Fatigue failure of constrained total knee replacement: A case report.

Hinged implants for total knee arthroplasty (TKA) improve stability and joint function in a ligamentously compromised knee, but potentially at the cost of reduced implant longevity due to increased mechanical stress on the construct. This report details the case of an 83-year-old woman who underwent a revision total knee arthroplasty for a chronically dislocated hinged knee prosthesis in August 2024 at our institution. The patient presented with a several month history of pain and instability with reported self-reduction of the prosthesis to aid in ambulation. The revision surgery revealed that the axle had fractured into three pieces. This finding represents a unique case of hinged TKA failure. The primary purpose of this case report is to describe the patient presentation and revision technique to contribute to the literature available on causes of hinged TKA mechanical failure.