QCT-based spatio-temporal aging atlas of the proximal femur BMD and cortical geometry.

Aging is associated with an increased risk of fragility fractures at the hip, resulting from a loss of bone mass. While this loss is typically reported as a decreased mean areal bone mineral density (aBMD) in the proximal femur or the femoral neck, its evolution is spatially inhomogeneous, which might also contribute to the increased risk of fractures. Yet, little is known about the evolution of BMD distribution and cortical thickness with age in the proximal femur.

Primary Stability of Dental Implants in Human Jawbones: Experiments & FE Analyses.

Objectives: Primary stability (PS) is a key factor for promoting osseointegration and long-term success of dental implants particularly for immediate loading protocols. Beyond the current assessments of PS, an accurate pre-operative evaluation of PS would contribute to the improvement of surgical planning and treatment outcome. This study used biomechanical testing and homogenized finite element (hFE) analysis to objectively measure PS in the laboratory, and digitally estimate PS from prior μCT reconstructions.

Asynchronous calibration of a CT scanner for bone mineral density estimation: sources of error and correction.

The estimation of BMD with CT scans requires a calibration method, usually based on a phantom. In asynchronous calibration, the phantom is scanned separately from the patient. A standardized acquisition protocol must be used to avoid variations between patient and phantom.

Homogenized finite element simulations can predict the primary stability of dental implants in human jawbone.

Adequate primary stability is a pre-requisite for the osseointegration and long-term success of dental implants. Primary stability depends essentially on the bone mechanical integrity at the implantation site. Clinically, a qualitative evaluation can be made on medical images, but finite element (FE) simulations can assess the primary stability of a bone-implant construct quantitatively based on high-resolution CT images.

Bone collagen tensile properties of the aging human proximal femur.

Despite the dominant role of bone mass in osteoporotic fractures, aging bone tissue properties must be thoroughly understood to improve osteoporosis management. In this context, collagen content and integrity are considered important factors, although limited research has been conducted on the tensile behavior of demineralized compact bone in relation to its porosity and elastic properties in the native mineralized state. Therefore, this study aims (i) at examining the age-dependency of mineralized bone and collagen micromechanical properties; (ii) to test whether, and if so to which extent, collagen properties contribute to mineralized bone mechanical properties.

Homogenized finite element analysis of distal tibia sections: Achievements and limitations.

High-resolution peripheral quantitative computed tomography (HR-pQCT) based micro-finite element (μFE) analysis allows accurate prediction of stiffness and ultimate load of standardised (∼1 cm) distal radius and tibia sections. An alternative homogenized finite element method (hFE) was recently validated to compute the ultimate load of larger (∼2 cm) distal radius sections that include Colles' fracture sites. Since the mechanical integrity of the weight-bearing distal tibia is gaining clinical interest, it has been shown that the same properties can be used to predict the strength of both distal segments of the radius and the tibia.

Tensile Mechanical Properties of Dry Cortical Bone Extracellular Matrix: A Comparison Among Two Osteogenesis Imperfecta and One Healthy Control Iliac Crest Biopsies.

Osteogenesis imperfecta (OI) is a genetic, collagen-related bone disease that increases the incidence of bone fractures. Still, the origin of this brittle mechanical behavior remains unclear. The extracellular matrix (ECM) of OI bone exhibits a higher degree of bone mineralization (DBM), whereas compressive mechanical properties at the ECM level do not appear to be inferior to healthy bone.

Does tissue fixation change the mechanical properties of dry ovine bone extracellular matrix?

Tissue fixation is a prevalent method for bone conservation. Bone biopsies are typically fixed in formalin, dehydrated in ethanol, and infiltrated with polymethyl methacrylate (PMMA) Since some experiments can only be performed on fixed bone samples, it is essential to understand how fixation affects the measured material properties. The aim of this study was to quantify the influence of tissue fixation on the mechanical properties of cortical ovine bone at the extracellular matrix (ECM) level with state-of-the-art micromechanical techniques.

Mechanical testing and comparison of porcine tissue, silicones and 3D-printed materials for cardiovascular phantoms.

Cardiovascular phantoms for patient education, pre-operative planning, surgical training, haemodynamic simulation, and device testing may help improve patient care. However, currently used materials may have different mechanical properties compared to biological tissue. The aim of this study was to investigate the mechanical properties of 3D-printing and silicone materials in comparison to biological cardiovascular tissues.

Composition and micromechanical properties of the femoral neck compact bone in relation to patient age, sex and hip fracture occurrence.

Current clinical methods of bone health assessment depend to a great extent on bone mineral density (BMD) measurements. However, these methods only act as a proxy for bone strength and are often only carried out after the fracture occurs. Besides BMD, composition and tissue-level mechanical properties are expected to affect the whole bone's strength and toughness.

A multi-stack registration technique to improve measurement accuracy and precision across longitudinal HR-pQCT scans.

Background: Recent applications of high-resolution peripheral quantitative computed tomography (HR-pQCT) have demonstrated that changes in local bone remodelling can be quantified in vivo using longitudinal three-dimensional image registration. However, certain emerging applications, such as fracture healing and joint analysis, require larger multi-stack scan regions that can result in stack shift image artifacts. These artifacts can be detrimental to the accurate alignment of the bone structure across multiple timepoints.

Corrigendum: History of falls and fear of falling are predictive of future falls: Outcome of a fall rate model applied to the Swiss CHEF trial cohort.

[This corrects the article DOI: 10.3389/fragi.2022.

In situ synchrotron radiation µCT indentation of cortical bone: Anisotropic crack propagation, local deformation, and fracture.

The development of treatment strategies for skeletal diseases relies on the understanding of bone mechanical properties in relation to its structure at different length scales. At the microscale, indention techniques can be used to evaluate the elastic, plastic, and fracture behaviour of bone tissue. Here, we combined in situ high-resolution SRµCT indentation testing and digital volume correlation to elucidate the anisotropic crack propagation, deformation, and fracture of ovine cortical bone under Berkovich and spherical tips.

Textile Design of an Intervertebral Disc Replacement Device from Silk Yarn.

Low back pain is often due to degeneration of the intervertebral discs (IVD). It is one of the most common age- and work-related problems in today's society. Current treatments are not able to efficiently restore the full function of the IVD.

The elasto-plastic nano- and microscale compressive behaviour of rehydrated mineralised collagen fibres.

The hierarchical design of bio-based nanostructured materials such as bone enables them to combine unique structure-mechanical properties. As one of its main components, water plays an important role in bone's material multiscale mechanical interplay. However, its influence has not been quantified at the length-scale of a mineralised collagen fibre.

Development of a personalized fall rate prediction model in community-dwelling older adults: a negative binomial regression modelling approach.

Background: Around a third of adults aged 65 and older fall every year, resulting in unintentional injuries in 30% of the cases. Fractures are a frequent consequence of falls, primarily caused in individuals with decreased bone strength who are unable to cushion their falls. Accordingly, an individual's number of experienced falls has a direct influence on fracture risk.

2D-3D reconstruction of the proximal femur from DXA scans: Evaluation of the 3D-Shaper software.

Osteoporosis is currently diagnosed based on areal bone mineral density (aBMD) computed from 2D DXA scans. However, aBMD is a limited surrogate for femoral strength since it does not account for 3D bone geometry and density distribution. QCT scans combined with finite element (FE) analysis can deliver improved femoral strength predictions.

Investigating the post-yield behavior of mineralized bone fibril arrays using a 3D non-linear finite element unit-cell model.

In this study, we propose a 3D non-linear finite element (FE) unit-cell model to investigate the post-yield behavior of mineralized collagen fibril arrays (FAY). We then compare the predictions of the model with recent micro-tensile and micropillar compression tests in both axial and transverse directions. The unit cell consists of mineralized collagen fibrils (MCFs) embedded in an extrafibrillar matrix (EFM), and the FE mesh is equipped with cohesive interactions and a custom plasticity model.

History of falls and fear of falling are predictive of future falls: Outcome of a fall rate model applied to the Swiss CHEF Trial cohort.

A third of adults aged 65 years and older fall every year, and falls are a common cause of unintentional injuries. Accurate identification of people at risk of falling is an important step in the implementation of preventive strategies. Our aim was to investigate the association of fall risk factors with number of reported falls in terms of incidence rate ratios and to develop a fall rate prediction model.

Personalized loading conditions for homogenized finite element analysis of the distal sections of the radius.

The microstructure of trabecular bone is known to adapt its morphology in response to mechanical loads for achieving a biomechanical homeostasis. Based on this form-function relationship, previous investigators either simulated the remodeling of bone to predict the resulting density and architecture for a specific loading or retraced physiological loading conditions from local density and architecture. The latter inverse approach includes quantifying bone morphology using computed tomography and calculating the relative importance of selected load cases by minimizing the fluctuation of a tissue loading level metric.

Influence of aging on mechanical properties of the femoral neck using an inverse method.

Today, we are facing rapid aging of the world population, which increases the incidence of hip fractures. The gold standard of bone strength assessment in the laboratory is micro-computed finite element analysis (μFEA) based on micro-computed tomography (μCT) images. In clinics, the standard method to assess bone fracture risk is based on areal bone mineral density (aBMD), measured by dual-energy X-ray absorptiometry (DXA).

Evaluation of Load-To-Strength Ratios in Metastatic Vertebrae and Comparison With Age- and Sex-Matched Healthy Individuals.

Vertebrae containing osteolytic and osteosclerotic bone metastases undergo pathologic vertebral fracture (PVF) when the lesioned vertebrae fail to carry daily loads. We hypothesize that task-specific spinal loading patterns amplify the risk of PVF, with a higher degree of risk in osteolytic than in osteosclerotic vertebrae. To test this hypothesis, we obtained clinical CT images of 11 cadaveric spines with bone metastases, estimated the individual vertebral strength from the CT data, and created spine-specific musculoskeletal models from the CT data.

Assessing minipig compact jawbone quality at the microscale.

Preclinical studies often require animal models for in vivo experiments. Particularly in dental research, pig species are extensively used due to their anatomical similarity to humans. However, there is a considerable knowledge gap on the multiscale morphological and mechanical properties of the miniature pigs' jawbones, which is crucial for implant studies and a direct comparison to human tissue.