title: Mechanical behaviour of Bioactive Glass granules and morselized cancellous bone allograft in load bearing defects.
abstract: Bioactive Glass (BAG) granules are osteoconductive and possess unique antibacterial properties for a synthetic biomaterial. To assess the applicability of BAG granules in load-bearing defects, the aim was to compare mechanical behaviour of graft layers consisting of BAG granules and morselized cancellous bone allograft in different volume mixtures under clinically relevant conditions. The graft layers were mechanically tested, using two mechanical testing modalities with simulated physiological loading conditions: highly controllable confined compression tests (CCT) and more clinically realistic in situ compression tests (ISCT) in cadaveric porcine bone defects. Graft layer impaction strain, residual strain, aggregate modulus, and creep strain were determined in CCT. Graft layer porosity was determined using micro computed tomography. The ISCT was used to determine graft layer subsidence in bone environment. ANOVA showed significant differences (p<0.001) between different graft layer compositions. True strains absolutely decreased for increasing BAG content: impaction strain -0.92 (allograft) to -0.39 (BAG), residual strain -0.12 to -0.01, and creep strain -0.09 to 0.00 respectively. Aggregate modulus increased with increasing BAG content from 116 to 653MPa. Porosity ranged from 66% (pure allograft) to 15% (pure BAG). Subsidence was highest for allograft, and remarkably low for a 1:1 BAG-allograft volume mixture. Both BAG granules and allograft morsels as stand-alone materials exhibit suboptimal mechanical behaviour for load-bearing purpose. BAG granules are difficult to handle and less porous, whereas allograft subsides and creeps. A 1:1 volume mixture of BAG and allograft is therefore proposed as the best graft material in load-bearing defects.
authors.affiliation: Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Centre, Maastricht, The Netherlands; Department of Orthopaedic Biomechanics, Faculty of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; MICT Department, Jeroen Bosch Ziekenhuis, ׳s-Hertogenbosch, The Netherlands. Electronic address: d.hulsen@jbz.nl.
authors.forename: D J W
authors.initials: DJW
authors.lastname: Hulsen
authors.affiliation: Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Geurts
authors.affiliation: Department of Orthopaedic Biomechanics, Faculty of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: N A P
authors.initials: NAP
authors.lastname: van Gestel
authors.affiliation: Department of Orthopaedic Biomechanics, Faculty of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: van Rietbergen
authors.affiliation: Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Centre, Maastricht, The Netherlands; Department of Orthopaedic Biomechanics, Faculty of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors.forename: J J
authors.initials: JJ
authors.lastname: Arts
mesh_terms: D064591:Allografts / Q000502:physiology*; D000818:Animals; D000071556:Cancellous Bone / Q000502:physiology*; D019245:Compressive Strength; D005898:Glass; D008422:Materials Testing; D055595:Mechanical Phenomena; D016062:Porosity; D013552:Swine; D016474:Weight-Bearing
keywords: Bioactive Glass; Bone allograft; Confined compression; Load-bearing defects; Mechanical behaviour