Medical Engineering & Physics最新文献

{"title":"Impact of femoral bone quality on stress transfer, remodeling, and failure risk in osseointegrated transfemoral prostheses.","authors":"Armin Omidvar Ghaziani, Reza Soheilifard, Sara Kowsar","doi":"10.1088/1873-4030/ae52f9","DOIUrl":"10.1088/1873-4030/ae52f9","url":null,"abstract":"<p><p>Osseointegrated transfemoral prostheses improve mobility but may induce stress shielding, periprosthetic bone loss, and long-term mechanical complications. Because amputees exhibit substantial variability in femoral geometry and cortical density, understanding how bone quality affects postoperative adaptation is essential. This study used three-dimensional finite element models coupled with a strain-energy-based remodeling algorithm to investigate how variations in femoral shaft diameter and initial apparent density influence stress transfer, density adaptation, and failure risk around the implant. Nine femur models were generated by combining three shaft diameters (24-28 mm) with three initial density levels. Remodeling was simulated over 60 months under physiological loading. Low-density femurs exhibited substantial proximal densification and pronounced distal bone loss, accompanied by elevated failure risk at the bone-implant interface. High-density femurs showed minimal remodeling and consistently lower stress and risk levels. Bone shaft diameter modulated, but did not override, the dominant effect of initial density. These findings highlight the importance of preoperative evaluation of cortical density and geometry when planning direct skeletal fixation in transfemoral amputees.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147475876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Weakly and semi-supervised segmentation of uterus using coarse annotations in MRI.","authors":"Ping Lou, Wei Huang, Jie Ying, Haima Yang, Le Fu","doi":"10.1088/1873-4030/ae5964","DOIUrl":"10.1088/1873-4030/ae5964","url":null,"abstract":"<p><p>Endometrial cancer (EC) seriously threatens women's lives via invasion and metastasis, potentially causing multi-system organ failure. Accurate segmentation of the uterus on MR images has important implications for determining the depth of myometrial infiltration in EC, and for benign uterine diseases such as uterine fibroids, it enables efficient quantification of uterine volume and clear visualization of anatomical contours, thereby providing essential support for clinical disease assessment and preoperative planning. However, current deep learning-based uterine segmentation relies on manual pixel-level labeling, which is time-consuming and subjective. This study proposes a new uterus segmentation framework based on a combination of weakly supervised and semi-supervised learning aimed at learning from a small amount of scribble-labeled data and a large amount of unlabeled data. Specifically, the framework includes a two-branch network with residual blocks and two different perturbations. On the other hand, there may be some incorrectly predicted pixels in the pseudo labels. In this paper, a confidence-guided strategy is used to filter out the incorrect pixels in the pseudo labels to improve the network segmentation performance. The proposed method is validated on MR images of 220 patients with uterine diseases. The results show that the proposed method outperforms existing weakly supervised and semi-supervised segmentation methods, especially when the labeled ratio is small. In addition, the proposed method achieves comparable performance to fully supervised methods for any labeling rate.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147595873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PBMGA-python-based bone material grouping and anisotropy, a software tool to automatically assign advanced material properties.","authors":"Daniel Strack, Kati Nispel, Jan S Kirschke, Karupppasamy Subburaj","doi":"10.1088/1873-4030/ae5a3f","DOIUrl":"https://doi.org/10.1088/1873-4030/ae5a3f","url":null,"abstract":"<p><p>The finite element (FE) method is a cornerstone of patient-specific biomechanical analysis, yet most workflows assign isotropic linear elastic behaviour, and neglect bone's intrinsic anisotropic and non-linear response to load. We present PBMGA (Python-based Bone material grouping and anisotropy), a novel open-source tool that automates the calculation and element-specific assignment of non-linear and transversely isotropic (and, in principle, more general anisotropic) bone material parameters using user-defined equations. PBMGA integrates three customisable material grouping strategies: Percentual Thresholding, Adaptive Clustering, and Equidistant Grouping, to compress the number of unique material sets, significantly reducing computational complexity in downstream FE simulations without compromising accuracy. Its modular architecture supports seamless integration with existing preprocessing workflows and scalable analysis of large clinical datasets. By combining accurate material modelling with high-throughput capability, PBMGA enhances biomechanical prediction and paves the way for more efficient clinical diagnostics and treatment planning.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":"147 5","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147646989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of design optimization on cyclic loading performance of novel pedicle screw and comparison with control device: a bilayer model simulation study.","authors":"Arvind Kumar Prajapati, Harikrishna Varma Parimanathukovilakom Ramavarma, Gurunathan Saravana Kumar, Chirathody Vayalappil Muraleedharan, Roy Joseph, Payanam Ramachandra Umashankar","doi":"10.1088/1873-4030/ae5963","DOIUrl":"10.1088/1873-4030/ae5963","url":null,"abstract":"<p><p>This study investigates the fatigue behaviour of a novel pedicle screw design, comparing its performance with a control device using the finite element (FE) method. Pedicle screw-based treatments are standard methods in spinal fusion procedures. However, complications such as screw loosening and breakage occur in both osteoporotic and non-osteoporotic patients, often due to high bone-implant interface stress and fatigue failure. A novel pedicle screw was designed, and its performance was compared with a control device. A cylindrical bone model of human vertebrae was developed with lamina and cortico-cancellous properties, and the screws were assigned properties of medical grade titanium alloy. The outer surfaces of the screw head model were constrained, and a time varying moment simulating clinical conditions was applied at a distance from the screw head. Stress and strain on the bone model, safety factor, life, and fatigue sensitivity on the screws were determined. Results indicate that the von Mises stress on the bone models was reduced for the novel design, and it performed better in terms of life than the control device. The novel design also provided a greater safety factor than the control device, which is likely to improve pedicle screw life. These findings suggest that the novel screw design enhances performance, potentially leading to better patient outcomes. The study offers valuable insights for researchers developing spinal pedicle screws and evaluating their cyclic performance using FE analysis.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147595884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of bone stress relaxation and abrasion on micromotions in uncemented femoral knee implants: a finite element study.","authors":"Thomas Gersie, Thom Bitter, Robert Freeman, Nico Verdonschot, Dennis Janssen","doi":"10.1088/1873-4030/ae5962","DOIUrl":"10.1088/1873-4030/ae5962","url":null,"abstract":"<p><p>Aseptic loosening is the main reason for revision in cementless total knee arthroplasty, underscoring the importance of reliable primary fixation. Studying fixation in pre-clinical models provides insight into the mechanical interactions between bone and implant. Although finite element (FE) analyses are widely used for this purpose, they often represent bone as a linear elastic material, which fails to capture its full mechanical behavior. Although incorporating bone plasticity enhances model realism, it generally results in lower predicted micromotions at the bone-implant interface than those observed experimentally-likely because viscoelastic and abrasive effects are often neglected. This study examined whether accounting for bone stress relaxation and abrasion could improve micromotion predictions at the bone-implant interface in an uncemented femoral knee implant. Experimental micromotion data from five cadaveric femora implanted with a femoral component were compared with subject-specific FE simulations using elastic, plastic, and plastic-viscoelastic bone material models that included varying levels of simulated abrasion. Stress relaxation had minimal impact on micromotions, which remained lower than experimental values. Introducing bone abrasion increased micromotions across all models. For the plastic-viscoelastic model with 0.75 mm abrasion, predicted micromotions (53.0 ± 43.0<i>µ</i>m) closely matched experiments (53.1 ± 42.3<i>µ</i>m), though simulations failed to converge for two specimens due to limited bone-implant contact. These results underscore the importance of incorporating bone abrasion effects in FE models and highlight the need to further refine representations of bone plasticity, friction, and abrasion to improve micromotion predictions.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147595852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the usability of the angular momentum method for estimating whole-body inertia in humans: a case study.","authors":"Anne Haitjema, Junhao Zhang, Bert-Jan F van Beijnum, Peter H Veltink, Jasper Reenalda, Frank J Wouda","doi":"10.1088/1873-4030/ae52fa","DOIUrl":"10.1088/1873-4030/ae52fa","url":null,"abstract":"<p><p>The moment of inertia (MoI) is an important parameter in biomechanical modeling that can influence the accuracy of kinetic estimations. The most commonly used approach to estimate MoI relies on anthropometric tables derived from a limited number of subjects, which may not account for subject-specific variability. This study evaluated the previously proposed angular momentum technique for estimating subject-specific body MoI in two healthy adult males. We were unable to obtain realistic MoI estimates using the angular momentum method, with MoI values being up to 36 times larger than reference values. Initial investigations revealed two promising alternative methods that yielded more realistic MoI estimates.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147475956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A biomechanical monitoring framework for supine sleep: continuous muscle state assessment using sEMG-JASA synchronized with interface pressure mapping.","authors":"Tianming Zhang, Xueyan Li, Li Ding, Yuran Huang, Wenze Chen, Fanglai Yao, Fujun Zhang","doi":"10.1088/1873-4030/ae52fc","DOIUrl":"10.1088/1873-4030/ae52fc","url":null,"abstract":"<p><p>Sleep quality is fundamentally linked to health, and prolonged static postures during sleep can induce muscular fatigue, discomfort, and musculoskeletal risk. A critical gap exists in understanding the continuous relationship between muscle state dynamics and body-mattress interface pressure throughout sleep, which is essential for developing ergonomically adaptive sleep systems. Ten healthy adults maintained a supine posture on a standardized mattress equipped with a high-resolution pressure array. Surface electromyography was recorded from the trapezius, erector spinae, gluteus medius, and biceps femoris muscles. Muscle states were classified using the joint analysis of EMG spectrum and amplitude (JASA) method across three hours of sleep. Regional pressure parameters were calculated for the shoulder, waist & back, hips, and thigh. Muscle states exhibited distinct regional and temporal patterns: trapezius activity remained stable (recovery/force decrease), erector spinae progressively shifted toward fatigue, gluteus medius transitioned from fatigue toward recovery, and biceps femoris showed increasing fatigue. Interface pressure was highest at the shoulder and hips. Statistically significant negative correlations were identified between muscle fatigue and regional pressure, most strongly between gluteus medius fatigue and hips pressure distribution (Kendall's<i>τ</i>=  -0.723,<i>p</i>< 0.01). Reduced interface pressure in partially suspended body regions appears to elicit compensatory muscle activation, leading to fatigue accumulation. The JASA method effectively discriminates muscle states during prolonged supine posture, providing a biomechanical basis for real-time, pressure-modulating interventions aimed at improving sleep recovery and comfort.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147475950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preliminary evaluation of a novel quantitative epidural access device (EpiduraFlow).","authors":"Michael A Vaninetti, Dylan Cullinane, Kyle Norton, Riley Danna, Natalia Berrios-Rivera, Eason Lai, Ashley Manalad","doi":"10.1088/1873-4030/ae52fb","DOIUrl":"10.1088/1873-4030/ae52fb","url":null,"abstract":"<p><p>Accurate identification of the epidural space is critical for procedures such as labor analgesia, postoperative pain management, and epidural steroid injections. The current loss-of-resistance (LOR) technique depends on subtle tactile cues, which are highly subjective and prone to variability and complications. The objective was to develop and evaluate a prototype device (EpiduraFlow) that provides real-time quantitative feedback using pressure and flow metrics to enhance the accuracy and reliability of epidural space identification. A prototype system was designed incorporating a piezoelectric micropump, differential pressure sensors, and a microcontroller with LCD display. The device infused saline at a controlled rate through a Tuohy epidural needle, continuously recording flow and pressure. Testing was performed on a validated epidural simulation model at the UCSD Health SimCenter. Flow and pressure changes were analyzed during needle advancement across simulated tissue layers. Mean flow rate during advancement through simulated soft tissue and ligaments layers was 1.02 ± 0.84 <i>µ</i>l s^-1, compared with 29.7 ± 5.3 <i>µ</i>l s^-1upon entry into the simulated epidural space (<i>p</i>≪0.001). Pressure dropped correspondingly at the moment of entry, and changes were displayed in real time on the LCD. Calibration of sensors against a manometer demonstrated high linearity (R2>0.98). EpiduraFlow reliably identified transitions into the epidural space during simulated procedures. This proof-of-concept demonstrates the feasibility of objective, quantitative epidural localization and supports further development toward handheld, sterile-compatible designs and preclinical validation.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147476103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitigating failures and enhancing reliability of a canine ventricular shunt through robust multi-objective design method.","authors":"Gehendra Sharma, Ryan Yingling, NaYeon Lee, Raheleh Miralami, Andy Shores, Anand Balu Nellippallil, Tonya W Stone, Raj K Prabhu","doi":"10.1088/1873-4030/ae4e2f","DOIUrl":"https://doi.org/10.1088/1873-4030/ae4e2f","url":null,"abstract":"<p><p>Hydrocephalus is a condition that can result in increased intracranial pressure due to the excessive accumulation of cerebrospinal fluid (CSF) or blockage of the outflow of CSF at the level of the third or fourth ventricle. The basic treatment for hydrocephalus is CSF drainage by inserting a surgical tube (shunt) into the ventricle. Despite many new shunt design solutions, shunt failures are a regular occurrence, further complicating treatment. To address this problem, we demonstrate the effectiveness of a robust multi-objective design method to optimize the design of a canine ventricular shunt. In this paper, we investigate the causes of shunt failures and utilize this knowledge to obtain design solutions that minimize the risk of failures in shunts. Key shunt performance parameters that influence shunt failures, such as flow velocity, pressure difference and shear stress, are identified and their relationships with shunt geometry are established. A multi-objective robust design problem is formulated to identify shunt designs that are relatively insensitive to uncertainties while satisfying multiple, conflicting design goals. By using a multi-objective robust formulation, (1) the risk of shunt failures is minimized by designing against multiple criteria that govern failures in shunt, and (2) the reliability of the undertaken design decisions is improved by identifying and managing uncertainties. The method presented is demonstrated using a canine shunt design. However, it is generic enough to be applied to the design of human ventricular shunts and similar biomedical devices.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":"147 4","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147482098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiopaque markers for enhanced radiographic visibility and wear detection in total knee arthroplasty inserts: a proof of concept study.","authors":"Crystal Kayaro Emonde, Max-Enno Eggers, Klaas Maximilian Heide, Florian Pape, Max Marian, Christof Hurschler, Max Ettinger, Berend Denkena","doi":"10.1088/1873-4030/ae4e2e","DOIUrl":"10.1088/1873-4030/ae4e2e","url":null,"abstract":"<p><p>Standard x-ray radiography is routinely used to monitor total knee arthroplasty (TKA) postoperatively for complications such as loosening, malpositioning and insert wear. However, the radiolucency of the polyethylene insert makes quantitative wear assessment challenging. This study investigates the integration of radiopaque markers into standard ultra-high molecular weight polyethylene (UHMWPE) inserts to enhance their radiographic visibility and enable quantitative wear assessment from standard radiographs. Preliminary experiments established suitable process parameters for micro-milling cavities into UHMWPE. Final inserts were machined with varying microstructure configurations comprising grooves and holes. These microstructures were filled with a radiopaque composite of high-density polyethylene (HDPE) +20 wt.% barium sulphate (BaSO₄) composite via extrusion. HDPE was employed as a substitute for UHMWPE due to processability challenges resulting from the latter's high melt viscosity. The marker-integrated inserts were successively fitted on a phantom knee setup fitted together with TKA components and radiographed in the anteroposterior view. A weighted scoring model was created to identify optimal marker geometries based on edge visibility, dimensional measurability, homogeneity, and implant-induced obscuration of the marker projections in standard radiographs. Vertical groove markers i.e. those oriented in parallel to the central ray exhibited superior radiographic visibility and measurability compared to horizontal grooves. Hole markers exhibited a higher homogeneity and were easier to fill, but showed slightly reduced radiographic edge definition in comparison to the vertical grooves. Overall, the vertical grooves were identified as the most favourable marker geometry, followed by the holes, whereas horizontal markers performed the poorest. The findings of this study provide a proof of concept for incorporating radiopaque markers into TKA inserts, establishing a methodological framework for future<i>in vitro</i>wear measurement based on dimensional marker change analysis. Further research into the development of a UHMWPE-compatible marker material is required before clinical relevance can be achieved.</p>","PeriodicalId":49836,"journal":{"name":"Medical Engineering & Physics","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147370848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}