Finite element analysis in repairing distal femoral bone loss in Revision Total Knee Arthroplasty

Abstract

Introduction: Distal femoral bone loss is often encountered in revision total knee arthroplasty (TKA). Cement, cement with screw reinforcement, and metal augments are choices for repair. The present study was conducted to determine whether cement with screw reinforcement can increase the initial stability than cement only, and the optimal size of defect to repair. Methods: Three-dimensional finite element models of TKA were constructed. Five groups of block-shaped bone defect of 4, 6, 8, 10, and 12 mm height in the distal medial femoral condyle were simulated. Three conditions of treatment options of cement (group 1), cement with screw reinforcement (group 2), and metal augment (group 3) were simulated to repair the bone defect. Loading and boundary condition were simulated to reflect the real situation. The displacement between the bone-cement interface, and maximum shear stress of the bone-cement interface were investigated. Results: Whatever the defect size, group 1 had the highest maximum bone-cement micromotion than group 2, followed by group 3. In defects of larger than 6 mm, the displacement in group 1 exceeded the threshold of loosening. In defect of 12 mm, the displacement in group 2 exceeded the threshold of loosening. The maximum shear stress of group 3 was lower than group 2, followed by group 1. Discussion and Conclusion: Cement with screw reinforcement showed better initial stability than cement only when defect was larger than 6 mm. Our study provides evidence for the use of cement with screw in repairing distal bone loss of > 6 mm in revision TKA.