Poroelastic behavior and water permeability of human skin at the nanoscale.

Topical skin care products and hydrating compositions (moisturizers or injectable fillers) have been used for years to improve the appearance of, for example facial wrinkles, or to increase "plumpness". Most of the studies have addressed these changes based on the overall mechanical changes associated with an increase in hydration state. However, little is known about the water mobility contribution to these changes as well as the consequences to the specific skin layers. This is important as the biophysical properties and the biochemical composition of normal stratum corneum, epithelium, and dermis vary tremendously from one another. Our current studies and results reported here have focused on a novel approach (dynamic atomic force microscopy-based nanoindentation) to quantify biophysical characteristics of individual layers of ex vivo human skin. We have discovered that our new methods are highly sensitive to the mechanical properties of individual skin layers, as well as their hydration properties. Furthermore, our methods can assess the ability of these individual layers to respond to both compressive and shear deformations. In addition, since human skin is mechanically loaded over a wide range of deformation rates (frequencies), we studied the biophysical properties of skin over a wide frequency range. The poroelasticity model used helps to quantify the hydraulic permeability of the skin layers, providing an innovative method to evaluate and interpret the impact of hydrating compositions on water mobility of these different skin layers.

Pelvic floor disorder assessment of knowledge and symptoms: an educational intervention for Spanish-speaking women (PAKS study).

INTRODUCTION AND HYPOTHESIS: Educational interventions have been effective in improving postpartum knowledge, performance of pelvic floor exercises, and bowel-specific quality-of-life. Our primary objective was to determine if a video-based educational intervention on pelvic floor disorders (PFDs) would increase Spanish-speaking women's knowledge of PFDs, and secondarily to assess if it would decrease pelvic floor symptoms. We hypothesized that Spanish-speaking women would improve their pelvic floor knowledge and symptoms post-intervention. METHODS: Inclusion criteria included women age 18 years and older and self-reported as a predominantly Spanish-speaker or equally bilingual English- and Spanish-speaker. Changes in knowledge were assessed with the Prolapse and Incontinence Knowledge Questionnaire (PIKQ). Changes in symptoms were assessed with the Pelvic Floor Distress Inventory-20 (PFDI-20). Linear regression assessed for independent effects. RESULTS: One hundred and fourteen women were enrolled and 112 completed the pre- and post-intervention PIKQ. Mean (standard deviation [SD]) age was 50 (14) years. Immediate post-intervention scores showed significant improvement in knowledge. Total PIKQ score improved by 5.1 (4.7) points (p < 0.001). POP subscore improved by 2.7 (2.7) points (p<0.001) and UI subscore improved by 2.3 (2.5) points (p < 0.001). Improvement in knowledge continued after four weeks (p < 0.001). PFDI-20 prolapse (p=0.02), colorectal-anal (p < 0.001) and urinary (p = 0.01) scores significantly improved only for the most symptomatic women at baseline. Using linear regression, total PIKQ (p = 0.03) and total PFDI-20 scores (p = 0.04) were associated with predominantly Spanish-speakers versus fully bilingual. CONCLUSION: Findings support the efficacy of a video-based educational intervention to improve knowledge of PFDs in Spanish-speaking women. The most symptomatic women benefitted from this intervention.

Supporting clinical competency in managing peripherally inserted central catheters during the COVID-19 pandemic: an education evaluation.

INTRODUCTION: Hospitals had to create new practices and training due to the severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) pandemic. An increase in patient acuity and the need for peripherally inserted central catheters (PICC) across the hospital required an urban community hospital to educate and support in-patient nurses to manage PICCs in acute and complex care units. Traditionally, these skills were performed by specialized registered nurses (RNs) from the Vascular Access Team (VAT). This paper highlights the education plan, implementation, and evaluation of a hospital-wide training for RNs and registered practical nurses (RPNs) in in-patient units during the SARS-CoV-2 pandemic. METHODS: Clinical Resource Leaders (CRLs) created a modular approach to upskill existing nurses and train new hires. Various education strategies, such as the use of competency assessments, creating practice supports, and incorporating specialists as a resource, were utilized to ensure knowledge transfer, application, and guidance of evidence-informed clinical practices. Vascular Access Team documentation was utilized to obtain Kirkpatrick's (2021) level 4 evaluation. RESULTS: This training program was implemented after the second wave of the pandemic and was also embedded into nursing orientation. This structured approach ensured that nurses were competent to support the increased acuity and needs of patients. Eighty percent of full-time and part-time nurses were trained to manage PICC lines. CONCLUSION: Education evaluation results show a decrease in PICC-related VAT assistance requests with a baseline of 570 calls down to 149 six months after education was implemented. Leaders are encouraged to ensure teams have role clarity, policies, and practice supports to be successful.

COVID-19 Vaccination Among Environmental Service Workers Using Agents of Change.

Introduction: Vaccine hesitancy remains a barrier to community immunity against SARS-CoV-2 infection. Health care workers are at risk both of infection and for nosocomial transmission, but have low rates of vaccine uptake due to hesitancy. This project sought to improve the SARS-CoV-2 vaccine uptake among environmental services (EVS) workers at a large academic regional medical center using a community-based participatory approach (CBPA). Methods: The CBPA engaged environmental service workers from January 2021 to March 2021. Public health experts and environmental services department leaders developed a 1-hour training for peer lay health educators (N=29), referred to as agents of change (AOC). AOC were trained on COVID-19 infection, benefits of SARS-CoV-2 vaccination, and techniques to address vaccine misinformation among their peers. Following the program, we conducted semistructured interviews with the AOC to document their experiences. Results: Analysis of the semistructured interviews shows that 89.6% of participants (N=26) felt the training was informative; 79.3% of participants (N=23) reported using personal testimony while engaging in discussions about vaccination with their peers, and the majority of participants (N=26, 89.6%) discussed vaccination outside of the workplace in other community settings. During the 2-month time span of the program, mRNA COVID-19 vaccination rates among the EVS staff increased by 21% (N=126 to N=189). Conclusion: Our CBPA program demonstrated an increase in mRNA COVID-19 vaccine uptake through using an AOC lay health educator model. As the need for COVID-19 vaccination continues, we must continue to investigate barriers and sources of hesitancy in order to address these through tailored interventions.

Socially-Directed Development of Materials for Structural Color.

Advancing a socially-directed approach to materials research and development is an imperative to address contemporary challenges and mitigate future detrimental environmental and social impacts. This paper reviews, synergizes, and identifies cross-disciplinary opportunities at the intersection of materials science and engineering with humanistic social sciences fields. Such integrated knowledge and methodologies foster a contextual understanding of materials technologies embedded within, and impacting broader societal systems, thus informing decision making upstream and throughout the entire research and development process toward more socially responsible outcomes. Technological advances in the development of structural color, which arises due to the incoherent and coherent scattering of micro-and nanoscale features and possesses a vast design space, are considered in this context. Specific areas of discussion include material culture, narratives, and visual perception, material waste and use, environmental and social life cycle assessment, and stakeholder and community engagement. A case study of the technical and social implications of bio-based cellulose (as a source for structurally colored products) is provided. Socially-directed research and development of materials for structural color hold significant capacity for improved planetary and societal impact across industries such as aerospace, consumer products, displays and sensors, paints and dyes, and food and agriculture.

Aggrecan: Approaches to Study Biophysical and Biomechanical Properties.

Aggrecan, the most abundant extracellular proteoglycan in cartilage (~35% by dry weight), plays a key role in the biophysical and biomechanical properties of cartilage. Here, we review several approaches based on atomic force microscopy (AFM) to probe the physical, mechanical, and structural properties of aggrecan at the molecular level. These approaches probe the response of aggrecan over a wide time (frequency) scale, ranging from equilibrium to impact dynamic loading. Experimental and theoretical methods are described for the investigation of electrostatic and fluid-solid interactions that are key mechanisms underlying the biomechanical and physicochemical functions of aggrecan. Using AFM-based imaging and nanoindentation, ultrastructural features of aggrecan are related to its mechanical properties, based on aggrecans harvested from human vs bovine, immature vs mature, and healthy vs osteoarthritic cartilage.

Healthcare Personnel (HCP) Attitudes About Coronavirus Disease 2019 (COVID-19) Vaccination After Emergency Use Authorization.

BACKGROUND: We previously reported on coronavirus disease 2019 (COVID-19) vaccination intent among healthcare personnel (HCP) before emergency use authorization. We found widespread hesitancy and a substantial proportion of HCP did not intend to vaccinate. METHODS: We conducted a cross-sectional survey of HCP, including clinical and nonclinical staff, researchers, and trainees between 21 February and 19 March 2021. The survey evaluated vaccine attitudes, beliefs, intent, and acceptance. RESULTS: Overall, 3981 (87.7%) of respondents had already received a COVID-19 vaccine or planned to get vaccinated. There were significant differences in vaccine acceptance by gender, age, race, and hospital role. Males (93.7%) were more likely than females (89.8%) to report vaccine acceptance (P < .001). Mean age was higher among those reporting vaccine acceptance (P < .001). Physicians and scientists showed the highest acceptance rate (97.3%), whereas staff in ancillary services showed the lowest acceptance rate (79.9%). Unvaccinated respondents were more likely to be females, to have refused vaccines in the past due to reasons other than illness or allergy, to care for COVID-19 patients, or to rely on themselves when making vaccination decision. Vaccine acceptance was more than twice previous intent among Black respondents, an increase from 30.8% to 73.8%, and across all hospital roles with all > 80% vaccine acceptance. CONCLUSIONS: The majority of HCP were vaccinated, much higher than reporting intent before vaccine was available. However, many HCP-particularly ancillary services-are still hesitant. Feasible and effective interventions to address the hesitant, including individually-tailored education strategies are needed, or vaccine can be mandated.

Community Health Worker Program Sustainability in Africa: Evidence From Costing, Financing, and Geospatial Analyses in Mali.

BACKGROUND: In Mali, community health workers (CHWs) deliver essential community care (ECC) to rural populations. The dominance of external funding for the program threatens the sustainability of this critical workforce as donor financing decreases. This article summarizes results of analyses aimed at assisting Mali's decision makers and leaders in initiating a transition to a sustainable CHW program supported by domestic funding through strategic and rational investment. METHODS: Data on ECC implementation norms, workforce, coverage, utilization, cost, and geospatial features were collected between 2016 and 2019. The data informed interlinked CHW financing analyses-situational, services costing, efficiency, and geospatial mapping. Analysis showed distribution of reported expenditures, estimates of required CHW funding, cost-saving options, and spatially visualized discrepancies between spending estimates and normative costs. RESULTS: Thirteen financing sources contributed to CHW program expenditures, 88% of which were from international donors, for a package of 23 curative, preventive, and promotive interventions. In 2015, the CHW program spent US$13.01 million; an estimated US$8.36 million would have been needed to achieve the same service volume under standard care protocols. Medicines and start-up training had US$6.88 million more than needed; supervision, program management, and recurrent training components were underfunded by US$2.2 million. Cost-saving opportunities of US$6.16 million were identified in 41 of 44 districts. Funding reallocation opportunities (after meeting technical efficiency requirements) were identified in 20 of 44 districts (US$2.56 million). Use of geospatial targeting and mapping suggests district- and village-level reallocation options for theoretical funding surpluses. CONCLUSION: CHW costs can be significantly reduced without sacrificing service technical quality. Spending can be geographically targeted to optimize service use by rural populations. Efficiency analyses provide evidence to build stronger engagement, support improved decision making, efficiently prioritize resources, and target investments for sustainable financing of CHW programs.

Persistent and Widespread Pain Among African-Americans Six Weeks after MVC: Emergency Department-based Cohort Study.

INTRODUCTION: African-Americans in the United States experience greater persistent pain than non-Hispanic Whites across a range of medical conditions, but to our knowledge no longitudinal studies have examined the risk factors or incidence of persistent pain among African-Americans experiencing common traumatic stress exposures such as after a motor vehicle collision (MVC). We evaluated the incidence and predictors of moderate to severe axial musculoskeletal pain (MSAP) and widespread pain six weeks after a MVC in a large cohort of Black adults presenting to the emergency department (ED) for care. METHODS: This prospective, multi-center, cohort study enrolled Black adults who presented to one of 13 EDs across the US within 24 hours of a MVC and were discharged home after their evaluation. Data were collected at the ED visit via patient interview and self-report surveys at six weeks after the ED visit via internet-based, self-report survey, or telephone interview. We assessed MSAP pain at ED visit and persistence at six weeks. Multivariable models examined factors associated with MSAP persistence at six weeks post-MVC. RESULTS: Among 787 participants, less than 1% reported no pain in the ED after their MVC, while 79.8 (95% confidence interval [CI], 77.1 - 82.2) reported MSAP and 28.3 (95% CI, 25.5 - 31.3) had widespread pain. At six weeks, 67% (95% CI, 64, 70%) had MSAP and 31% (95% CI, 28, 34%) had widespread pain. ED characteristics predicting MSAP at six weeks post-MVC (area under the curve = 0.74; 95% CI, 0.72, 0.74) were older age, peritraumatic dissociation, moderate to severe pain in the ED, feeling uncertain about recovery, and symptoms of depression. CONCLUSION: These data indicate that African-Americans presenting to the ED for evaluation after MVCs are at high risk for persistent and widespread musculoskeletal pain. Preventive interventions are needed to improve outcomes for this high-risk group.

Bioinspired design of flexible armor based on chiton scales.

Man-made armors often rely on rigid structures for mechanical protection, which typically results in a trade-off with flexibility and maneuverability. Chitons, a group of marine mollusks, evolved scaled armors that address similar challenges. Many chiton species possess hundreds of small, mineralized scales arrayed on the soft girdle that surrounds their overlapping shell plates. Ensuring both flexibility for locomotion and protection of the underlying soft body, the scaled girdle is an excellent model for multifunctional armor design. Here we conduct a systematic study of the material composition, nanomechanical properties, three-dimensional geometry, and interspecific structural diversity of chiton girdle scales. Moreover, inspired by the tessellated organization of chiton scales, we fabricate a synthetic flexible scaled armor analogue using parametric computational modeling and multi-material 3D printing. This approach allows us to conduct a quantitative evaluation of our chiton-inspired armor to assess its orientation-dependent flexibility and protection capabilities.

Biological connective tissues exhibit viscoelastic and poroelastic behavior at different frequency regimes: Application to tendon and skin biophysics.

In this study, a poroviscoelastic finite element model (FEM) was developed and used in conjunction with an AFM-based wide-bandwidth nanorheology system to predict the frequency-dependent mechanical behavior of tendon and dermis subjected to compression via nanoindentation. The aim was to distinguish between loading rates that are dominated by either poroelasticity, viscoelasticity, or the superposition of these processes. Using spherical probe tips having different radii, the force and tip displacement were measured and the magnitude, E∗, and phase angle, ϕ, of the dynamic complex modulus were evaluated for mouse supraspinatus tendon and mouse dermis. The peak frequencies of the phase angle were associated with the characteristic time constants of poroelastic and viscoelastic material behavior. The developed FE model could predict the separate poroelastic and viscoelastic responses of these soft tissues over a 4 decade frequency range, showing good agreement with experimental results. We observed that poroelasticity was the dominant energy dissipation mechanism for mouse dermis and supraspinatus tendon at higher indentation frequencies (102 to 104 Hz) whereas viscoelasticity was typically dominant at lower frequencies (<102 Hz). These findings show the underlying mechanical behavior of biological connective tissues and give insight into the role played by these different energy dissipation mechanisms in governing the function of these tissues at nanoscale. STATEMENT OF SIGNIFICANCE: Soft biological tissues exhibit complex, load- and time-dependent mechanical behavior. Evaluating their mechanical behavior requires sophisticated experimental tools and numerical models that can capture the fundamental mechanisms governing tissue function. Using an Atomic-force-microscopy-based rheology system and finite element models, the roles of the two most dominant time-dependent mechanisms (poroelasticity and viscoelasticity) that govern the dynamic loading behavior of mouse skin and tendon have been investigated. FE models were able to predict and quantify the contribution of each mechanism to the overall dynamic response and confirming the presence of these two distinct mechanisms in the mechanical response. Overall, these results provide novel insight into the viscoelastic and poroelastic properties of mouse skin and tendon and promote better understanding of the underlying origins of each mechanism.

Mutable polyelectrolyte tube arrays: mesoscale modeling and lateral force microscopy.

In this study, the pH-dependent friction of layer-by-layer assemblies of poly(allylamine hydrochloride) and poly(acrylic acid) (PAH/PAA) are quantified for microtube array structures via experimental and simulated lateral force microscopy (LFM). A novel coarse-grain tube model is developed, utilizing a molecular dynamics (MD) framework with a Hertzian soft contact potential (such that F ∼ δ3/2) to allow the efficient dynamic simulation of 3D arrays consisting of hundreds of tubes at micrometer length scales. By quantitatively comparing experimental LFM and computational results, the coupling between geometry (tube spacing and swelling) and material properties (intrinsic stiffness) results in a transition from bending dominated deformation to bending combined with inter-tube contact, independent of material adhesion assumptions. Variation of tube spacing (and thus control of contact) can be used to exploit the normal and lateral resistance of the tube arrays as a function of pH (2.0/5.5), beyond the effect of areal tube density, with increased resistances (potential mutability) up to a factor of ∼60. This study provides a novel modeling platform to assess and design dynamic polyelectrolyte-based substrates/coatings with tailorable stimulus-responsive surface friction. Our results show that micro-geometry can be used alongside stimulus-responsive material changes to amplify and systematically tune mutability.

The effects of morphological irregularity on the mechanical behavior of interdigitated biological sutures under tension.

Irregular interdigitated morphology is prevalent in biological sutures in nature. Suture complexity index has long been recognized as the most important morphological parameter to govern the mechanical properties of biological sutures. However, the suture complexity index alone does not reflect all aspects of suture morphology. The goal of this investigation was to determine that besides suture complexity index, whether the degree of morphological irregularity of biological sutures has influences on the mechanical properties, and if there is any, how to quantify these influences. To explore these issues, theoretical and finite element (FE) suture models with the same suture complexity index but different levels of morphological irregularity were developed. The quasi-static stiffness, strength for damage initiation and post-failure process of irregular sutures were studied. It was shown that for the same suture complexity index, when the level of morphological irregularity increases, the overall strain to failure will increase while tensile stiffness is retained; also, the total energy to fracture increases with a sacrifice in strength to damage initiation. These results reveal that morphological irregularity is another important independent parameter to govern and balance the mechanical properties of biological sutures. Therefore, from the mechanics point of view, the prevalence of irregular suture morphology in nature is a merit, not a defect.

Geometry-dependent compressive responses in nanoimprinted submicron-structured shape memory polyurethane.

High resolution surface textures, when rationally designed, provide an attractive surface engineering approach to enhance surface functionalities. Designing smart surfaces by coupling surface texture with shape memory polymers has garnered attention in achieving tunable mechanical properties. We investigate the structure-mechanical property relationships for programmable, shape-memorizing submicron-scale pillar arrays subjected to flat-punch compression. The geometrically-dependent deformation of structured surfaces with two different aspect ratios (250 nm-pillars 1 : 1 and 550 nm-pillars 2.4 : 1) were investigated, and their moduli were found to be lower than that of non-patterned surface. From finite element analysis, the pillar deformation is correlated to a mechanistic transition from a discrete, unidirectional compression of 250 nm-pillars to lateral constraints caused by interpillar contact in 550 nm-pillars. This lateral pillar-pillar contact in the 550 nm-pillars resulted in an increased and maximum strain-dependent modulus but lower elastic recovery and energy dissipation as compared with the 250 nm-pillars. Furthermore, the compressive responses of temporarily shaped pillars (programmed by stretching) were compared with the permanently shaped pillars. The extent of lateral constraints controlled by pillar shape and spacing in 550 nm-pillars was responsible for the modulus differences between the original and stretched patterns, whereas the modulus of 250 nm-pillars remained as a constant value with different levels of stretching. This study provides mechanistic insights into how the mechanical behavior can be modulated by designing the aspect ratio of shape memory pillar arrays and by programming the surface geometry, thus revealing the potential of developing ingenious designs of responsive surfaces sensitive to mechanical deformation.

Wide bandwidth nanomechanical assessment of murine cartilage reveals protection of aggrecan knock-in mice from joint-overuse.

Aggrecan loss in human and animal cartilage precedes clinical symptoms of osteoarthritis, suggesting that aggrecan loss is an initiating step in cartilage pathology. Characterizing early stages of cartilage degeneration caused by aging and overuse is important in the search for therapeutics. In this study, atomic force microscopy (AFM)-based force-displacement micromechanics, AFM-based wide bandwidth nanomechanics (nanodynamic), and histologic assessments were used to study changes in distal femur cartilage of wildtype mice and mice in which the aggrecan interglobular domain was mutated to make the cartilage aggrecanase-resistant. Half the animals were subjected to voluntary running-wheel exercise of varying durations. Wildtype mice at three selected age groups were compared. While histological assessment was not sensitive enough to capture any statistically significant changes in these relatively young populations of mice, micromechanical assessment captured changes in the quasi-equilibrium structural-elastic behavior of the cartilage matrix. Additionally, nanodynamic assessment captured changes in the fluid-solid poroelastic behavior and the high frequency stiffness of the tissue, which proved to be the most sensitive assessment of changes in cartilage associated with aging and joint-overuse. In wildtype mice, aging caused softening of the cartilage tissue at the microscale and at the nanoscale. Softening with increased animal age was found at high loading rates (frequencies), suggesting an increase in hydraulic permeability, with implications for loss of function pertinent to running and impact-injury. Running caused substantial changes in fluid-solid interactions in aggrecanase-resistant mice, suggestive of tissue degradation. However, higher nanodynamic stiffness magnitude and lower hydraulic permeability was observed in running aggrecanase-resistant mice compared to running wildtype controls at the same age, thereby suggesting protection from joint-overuse.

Multifunctionality of chiton biomineralized armor with an integrated visual system.

Nature provides a multitude of examples of multifunctional structural materials in which trade-offs are imposed by conflicting functional requirements. One such example is the biomineralized armor of the chiton Acanthopleura granulata, which incorporates an integrated sensory system that includes hundreds of eyes with aragonite-based lenses. We use optical experiments to demonstrate that these microscopic lenses are able to form images. Light scattering by the polycrystalline lenses is minimized by the use of relatively large, crystallographically aligned grains. Multiscale mechanical testing reveals that as the size, complexity, and functionality of the integrated sensory elements increase, the local mechanical performance of the armor decreases. However, A. granulata has evolved several strategies to compensate for its mechanical vulnerabilities to form a multipurpose system with co-optimized optical and structural functions.

Morphometric structural diversity of a natural armor assembly investigated by 2D continuum strain analysis.

Many armored fish scale assemblies use geometric heterogeneity of subunits as a design parameter to provide tailored biomechanical flexibility while maintaining protection from external penetrative threats. This study analyzes the spatially varying shape of individual ganoid scales as a structural element in a biological system, the exoskeleton of the armored fish Polypterus senegalus (bichir). X-ray microcomputed tomography is used to generate digital 3D reconstructions of the mineralized scales. Landmark-based geometric morphometrics is used to measure the geometric variation among scales and to define a set of geometric parameters to describe shape variation. A formalism using continuum mechanical strain analysis is developed to quantify the spatial geometry change of the scales and illustrate the mechanisms of shape morphing between scales. Five scale geometry variants are defined (average, anterior, tail, ventral, and pectoral fin) and their functional implications are discussed in terms of the interscale mobility mechanisms that enable flexibility within the exoskeleton. The results suggest that shape variation in materials design, inspired by structural biological materials, can allow for tunable behavior in flexible composites made of segmented scale assemblies to achieve enhanced user mobility, custom fit, and flexibility around joints for a variety of protective applications.

Biomechanics. Mechanistic origins of bombardier beetle (Brachinini) explosion-induced defensive spray pulsation.

Bombardier beetles (Brachinini) use a rapid series of discrete explosions inside their pygidial gland reaction chambers to produce a hot, pulsed, quinone-based defensive spray. The mechanism of brachinines' spray pulsation was explored using anatomical studies and direct observation of explosions inside living beetles using synchrotron x-ray imaging. Quantification of the dynamics of vapor inside the reaction chamber indicates that spray pulsation is controlled by specialized, contiguous cuticular structures located at the junction between the reservoir (reactant) and reaction chambers. Kinematics models suggest passive mediation of spray pulsation by mechanical feedback from the explosion, causing displacement of these structures.

Biomechanical properties of murine meniscus surface via AFM-based nanoindentation.

This study aimed to quantify the biomechanical properties of murine meniscus surface. Atomic force microscopy (AFM)-based nanoindentation was performed on the central region, proximal side of menisci from 6- to 24-week old male C57BL/6 mice using microspherical tips (Rtip≈5µm) in PBS. A unique, linear correlation between indentation depth, D, and response force, F, was found on menisci from all age groups. This non-Hertzian behavior is likely due to the dominance of tensile resistance by the collagen fibril bundles on meniscus surface that are mostly aligned along the circumferential direction. The indentation resistance was calculated as both the effective modulus, Eind, via the isotropic Hertz model, and the effective stiffness, Sind = dF/dD. Values of Sind and Eind were found to depend on indentation rate, suggesting the existence of poro-viscoelasticity. These values do not significantly vary with anatomical sites, lateral versus medial compartments, or mouse age. In addition, Eind of meniscus surface (e.g., 6.1±0.8MPa for 12 weeks of age, mean±SEM, n=13) was found to be significantly higher than those of meniscus surfaces in other species, and of murine articular cartilage surface (1.4±0.1MPa, n=6). In summary, these results provided the first direct mechanical knowledge of murine knee meniscus tissues. We expect this understanding to serve as a mechanics-based benchmark for further probing the developmental biology and osteoarthritis symptoms of meniscus in various murine models.