Mechanical Strength of Bone Cement with and Without Adjuvant Screw Fixation

Abstract

Knee replacement surgery is a challenging, invasive procedure, so it is prudent that reliable components are used to minimize the likelihood of implant failure and subsequent risky, post-operation corrections. Each artificial component is adhered to a bone interface by composite acrylic-based cement. It is theorized that the structural integrity and, by extension, longevity of bone cement used to fill voids in knee replacement surgery is augmented by adjuvant screws embedded in the cement and anchored in bone, analogous to rebar-reinforced concrete. While the screw fixation method has exhibited positive results in arthroplasty patients, no conclusive evidence has been produced demonstrating its value over cement without screw fixation. It was the purpose of this research to examine which, if either, method is more effective. Porous polyurethane blocks were used to emulate human bones, in which uniform defects were generated and filled with bone cement in two cases, with and without the addition of screws. To test their mechanical properties, the specimens were loaded in compression by a material testing machine to mimic the forces created by the body, with focus on micro-motion of the cement. Additionally, nondestructive damage detection techniques were performed during fatigue testing by high frequency interrogation using piezoceramic actuators and sensors. Damage detection and classification algorithms were explored from attained data.