CT Diagnosis of Tibial Post Fracture in a Posterior-Stabilized Total Knee Arthroplasty

Abstract

Fracture of the polyethylene tibial post is a rare complication of posterior-stabilized total knee arthroplasty and is frequently missed on conventional radiography due to the radiolucent nature of polyethylene. We report a case of post-traumatic instability in which computed tomography demonstrated a displaced polyethylene fragment with characteristic low attenuation values. The diagnosis was confirmed intraoperatively, and isolated polyethylene exchange resulted in a good clinical outcome. Teaching point: CT attenuation measurements can aid in identifying displaced polyethylene fragments and facilitate the diagnosis of tibial post fracture in posterior-stabilized knee arthroplasty.