# Intraprosthetic Dislocation Following Reduction of Dual-mobility Total Hip Arthroplasty

## TL;DR

A patient with a dual-mobility hip implant experienced a rare complication where the inner part of the implant shifted after a dislocation, requiring advanced imaging for diagnosis.

## Contribution

This paper reports a rare case of intraprosthetic dislocation in dual-mobility hip prosthetics and emphasizes the need for advanced imaging in diagnosis.

## Key findings

- Intraprosthetic dislocation occurred despite successful closed reduction of the hip.
- Computed tomography was necessary to confirm liner displacement due to its radiolucency.
- Dual-mobility prosthetics have unique risks not seen in other implant types.

## Abstract

A 62-year-old man was brought into the emergency department by ambulance with right hip pain and deformity following a suspected hip dislocation. A plain film radiograph confirmed the diagnosis. He was sedated for closed reduction at the bedside. Despite apparently successful reduction, his case was complicated by persistent intraprosthetic dislocation of a polyurethane liner component of his prosthetic joint articulation. Computed tomography confirmed displacement of the liner, which required operative intervention.

Intraprosthetic dislocation is a complication specific to dual-mobility hip prosthetics, characterized by displacement of the polyurethane liner unique to this type of device. This liner was designed to offer some benefits over other types of hip prosthetics, including improved biomechanics and lower risk of dislocation. The liner can become dislodged during a hip dislocation and remain displaced despite successful reduction of the metallic prosthetic components. Due to its radiolucency, diagnosis can be challenging on plain radiographs, often requiring advanced imaging. This case highlights the importance of recognizing this potential complication in patients with dual-mobility prostheses.