Disengagement of Polyethylene Insert Locking Mechanism in Modular Tibial Components for Knee Arthroplasty: A Case Report

Abstract

Background. Modular tibial components for knee arthroplasty are used in the majority of modern knee replacement systems. Despite a number of limitations, there are many aspects that make these types of implants indispensable for orthopedic surgeons. Aim — to demonstrate possible risks associated with a modular polyethylene liner with metal locking clip using a clinical case as an example. Case description. We present a case of primary total knee arthroplasty in a 70-year-old female patient. The surgery was performed by an experienced surgical team and resulted in good early radiologic and functional treatment outcome. After discharge, approximately 10 days after surgery, the patient developed knee pain. Control X-rays showed migration of the metal pin locking the polyethylene insert. The patient underwent an emergency revision surgery with replacement of the clip. The authors analyze possible causes of this complication and ways of its prevention. Conclusion. Migration of the insert locking element and dislocation of the insert in locked systems are quite rare complications of the knee arthroplasty. Their causes are soft tissue imbalance of the knee joint during arthroplasty and a number of technical errors. The very fact of using modular components of the joint is a predisposing factor for the disassociation of these modules.

Keywords

• total knee arthroplasty
• liner dislocation
• complications after arthroplasty