Rheumatoid Deformities of the Lesser Toes.

Dynamic response of muscle tissue under waterjet impact based on a visco-hyperelastic constitutive model considering large deformation failure.

Recent advances in computational microscopy enable highspeed high-resolution intravital 3D imaging with low phototoxicity. However, inevitable sample vibration and tissue deformation in multi-cellular organisms make it extremely challenging to maintain samples stably in focus over long-term even with an extended effective depth of field. Here, we propose a real-time robust autofocus method based on scanning light-field microscopy (AFsLF), enabling sustained high-speed 3D imaging of diverse samples across several days by continuously tracking the sample focal plane without hardware modifications. Based on the intrinsic disparity of light-field angular measurements, AFsLF estimates the focal plane with less than 2 µm error over a 500 µm depth range, completing within 0.1 s, 300-time faster than previous methods. We validate AFsLF across diverse tissues and challenging conditions, including low excitation power, multichannel illumination, and large axial displacements, enabling stable, long-term, multichannel subcellular imaging of neural activities and immune responses in mouse brain and liver.

Wearable-device geometry and tissue mechanical variability determine sacral soft-tissue loading and pressure injury risk.

Postoperative wound stability in microsurgical suturing depends on time-dependent deformation of sutures and tissues. This study develops a multimodal suturing mechanics measurement system (MSMMS) to evaluate real-time suture tension and wound closure strength, defined as the extra stress needed to initiate wound reopening. The MSMMS integrates micro-force suture tension sensing, global load and displacement measurement, and full-field digital image correlation (DIC). Sutured silicone specimens with pre-cut wounds were used as controlled surrogates. Stress relaxation was tested under uniaxial and sutured conditions, and relaxation parameters were extracted using a dual Maxwell model. Synchronized mechanical and DIC data identified crack initiation and wound closure strength. The MSMMS captured two-phase relaxation in both sutures and silicone. Under the same initial stress, the sutured configuration produced about 20% greater suture relaxation than uniaxial loading. Wound closure strength showed a non-monotonic dependence on relaxation time: it decreased by 5-10% after short relaxation and partially recovered at longer times. Increasing the initial suture tension from 0.3 to 0.5 N increased wound closure strength by less than 5%. Unlike conventional force-only or endpoint tests, the MSMMS enables synchronized characterization of suture tension, global loading, and wound closure strength. This framework provides a quantitative basis for optimizing surgical tension and evaluating smart suturing devices. The characterization of relaxation time constants may also help identify the optimal postoperative time window for suture adjustment.

Accelerating the regeneration of infected wounds necessitates a multifaceted therapeutic intervention that simultaneously eradicates bacterial pathogens, adapts seamlessly to dynamic tissue deformations, and provides uninterrupted barrier protection, ultimately fostering a pro-healing microenvironment. To address these requirements, a dynamic multi-network nanocomposite hydrogel (OG/PCDs) was developed that couples on-demand photothermal therapy with orchestrated tissue remodeling. Specifically, polydopamine carbon dots (PDA-CDs) with exceptional near-infrared (NIR) photothermal conversion efficiency were initially synthesized as broad-spectrum antimicrobial agents. By combining intrinsic physical membrane disruption with NIR-triggered photothermal ablation, the PDA-CDs exhibit potent antibacterial activity while effectively mitigating the risk of bacterial resistance development. Subsequently, the OG/PCDs hydrogel was rationally engineered via the integration of dynamic Schiff base linkages, boronate ester bonds, and UV-triggered free-radical polymerization. Benefiting from its sophisticated architecture, the resulting hydrogel exhibited rapid autonomous self-healing capabilities, reliable tissue adhesion, and an intelligent pH-responsive release profile tailored for acidic infective microenvironments. Crucially, the hydrogel inherits the superior photothermal performance of PDA-CDs, enabling the efficient elimination of both planktonic bacteria and resilient biofilms. In vivo evaluations using an S. aureus-infected wound model demonstrated that the NIR-activated OG/PCDs hydrogel effectively sterilized the wound bed (>99% bacterial eradication) and significantly accelerated tissue remodeling, culminating in an impressive 98.42% wound closure rate over 14 days. Overall, by synergizing targeted photothermal antimicrobial efficacy with dynamic structural adaptability, the nanocomposite hydrogel presents a promising therapeutic platform to combat bacterial infections and facilitate tissue regeneration.

Mixed reality (MR) surgical navigation systems have achieved notable success in procedures involving rigid anatomical structures but face substantial challenges in soft tissue interventions due to intraoperative deformation. Current literature reveals a significant gap in MR-based navigation systems that provide quantitative validation through subsurface targeting experiments representative of clinical workflow. This study presents a comprehensive MR surgical navigation platform for liver interventions enhanced with new features including soft-tissue deformation correction, real-time microwave (MW) probe trajectory visualization, and distance-to-target measurement capabilities. In addition to novel platform design, the first standardized experimental protocol specifically designed for validating subsurface targeting accuracy in the context of MR surgical navigation systems has been established. The validation methodology provides a quantitative targeting evaluation that can be universally adopted for comparative analysis with other MR approaches. Using the MW probe navigation capabilities, surgical workflow maintained clinically viable efficiency with a navigation-to-target time of 5.5 ± 1.3 minutes per targeting session that spanned 13 subsurface targets per session. With respect to the correction for soft-tissue deformations, our non-rigid registration method (NRM) demonstrated superior performance compared to rigid registration method (RRM), achieving 41.3% reduction in user-navigated targeting error (from 10.4 ± 3.9 mm to 6.1 ± 2.8 mm) and 42.3% reduction in ground-truth measured targeting error (from 13.0 ± 5.5 mm to 7.5 ± 3.3 mm). Other novelties to the platform design are an integrated real-time ablation zone prediction and visualization tool as a potential direction for clinical application. The advancement positions the technology as a powerful surgical guidance approach for hepatic interventions. This research is the first to establish a validation framework standard for MR surgical navigation system which successfully compensates for soft tissue deformation.

Integrating CO₂ laser photoacoustic spectroscopy with explainable CNNs for post-harvest quality assessment of Diospyros kaki.

Poor repair outcomes of abdominal wall soft tissue defects often lead to hernia recurrence and tissue adhesion, thereby increasing the medical burden. An ideal repair material should simultaneously fulfill the requirements of anti-adhesion properties, wet tissue adhesion capability, biodegradability, and the ability to promote functional tissue regeneration. Herein, inspired by the natural abdominal wall architecture, we designed a biomimetic Janus-structured repair patch, denoted as PS-PDH. This patch integrates a biodegradable poly(4-hydroxybutyrate) (P4HB) electrospun fibrous membrane with a glutathione-responsive degradable poly(sulfobetaine methacrylate) (PSBMA) hydrogel via polydopamine (PDA). It exhibits excellent asymmetric adhesive properties: the fibrous side facilitates cell adhesion and proliferation, while the hydrogel side effectively resists cell and protein adhesion. Furthermore, PS-PDH possesses robust mechanical properties, enabling it to adapt to dynamic tissue deformation. Notably, the patch effectively scavenges free radicals and intracellular reactive oxygen species (ROS), while promoting macrophage polarization from the pro-inflammatory M1 to the pro-regenerative M2 phenotype. In a mouse full-thickness abdominal wall defect model, PS-PDH effectively prevented postoperative adhesion and fibrosis, modulated the inflammatory microenvironment, and promoted functional muscle and vascular regeneration. Therefore, this biomimetic Janus-structured patch offers a reliable and highly clinically translatable strategy for the functional repair of abdominal wall soft tissue defects.

IntroductionPostmortem imaging at ultrahigh field strengths, such as 7 Tesla (7T) magnetic resonance imaging (MRI), enables unprecedented visualization of fine brain structures and pathology. However, precise registration between MRI and histology is often compromised by tissue deformation and lack of standardized tools for preserving anatomical orientation. A reliable, high-resolution MRI-to-histology workflow is essential for MRI-guided sampling to investigate neurodegenerative diseases.MethodsWe developed a human postmortem brain container composed of stereotaxic enclosure and cutting guide system using iterative 3D printing. The final design is constructed from Victrex AM™ 200, a polyaryletherketone material engineered with MRI compatibility, high mechanical strength, and high resistance to fixatives. Human brains were embedded in an agar/sucrose mixture within the container and scanned at 7T using high-contrast and high-resolution imaging sequences. The cutting guide enables reproducible sectioning at defined tissue coronal slab thicknesses (9.2 ± 0.6 mm). Block face photographs of each coronal slab were then co-registered with MRI for targeted tissue sampling.ResultsTo date, 215 human postmortem brains have been imaged ex vivo using this container. The container maintains consistent spatial orientation from imaging through sectioning, supporting correlation between MR-visible features and histological findings. Imaging-visible abnormalities, such as white matter hyperintensities and cerebral microbleeds, were localized and sampled with minimal deformation. The container enables single-scan workflows, avoiding custom cutting templates or repeat imaging. It supports deep learning-based lesion segmentation and MRI-guided histology registration, facilitating large-scale neuropathological investigations.ConclusionThe stereotaxic cutting guide system addresses a critical gap in postmortem imaging by integrating MRI-compatible materials, precision-guided sectioning, and high-throughput imaging. It has enabled multimodal studies of aging and neurodegeneration and is being adopted in neuropathological workflows. This platform provides a reproducible, scalable, and anatomically precise solution for aligning ultrahigh field MRI with histology, enhancing both clinical research and digital pathology efforts.

Mitigating structural recalcitrance: Microwave pretreatment governs anatomy-dependent moisture migration and dimensional stability of moso bamboo.

Subcutaneous (SC) administration offers multiple advantages over intravenous (IV) administration across different therapeutic areas and chemical modalities. Despite progress, some knowledge gaps persist in understanding the SC injection process, drug fate within the SC site, and SC absorption and bioavailability. This review provides an overview of emerging modeling and simulation techniques to tackle these knowledge gaps. Various in silico mechanistic models have been used to simulate SC injection dynamics, injection depot geometry, tissue backpressure, tissue deformation, changes in tissue porosity and permeability, drug migration within the SC site, and drug absorption. On the other hand, in vitro models and methods have advanced to emulate in vivo SC tissue, assess critical quality attributes of SC drug products, and establish in vitro-in vivo correlations. Additionally, this review discussed predictive methods for mAb SC bioavailability. Advances in modeling and simulation techniques can accelerate the development of SC drug products.

ABSTRACTBackgroundThis study evaluated the short‐term biomechanical response of wound tissue following low‐level laser therapy (LLLT) by examining changes in skin stiffness, a surrogate biomechanical indicator of short‐term tissue response, across different limb regions.MethodsA 660 nm LLLT protocol was applied to wound sites. Skin stiffness was quantified using optical coherence tomography (OCT) combined with an air‐jet indentation system, enabling non‐contact measurement of tissue deformation. For accurate layer‐specific assessment, a U‐Net–based model was employed to automate OCT image segmentation.ResultsThe automated segmentation by the U‐Net model achieved a segmentation accuracy of 92%, facilitated precise segmentation of skin layers. LLLT significantly reduced skin stiffness after treatment, indicating an acute modulation of tissue compliance.ConclusionShort‐duration LLLT reduces skin stiffness immediately post‐treatment, indicating its potential as a non‐invasive intervention to modulate the biomechanical environment of wounds.Trial Registration:ClinicalTrials.gov identifier: NCT07177274

ABSTRACTBackgroundThis study aimed to evaluate the prevalence of peri‐implant soft tissue deformities, including dehiscences (PSTDs) and deficiencies, around bone‐level (BL) and tissue‐level (TL) implants in the anterior maxilla, assess associated variables, and patient‐reported outcomes (PROs).MethodsAdults with implant‐supported prostheses (ISPs) in the anterior maxilla were recruited. Clinical and digital assessments were performed, and related variables were analyzed.ResultsA total of 205 ISPs in 193 patients were evaluated. Mean follow‐up after implant placement was 11.3 ± 1.4 years. PSTD prevalence was comparable between BL and TL implants (88.8% vs. 94.4%; p = 0.19), or when PSTD ≥ 1 mm (23.9% vs. 22.5%; p = 0.97). Similarly, 99.25% and 100% of BL and TL showed deformities, p = 1.00. Prevalence of prosthetic interface/abutment (12.7% vs. 2.5%) and implant shoulder exposure (4.2% vs. 0%), and overcontoured ISP (35.2% vs. 12.7%) was significantly higher in TL implants (p < 0.01). Greater papilla dimensions and lower volume deficiency (90.3% vs. 98.6%; p < 0.01) were observed around BL implants, while mucosal discoloration was similar between groups (16.4% vs. 15.5%; p > 0.05). Greater PSTD depth was associated with older age, reduced keratinized mucosa width (< 2 mm), wider implant diameter, prosthetic overcontouring, lower mucosal volume, and papilla deficiencies (p < 0.05). Wider prosthetic emergence angles were associated with reduced papilla dimensions (p < 0.05). Thin mucosa (< 2 mm) was associated with grayish mucosal discoloration (OR = 2.79). Despite these findings, OHIP‐14 scores were low, and PROs were high, with no significant differences between groups.ConclusionsPrevalence of peri‐implant soft tissue deformities in the anterior maxilla is high irrespective of implant type and is associated with age, soft tissue phenotype, mucosal volume, papilla deficiencies, wider implant diameters, and prosthetic overcontouring. However, this does not seem to have a measurable impact on patient perception.

A hybrid implicit-explicit finite element framework for real-time bioheat transfer simulation in deformable biological tissue.

MRI-guided neurosurgery requires high-precision puncture, but is challenged by magnetic field constraints and brain tissue deformation. The mechanism is constructed from non-magnetic materials (e.g.,PEEK and ceramic bearings) and driven by ultrasonic piezoelectric actuators to ensure safety in strong magnetic fields. A composite swing-arc RCM design extends the RCM workspace to a hemispherical region, enabling dynamic adjustment within a 220mm diameter. D-H parameters are refined through multimodal calibration, and RCM stability is experimentally validated. After calibration, the end-effector absolute error is 2.16mm with a repeatability of ±1.02mm, and the mean RCM deviation is 0.57mm. The system supports autonomous puncture under real-time MRI, covers the cranial workspace and provides a precise, flexible solution for neurosurgical procedures.

Rapid prediction of meningeal deformation and puncture force is essential for surgical simulation and planning. This study proposes a reduced-order hybrid model combining a mass–spring–damper framework with a potential field method. The brain is simplified into meningeal, cerebrospinal fluid, and tissue layers to capture compression-induced deformation, interlayer interaction, and tissue resistance. Implemented in MATLAB, the model was validated using Abaqus simulations and brain-like phantom puncture experiments. At 5 mm puncture depth, it accurately predicted deformation and puncture force while running over two orders of magnitude faster than the conventional finite element method, enabling efficient simulation of puncture-induced tissue deformation.

Medical image registration is a fundamental task in medical image analysis, enabling the alignment of images from different modalities or time points. However, intensity inconsistencies and nonlinear tissue deformations pose significant challenges to the robustness of registration methods. Recent approaches leveraging self-supervised representation learning show promise by pre-training feature extractors to generate robust anatomical embeddings, that further used for the registration. In this work, we propose a novel framework that integrates equivariant contrastive learning directly into the registration model. Our approach leverages the power of contrastive learning to learn robust feature representations that are invariant to tissue deformations. By jointly optimizing the contrastive and registration objectives, we ensure that the learned representations are not only informative but also suitable for the registration task. We evaluate our method on abdominal and thoracic image registration tasks, including both intra-patient and inter-patient scenarios. Experimental results demonstrate that the integration of contrastive learning directly into the registration framework significantly improves performance, surpassing strong baseline methods.

Keypoint-based tracking and navigation are central to many image-guided surgical systems, yet their reliability degrades significantly in the presence of soft-tissue deformation, as commonly observed in procedures such as liver surgery. Existing keypoint descriptors often fail to remain stable under large affine and non-rigid transformations. This work introduces Stretcher, a framework designed to improve the deformation robustness of keypoint descriptors for surgical tracking and navigation. Instead of directly matching keypoint descriptors across deformed images, Stretcher learns a neural model that explicitly captures the effect of affine deformations on descriptor representations. At inference time, a grid of affine transformations is simulated, and keypoint descriptors are efficiently adjusted using the learned model, avoiding redundant descriptor recomputation. This enables robust descriptor adaptation under deformation while maintaining computational efficiency. Stretcher is evaluated on liver surgery images exhibiting large tissue deformation. Experimental results show that the proposed approach improves keypoint matching robustness in highly deformed regions. Across all evaluated scenarios, Stretcher maintains state-of-the-art precision while providing higher matching accuracy compared to existing descriptor-based methods, particularly where deformation is severe. By explicitly modeling the impact of affine deformations on keypoint descriptors, Stretcher enables reliable keypoint matching under complex tissue motion. The proposed framework improves robustness in challenging surgical scenarios without sacrificing efficiency, making it well suited for deformation-prone intraoperative tracking and navigation tasks. Code is available at https://github.com/constiwitzleben/Stretchers .

Hedgehog-driven adaxial cell constriction patterns slow muscle fate and somite boundary remodeling in the presomitic mesoderm.