Annals of Biomedical Engineering最新文献

Purpose: Residual stresses are intrinsic stresses present in arteries even in the absence of external loads or blood pressure. They originate during growth and remodeling and contribute to vascular mechanical equilibrium. Despite advances in computational methods, incorporating residual stresses into patient-specific vascular models remains challenging. Evidence regarding the influence of circumferential residual stresses on physiological loading in realistic anatomies is still limited.

Methods: We combined in vitro imaging, mechanical testing, and finite element (FE) simulations to incorporate residual stresses into a pressurized porcine aorta model. Medical images were acquired in both pressurized and zero-stress states, the latter obtained after 2 h of longitudinal cutting. Locally measured mechanical properties from distinct aortic regions were used to define an orthotropic hyperelastic material response. Residual stresses were restored by simulating vessel closure under displacement-controlled boundary conditions with a tied contact interface. Stress distributions were then compared in FE pressurization simulations performed with and without residual stresses.

Results: Residual stresses substantially influenced the predicted stress fields. They homogenized stress across the vessel thickness and reduced stress concentrations near the lumen. Moreover, lumen cross-sectional areas at 120 mmHg aligned more closely with experimental measurements when residual stresses were included. In contrast, neglecting residual stresses produced an average overestimation of lumen area by 4.84% and stress peaks up to 50% higher in the inner wall.

Conclusion: This study highlights the importance of accounting for residual stresses in biomechanical vascular simulations. Incorporating them improves prediction accuracy and reduces artificial stress concentrations, which is crucial for patient-specific risk assessment and surgical planning.

The escalating demand for functional tissue-engineered constructs has highlighted the critical need for scaffolds that are not only biocompatible but also cost-effective and scalable, qualities that are often lacking in traditional synthetic or animal-derived materials. Driven by this necessity, plant-derived biomaterials have emerged as promising candidates due to their natural abundance and structurally versatile architecture. Primarily composed of cellulose-rich extracellular matrices, hemicellulose, lignin, and pectin, these materials provide physicochemical properties that can be tailored to emulate specific tissue microenvironments. Notably, native plant vasculature contains intrinsic microchannels that facilitate perfusion, making them uniquely advantageous for cell infiltration and angiogenesis. This review aims to synthesize current progress in plant-based scaffolds for tissue engineering, with emphasis on structure-function relationships, processing strategies, and translational readiness. We outline key biofabrication workflows centered on decellularization and preservation of ultrastructure, followed by recellularization approaches and considerations of degradation behavior and mechanical stability. This review also summarizes mechanistic foundations of regeneration, including cell-material interactions, hierarchical microarchitecture, and contributions of intrinsic or incorporated bioactive constituents. Finally, we discuss therapeutic applications across soft and hard tissues and highlight performance enhancement strategies. Importantly, it is worth noting that the current evidence base remains strictly preclinical, with no human clinical trials reported to date. Significant challenges persist, including incomplete decellularization, limited long-term mechanical stability under physiological loading, and the lack of standardized manufacturing protocols. Overall, plant-based scaffolds represent a maturing and sustainable platform with strong potential for future regenerative strategies, contingent upon rigorous standardization and comprehensive safety evaluation.

Purpose: The extracellular matrix (ECM) is crucial for tissue structure and cell behavior, positioning decellularized ECM (dECM) as a valuable biomaterial for regenerative medicine. The human placenta, abundant and bioactive, is an ideal ECM source. This study optimized decellularization protocols for human placental tissue to balance cellular removal with ECM integrity.

Methods: Four protocols (P1-P4) were compared, using combinations of ionic/non-ionic detergents (SDS, Triton X-100), enzymatic agents (trypsin, DNase), and sterilizing treatments. Lyophilized dECM was processed into injectable hydrogels, characterized for mechanical, rheological, and degradation properties.

Results: DNase-treated protocols reduced DNA to < 50 ng/mg dry weight, confirming effective cell removal, but ECM retention varied. P2, containing the highest concentrations of SDS among our tested protocols, results in depletion of glycosaminoglycans (GAGs), loss of fibronectin, and disruption of collagen organization. Milder protocols regarding SDS concentration, including P1 and P3, preserved GAGs and ECM proteins (collagen IV, fibronectin, laminin), as shown by immunofluorescence and histology. All protocols successfully formed stable hydrogels, but mechanical stiffness and viscoelastic properties differed. The high-SDS protocol without DNase treatment (P2-) exhibited the lowest storage modulus (G':13.7 ± 2.9 Pa), likely due to excessive ECM disruption. In contrast, the NaOH protocol (P3) with a lower SDS concentration than P2 showed the most consistent performance, with comparable G' values in DNase-treated (53.0 ± 20.0 Pa) and untreated (49.3 ± 3.3 Pa) hydrogels.

Conclusion: Detergent choice and DNase treatment influence ECM retention and hydrogel functionality. The NaOH protocol with DNase treatment (P3+) offers superior ECM preservation for placenta-derived dECM scaffolds, laying a foundation for regenerative medicine applications.

Purpose: This paper aims to categorize the mechanical properties of eight percutaneous transluminal coronary angioplasty (PTCA) balloon catheters and translate them into clinical needs.

Method: Objective bench tests quantified PTCA balloon catheters' mechanical properties, including tensile strength, kink resistance, bending, torsional behavior, friction, radio-opacity, pushability, and trackability. The results were compared against each other and supplemented by a survey of interventional cardiologists.

Results: Clinical needs with respect to deliverability, dilatation efficiency, and crossability were assessed for each catheter. Results indicate that SC Maverick2 excels in deliverability and crossability but lags in dilatation efficiency compared to NC catheters, though it is rated best to fulfill clinical needs. SC EasyT outperforms Maverick2 in dilatation efficiency but has inferior deliverability, similar to NC catheters. The NC balloons were comparable. However, Accuforce exhibits highest deliverability, Pantera LEO shows superior dilatation efficiency, NC Emerge shows best crossability, and Sapphire NC24 exhibits lowest performance. According to the survey, Accuforce, Sapphire NC24, and NC Trek are favored over NC Emerge and Pantera LEO. OPN NC offers limited deliverability but can treat lesions where standard NC catheters fail due to its unique rated burst pressure. Trackability and pushability estimates align better with survey results than those obtained from simulated use-case tests, except for Sapphire NC24 and OPN NC. Torquability measurements show discrepancies with survey ratings, indicating additional influences and rating challenges.

Conclusion: Our study comprehensively analyzes PTCA balloon catheters, emphasizing the importance of integrating mechanical and design attributes throughout development. Performance properties like trackability and pushability were measured, providing unbiased insights for comparison independent of individual practitioner preferences.

Purpose: Osteoporosis often leads to a site-specific vertebral fracture due to the regional heterogeneity of mechanical competence. High-impact combined with resistance exercise showed promise in improvement of volumetric bone mineral density (vBMD) at global spine-segment level. However, localized effects of such exercise on bone mineral density and mechanical strength remain under-explored.

Methods: Thirty healthy postmenopausal women with low bone mass were recruited in randomized clinical trial of 6 months of high-impact and resistance exercises (ChiCTR2400081574). A voxel-based 3D registration method was designed to extract the identical seven anatomical sub-regions from QCT images scanned before and after this exercise. Seven finite-element models of each sub-region were developed to analyze the regional change of ultimate compressive strength (UCS) for the first time.

Results: Regionally, significantly lower changes of BMD were observed in the exercise group (EG) than the control group (CG) in the inferior articular process, transverse process, and anterior vertebral body (p < 0.05), although the BMD losses were found in both groups. While significant increases of UCS (up to 4.58%) were observed due to exercise in the vertebral body, superior articular process, and inferior articular processes, compared to the decrease of the CG (up to - 1.24%). The exercise also reduced up to 24% inter-regional variability in strength, promoting a more balanced mechanical distribution across the lumbar spine.

Conclusion: Six-month high-impact and resistance training enhances mechanical integrity of the lumbar spine by preserving the density and disproportionately improving strength in vulnerable regions. These findings support the use of region-specific biomechanical assessments to evaluate exercise efficacy in osteoporotic populations.

Purpose: This study evaluated tibiofemoral loading and medial meniscal stress distribution in individuals with flexible flatfoot (FFF) during walking under different foot progression angle (FPA) conditions.

Methods: This study analyzed the gait of 28 FFF patients (16 males, 12 females) under three FPA conditions (neutral, toe-in, toe-out). Kinematic (Vicon) and kinetic (Kistler) data were used to estimate tibiofemoral forces in OpenSim. Subsequently, joint angles and muscle forces at peak tibiofemoral forces were used to drive a finite element (FE) model of the knee, enabling the comparison of meniscal von Mises stress, maximum shear stress, and contact pressure across FPA conditions.

Results: Tibiofemoral force increased during early stance (9-11%) in the toe-in condition with this increase reaching statistical significance in males (p = 0.008, mean partial ${\eta }^2=0.70$ within the SPM-identified cluster). FE analysis showed that peak stresses and contact pressure were primarily localized in the anterior region of the medial meniscus. A consistent directional response to FPA was observed with the lowest peak values occurring in the toe-in condition and the highest values in the toe-out condition.

Conclusion: Adjusting FPA modulates intra-articular knee loading via the kinetic chain. For FFF patients, neutral FPA provides stable loading. The toe-in condition presents a complex mechanism: despite increasing tibiofemoral force (notably in males), it reduces peak stress by altering contact mechanics and stress distribution. Therefore, FFF gait interventions must be individualized based on factors like foot morphology, sex, and functional goals.

Purpose: This study aims to investigate the relationship between increasing internal tibial torque (ITT) and the distribution of stress on the anterior cruciate ligament (ACL), with a focus on identifying the location of tear initiation and propagation. In particular, the study emphasizes the femoral enthesis as a potential site of geometric vulnerability during pivot landing.

Methods: A three-dimensional finite element model of the ACL was developed and combined with an extended finite element method framework to simulate tear initiation and propagation. The model was driven by torque-indexed, three-dimensional knee kinematics obtained from previous in silico knee simulations that were validated against in vitro cadaveric knee tests (15 specimens). ITT was applied in graded steps to reproduce pivot landing-relevant internal rotation loading. Stress/strain fields were evaluated, and tear initiation/propagation were tracked to quantify damage evolution.

Results: Maximum von Mises stress increased proportionally with ITT and localized near the femoral enthesis, with a mean increase of 26.56% for each 5Nm increase in torque. Stress concentration consistently occurred at the posterolateral bundle attachment on the femoral side, where tear initiation was predicted. With further ITT increases, the tear propagated from the femoral enthesis, indicating a torque-dependent damage progression mechanism.

Conclusion: Increased ITT produced reproducible stress/strain concentration at the femoral enthesis, supporting structural vulnerability during pivot landing. This approach extends stress-only analyses by predicting rupture initiation and tear progression. These findings may inform prevention and rehabilitation by highlighting the roles of ITT and femoral insertion morphology in ACL tear initiation and propagation.

Biomedical engineers produce knowledge and artifacts. Across the life cycle of an idea, errors can creep in. In this letter, we propose the term linguistic, orthographic, and typographical errors in science (LOTS) to represent a category of errors that threaten the truthfulness and integrity of scientific literature and engineering projects. They include documented cases of the misuse of generative artificial intelligence (GAI). LOTS consist of four categories: (1) simple spelling errors; (2) the semantic deformation of technical terms, in the form of 'tortured phrases'; (3) letter or symbol-switching; and (4) formatting errors that impact the veracity of knowledge, or distort the precision of scientific representation, such as the absence or overuse of capitalization, the incorrect use or absence of italicization, the failure to deanonymize information, cloned template text, or GAI-generated "hallucinations." We introduce small analyses to assess the incidence of dopamine-ß-hydroxylase, ß-secretase, and ß-adrenoreceptors (erroneous Eszett formats) supposedly representing dopamine-β-hydroxylase (DBH), β-secretase, and β-adrenoreceptors, respectively, in PubMed. We suggest that virtuous biomedical engineers should address LOTS. To improve the screening of LOTS, we argue in favor of a common framework for scholarly text integrity analysis.

Purpose: Interossei muscles of the hand, innervated primarily by the ulnar nerve, are essential for coordinated finger abduction and adduction. Quantitative strength assessment of these key actions, which support precision grip and fine motor control, may aid in the diagnosis and monitoring of neuropathic conditions including cubital tunnel syndrome. This study aimed to develop and validate a novel Hand Interossei Muscle Dynamometer (HIMDNA) for quantifying finger abduction and adduction strength for the index to little fingers and to establish normative values for healthy adults.

Methods: HIMDNA was designed based on hand morphology, incorporating a load cell within a fixed frame and a linear guide mechanism to ensure uniaxial, examiner-independent force measurements. The abduction and adduction strengths of 48 healthy adults aged 20-39 years were measured and validated against index and little finger abduction measurements obtained with a handheld dynamometer (HHD). The inter- and intra-rater reliabilities and overall usability of HIMDNA were then compared with those of HHD.

Results: HIMDNA demonstrated excellent agreement with HHD (Pearson's r = 0.927 ~ 0.967; ICC = 0.911 ~ 0.956) and superior inter- and intra-rater reliabilities (ICC = 0.963 ~ 0.983). Normative values were approximately 4.5 ~ 23.4 N, with greater strength in the radial than ulnar direction except for the little finger. Participants rated HIMDNA higher in usefulness, effectiveness, and overall satisfaction than HHD.

Conclusion: HIMDNA provided a reliable, valid, and user-friendly way of quantifying finger abduction and adduction strengths, suggesting its potential as a standardized and clinically applicable tool for evaluating the strength of interossei muscles quantitatively in patients with ulnar nerve disorders.

Purpose: Antibiotic-loaded bone cements (ALBCs) are widely used in managing prosthetic joint infection (PJI). This study aimed to compare the antibiotic elution, surface porosity, and mechanical properties of polymethylmethacrylate (PMMA) cement loaded with vancomycin using powdered and liquid incorporation methods.

Methods: High-viscosity Palacos R® PMMA was impregnated with 1-4 g vancomycin (powdered or dissolved in water) per 40 g cement. Beads, cylinders, and blocks were fabricated. Antibiotic release was quantified by high-performance liquid chromatography HPLC over 6 weeks. Porosity was assessed by micro-CT whilst compressive and bending strength were measured on an Instron® material testing system.

Results: Powder-mixed beads showed higher cumulative vancomycin release, whilst liquid-mixed beads showed greater porosity than powder-mixed beads. For both powder and liquid-mixed formulations, increasing vancomycin concentration was associated with a dose-dependent reduction in compressive and bending strength compared with control group. Differences between liquid and powder mixed specimens were formulation and loading mode-dependent and were not uniformly directional across concentrations.

Conclusion: Smaller PMMA beads and powder-mixed formulations demonstrated greater early release and higher sustained elution over time, resulting in superior cumulative antibiotic delivery compared with larger beads and liquid-mixed formulations. These findings highlight the need to balance antimicrobial efficacy and mechanical requirements when tailoring formulation of ALBC, particularly in spacer relevant clinical applications.