The fact that you have little pulse in your legs is an interesting diagnosis. I have a bit of experience with that as it happened to my husband two years ago. In his case, he had no leg pain (he has diabetic neuropathy which may have masked any pain), but he kept falling down suddenly and his legs would stiffen up. When a doppler test was done it was discovered he had almost no blood flowing to his legs. He was immediately sent to a vascular surgeon (Dr. McCroskey) who put 3 stents in his abdomen in a cath procedure and he got the use of his legs back.
If the doppler shows you do have blockage, I strongly suggest that you get an opinion from Dr. McCroskey or another vascular surgeon before they try anything at the pain clinic.
Have you ever had a cardio scan or any indication that you had any arterial problems? High cholesterol? High blood pressure?
I must admit this idea never occurred to me before, but I suppose it possible. It would at least make some sense of the fact that your pain is equal in both knees, which is not likely if it was a problem with the implants themselves.
I know this must be so frustrating for you, but I hope you can hang in there. I know from my husband's journey to find answers to his problems that it can take a lot of time, many doctors and dedication to keep trying to actually get there. But, never give up hope!!! Medicine is not perfect and sometimes it takes a while for the right doctor to suggest something and "stumble" across the real problem.