Spontaneous, Recurrent Dislodgment of the Polyethylene Tibial Insert After Total Knee Arthroplasty

Abstract

D islodgment of a polyethylene insert from the tibial baseplate following total knee arthroplasty is an uncommon event. To our knowledge, it has been described in only four reports in the English-language literature1-4. The extremely low rate of this complication contrasts with the frequent dissociation of polyethylene liners from total hip replacements, as reported at our institution5 and by others6, occurring in association with so-called first-generation uncemented, modular acetabular cup designs. The purpose of the present report was threefold: (1) to present the assessment and management of a patient who had a dislodged polyethylene insert following total knee replacement, (2) to review the literature on this rare complication, and (3) to discuss possible mechanisms of failure. The patient was informed that data concerning the case would be submitted for publication. A fifty-five-year-old man (height, 170 cm; weight, 109 kg; body mass index, 38) had undergone a cruciate-retaining left total knee arthroplasty (Duracon; Howmedica, Rutherford, New Jersey) for the treatment of posttraumatic arthritis. He returned to his orthopaedic surgeon seven years after surgery because of a new onset of knee pain and swelling. A diagnosis of patellofemoral degeneration of an unresurfaced patella was made, and the patient underwent revision surgery for resurfacing of the patella. According to the operative note that was obtained, delamination and cold flow deformation were noted at the posteromedial aspect of the 9-mm tibial polyethylene liner, suggesting excessive posterior medial loading of the insert. The patella was resurfaced, and a new 19-mm tibial insert was implanted. Six months later, the patient presented with spontaneous onset of knee pain, swelling, instability, and clicking due to dislodgment of the polyethylene insert from the tibial baseplate. During further revision surgery, the posterior metallic rims and the anterior locking tab of the baseplate were …