L., did he go to physical therapy? Did he and is he doing all the exercises they prescribed?
If he stopped doing them, he should start again, a little at a time - not all of them at one fell swoop. Did the doctor order a type of ibruprophen for swelling? He should start back on those as well.
He should go back to the doctor and ask them to check for scar tissue. It could be that the PT could massage that scar tissue out (yeah, it's painful, but it's worth it) - only the doc and the PT know that for sure.
He has to be just as much a part of his recovery as the surgeon. It's an ongoing process. Get him back to the doctor to see what's what.
Good luck!
Dawn