Acute, recurrent total knee dislocation: Polyethylene dislocation and malreduction

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

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.

Complete 180-Degree Dislocation of a Rotating Platform after Closed Reduction for Mobile Bearing Spinout

Rotating-platform total knee arthroplasty was designed to help decrease backside polyethylene wear and allow maximal conformity between the femoral and tibial components, but there have been multiple reports of dislocation and spinout of these implants. There are 4 case reports in the literature of knee dislocations with 180° rotation of the platform, 3 of which occurred during relocation attempts. This is only the second case in a posterior-stabilized mobile-bearing device. We present a case of complete 180° dislocation of a rotating platform after closed reduction in a posterior-stabilized total knee arthroplasty, with subsequent conversion to hinge knee arthroplasty.

Spontaneous 180-Degree Rotatory Dislocation of Rotating-Platform Total Knee Arthroplasty

Rotating-bearing total knee arthroplasty has been theorized to have some advantages in the kinematics and wear characteristics of total knee arthroplasty. A rare complication of rotating-bearing total knee arthroplasty is rotary dislocation, spinout, of the polyethylene component. When these dislocations occur, they typically result in a 90-degree dislocation in respect to the axial axis of the knee. This case is unique in that it presents a complete 180-degree polyethylene dislocation without trauma.

A novel technique of reshaping the post of a constrained liner to avoid post and primary box mismatch in a case of recurrent dislocation after total knee arthroplasty

Knee dislocation after total knee arthroplasty, although rare, is a dangerous injury that can lead to neurovascular compromise and permanent disability. With the increase in number of total knee arthroplasty, more and more cases of dislocations are being reported. We describe a novel technique of reshaping the post of a constrained liner to fit into the box of a vanguard primary knee system in a patient with recurrent posterior knee dislocation after a PS TKA with a follow-up of 5 years.