title: Mechanical stability in a human radius fracture treated with a novel tissue-engineered bone substitute: a non-invasive, longitudinal assessment using high-resolution pQCT in combination with finite element analysis.
abstract: The clinical gold standard in orthopaedics for treating fractures with large bone defects is still the use of autologous, cancellous bone autografts. While this material provides a strong healing response, the use of autografts is often associated with additional morbidity. Therefore, there is a demand for off-the-shelf biomaterials that perform similar to autografts. Biomechanical assessment of such a biomaterial in vivo has so far been limited. Recently, the development of high-resolution peripheral quantitative computed tomography (HR-pQCT) has made it possible to measure bone structure in humans in great detail. Finite element analysis (FEA) has been used to accurately estimate bone mechanical function from three-dimensional CT images. The aim of this study was therefore to determine the feasibility of these two methods in combination, to quantify bone healing in a clinical case with a fracture at the distal radius which was treated with a new bone graft substitute. Validation was sought through a conceptional ovine model. The bones were scanned using HR-pQCT and subsequently biomechanically tested. FEA-derived stiffness was validated relative to the experimental data. The developed processing methods were then adapted and applied to in vivo follow-up data of the patient. Our analyses indicated an 18% increase of bone stiffness within 2 months. To our knowledge, this was the first time that microstructural finite element analyses have been performed on bone-implant constructs in a clinical setting. From this clinical case study, we conclude that HR-pQCT-based micro-finite element analyses show high potential to quantify bone healing in patients.
authors.affiliation: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Mueller
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Wirth
authors.forename: G Harry
authors.initials: GH
authors.lastname: van Lenthe
authors.forename: Joerg
authors.initials: J
authors.lastname: Goldhahn
authors.forename: Jason
authors.initials: J
authors.lastname: Schense
authors.forename: Virginia
authors.initials: V
authors.lastname: Jamieson
authors.forename: Peter
authors.initials: P
authors.lastname: Messmer
authors.forename: Daniel
authors.initials: D
authors.lastname: Uebelhart
authors.forename: Dominik
authors.initials: D
authors.lastname: Weishaupt
authors.forename: Marcus
authors.initials: M
authors.lastname: Egermann
authors.forename: Ralph
authors.initials: R
authors.lastname: Müller
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density; D018786:Bone Substitutes / Q000737:chemistry*; D016025:Bone Transplantation; D005240:Feasibility Studies; D020342:Finite Element Analysis; D006801:Humans; D010281:Parathyroid Hormone / Q000737:chemistry; D011446:Prospective Studies; D011885:Radius Fractures / Q000000981:diagnostic imaging*; D012756:Sheep; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D018786:Bone Substitutes; D010281:Parathyroid Hormone