I still get pain in my right calf ten months after TKR. Neither the doctor who performed the surgery nor any of the other doctors or physical therapists I've seen since the pain started have been able to tell me what's causing it, but it is DEFINITELY a direct result of the surgery itself since I never experienced it until immediately after my surgery. I think it's caused by a damaged nerve and isn't a soft tissue (tendon, ligament, muscle, Myofascial tissue, etc.) issue like resulted on my other knee immediately after its TKR. The only thing I found to have given me some relief are nerve medications like pregabalin (Lyrica) and gabapentin. My response to the pain is as I would expect it to be if I had restless leg syndrome because I'm often changing my leg position in an attempt to avoid it. I wish you very well trying to uncover and treat the root cause of your calf pain. I empathize with your situation.