Journal of Biomechanical Engineering-Transactions of the Asme最新文献

The periprosthetic acetabular osteotomy (PAO) is a commonly used technique in orthopedics for treating developmental hip dysplasia and hip dislocation, as the most effective treatment for developmental dysplasia of the hip (DDH). However, performing PAO can be challenging for surgeons due to limited visibility and difficulty in detecting any deformations of osteotome chisels when they are deeply immersed in the pelvis. These challenges can result in serious complications, such as excessive bleeding and nerve injuries. We propose a novel precision tracking system to mitigate these risks by acquiring the chisel deformation in real-time. This system consists of a newly designed osteotome chisel with five built-in microsensors, which are finely chosen with the help of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). We propose a fast finite element method (FFEM) model to calculate the deformation of the chisel from flexibility information collected by these five sensors, where the model deformation can be predicted from a well-designed light deep neural network (DNN) model. Our model has achieved an impressive R2 value of 0.98781 and an average deformation error of only 0.07 mm in nodes compared to the experiment. The prediction time of FFEM model has been shortened to 0.33 s, and the total time including three-dimensional reconstruction and visualization has been shortened to 3.84 s. Implementing such an osteotome chisel with a deformation tracking system has shown immense potential in increasing surgical accuracy and reducing medical negligence for PAO operations.

The geometry and motility of the stomach play a critical role in the digestion of ingested liquid meals. Sleeve gastrectomy, a common type of bariatric surgery used to reduce the size of the stomach, significantly alters the stomach's anatomy and motility, which impacts gastric emptying and digestion. In this study, we use an imaging data-based computational model, StomachSim, to investigate the consequences of sleeve gastrectomy. The pre-operative stomach anatomy was derived from imaging data, and the postsleeve gastrectomy shapes were generated for different resection volumes. We investigate the effect of sleeve sizes and motility patterns on gastric mixing and emptying. Simulations were conducted using an immersed-boundary flow solver, modeling a liquid meal to analyze changes in gastric mixing and emptying rates. The results reveal that different degrees of volume reduction and impaired gastric motility have complex effects on stomach's mixing and emptying functions, which are important factors in gastric health of the patient. Specifically, the total gastric liquid emptying rates increased by 21% with a 30% volume reduction and by 51% with reductions exceeding 50%, due to altered intragastric pressure. Additionally, impaired motility functions resulted in slower mixing, leading to delayed food emptying. These findings provide insights into the biomechanical effects of sleeve gastrectomy on gastric digestion and emptying functions, highlighting the potential of computational models to inform surgical planning and postoperative management.

Multiscale coupling between cell-scale biology and tissue-scale mechanics is a promising approach for modeling disease growth. In such models, tissue-level growth and remodeling (G&R) are driven by cell-level signaling pathways and systems biology models, where each model operates at different scales. Herein, we generate multiscale G&R models to capture the associated multiscale connections. At the cell-scale, we consider systems biology models in the form of systems of ordinary differential equations (ODEs) and partial differential equations (PDEs) representing the reactions between the biochemicals causing the growth based on mass-action or logic-based Hill-type kinetics. At the tissue-scale, we employ kinematic growth in continuum frameworks. Two illustrative test problems (a tissue graft and aneurysm growth) are examined with various chemical signaling networks, boundary conditions, and mechano-chemical coupling strategies. We extend two open-source software frameworks-febio and fenics-to disseminate examples of multiscale growth and remodeling simulations. One-way and two-way coupling between the systems biology and the growth models are compared and the effect of biochemical diffusivity and ODE versus PDE-based systems biology modeling on the G&R results are studied. The results show that growth patterns emerge from reactions between biochemicals, the choice between ODEs and PDEs systems biology modeling, and the coupling strategy. Cross-verification confirms that results for febio and fenics are nearly identical. We hope that these open-source tools will support reproducibility and education within the biomechanics community.

This paper predicts the optimal motion for a repetitive lifting task considering muscle fatigue. The Denavit-Hartenberg (DH) representation is employed to characterize the two-dimensional (2D) digital human model with 10 degrees-of-freedom (DOFs). Two joint-based muscle fatigue models, i.e., a three-compartment controller (3CC) muscle fatigue model (validated for isometric tasks) and a four-compartment controller with augmented recovery (4CCr) muscle fatigue model (validated for dynamic tasks), are utilized to account for the fatigue effect due to the repetitive motion. The lifting problem is formulated mathematically as an optimization problem, with the objective of minimizing dynamic effort and joint acceleration subjected to both physical and task-specific constraints. The design variables include joint angle profiles, discretized by quartic B-splines, and the control points of the profiles of the fatigue compartments associated with major body joints (spinal, shoulder, elbow, hip, and knee joints). The outcomes of the simulation encompass profiles of joint angles, joint torques, and the advancement of joint fatigue. It is notable that the profiles of joint angles and torques exhibit distinct periodic patterns. Numerical simulations and experiments with a 20 kg box reveal that the maximum predicted lifting cycles are 11 for the 3CC fatigue model and 13 for the 4CCr fatigue model while the experimental result is 13 cycles. The results indicate that the 4CCr muscle fatigue model provides enhanced accuracy over the 3CC model for predicting task duration (number of cycles) of repetitive lifting.

Topological features of time-dependent, three-dimensional (3D) vector flow fields, such as wall shear stress (WSS) fixed points, are considered surrogates of pathological blood flow dynamics in cardiovascular diseases. Fixed-point visualizations are typically constrained to two-dimensional (2D) spaces, yet they aim to display complex spatiotemporal (four-dimensional (4D)) dynamics. There is a need for visualization strategies to reduce occlusion and reliance on animations to allow the detection of holistic flow patterns. Using intracranial aneurysms as a use case, we present the fixed-point carousel, a novel approach to visually depicting the "4D" nature of WSS fixed points via (1) topographic mapping of the 3D aneurysm sac to overcome occlusion while preserving fixed-point distances and sac morphological features; and (2) arranging these into a carousel model to present with temporal dimension holistically. Examples are presented for image-based computational fluid dynamic (CFD) models of intracranial aneurysms, illuminating the intricate and distinct fixed-point trajectories and interactions, a necessary step toward understanding the volumetric flow manifolds that drive them for this and other cardiovascular-and potentially nonbiomedical-fluid dynamics applications.

The Norwood procedure creates a reconstructed neo-aorta to provide unobstructed systemic cardiac output for hypoplastic left heart syndrome patients. We used patient-specific computational fluid dynamics (CFD) simulations incorporating physiologic boundary conditions to quantify hemodynamics for reconstructed aortic arch geometries versus native aortic arches from a control group of single ventricle patients. We hypothesized that reconstructed arches from Norwood patients (n = 5) would experience significant differences in time-averaged wall shear stress normalized to body surface area (TAWSSnBSA), oscillatory shear index (OSI), energy efficiency (Eeff), and energy loss (EL) versus controls (n = 3). CFD simulations were conducted using 3 T cardiac magnetic resonance imaging, blood flow, and pressure data. Simulations incorporated downstream vascular resistance and compliance to replicate patient physiology. TAWSSnBSA and OSI were quantified axially and circumferentially. Global differences in Eeff and EL were compared. Significance was assessed by Mann-Whitney U test. Norwood patients had higher TAWSSnBSA distal to the transverse arch at locations of residual narrowing presenting following coarctation correction, as well as higher OSI within ascending aorta and transverse arch regions (p < 0.05). EL correlated with patient features including cardiac output (r = 0.9) and BT-shunt resistance (r = -0.63) but did not correlate with arch measurements or morphology. These results indicate reconstructed arches from Norwood patients are exposed to altered wall shear stress and energy indices linked to cellular proliferation and inefficiency in prior studies. These results may help clinicians further understand what constitutes an optimally reconstructed arch after confirmation in larger studies.

A lumbar spine statistical shape model (SSM) was developed to explain morphological differences in a population with adolescent idiopathic scoliosis (AIS). Computed tomography (CT) was used to collect data on the lumbar spine vertebrae and curvature of 49 subjects. The CT data were processed by segmentation, landmark identification, and template mesh mapping, and then SSMs of the individual vertebrae and entire lumbar spine were established using generalized Procrustes analysis and principal component analysis (PCA). Scaling was the most prevalent variation pattern. The weight coefficient was optimized using the Levenberg-Marquardt (LM) algorithm, and multiple regression analysis was used to establish a prediction model for age, sex, height, and body mass index (BMI). The effectiveness of the SSM and prediction model was quantified based on the root-mean-square error (RMSE). An automatic measurement method was developed to measure the anatomical parameters of the geometric model. The lumbar vertebrae size was significantly affected by height, sex, BMI, and age, with men having lower vertebral height than women. The trends in anatomical parameters were consistent with previous studies. The vertebral SSMs characterized the shape changes in the processes, while the lumbar spine SSM described alignment changes associated with translatory shifts, kyphosis, and scoliosis. Quantifying anatomical variation with SSMs can inform implant design and assist clinicians in diagnosing pathology and screening patients. Lumbar spine SSMs can also support biomechanical simulations of populations with AIS.

Evaluation of patients with neck pain often relies on end-range flexion and extension radiographs that do not capture mid-range or multiplanar motion. The purpose of this study was to determine if end-range flexion/extension range of motion (ROM) predicts axial rotation ROM or mid-range ROM during either flexion/extension or axial rotation in patients with neck pain or in asymptomatic controls. It was hypothesized that end-range flexion/extension ROM would predict mid-range flexion/extension ROM, but not mid-range or end-range axial rotation ROM. Dynamic flexion/extension and axial rotation were performed by 75 patients prior to surgery and 71 asymptomatic controls, while synchronized biplane radiographs were collected at 30 images per second. Intervertebral motion from C2 to C7 was tracked using a validated volumetric model-based tracking process that matched subject-specific computed tomography (CT)-based bone models to the radiographs. The main findings were that intervertebral end-range flexion/extension ROM is a strong to very strong predictor of mid-range flexion/extension at all subaxial motion segments of the cervical spine (all r = 0.61 to 0.91), but, in general, a weak to moderate predictor of axial rotation mid-range (all ρ = 0.002 to 0.50) and end-range (all r = 0.2 to 0.68) ROM. This study suggests that the current standard of care end-range flexion/extension ROM is not sufficient to characterize the multiplanar motion that occurs in the cervical spine during activities of daily living.

Although diabetes is associated with alterations in the structural and functional properties of soft tissue, the response of the human Achilles tendon to location-dependent variations in both quasi-static and dynamic loading is unclear. This study aimed to characterize the elastic, viscoelastic, hysteresis, and failure properties of the distal, midsubstance, and proximal Achilles tendons in diabetic and nondiabetic patients and to investigate the relationship between biomechanical and clinical observations. Tendons were obtained from patients who underwent above- or below-knee amputation. Dumbbell-shaped specimens were harvested from the three sites. Relaxation tests were performed to determine viscoelastic characteristics. Cyclic loading tests at various frequencies were deployed to determine the dynamic modulus and phase angles. Incremental cyclic loading tests were carried out to investigate the backbone curve and energy dissipation due to hysteresis. Additionally, monotonic loading tests were performed to determine the elastic and failure properties. The results show that biomechanical parameters are not significantly different among the three sites. However, the midsubstance site exhibits significantly higher energy dissipation compared to other sites. Additionally, an increase in cyclic frequency enhances the phase angle, indicating that higher energy dissipation may protect the tendon from high loading rates. Furthermore, an increase in body mass index (BMI) and hemoglobin A1c (HbA1c) is significantly and negatively correlated with stiffness and viscoelasticity, suggesting that improving metabolic health may prevent tendon impairment. These findings may assist in creating more effective therapeutic strategies for tendon repair.

Given the increasing complexity of revision total hip arthroplasty, ensuring optimal stability of acetabular revision cups (ARCs) is crucial, especially in cases of bone stock loss. In this study, the primary stability of ARCs was investigated by modeling various configurations of screw placements, including all standard, all locking, and mixed setups, under different load scenarios. Finite element (FE) models were implemented to evaluate the stress distribution and micromotions at the bone-prosthesis interface, simulating three primary load cases: "walking," "stairs-down," and "stand-up." The results indicated that the stairs-down load case generated the highest von Mises stresses and sliding distances, marking it as the most critical load scenario. Configurations using all standard screws showed higher peak stresses and reduced stable areas, compared to those utilizing locking screws. While the locking screws provided a stiffer connection, the mixed screw configuration offered a balanced performance by combining the compression benefits of standard screws with the rigid fixation of locking screws. Configurations with a single standard screw complemented by locking screws showed enhanced stability, suggesting this combination could be advantageous in clinical applications. This study underscores the importance of screw type and placement in ensuring the primary stability of ARCs. Locking screws are recommended for use when feasible. For ARCs allowing both screw types, a mixed configuration starting with a standard compression screw followed by locking screws appears optimal. Future research should further explore various combinations of screw geometries and lengths to refine these findings and enhance surgical outcomes in acetabular revisions.