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

## TL;DR

This paper presents a case where CT scans helped diagnose a rare tibial post fracture in a knee replacement that was missed on regular X-rays.

## Contribution

The study highlights the use of CT attenuation measurements to identify polyethylene fractures in knee implants.

## Key findings

- CT demonstrated a displaced polyethylene fragment with low attenuation values.
- Intraoperative confirmation and polyethylene exchange led to a good clinical outcome.

## 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.