Bone Material Research Articles

A Rab33b missense mouse model for Smith-McCort dysplasia shows bone resorption defects and altered protein glycosylation.

Smith McCort (SMC) dysplasia is a rare, autosomal recessive, osteochondrodysplasia that can be caused by pathogenic variants in either RAB33B or DYM genes. These genes codes for proteins that are located at the Golgi apparatus and have a role in intracellular vesicle trafficking. We generated mice that carry a Rab33b disease-causing variant, c.136A>C (p.Lys46Gln), which is identical to that of members from a consanguineous family diagnosed with SMC. In male mice at 4months of age, the Rab33b variant caused a mild increase in trabecular bone thickness in the spine and femur and in femoral mid-shaft cortical thickness with a concomitant reduction of the femoral medullary area, suggesting a bone resorption defect. In spite of the increase in trabecular and cortical thickness, bone histomorphometry showed a 4-fold increase in osteoclast parameters in homozygous Rab33b mice suggesting a putative impairment in osteoclast function, while dynamic parameters of bone formation were similar in mutant versus control mice. Femur biomechanical tests showed an increased in yield load and a progressive elevation, from WT to heterozygote to homozygous mutants, of bone intrinsic properties. These findings suggest an overall impact on bone material properties which may be caused by disturbed protein glycosylation in cells contributing to skeletal formation, supported by the altered and variable pattern of lectin staining in murine and human tissue cultured cells and in liver and bone murine tissues. The mouse model only reproduced some of the features of the human disease and was sex-specific, manifesting in male but not female mice. Our data reveal a potential novel role of RAB33B in osteoclast function and protein glycosylation and their dysregulation in SMC and lay the foundation for future studies.

Biomaterials as Implants in the Orthopedic Field for Regenerative Medicine: Metal versus Synthetic Polymers.

Patients suffering bone fractures in different parts of the body require implants that will enable similar function to that of the natural bone that they are replacing. Joint diseases (rheumatoid arthritis and osteoarthritis) also require surgical intervention with implants such as hip and knee joint replacement. Biomaterial implants are utilized to fix fractures or replace parts of the body. For the majority of these implant cases, either metal or polymer biomaterials are chosen in order to have a similar functional capacity to the original bone material. The biomaterials that are employed most often for implants of bone fracture are metals such as stainless steel and titanium, and polymers such as polyethene and polyetheretherketone (PEEK). This review compared metallic and synthetic polymer implant biomaterials that can be employed to secure load-bearing bone fractures due to their ability to withstand the mechanical stresses and strains of the body, with a focus on their classification, properties, and application.

Universal mtDNA fragment for Cervidae barcoding species identification using phylogeny and preliminary analysis of machine learning approach

The aim of the study was to use total DNA obtained from bone material to identify species of free-living animals based on the analysis of mtDNA fragments by molecular methods using accurate bioinformatics tools Bayesian approach and the machine learning approach. In our research, we present a case study of successful species identification based on degraded samples of bone, with the use of short mtDNA fragments. For better barcoding, we used molecular and bioinformatics methods. We obtained a partial sequence of the mitochondrial cytochrome b (Cytb) gene for Capreolus capreolus, Dama dama, and Cervus elaphus, that can be used for species affiliation. The new sequences have been deposited in GenBank, enriching the existing Cervidae mtDNA base. We have also analysed the effect of barcodes on species identification from the perspective of the machine learning approach. Machine learning approaches of BLOG and WEKA were compared with distance-based (TaxonDNA) and tree-based (NJ tree) methods based on the discrimination accuracy of the single barcodes. The results indicated that BLOG and WEKAs SMO classifier and NJ tree performed better than TaxonDNA in discriminating Cervidae species, with BLOG and WEKAs SMO classifier performing the best.

Relative Effects of Radiation-Induced Changes in Bone Mass, Structure, and Tissue Material on Vertebral Strength in a Rat Model.

The observed increased risk of fracture after cancer radiation therapy is presumably due to a radiation-induced reduction in whole-bone strength. However, the mechanisms for impaired strength remain unclear, as the increased fracture risk is not fully explained by changes in bone mass. To provide insight, a small animal model was used to determine how much of this whole-bone weakening effect for the spine is attributable to changes in bone mass, structure, and material properties of the bone tissue and their relative effects. Further, because women have a greater risk of fracture after radiation therapy than men, we investigated if sex had a significant influence on bone's response to irradiation. Fractionated in vivo irradiation (10 × 3 Gy) or sham irradiation (0 Gy) was administered daily to the lumbar spine in twenty-seven 17-week-old Sprague-Dawley rats (n = 6-7/sex/group). Twelve weeks after final treatment, animals were euthanized, and lumbar vertebrae (L4 and L5 ) were isolated. Using a combination of biomechanical testing, micro-CT-based finite element analysis, and statistical regression analysis, we separated out the effect of mass, structural, and tissue material changes on vertebral strength. Compared with the sham group (mean ± SD strength = 420 ± 88 N), the mean strength of the irradiated group was lower by 28% (117 N/420 N, p < 0.0001). Overall, the response of treatment did not differ with sex. By combining results from both general linear regression and finite element analyses, we calculated that mean changes in bone mass, structure, and material properties of the bone tissue accounted for 56% (66 N/117 N), 20% (23 N/117 N), and 24% (28 N/117 N), respectively, of the overall change in strength. As such, these results provide insight into why an elevated clinical fracture risk for patients undergoing radiation therapy is not well explained by changes in bone mass alone. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Assessment of bone morphogenetic protein-7 loaded chitosan/β-Glycerophosphate hydrogel on periodontium tissues regeneration of class III furcation defects

BackgroundPeriodontitis is a long-term, multifactorial inflammatory condition that is triggered by bacterial germs and interacts with the host's immune system. The unique attachment of fibrous tissue between the cementum and bone presents a challenge for periodontal regeneration. AimTo achieve the lowest optimum dose of BMP-7 that helps in periodontal regeneration, involving newly formed cementum, PDL and bone Materials and methodsFive healthy mongrel dogs were used for the study. A critical class III furcation defect was created using rotating burs. The bone defects (ten defects for each group) were allocated to one of the subsequent groups: (Group 1) control with the surgical defect only. (Group 2) Surgical defect implanted with hydrogel only (CS/β-GP). (Group 3) Surgical defect implanted with CS/BMP-7 (50 ng/ml). (Group 4) Surgical defect implanted with CS/BMP-7 (100 ng/ml). ResultsHistomorphometric and H&E analysis revealed a statistically significant difference in bone, PDL, and cementum regeneration defects filled with CS/BMP-7 (100 ng/ml) compared with other groups. ConclusionThe standard effective dose for BMP-7 use in periodontal regeneration is 100 ng/ml.

Functional β-TCP/MnO2 /PCL artificial periosteum promoting osteogenic differentiation of BMSCs by reducing locally reactive oxygen species level.

Segmental bone defects caused by trauma, tumor resection or congenital malformations are often reconstructed with autologous, allogeneic bone grafts or artificial bone materials, of which, about 5% ~ 10% will have delayed healing or even nonunion of fractures. The loss of periosteum and excessive accumulation of ROS in fracture site leads to the aging of osteoblasts and the decline of their proliferation and differentiation, thus affecting the fracture healing process. In this study, we prepared a functional modified artificial periosteum β-TCP/MnO2 /PCL(β-TMP) by electrospinning with a function of catalyzing decomposition of H2 O2 . We examined the surface morphology of β-TMP, the concentration of Ca, P and Mn of β-TMP, as well as the diameter distribution range of nanofibers on β-TMP. Through X-ray diffraction patterns and Fourier transform infrared spectra, β-TMP was characterized and its hydrophilicity was tested. The release of Mn2+ and Ca2+ of 0.1 and 0.05% β-TMP in different pH values (7.4 and 5.5) determined by ICP. We also identified that β-TMP could reduce the level of ROS in cells by lowering the level of H2 O2 . 0%, 0.05% and 0.1% β-TMP displayed good cell compatibility, cell adhesion and cellular morphology in the condition with or without H2 O2 . 0.5% β-TMP showed compromised cell compatibility in normal condition, however, the compromised phenotypes could be partially rescued in the present of H2 O2 . Compared with 0%, 0.05% and 0.1% β-TMP displayed higher osteoblastic differentiation with or without H2 O2 in BMSCs as well as in MG-63. In sum, β-TMP helped osteogenesis and promoted repair of bone defects.

Surface Characteristics, Osteogenic Activity and Antibacterial Effect of Magnesium-Doped Porous Coating on Titanium Surface

Biomedical titanium and its alloys have become the preferred materials for bone and joint implants due to their excellent biocompatibility, high specific strength, and low elastic modulus. However, poor biological activity and bacterial infection on the surface of titanium alloys have become major obstacles to their clinical application. Improving the osteogenic and antibacterial properties of titanium through surface modification is currently an important research area. In this study, a microporous magnesium-doped titanium dioxide coating was prepared on a titanium surface via microarc oxidation. This coating not only has a good porous surface morphology, with magnesium distributed on the surface of the coating, but also exhibits good resistance to corrosion and wear. In vitro cell experiments showed that the coating promoted proliferation, differentiation and mineralization in bone marrow mesenchymal stem cells, while bacterial experiments showed that the coating inhibited the growth of Staphylococcus aureus and Escherichia coli, with good antibacterial activity. This study provides a new theoretical and experimental basis for improving the biological activity of titanium.

Influence of titanium ion doping on structural changes in porous hydroxyapatite ceramics

Biocompatible titanium (Ti) is commonly used as an implant material. Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is a biomaterial that is similarly applied in the medical field owing to its biocompatibility. HAp is used as an alternative material for bones and teeth; for such purpose, the pores should have diameters of at least 200 μm. However, no studies have reported porous Ti-doped HAp. In this study, we fabricated five types of porous Ti-doped HAp ceramics using different amounts of 30% titanium sulfate solution (0.1, 0.2, 0.3, 0.4, and 0.5 g) as additive Ti ions in the chemical route. In general, the lattice parameters of Ti-doped HAp decrease because Ti ions are substituted for Ca ions but have a smaller ionic radius. However, the lattice parameters a and c actually increased in the porous Ti-doped HAp ceramics produced in this study, and only decreased in sample fabricated with 0.5 g of Ti solution. This change in structure was attributed to dehydroxylation of OH ions from the HAp lattice. Ti ions inserted into OH channels parallel to the c-axis in HAp lattices generate O–Ti–O bonds. Consequently, the lattice parameter c increased. The interaction between the dislocated OH ions and protonated HPO4 ions in the HAp lattices increased the lattice parameter a. The formation of O–Ti–O bonds did not maintain the charge balance, owing to the tetravalent Ti ions. However, the development of the c-plane in the HAp lattices increased as the amount of added Ti increased. Consequently, the growth of the negatively charged c-plane maintained the charge balance by compensating for the extra charges of the Ti ions.

Bone Grafts in Dental Medicine: An Overview of Autografts, Allografts and Synthetic Materials.

This review provides an overview of various materials used in dentistry and oral and maxillofacial surgeries to replace or repair bone defects. The choice of material depends on factors such as tissue viability, size, shape, and defect volume. While small bone defects can regenerate naturally, extensive defects or loss or pathological fractures require surgical intervention and the use of substitute bones. Autologous bone, taken from the patient's own body, is the gold standard for bone grafting but has drawbacks such as uncertain prognosis, surgery at the donor site, and limited availability. Other alternatives for medium and small-sized defects include allografts (from human donors), xenografts (from animals), and synthetic materials with osteoconductive properties. Allografts are carefully selected and processed human bone materials, while xenografts are derived from animals and possess similar chemical composition to human bone. Synthetic materials such as ceramics and bioactive glasses are used for small defects but may lack osteoinductivity and moldability. Calcium-phosphate-based ceramics, particularly hydroxyapatite, are extensively studied and commonly used due to their compositional similarity to natural bone. Additional components, such as growth factors, autogenous bone, and therapeutic elements, can be incorporated into synthetic or xenogeneic scaffolds to enhance their osteogenic properties. This review aims to provide a comprehensive analysis of grafting materials in dentistry, discussing their properties, advantages, and disadvantages. It also highlights the challenges of analyzing in vivo and clinical studies to select the most suitable option for specific situations.

Free Fibula Flap in Traumatic Femoral Bone Reconstruction: A 10-year Review.

The loss of femoral bone substance represents a major therapeutic issue. When the loss of bone substance is extensive, or the local condition is unfavourable, there are few satisfactory solutions. In this study, we share our experience of large femoral bone reconstruction by free fibula flap. A retrospective monocentric chart review (2007-2017) was performed for 26 patients after receiving a pure bone-free fibula flap operation. The times of consolidation and hypertrophy of the graft were analysed according to the fixation with a 2-year follow-up. The time to consolidation was 8.7 months (range, 6-15) for double plates, 7.2 months (range, 5-11) for locked plates, 6 months (range, 5-7) for external fixators and plate blades and 8 months (range, 7-9) for intramedullary nails.Full weight-bearing was resumed at an average of 6.5 months (range, 5-10) postoperatively. It was authorised at 7 months (range, 5-10) for patients fixed by double plate, at 6.3 months (range, 5-9) for those fixed by a locked plate, at 5.5 months (range, 5-6) for those fixed by an external fixator or plate blade and at 7 months for those fixed by an intramedullary nail. Free fibula flap remains reliable in the face of a great loss of bone material after trauma, with high consolidation rates. The choice of fixation must be reasoned and should offer a compromise between stability, allowing consolidation and hypertrophy of the graft, and rigidity, exposing the risk of massive osteosynthesis dismantling. Other multicentric studies, including more patients, should be carried out to compare the techniques of fixation. Viaud-Ambrosino S, Bargemon JBV, Kachouh N, et al. Free Fibula Flap in Traumatic Femoral Bone Reconstruction: A 10-year Review. Strategies Trauma Limb Reconstr 2023;18(1):44-50.

At the onset of settled pastoralism – Implications of archaeozoological and isotope analyses from Bronze age sites in the North Caucasus

Bioarchaeological studies provide a valuable contribution to the understanding of the economy and activities of prehistoric populations in mountain regions. The Late Bronze Age in the Caucasus is an epoch of fundamental transformations that is accompanied by the development of a semi-stationary pastoral economy and ultimately by the emergence of combined mountain agriculture. So far, only a few archaeozoological assemblages from this period have been published. The site of Ransyrt-1 in the North Caucasus offers a substantial collection of bone material from the remains of a mountain sanctuary. Analysis of the animal remains as well as preliminary isotopic analyses of strontium, oxygen, and carbon shed light on animal exploitation at this site. Comparisons with slightly later settlements in the North and South Caucasus illustrate the development of intensive livestock management strategies in the Late Bronze Age in this region at the interface between Southwest Asia and the Eurasian steppe.

Evaluation of a design for a three‐dimensional‐printed artificial bone structure

AbstractIn this work, artificial bones composed of hydroxyapatite (HA)/polyacrylonitrile (PAN) and polylactic acid (PLA) were prepared as a potential replacement for natural bone. The cylindrical specimens included an auxetic system with artificial osteons. HA/PAN and PLA were used to fabricate composite filaments by fused deposition modeling three‐dimensional (3D) printing, and the obtained filaments were applied to produce reentrant artificial bone materials. Scanning electron microscopy was used to analyze the scaffold morphology and functional groups. Energy‐dispersive X‐ray spectroscopy was used for elemental analysis. The compressive properties of the samples were studied to determine the optimal scaffolding prototype. Compressive tests were also performed to assess the behavior of the cellular structure from a mechanical perspective. Finally, ANOVA and residual plots were used to investigate the contributions of the design elements, predict the y‐coordination of the stress values, and evaluate the printing orientation. The results indicated that the auxetic cells influenced the bone macrostructure, which displayed different stiffness characteristics in one working direction. Polymeric solution biomaterials based on HA/PAN and PLA biopolymers have enormous potential as high‐performance liquid synthetic organic polymers for light‐supported extrusion‐based 3D printing. PLA/HA scaffoldings with outstanding medical conversion capability may be used as biomaterial composites for bone deficiency restoration.Highlights Composite filaments for FDM 3D printing were used to manufacture reentrant artificial bone. A replacement method was utilized to determine the porosity of the scaffolds. Mechanically, this cellular structure was evaluated using compressive studies. SEM was used to assess scaffold morphology, functional categories, and elements. Create biodegradable constructions using as little material as possible.

Effects of Development on Bone Mineral Density and Mechanical Properties in the Aquatic Frog, Xenopus Laevis, and a Terrestrial Frog, Lithobates Catesbianus.

The limb bones of vertebrates have a critical role in supporting the weight of the body and transmitting forces that power locomotion. The loads that limb bones experience can vary in association with a range of factors, including locomotor environment or developmental stage. Limbed vertebrates that are habitually found in environments with low locomotor loads (e.g., water) might be predicted to also exhibit limb bones with less elevated mechanical properties, such as yield stiffness and yield stress. Frogs provide a distinctive case, in which these ideas can be tested as they experience changes in both locomotor style and habitat as they develop. However, while many frog taxa shift from aquatic to terrestrial habitats as they metamorphose, some lineages, such as pipids, maintain an aquatic lifestyle even after metamorphosis, providing a comparative framework for the effects of habitat shifts on developing limbs in vertebrates. This study compares the material composition and mechanical properties of the femur between frog species that are aquatic specialists (Xenopus laevis) vs generalists that spend considerable time both on land and in water (Lithobates catesbeianus) as they transition from metamorphic tadpoles to fully grown adults. MicroCT scanning was used to determine changes in bone density related to developmental stage and hindlimb use during swimming. Microindentation was then used to collect hardness values from the cortical bone of each femur, which was used to evaluate bone material properties. We found that aquatic frogs had less overall bone mineral density (BMD) than terrestrial frogs and that BMD was more elevated in the cortical region of the diaphysis than trabeculae and distal and proximal epiphyses. Despite its less elevated BMD, bone mechanical properties were not significantly different in aquatic specialist X. laevis than in more terrestrial L. catesbeianus. Our results suggest that the limb bones of aquatic frogs may experience compensatory effects through development to offset their lower BMD. Furthermore, changes in bone density and material properties across development may help to explain some of the differences in locomotor performance found between aquatic and terrestrial metamorphic frogs, providing insight into how environmental factors might correlate with bone ossification.

Bone and antler artifact use in the 1st millennium CE of Cusco, Peru: Insights on textile production and food processing from the site of Ak'awillay

There is a long history in the use of osseous materials from some of the earliest contexts of the Andes, yet most technology studies have focused on durable materials of ceramic, metal, and stone. In this paper, we present evidence for the continual use of osseous raw materials before and during Wari state expansion in the 1st millennium CE in the Cusco region of Peru. Results indicate that, at the site of Ak'awillay, communities were exploiting osseous raw material to produce artifacts used in textile manufacture, food processing, and ceremonial activities. We argue that wide-scale access to bone and antler raw material fostered social interactions that mediated emergent power dynamics in private and public spaces. This key line of evidence reveals that communal practices in public spaces at Ak'awillay involved food processing activities, while private settings were reserved for sharing of familial knowledge around textile production. We emphasize the greater need in the Andes for a close look at osseous technology to detect these subtle, yet integral patterns to understand social and power relations in the past.

Identification of donkey-hide gelatin and donkey-bone gelatin based on marker peptides

Donkey-hide gelatin (DHG) is a food and drug product prepared using donkey skins. However, the detection of the illegal addition of donkey bone materials to DHG remains impossible. Herein, a new method using marker peptides from bone-related specific preteins was developed to identify donkey bone gelatin (DBG) and DHG. The bone-specific proteins were identified and verified by proteomic approaches. Peptides derived from the bone-specific protein were synthesized and used to develop a liquid chromatography multiple-reaction-monitoring mass spectrometry (LC-MRM-MS) method. The capability of this method was tested using homemade adulterated gelatins and commercial DHG products. It was found that several proteins were unique to donkey bone including collagen type II, osteocalcin, and osteonectin. Three of seven marker peptides from type II collagen showed good specificity for DBG. Adulteration with DBG could be identified at a level of 50 mg/g using the LC-MRM-MS method. Among the 23 batches of commercial DHG products, three were suspected of containing donkey bone materials owing to the detection of the marker peptides. The new method established in this study could enhance the quality control of DHG, and this strategy can also be adapted to identify other foods and drugs containing protein components.

NUMERICAL AND EXPERIMENTAL ANALYSIS OF THE CHANGE IN THE MECHANICAL PROPERTIES INDUCED BY DIFFERENT MATERIAL INTERNAL FEATURES

In orthopedic medical devices, differences in elasto-plastic behavior between bone and metallic materials could lead to mechanical issues at the bone-implant interface, such as stress shielding, bone fracture or implant failure. To reduce mismatching-related adverse events between bone and prosthetic mechanical properties, an in-body geometry optimization could be the right approach to reduce prosthetic stiffness. Therefore, this study aims to assess the elastic behavior of four different in-body gap prismatic geometries (quadratic, hexagonal, octagonal, and circular) and how much they reduce bulk stiffness. Uniaxial compression tests were performed on five cubes with a 20[Formula: see text]mm thickness, each containing a different set of internal prismatic gaps. For each design, the elastic response was calculated and compared with a full-volume cube, used as control. All cubes showed a stiffness reduction compared to the control, greater in cubes with quadratic (21%), octagonal (18%), and circular (17%) transversal sections, compared to the hexagonal one (6%). Moreover, finite element models were implemented and tested, showing coherent values obtained through the experimental tests. In addition, a bi-material approach was studied in silico and the results suggested that variable elastic behavior could be obtained by using composite material, providing lower mechanical properties than commonly used commercial prosthetic materials.

The natural mineral bone material that doesn't wash away.

The natural mineral bone material that doesn't wash away.

Effect of extended field-of-view approaches on the accuracy of stopping power ratio estimation for single-energy computed tomography simulators.

Extended field-of-view (eFOV) methods have been proposed to generate larger demonstration FOVs for computed tomography (CT) simulators with a limited scanning FOV (sFOV) size in order to ensure accurate dose calculation and patient collision avoidance. Although the efficacy of these strategies has been evaluated for photon applications, the effect of stopping power ratio (SPR) estimation on proton therapy has not been studied. This study investigated the effect of an eFOV approach on the accuracy of SPR to water estimation in homogeneous and heterogeneous phantoms. To simulate patient geometries, tissue-equivalent material (TEM) and customized extension phantoms were used. The TEM phantom supported various rod arrangements through predefined holes. Images were reconstructed to three FOV sizes using a commercial eFOV technique. A single-energy CT stoichiometric method was used to generate Hounsfield unit (HU) to SPR (HU-to-SPR) conversion curves for each FOV. To investigate the effect of rod location in the sFOV and eFOV regions, eight TEM rods were placed at off-center distances in the homogeneous phantom and scanned individually. Similarly, 16 TEM rods were placed in the heterogeneous TEM phantom and scanned simultaneously. The conversion curves derived from the sFOV and eFOV data were identical. The average SPR differences of soft-tissue, bone, and lung materials for rods placed at various off-center locations were 3.3%, 4.8%, and 39.6%, respectively. In the heterogeneous phantom, the difference was within 1.0% in the absence of extension. However, in the presence of extension, the difference increased to 2.8% for all rods, except for lung materials, whose difference was 4.8%. When an eFOV method is used, the SPR variation in phantoms considerably increases for all TEM rods, especially for lung TEM rods. This phenomenon may substantially increase the uncertainty of HU-to-SPR conversion. Therefore, image reconstruction with a standard FOV size is recommended.

Breed and loading history influence in vivo skeletal strain patterns in pre-pubertal female chickens

The influence of loading history on in vivo strains within a given specie remains poorly understood, and although in vivo strains have been measured at the hindlimb bones of various species, strains engendered during modes of activity other than locomotion are lacking, particularly in non-human species. For commercial egg-laying chickens specifically, there is an interest in understanding their bones' mechanical behaviour, particularly during youth, to develop early interventions to prevent the high incidence of osteoporosis in this population. We measured in vivo mechanical strains at the tibiotarsus midshaft during steady activities (ground, uphill, downhill locomotion) and non-steady activities (perching, jumping, aerial transition landing) in 48 pre-pubescent female (egg-laying) chickens from two breeds that were reared in three different housing systems, allowing varying amounts and types of physical activity. Mechanical strain patterns differed between breeds, and were dependent on the activity performed. Mechanical strains were also affected by rearing environment: chickens that were restricted from performing dynamic load bearing activity due to caged-housing generally exhibited higher mechanical strain levels during steady, but not non-steady activities, compared to chickens with prior dynamic load-bearing activity experience. Among chickens with prior experience of dynamic load bearing activity, those reared in housing systems that allowed more frequent physical activity did not exhibit lower mechanical strains. In all groups, the tibiotarsus was subjected to a loading environment consisting of a combination of axial compression, bending, and torsion, with torsion being the predominant source of strain. Aerial transition landing produced the highest strain levels with unusual strain patterns compared to other activities, suggesting it may produce the strongest anabolic response. These results exemplify how different breeds within a given specie adapt to maintain different patterns of mechanical strains, and how benefits of physical activity in terms of resistance to strain are activity-type dependent and do not necessarily increase with increased physical activity. These findings directly inform controlled loading experiments aimed at studying the bone mechanoresponse in young female chickens and can also be associated to measures of bone morphology and material properties to understand how these features influence bone mechanical properties in vivo.

Conceptual design of compliant bone scaffolds by full-scale topology optimization

A promising new treatment for large and complex bone defects is to implant specifically designed and additively manufactured synthetic bone scaffolds. Optimizing the scaffold design can potentially improve bone in-growth and prevent under- and over-loading of the adjacent tissue. This study aims to optimize synthetic bone scaffolds over multiple-length scales using the full-scale topology optimization approach, and to assess the effectiveness of this approach as an alternative to the currently used mono- and multi-scale optimization approaches for orthopaedic applications. We present a topology optimization formulation, which is matching the scaffold's mechanical properties to the surrounding tissue in compression. The scaffold's porous structure is tuneable to achieve the desired morphological properties to enhance bone in-growth. The proposed approach is demonstrated in-silico, using PEEK, cortical bone and titanium material properties in a 2D parameter study and on 3D designs. Full-scale topology optimization indicates a design improvement of 81% compared to the multi-scale approach. Furthermore, 3D designs for PEEK and titanium are additively manufactured to test the applicability of the method. With further development, the full-scale topology optimization approach is anticipated to offer a more effective alternative for optimizing orthopaedic structures compared to the currently used multi-scale methods.