Dissociation of a Medial Pivot Polyethylene in a Kinematically Aligned Total Knee Arthroplasty.

An 81-year-old male patient who underwent a Medacta GMK sphere kinematically aligned (KA) total knee arthroplasty (TKA) for end-stage knee osteoarthritis presented with a dislocated medial pivot (MP) tibia polyethylene (PE) insert on routine six-week postoperative x-rays. The patient presented asymptomatic with a normal range of motion. Dissociation of a fixed-bearing (FB) PE implant is an uncommon complication after TKA. There are only a few cases reported in the literature. We report for the first time a case of non-traumatic dissociation of MP PE from the tibial baseplate in a KA TKA in an asymptomatic patient but identified on routine postoperative radiographs.