Impact of bone health on the mechanics of plate fixation for Vancouver B1 periprosthetic femoral fractures. (December 2022)

• Record Type: Journal Article
• Authors: Chen, Xiang; Myers, Casey A.; Clary, Chadd W.; Varga, Peter; Coombs, Dana; DeWall, Ryan J.; Fritz, Bryan; Rullkoetter, Paul J.
• Is Part Of: Clinical biomechanics. Volume 100(2022)
• Publication Date: 2022-12
• Subjects: Periprosthetic femoral fracture -- Total hip arthroplasty -- Finite element analysis -- Bone property -- Bone strain -- Load transfer; Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2022.105801
• Languages: English
• ISSNs: 0268-0033

Abstract

Abstract: Background: Condyle-spanning plate-screw constructs have shown potential to lower the risks of femoral refractures after the healing of a primary Vancouver type B1 periprosthetic femoral fracture. Limited information exists to show how osteoporosis (a risk factor for periprosthetic femoral fractures) may affect the plate fixation during activities of daily living. Methods: Using total hip arthroplasty and plate-implanted finite element models of three osteoporotic femurs, this study simulated physiological loads of three activities of daily living, as well as osteoporosis associated muscle weakening, and compared the calculated stress/strain, load transfer and local stiffness with experimentally validated models of three healthy femurs. Two plating systems and two construct lengths (a diaphyseal construct and a condyle-spanning construct) were modeled. Findings: Osteoporotic femurs showed higher bone strain (21.9%) and higher peak plate stress (144.3%) as compared with healthy femurs. Compared with shorter diaphyseal constructs, condyle-spanning constructs of two plating systems reduced bone strains in both healthy and osteoporotic femurs (both applying 'the normal' and 'the weakened muscle forces') around the most distal diaphyseal screw and in the distal metaphysis, both locations where secondary fractures are typically reported. The lowered resultant compressive force and the increased local compressive stiffness in the distal diaphysis and metaphysis may be associated with strain reductions via condyle-spanning constructs. Interpretation: Strain reductions in condyle-spanning constructs agreed with the clinically reported lowered risks of femoral refractures in the distal diaphysis and metaphysis. Multiple condylar screws may mitigate the concentrated strains in the lateral condyle, especially in osteoporotic femurs. Highlights: Condyle-spanning construct may lower risks of refracture in osteoporotic femurs. Multiple condylar screws avoided strain elevation caused by distal load transfer. Combined testing and modeling protocol for pre-clinical femoral implant evaluation