Annals of Biomedical Engineering最新文献

Patient-specific mandibular reconstruction plates (PSMRPs) have gained prominence for their precise adaptation to mandibular contours and reported enhanced mechanical performance compared to the manual-bent mandibular reconstruction plates (MBMRPs). However, clinical adoption remains cautious due to insufficient biomechanical evidence directly and carefully comparing their performance. Hence, this study investigated the biomechanical behavior between two mandibular reconstruction assemblies with MBMRP and PSMRP, respectively. Mechanical properties of these two reconstruction systems, including yield and ultimate strength, fatigue strength and life, were evaluated through finite element analyses (FEA) and biomechanical tests, during which digital image correlation (DIC) was used to measure full-field displacements and strains. Results revealed that the PSMRP provides higher stiffness and longer fatigue life to the reconstruction system than the MBMRP, signified by above 33% higher stiffness in the quasi-static compression and exceeding 90% more life cycles in the cyclic test, respectively. These findings not only highlight the biomechanical advantages of PSMRP over MBMRP but also underline the strong correlation between FEA predictions and experimental outcomes in the mandibular reconstruction system, validating the FEA’s utility for preoperative biomechanical evaluation. Collectively, this work provides critical evidence supporting the biomechanical superiority of PSMRPs in mandibular reconstruction—potentially reducing risks of plate failure and reoperation—and establishes a translational framework that combines computational and experimental biomechanics to advance patient-specific implant design in oral, dental, and craniofacial surgery.

Graphical Abstract

Purpose

Pulmonary arterial hypertension (PAH) induces chronic pressure overload on the right ventricle (RV), driving remodeling, while the left ventricle (LV) remains largely preserved. The interventricular septum is often modeled as part of the LV; however, its role as a mechanically adaptive structure during PAH progression remains poorly understood. This study investigates full-thickness septal tissue mechanics in male and female rats.

Methods

RV and LV hemodynamics, septal morphology, and planar biaxial septum mechanical properties were measured in normotensive controls and rats at Weeks 4, 8, and 12 of pulmonary hypertension using the sugen-hypoxia (SuHx) rat model of PAH. Biaxial stress-strain data were fit with an exponential Fung-type constitutive model for quantitative comparison across groups.

Results

RV hemodynamics varied by both sex and disease stage, while LV hemodynamics only showed sex differences (males had larger LV volumes). Despite similar RV end-systolic pressures, septal adaptation was sex-specific. Septal tissues exhibited nonlinear, nearly isotropic mechanical behavior. Starting from the same baseline stiffness, female septal tissues became significantly more compliant at Week 4, while male septal tissues remained unchanged. By Week 8, the females returned to baseline stiffness, while the males hit their peak compliance. By Week 12, male and female septa converged to similar stiffnesses.

Conclusion

Septal mechanical properties adapt during RV pressure overload, becoming more compliant with advancing RV remodeling. The degree and timing of remodeling are sex- and disease stage-dependent. These distinct patterns suggest septal mechanics play a functional role in modulating RV-LV interaction and support the need to treat the septum as an independent structure contributing to both chambers.

Purpose

This study proposes a novel algorithm framework for optical coherence tomography (OCT) and carotid angiography co-registration (cACR), aiming to improve diagnostic precision and treatment planning for carotid artery disease.

Methods

The OCT-cACR algorithm integrates an enhanced U-Net segmentation model and a marker detection algorithm for segmenting target carotid vessels and detecting OCT probe markers. Based on the segmented target region, the You Only Look Once (YOLO) algorithm is further utilized to detect and track the OCT probe marker. The acquisition time point of each frame served as the matching parameter to achieve registration between the two modalities. Following registration, an expert compared the identified marker position on each angiography frame with its corresponding actual location to measure the resulting geographical error. The accuracy of cACR was validated using four real clinical cases, with a geographical error of less than 0.35 mm as the evaluation criterion.

Results

The segmentation model achieved higher accuracy (Dice coefficient: 0.867 ± 0.166) compared to baseline U-Net models. OCT-cACR demonstrated an accuracy of 93.33 to 100% in four test cases, thus achieving precise alignment of angiography and OCT images.

Conclusion

The proposed cACR approach is feasible and accurate and may serve as a promising tool for improving the diagnosis and treatment of carotid artery diseases.

This study combines optogenetics and retrograde transfection techniques to functionally target external urethral sphincter (EUS)-related neurons in the spinal cord and to demonstrate a proof-of-concept approach for modulating EUS activation, thereby influencing micturition. Experiments were conducted using C57BL/6 mice, in which an AAV vector (AAV2/6-eSyn-hChR2(H134R)-EGFP) was delivered to the EUS muscle, enabling retrograde transport and subsequent expression of light-sensitive proteins in motor neuron cell bodies within the spinal cord. Electromyography (EMG) of the EUS muscle in response to spinal cord photostimulation was then analyzed using fiber optics, showing that the muscle could maintain electrical activity for up to 60 s during illumination under our stimulation conditions. Finally, the real-time effects of spinal cord photostimulation on micturition were assessed via cystometry. When the bladder was sufficiently filled, 60 s of spinal cord stimulation extended continence time in proportion to the stimulation period (from 45 ± 8 s to 101 ± 14 s). These findings demonstrate that retrograde transfection from peripheral muscle to spinal motor neurons enables expression of light-sensitive proteins and allows optogenetic activation of neurons associated with the EUS. Moreover, fiber-optic stimulation effectively modulated EUS activity and micturition in situ. This electroceutical approach provides a proof-of-concept framework that may inform future strategies for treating urinary disorders and for investigating neural circuit function.

Purpose

Borderline left ventricle (BLV) presents a dilemma between pursuing a biventricular repair (BiVR) and a Stage 1 palliation (S1P) because a discordant pursuit of BiVR increases mortality risk. We aim to develop and validate a personalized computational model to assist surgical decision-making by predicting virtual surgery hemodynamics in BLV patients.

Methods

We developed a novel multi-block lumped parameter network (LPN) model of a BLV circulatory system. Patient-specific model parameters were estimated using a semi-automatic tuning framework to fit clinical data in ten retrospectively identified BLV patients. Virtual surgeries (BiVR and S1P) were performed on each patient to quantify post-operative hemodynamics.

Results

In patients who clinically received S1P (Group I, N = 5), a virtual BiVR predicted significantly elevated mean pulmonary artery pressure (PAP_mean: 38.00 ± 10.0 vs. 17.50 ± 2.7 mmHg, p < 0.01), mean left atrial pressure (LAP_mean: 25.40 ± 8.2 vs. 6.20 ± 1.2 mmHg, p < 0.0001), and single-ventricle end-diastolic pressure (SVEDP: 21.80 ± 8.7 vs. 4.80 ± 1.3 mmHg, p < 0.0001) compared with a virtual S1P. A virtual BiVR in patients who clinically underwent BiVR (Group II, N = 5) did not predict any adverse hemodynamic outcome.

Conclusion

A novel subject-specific computational modeling framework was developed to predict hemodynamics following virtual surgeries in BLV patients. The model predictions align with the clinically adopted procedure in this retrospectively selected cohort by predicting unacceptable PAP, LAP, and SVEDP. This predictive tool may guide surgeons in determining the hemodynamically optimal surgery for BLV infants, but it needs prospective validation on a larger cohort.

Central Message

Patient-specific computational modeling can predict hemodynamics following virtual surgery in borderline left ventricles and may assist surgical decision-making.

Perspective

A critical dilemma pediatric heart surgeons and pediatric cardiologists face is choosing between biventricular repair and single-ventricle palliation in patients born with a borderline left ventricle. Computational modeling using lumped parameter networks predicts hemodynamics from virtual surgery simulations and may enable clinicians to decide on the hemodynamically optimal procedure.

Purpose

Changes in residual limb volume and shape pose significant challenges in achieving and maintaining an accurate and comfortable fit for prosthetic socket. While numerous techniques for measuring residual limb volume have been proposed, their clinical application remains limited by insufficient resolution and the inability to perform in-socket measurements. To address this issue, this study develops a novel method for predicting residual limb soft tissue deformation to guide prosthetic socket design.

Methods

A three-dimensional (3D) finite element (FE) model of the human thigh was developed to simulate the soft tissue deformation during daily activities, driven by muscle contraction to replicate natural biomechanics. The model included hard tissue and muscle components, with the muscle modeled as a structure of evenly distributed, contractile fibers that generate movement. Parameters controlling fiber contraction were iteratively adjusted to best match the calculated tissue deformation and that observed in physical muscle models.

Results

The optimized FE model significantly improved the accuracy of predicting dynamic soft tissue deformation, with average errors of 0.83% and 1.86% for tissue expansion and contraction regions, respectively. For various gait patterns, the average differences in equivalent volume and cross-sectional area changes were also less than 0.83% and 1.86%, respectively.

Conclusion

The model demonstrated consistent prediction accuracy across different gait data. The fiber-driven soft tissue model developed offers a valuable tool for pre-design simulations of prosthetic sockets and orthoses. It is equally applicable to other wearable devices that interface with the skin, providing a robust framework for improving device design and functionality.

Purpose

Vascular remodelling is increasingly recognised as a key pathological feature in Chronic Obstructive Pulmonary Disease (COPD), with changes in pulmonary blood flow offering early biomarkers of disease. However, computational models capable of capturing the evolution of pulmonary haemodynamics across COPD severity stages are lacking. This study presents an anatomically based in silico model of the pulmonary circulation designed to investigate haemodynamic changes in response to vascular remodelling and parenchymal destruction in smokers without COPD and in patients with varying stages of COPD.

Methods

A one-dimensional, steady-state model of pulmonary blood flow was adapted to simulate extra-acinar arterial remodelling and intra-acinar capillary pruning consistent with emphysema. The model was parameterised using morphometric and clinical haemodynamic data at rest and during exercise across GOLD stages 1–4.

Results

Model-predicted mean pulmonary arterial pressure (mPAP) increased progressively from 13.5 mmHg (baseline) to 16.1 mmHg (GOLD 2), 21.2 mmHg (GOLD 3), and 25.9 mmHg (GOLD 4), with increasing vascular remodelling, matching clinical data within reported error bounds. In the most severe COPD case, GOLD 4, 70% of arterial vessels and 35% of acinar units were modified to represent disease. Height-dependent flow and pressure gradients were markedly altered in GOLD 4 indicating significant redistribution and increased heterogeneity of pulmonary blood flow.

Conclusion

This model reproduces clinically measured mPAP and pulmonary vascular resistance values across COPD stages and quantifies how specific degrees of remodelling and pruning drive haemodynamic deterioration. This model provides a tool for hypothesis testing, patient stratification, and evaluation of potential targeted therapies in obstructive lung disease.

Purpose

In clinics, musculoskeletal assessment mainly relies on conventional imaging which is expensive, involves radiation exposure, and lacks accessibility. Inferring skeletal morphology from 3D body surface scans shows potential as an alternative screening aid, although lacks detail in particular at extremities. This study leverages Statistical Shape Models (SSMs) to estimate position and orientation of the hand and foot bones from the skin surface.

Methods

Two datasets (140 feet, 79 hands with diverse morphologies and poses) were collected. For each dataset, a coupled skin-bone SSM was created. A nested cross-validation approach was used to optimize hyperparameters and prevent overfitting while fitting the isolated skin model of the coupled SSM to unseen skin data to infer bone structure and position.

Results

For the feet, the mean absolute error (MAE) was 1.68 mm, with the highest errors occurring at the hindfoot. Similarly, for the hands, the MAE reached 1.37 mm, with the largest deviations observed at carpal bones.

Conclusion

This study demonstrates the feasibility of predicting bone morphology from skin surfaces using SSM-based shape completion, offering a potential non-invasive and accessible alternative to traditional imaging for musculoskeletal assessments.

Purpose

Prolonged wear of generic respiratory masks such as the N95 could provide discomfort due to poor fitting to the user face morphology and excessive tightening. This study aims to personalize the design of respiratory masks and simulate the fitting using finite element analysis.

Methods

A cohort of 10 participants was recruited to evaluate the fit of a 3D respiratory mask created by scanning the face with the ARKit framework and a high-resolution 3D infrared camera. The respiratory mask pressure and seal were calculated using numerical simulations with Ansys Mechanical. A pressure map illustrates the pattern that the respiratory mask will produce on a given user’s face, to assert the desired comfort criteria. A map of the gap between the mask and the face shows the sealing capability of the mask. To ensure the consistency of the numerical results, experimental pressure measurements were also performed on the participants. Facial pressure calculation and measurement tests were performed under three levels of tightening. User’s feedback on the respiratory mask was also obtained.

Results

Simulation results appeared to be lower than those obtained experimentally, so a global correction was made. Only 14% of the results obtained after correction differ by more than 1N from the experimental reference value.

Conclusion

The outcome of this study could provide insights in the design of respiratory masks through face scanning technologies and numerical simulation. Moreover, it could contribute to fully customize the respiratory mask to the user’s face, for enhanced comfort and proper sealing.