Texas Subscriber
Answer: You have two choices in this instance. Your first option is to report 27486-52 (Revision of total knee arthroplasty, with or without allograft; one component; reduced services). This code applies because the surgeon is revising part of the tibial component (the liner) while retaining the existing tray.
Your second option is to report 27599 (Unlisted procedure, femur or knee) for the surgeon's work performing the liner exchange.
In either case, you should submit the surgeon's op report with your claim, along with a letter from the surgeon explaining what he performed and how much reimbursement he requests for the procedure.