I Am Almost 2 Months Post Op From A Total

I am almost 2 months post op from a total knee revision. Everything has gone well until about two weeks ago, when the knee in question became extremely painful when bending. Additionally, a loud, ugly crackling sound could be heard across the room and large ripples of movement could be felt when touching the knee. I am trying to explain tcis to my employer: my surgeon referred to it as severe synvisc___ --I can't remember the entire term. Can you refresh my memory?