# Recurrent Left Periprosthetic Posterior Knee Dislocation in an Elderly Woman With Dementia and Altered Mental Status: A Case Report

## TL;DR

An elderly woman with dementia and altered mental status experienced multiple knee dislocations, requiring surgical intervention and highlighting the challenges in treating such cases.

## Contribution

This case report adds to the limited literature on recurrent periprosthetic knee dislocations in patients with altered mental status.

## Key findings

- The patient experienced multiple left posterior periprosthetic knee dislocations despite prior treatment.
- A hinged prosthesis was successfully used in revision surgery, resulting in postoperative stability and minimal pain.
- The case emphasizes the need for early diagnosis and tailored treatment in patients with cognitive impairments.

## Abstract

The case presented in this article is one of recurrent left posterior periprosthetic knee dislocation (PPKD) in a patient with altered mental status (AMS). The patient, a 69-year-old female with a complex medical history including dementia, Ménière’s syndrome, and left total knee arthroplasty, presented to the emergency department with AMS whereupon a left PPKD was discovered. Less than three weeks before this presentation, she sustained a left PPKD during a previous admission. During her current admission, she sustained yet another left PPKD after trials of closed reduction and immobilization. The patient eventually underwent a left cemented revision total knee arthroplasty with a hinged prosthesis. The implant was noted to be stable, and the patient had minimal pain postoperatively with no vascular or neurological injury. Upon outpatient follow-up, the patient reported doing well. There have been few documented cases of recurrent or chronic PPKD in individuals with AMS or restricted intellect. These comorbidities create a complex approach to diagnosing and treating the aforementioned orthopedic injury, and as this injury can have devastating consequences, quickly and effectively delivering diagnosis and treatment is vital. This case highlights the importance of early identification, risk factors, preoperative management, and appropriate operative course for patients with AMS and recurrent PPKDs.