Recurrent yoke fracture in rotating-hinge total knee arthroplasty: A case report and literature review.

Abstract

Rotating-hinge total knee arthroplasty is a valuable option in complex primary and revision procedures, Rotating-hinge total knee arthroplasty is commonly used in complex primary and revision procedures when severe ligamentous deficiency, bone loss, or instability precludes the use of less constrained implants. Although modern hinge designs aim to reduce mechanical complications, structural failure of the polyethylene insert and its metal-reinforced yoke remains a rare but serious event, often requiring further revision. We report the case of a 62-year-old man who underwent revision total knee arthroplasty with a rotating-hinge prosthesis for a distal femoral periprosthetic fracture. Initial postoperative recovery was satisfactory. Two years later, he presented with sudden knee pain and swelling, and imaging revealed a fracture of the hinge insert keel with associated femoral component loosening. Intraoperative findings confirmed a fracture involving both the polyethylene and the metal reinforcement. Synovectomy and isolated insert exchange were performed, and cultures grew Staphylococcus aureus and Corynebacterium striatum, leading to chronic suppressive antibiotic therapy. One year later, a second identical hinge insert fracture occurred despite infection control. Revision surgery with upsizing of the femoral component and a thicker polyethylene insert was performed. Intraoperative cultures were negative. At 12-month follow-up, the patient demonstrated stable implant positioning and satisfactory joint motion, with return to prior activity levels. This case highlights the biomechanical vulnerability of the cone-cylinder junction of the hinge insert under cyclic loading, particularly when postoperative soft-tissue tension and flexion-extension balance are suboptimal. Isolated insert exchange alone may not sufficiently address the underlying mechanical stresses. Strategic upsizing of the femoral component can restore joint line height, improve the extensor lever arm, and reduce distraction forces transmitted through the hinge. Early recognition of instability and consideration of mechanical contributors during revision planning may reduce recurrence risk. LEVEL OF EVIDENCE: V.