes, as if he/she speaks for all surgeons, and that is just not true.
In the US, there are doctors in clinics researching all kinds of alternatives (such as IV steroids or anakinra/Kineret), and the UK must have people doing similar things. There are always alternatives.
Best of luck.