Has anyone had surgery to replace the implant cushion?

After 3.5 yrs of considerable discomfort with both knees (TKR for both done at the same time) an orthopedic specialist is recommending that I do the surgery to replace the implant cushion with a thicker one to correctly tension ligaments and tendons. Both knees are unstable which causes pain and soft tissue tightness and swelling as knees try to compensate for instability. I will only do one knee at a time this time, learned my lesson!
So I am looking for feedback from anyone who has done this surgery. Thanks!