Journal of the Mechanical Behavior of Biomedical Materials

The identification of material parameters accurately describing the region-dependent mechanical behavior of human brain tissue is crucial for computational models used to assist, e.g., the development of safety equipment like helmets or the planning and execution of brain surgery. While the division of the human brain into different anatomical regions is well established, knowledge about regions with distinct mechanical properties remains limited. Here, we establish an inverse parameter identification scheme using a hyperelastic Ogden model and experimental data from multi-modal testing of tissue from 19 anatomical human brain regions to identify mechanically distinct regions and provide the corresponding material parameters. We assign the 19 anatomical regions to nine governing regions based on similar parameters and microstructures. Statistical analyses confirm differences between the regions and indicate that at least the corpus callosum and the corona radiata should be assigned different material parameters in computational models of the human brain. We provide a total of four parameter sets based on the two initial Poissons ratios of 0.45 and 0.49 as well as the pre- and unconditioned experimental responses, respectively. Our results highlight the close interrelation between the Poissons ratio and the remaining model parameters. The identified parameters will contribute to more precise computational models enabling spatially resolved predictions of the stress and strain states in human brains under complex mechanical loading conditions.

Soft hydrated materials, including biological tissues and hydrogels, exhibit complex time-dependent mechanical behaviors due to their poroelastic and viscoelastic properties. These properties often manifest on overlapping time scales, making it challenging to isolate the individual contributions of poroelasticity and viscoelasticity to the overall mechanical response. This study presents a novel semi-analytical model for characterizing these properties through sequential microscale load relaxation indentation testing. By extending existing theories, we developed a poroviscoelastic framework that enables the deconvolution of poroelastic and viscoelastic effects. Using this model to fit sequential microscale indentation data, we characterized porcine heart and liver tissues, as well as collagen and GelMA hydrogels, revealing distinct differences in their poroelastic and viscoelastic parameters. Our findings demonstrate that this approach not only provides rapid and detailed insights into the mechanical properties at the microscale but also offers significant advantages over traditional methods in terms of speed, computational efficiency, and practicality. This methodology has broad implications for advancing the understanding of tissue mechanics and the design of biomimetic materials for tissue engineering applications. Statement of SignificanceThis study introduces a novel approach to understanding the mechanical behavior of soft hydrated materials, like tissues and hydrogels. This study introduces a semi-analytical model to describe the time dependent behavior and a practical approach to distinguish between poroelasticity and viscoelasticity at the microscale. By providing this model along with a rapid and efficient characterization method, our approach enhances understanding of time-dependent mechanical behaviors critical for soft tissue mechanics and biomaterials design.

When making contact, fingertip mechanoreceptors respond to the skin deformation, and provide essential information for tactile perception and object manipulation. Since subsurface measurements remain challenging, strains close to the receptors are commonly estimated using numerical models. Here, we present a biomechanical finite element model simulating fingertip normal loading against a flat plate. Several model variants are designed to isolate the role of tissue heterogeneity and collagen-induced anisotropy. Their predictions are compared to experimental data of fingertip surface strains obtained with 3-D stereo imaging. By varying the stiffness contrast and fiber orientation, we demonstrate that incorporating collagen anisotropy is required to reproduce strain localization at the contact edge while maintaining realistic global shape changes. In particular, fibers aligned parallel to the skin surface induce local skin thickening and a pronounced radial expansion beneath the contact edge, affecting mechanoreceptors. This observation suggests a collagen-mediated contribution to the deep transmission of mechanical stimuli. These results highlight collagen architecture as a key determinant of fingertip mechanics and underscore its importance for accurate modeling of tactile interactions.

Cellulosic, hemicellulosic and pectinaceous mucilages produced by certain angiosperms as adaptation in myxodiaspory are investigated in the past for seed dispersal. The present understanding of zoochory and telechory are based on mucilage amount, state of hydration and to a limited extent, role of mucilage microstructure studied using adhesion and friction. Pectinaceous mucilages have less adhesion and supports dispersal by zoochory. However, in the case of cellulosic mucilages, the role played by the cellulosic fibrils in seed dispersal is not clear, especially, since they have a negative correlation with endozoochory. Using fresh cellulosic seed mucilages from, sweet basil (Ocimum basilicum) and chia (Salvia hispanica) we investigate the role of microstructure of the mucilage in two key behaviours: anchoring and adhesion properties of the seeds through rheology. We report a special large deformation mechanism triggered through strain stiffening operational in these cellulosic mucilages. In many biopolymers semi-flexible polymer chains and other aligning elements contribute to the strain stiffening. However, the strain stiffening and strong wet adhesion observed in these mucilages have a significant role from the cellulosic components. This behaviour is more pronounced in basil seeds and presents a plausible structure-property mechanism for anti-telechory favoured by plant species found in arid habitats.

When thrombus fractures and breaks off it can occlude vital vessels such as those of the heart, lung, or brain. These thromboembolic conditions are responsible for 1 in 4 deaths world-wide. This problem is also of significant current interest as 1 in 3 COVID-19 intensive care patients exhibit thromboembolic complications. Thrombus resistance to fracture is driven by its intrinsic fracture toughness as well as other, non-surface-creating dissipative mechanisms. In our current work, we identify and quantify these latter mechanisms toward future studies that aim to delineate fracture from other forms of dissipation. To this end, we use an in vitro thrombus mimic system to produce whole blood clots and explore their dissipative mechanics under simple uniaxial extension, cyclic loading, and stress-relaxation. We found that whole blood clots exhibit Mullins effect, hysteresis, permanent set, strain-rate dependence, and nonlinear stress-relaxation. Interestingly, we found that performing these tests under dry or submerged conditions did not change our results. However, performing these tests under room temperature or body temperature conditions yielded differences. Overall, we have demonstrated that whole blood clots show several dissipative phenomena - similarly to hydrogels - that will be critical to our understanding of thrombus fracture.

The treatment of Achilles tendinopathy is challenging, as 40% of patients do not respond to the existing rehabilitation protocols. These rehabilitation protocols do not consider the individual differences in the Achilles tendon (AT) characteristics, which are crucial in creating the optimal strain environment that promotes healing. While previous research suggests an optimal strain for AT regeneration (6% tendon strains), it is still unclear if the current rehabilitation protocols meet this condition. Consequently, this study aimed to investigate the influence of a selection of rehabilitation exercises on strains in patients with Achilles tendinopathy using subject-specific finite element (FE) models of the free AT. Secondly, the study aimed to explain the influence of muscle forces and material properties on the AT strains. The 21 FE models of the AT included the following subject-specific features: geometry estimated from 3D freehand ultrasound images, Elastic modulus estimated from the experimental stress-strain curve, and muscle forces estimated using a combination of 3D motion capture and musculoskeletal modelling. These models were used to determine tendon strain magnitudes and distribution patterns in the mid-portion of the AT. The generalized ranking suggested a progression of exercises to gradually increase the strains in the mid-portion of the AT, starting from the concentric and eccentric exercises and going to more functional exercises, which impose a higher load on the AT: bilateral heel rise (0.031 {+/-} 0.010), bilateral heel drop (0.034 {+/-} 0.009), unilateral heel drop (0.066 {+/-} 0.023), walking (0.069 {+/-} 0.020), unilateral heel drop with flexed knee (0.078 {+/-} 0.023), and bilateral hopping (0.115 {+/-} 0.033). Unilateral heel drop and walking exercises were not significantly different and they both fell within the optimal strain range. However, when examining individual strains, it became evident that there was diversity in exercise rankings among participants, as well as exercises falling within the optimal strain range. Furthermore, the strains were influenced more by the subject-specific muscle forces compared to the material properties. Our study demonstrated the importance of tailored rehabilitation protocols that consider not only individual subject-specific morphological and material characteristics but especially subject-specific muscle forces. These findings make a significant contribution to shape future rehabilitation protocols with a foundation in biomechanics.

The nature of contact between human skin and external object (such as medical device, personal care device, fabric and so on) significantly influences the tactile perception and/or the functionality of the object. The contact mechanics depends strongly on the indenter properties and the mechanical properties of skin. Further, the topmost layer i.e., stratum corneum plays the most important role in tactile perception. In this study we use a representative volume element (RVE) based FEM model including the four layers of skin - stratum corneum, epidermis, dermis, and hypodermis - to simulate the contact mechanics between skin and a spherical indenter. The RVE model captures the mechanical properties of the microscopic constituents of the stratum corneum, which is the topmost layer of skin. We found that the RVE model can be used to simulate a variety of stratum corneum conditions (for example, dry and wet stratum corneum) and compositions. Using the RVE model in conjunction with an FEM model, we compute the frictional stress between skin and an indenter, as a function of stratum corneum microstructure, indentation depth, and local coefficient of friction. Both, the RVE model and the contact mechanics model predictions show good qualitative agreement with experimental findings in literature. Such studies will be very useful in in-silico design and optimization of devices that interact with skin. The current framework gives control over several parameters like skin microstructure, indenter or skin geometry and hence can be used to augment/substitute experimental testing.

The material properties of muscle play a central role in how muscle resists joint motion, transmits forces internally, and repairs itself. While many studies have evaluated muscles tensile material properties, few have investigated muscles shear properties. None of which have taken into account muscles anisotropic structure or investigated how different muscle architecture affect muscles shear properties. The objective of this study was to quantify the shear moduli of skeletal muscle in three orientations relevant to the function of whole muscle. We collected data from the extensor digitorum longus, tibialis anterior, and soleus harvested from both hindlimbs of 12 rats. These muscles were chosen to further evaluate the consistency of shear moduli across muscles with different architectures. We calculated the shear modulus in three orientations: parallel, perpendicular, and across with respect to muscle fiber alignment; while the muscle was subjected to increasing shear strain. For all muscles and orientations, the shear modulus increased with increasing strain. The shear modulus measured perpendicular to fibers was greater than in any other orientation. Despite architectural differences between muscles, we did not find a significant effect of muscle type on shear modulus. Our results show that in rat, muscles shear moduli vary with respect to fiber orientation and are not influenced by architectural differences in muscles.

Poor socket fit is the leading cause of prosthetic limb discomfort. However, currently clinicians have limited objective data to support and improve socket design. Prosthesis fit could be predicted by finite element analysis to help improve the fit, but this requires internal and external anatomy models. While external 3D surface scans are often collected in routine clinical computer aided design practice, detailed imaging of internal anatomy (e.g. MRI or CT) is not. This paper presents a prototype Statistical Shape Model (SSM) describing the transtibial amputated residual limb, generated using a sparse dataset of 10 MRI scans. To describe the maximal shape variance, training scans are size-normalised to their estimated intact tibia length. A mean limb is calculated, and Principal Component Analysis used to extract the principal modes of shape variation. In an illustrative use case, the model is interrogated to predict internal bone shapes given a skin surface shape. The model attributes [~]82% of shape variance to amputation height and [~]7.5% to soft tissue profile. Leave-One-Out cross-validation allows mean shape reconstruction with 0.5-3.1mm root-mean-squared-error (RMSE) surface deviation (median 1.0mm), and left-out-shape reconstruction with 4.8-8.9mm RMSE (median 6.1mm). Linear regression between mode scores from skin- only- and full-model SSMs allowed prediction of bone shapes from the skin surface with 4.9-12.6mm RMSE (median 6.5mm). The model showed the feasibility of predicting bone shapes from skin surface scans, which will enable more representative prosthetic biomechanics research, and address a major barrier to implementing simulation within clinical practice. Impact StatementThe presented Statistical Shape Model answers calls from the prosthetics community for residual limb shape descriptions to support prosthesis structural testing that is representative of a broader population. The SSM allows definition of worst-case residual limb sizes and shapes, towards testing standards. Further, the lack of internal anatomic imaging is one of the main barriers to implementing predictive simulations for prosthetic socket interface fitting at the point-of-care. Reinforced with additional data, this model may enable generation of estimated finite element analysis models for predictive prosthesis fitting, using 3D surface scan data already collected in routine clinical care. This would enable prosthetists to assess their design choices and predict a sockets fit before fabrication, important improvements to a time-consuming process which comes at high cost to healthcare providers. Finally, few researchers have access to residual limb anatomy imaging data, and there is a cost, inconvenience, and risk associated with putting the small community of eligible participants through CT or MRI scanning. The presented method allows sharing of representative synthetic residual limb shape data whilst protecting the data contributors privacy, adhering to GDPR. This resource has been made available at https://github.com/abel-research/openlimb, open access, providing researchers with limb shape data for biomechanical analysis.

Rheology and the study of viscoelastic materials is an integral part of engineering and the study of biophysical systems however the cost of a rheometer is only feasible for colleges, universities and research laboratories. Even if a rheometer can be purchased it is bulky and delicately calibrated limiting its usefulness to the laboratory itself. The design presented here is less than a tenth of the cost of a professional rheometer and portable making it the ideal solution for high school students as a way to introduce viscoelasticity at a younger age as well as for use in the field for obtaining preliminary rheological data.

Curved fibered structures are ubiquitous in nature and this organization is found in the majority of biological tissues. Indeed, the mechanical behavior of these materials is of pivotal importance in biomechanics and mechanobiology fields. In this paper, we develop a multiscale formulation to characterize the macroscopic mechanical nonlinear behavior from the microstructure of fibered matrices. From the analysis of the mechanics of a randomly curved single fiber, a fibered matrix model is built to determine the macroscopic behavior following a homogenization approach. The model is tested for tensile, compression and shear loads in a number of applications reminiscent to collagen extracellular matrices. However, any other fibered microstructures can be studied following the proposed formulation. The presented approach naturally recovers instabilities at compression as well as the strain stiffening regime, which are observed experimentally in the mechanical behavior of collagen matrices. Indeed, it was found that the bending energy associated to fiber unrolling, is the most important source of energy developed by fibers for the analyzed cases in tensile and shear in all deformation regions (except the strain stiffening region), whereas bending energy dominates at compression too during buckling. The proposed computational framework can also be used to perform multiscale simulations in the referred applications. As a result, the developed methodology may be an interesting and complementary tool to characterize the nonlinear behavior and evolution of curved fibered structures present in biology and engineered materials.

The human masseter muscle is one of the primary muscles responsible for mastication and mandibular movement; however, its intrinsic mechanical properties remain insufficiently characterized. In this experimental study, the nonlinear, viscoelastic, and history-dependent behaviour of the human masseter muscle was investigated using ex vivo uniaxial cyclic tensile tests. The masseter muscle samples prepared from fresh and formalin-preserved cadavers were tested under two loading protocols: a continuous stretch protocol with increasing stretch levels and a constant stretch protocol with repeated loading to a fixed maximum stretch. Tests were conducted at two strain rates, and their influences on the mechanical behaviour of the tissue were examined. The effect of formalin preservation was also investigated. The results showed that the stiffness of the tissue increases for formalin-preserved samples. Under cyclic loading, the features including energy dissipation, stress-softening, residual deformation, and cyclic conditioning progressively changed during the initial loading cycles and reached stabilization during the final cycle. These findings provide experimental evidence that the human masseter muscle exhibits nonlinear, viscoelastic, and history-dependent mechanical behaviour under cyclic tensile loading. The experimental data obtained in this study may be used for biomechanical modelling of the human masticatory system and the development of constitutive models for cranio-maxillofacial surgical simulation, prosthetic design, and facial soft-tissue biomechanics. Statement of significanceThe masseter muscle is one of the primary muscles of mastication. To address the current gap in craniofacial biomechanics that has largely focused on the mechanical characterization of the masseter muscle based on imaging techniques or monotonic loading, this study quantifies the nonlinear and viscoelastic mechanical response of masseter tissue under cyclic continuous and constant stretch loading, including strain-rate and preservation effects. The results show that the mechanical behaviour of the masseter muscle, including stiffness, hysteresis, stress-softening, and residual strain behaviour, is strongly influenced by strain-rate and formalin preservation. The experimental results provide mechanical data for constitutive modelling of the masticatory system with applications in cranio-maxillofacial surgical simulation, prosthetic design, and facial soft tissue modelling.

Technological advancements in the field of robotics have led to endoscopic biopsy devices able to extract diseased tissue from between the layers of the gastrointestinal tract. Despite this, the layer-dependent properties of these tissues have yet to be mechanically characterised using human tissue. In this study, the ex vivo mechanical properties of the passive muscularis propia layer of the human oesophagus were extensively investigated. For this, a series of uniaxial tensile tests were conducted. The results displayed hyperelastic behaviour, while the differences between loading the tissue in both the longitudinal and circumferential directions showcased its anisotropy. The anisotropy of the muscular layer was present at different strain rates, with the longitudinal direction being consistently stiffer than the circumferential one. The circumferential direction was found to have little strain-rate dependency, while the longitudinal direction results suggest pronounced strain-rate-dependent behaviour. The repeated trials showed larger variation in terms of stress for a given strain in the longitudinal direction compared to the circumferential direction. The possible causes of variation between trials are discussed, and the experimental findings are linked to the histological analysis which was carried out via various staining methods. Finally, the direction-dependent experimental data was simulated using an anisotropic, hyperelastic model.

PurposeThe purpose of this study is to investigate the mechanical behaviour of the tracheal tissue under biaxial tensile loading. Furthermore, the study examines the material properties of the tissue through a study of the model parameters for six constitutive models. Materials and methodsThe fourteen (n = 13) trachea sheep (Vleis Merino) pieces of tissues measured to be ~ 30 x 20 mm where only the effective area subjected to engineering strain was ~ 25 x 16 mm. In this study, we assume that the tracheal tissue is anisotropic and incompressible, therefore we apply and study the material parameters from six models namely the Fung, Choi-Vito, Holzapfel (2000), Holzapfel (2005), Polynomial (Anisotropic) and Four-Fiber Family models. ResultsThe results show that the trachea tissue is twice as stiff along the circumferential direction as it is along the longitudinal direction. It is also observed that the material properties are different (non-homogeneous) along the trachea. ConclusionsThe findings of this study will benefit computational models for the study of tracheal diseases or injuries. Furthermore, these findings will assist in the development of regenerative medicine for different tracheal pathologies and in the bioengineering of replacement tissue in cases of damage.

I.Bone fragility is a major ang growing public health concern for many with degenerative bone diseases. A better understanding of fracture propagation in bone can better inform treatment options for these individuals. Human bone is an anisotropic material, with directional microstructure that fractures can propagate around. In a healthy individual, the bone remodeling process repairs damaged tissue. Calcium sulfate dihydrate is a well established surrogate material for bone. This study will mechanically investigate damage repaired plaster samples using three point bending to characterize crack propagation around repaired damage.

Finite element (FE) models have been effectively utilized in studying biomechanical aspects of myocardial infarction (MI). Although the rat is a widely used animal model for MI, there is a lack of material parameters based on anisotropic constitutive models for rat myocardial infarcts in literature. This study aimed at employing inverse methods to identify the parameters of an orthotropic constitutive model for myocardial infarcts in the acute, necrotic, fibrotic and remodelling phases utilizing the biaxial mechanical data developed in a previous study. FE model was developed mimicking the setup of the biaxial tensile experiment. The orthotropic case of the generalized Fung constitutive model was utilized to model the material properties of the infarct. The parameters of Fung model were optimized so that the FE solution best fitted the biaxial experimental stress-strain data. A genetic algorithm was used to minimize the objective function. Fung orthotropic material parameters for different infarct stages were identified. The FE model predictions best approximated the experimental data of the 28 days infarct stage with 3.0% mean absolute percentage error. The worst approximation was for the 7 days stage with 3.6% error. This study demonstrated that the experimental biaxial stress-strain data of healing rat infarcts could be successfully approximated using inverse FE methods and genetic algorithms. The material parameters identified in this study will provide an essential platform for FE investigations of biomechanical aspects of MI and the development of therapies.

Intramyocardial delivery of biomaterials is a promising concept for treating myocardial infarction. The delivered biomaterial provides mechanical support and attenuates wall thinning and elevated wall stress in the infarct region. This study aimed at developing a biventricular finite element model of an infarcted rat heart with a microstructural representation of an in situ biomaterial injectate, and a parametric investigation of the effect of the injectate stiffness on the cardiac mechanics. A three-dimensional subject-specific biventricular finite element model of a rat heart with left ventricular infarct and microstructurally dispersed biomaterial delivered one week after infarct induction was developed from ex vivo microcomputed tomography data. The volumetric mesh density varied between 303 mm-3 in the myocardium and 3,852 mm-3 in the injectate region due to the microstructural intramyocardial dispersion. Parametric simulations were conducted with the injectates elastic modulus varying from 4.1 to 405,900 kPa, and myocardial and injectate strains were recorded. With increasing injectate stiffness, the end-diastolic median myocardial fibre and cross-fibre strain decreased in magnitude from 3.6% to 1.1% and from -6.0% to -2.9%, respectively. At end-systole, the myocardial fibre and cross-fibre strain decreased in magnitude from -20.4% to -11.8% and from 6.5% to 4.6%, respectively. In the injectate, the maximum and minimum principal strains decreased in magnitude from 5.4% to 0.001% and from -5.4% to -0.001%, respectively, at end-diastole and from 38.5% to 0.06% and from -39.0% to -0.06%, respectively, at end-systole. With the microstructural injectate geometry, the developed subject-specific cardiac finite element model offers potential for extension to cellular injectates and in silico studies of mechanotransduction and therapeutic signalling in the infarcted heart with an infarct animal model extensively used in preclinical research.

Aortic aneurysm rupture is a sudden local event with high mortality. It is generally accepted that the adventitia acts as the final barrier protecting the aorta from over-expansion. Currently, the knowledge of microscopic structural determinants of the tissues mechanical response and failure is very limited. The purpose of this study is to provide data on the directional failure properties of the adventitia, combined with micro-structural imaging and structure based constitutive modeling to quantify fiber-scale rupture criteria. Eleven healthy porcine aortas were used in this study. Cylindrical portions of the abdominal section were excised, cut-open longitudinally, the medial and adventitial layers separated methodically. Picrosirius red staining was used to image the collagen fiber morphology via an optical microscope. Subsequently, dog-bone shaped specimens were subjected to uniaxial testing until failure while being recorded by a Nikon digital camera. A fiber-scale damage model was utilized to explain the tissue-scale failure. The ultimate tensile stress in the circumferential and longitudinal directions were recorded to be 0.96 {+/-} 0.29 MPa and 0.85 {+/-} 0.36 MPa respectively. Meanwhile, the ultimate stretch to failure in the circumferential and longitudinal directions were recorded to be 1.72 {+/-} 0.16 and 1.88 {+/-} 0.13 respectively. Further, correlation between the failure properties of the tissue and mean fiber orientation have been reported. Finally, the critical fiber stretch for damage initiation and eventual tissue failure were identified to be 1.19 {+/-} 0.07 and 1.24 {+/-} 0.05 for circumferential and longitudinal specimens respectively. Our approach provides valuable insight into the (patho)physiological mechanical role of collagen fibers at different loading states. This study is useful in enhancing the utilization of structurally motivated material models for predicting arterial tissue failure.

The mechanical properties of human skin have been investigated for decades, yet studies using fresh human tissue remain limited. In this study, we examined the anisotropic behavior of human abdominal skin by assessing tensile strength in panniculectomy specimens obtained from eight female patients. Rectangular 7-mm-long skin samples (0.5, 1.0, and 1.5 cm widths) were excised from each pannus specimen and subjected to uniaxial dynamic tensometry, with the long axis oriented either parallel or perpendicular to Langers lines. Samples tested parallel to Langers lines exhibited a 2- to 3-fold greater maximum load capacity compared with those tested perpendicular. No statistically significant correlation was detected between tensile strength and body mass index (BMI), skin thickness, or age. Histology confirmed that higher tensile strength occurred when dermal collagen fibers were aligned parallel to the direction of the applied load. These findings demonstrate that collagen orientation strongly influences the mechanical behavior of human skin, with implications for surgical planning, implantable prosthetic design, and wound healing.

Anatomical 3-D printing has potential for many uses in education, research and development, implant training, and procedure planning. Conventionally, the material properties of 3D printed anatomical models have often been similar only in form and not in mechanical response compared to biological tissue. The new Digital Anatomy material from Stratasys utilizes composite printed materials to more closely mimic the mechanical properties of tissue. Work was done to evaluate Digital Anatomy myocardium under axial loading for comparison with porcine myocardium regarding puncture, compliance, suturing, and cutting performance.\n\nIn general, the Digital Anatomy myocardium showed promising comparisons to porcine myocardium. For compliance testing, the Digital Anatomy was either within the same range as the porcine myocardium or stiffer. Specifically, for use conditions involving higher stress concentrations or smaller displacements, Digital Anatomy was stiffer. Digital Anatomy did not perform as strongly as porcine myocardium when evaluating suture and cutting properties. The suture tore through the printed material more easily and had higher friction forces both during needle insertion and cutting. Despite these differences, the new Digital Anatomy myocardium material was much closer to the compliance of real tissue than other 3D printed materials. Furthermore, unlike biological tissue, Digital Anatomy provided repeatability of results. For tests such as cyclic compression, the material showed less than two percent variation in results between trials and between parts, resulting in lower variability than tissue. Despite some limitations, the myocardium Digital Anatomy material can be used to configure structures with similar mechanical properties to porcine myocardium in a repeatable manner, making this a valuable research tool.