The different contributions of cortical and trabecular bone to implant anchorage in a human vertebra

• Published in: Bone (New York, N.Y.) Vol. 50; no. 3; pp. 733 - 738
• Main Authors: Ruffoni, Davide, Wirth, Andreas J, Steiner, Juri A, Parkinson, Ian H, Müller, Ralph, van Lenthe, G. Harry
• Format: Journal Article Web Resource
• Language: English
• Published: Amsterdam Elsevier 01-03-2012; Elsevier Science Inc
• Subjects: Aged; Biological and medical sciences; Biomechanical Phenomena; Bone and Bones - diagnostic imaging; Bone Density; Cortical shell; Endocrinologie, métabolisme & nutrition; Endocrinology, metabolism & nutrition; Fundamental and applied biological sciences. Psychology; Human health sciences; Humans; Implant pull-out stiffness; Male; Micro-finite element; Orthopedics; Pen-implant bone; Prostheses and Implants; Radiography; Sciences de la santé humaine; Spinal fixation; Thoracic Vertebrae - diagnostic imaging; Thoracic Vertebrae - surgery; Vertebra; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Peri-implant bone; Vertebra; Micro-finite element; Cortical shell; Spinal fixation; Implant pull-out stiffness; Human; Implant; Spine; Morphology; Stiffness; Spongious bone; Cortical bone; Finite element
• ISSN: 8756-3282; 1873-2763; 1873-2763
• DOI: 10.1016/j.bone.2011.11.027

Abstract The quality of the peri-implant bone and the strength of the bone–implant interface are important factors for implant anchorage. With regard to peri-implant bone, cortical and trabecular compartments both contribute to the load transfer from the implant to the surrounding bone but their relative roles have yet to be investigated in detail. However, this knowledge is crucial for the better understanding of implant failure and for the development of new implants. This is especially true for osteoporotic bone, which is characterized by a deterioration of the trabecular architecture and a thinning of the cortical shell, leading to a higher probability of implant loosening. The aim of this study was to investigate the relative biomechanical roles of cortical and trabecular bone on implant pull-out stiffness in human vertebrae. The starting point of our investigation was a micro-computed tomography scan of an adult human vertebra. The cortical shell was identified and an implant was digitally inserted into the vertebral body. Pull-out tests were simulated with micro-finite element analysis and the apparent stiffness of the system with various degrees of shell thickness and bone volume fraction was computed. Our computational models demonstrated that cortical bone, although being very thin, plays a major role in the mechanical competence of the bone–implant construct.