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Force plate testing is commonly used to assess athlete performance. However, there is limited research on the effect the surface underneath the force plate has on derived variables. The aim of this study was to investigate whether different surfaces underneath a force plate would elicit differences in derived force plate variables using a mechanical testing device. A device was used rather than human participants to ensure controlled and repeatable impacts. The device was used to assess force reduction, peak force, rate of force development (RFD) and contact time across seven common testing surfaces: vinyl, rubber, Olympic lifting platform, ground (CarpetG) and first floor (CarpetF) carpet, Mondo track and a sprung gymnasium floor (Sprung). Significant differences in force reduction, peak force, RFD, and contact time were found between flooring conditions (p < 0.05), with large to extremely large effect sizes. Sprung flooring exhibited the highest force reduction and lowest peak forces, while CarpetF demonstrated the lowest RFD and longest contact time. These findings highlight the flooring surface underneath the force plate during testing significantly influenced derived variables. Practitioners should exert caution and consideration to force plate testing location and advocate standardisation in flooring surface in order to ensure consistent and accurate results.

Quantifying the material properties of tissues and hydrogels aids in the development of biomedical applications through better understanding of the mechanics and mechanobiological principles at play. This study introduces a mechanical testing platform designed to address challenges in measuring mm-scale tissue and hydrogel material properties. Using a floating buoy design, the platform enables horizontal submerged tensile testing with non-submersible load cells. Buoy drag testing without a sample attached resulted in signal noise (mean ± standard deviation) of −1.6E-4 ± 2.8E-2 mN for stationary recording and 1.3E-2 ± 6.7E-2 mN for maximum buoy displacement speed (1000 µm/s), suggesting the magnitude of drag forces from buoy movement are negligible in comparison to the minimum resolution of force measurement. Validation testing with latex orthodontic bands showed a ∼ 28 × reduction in signal noise with the buoy approach compared to a previously used approach, and similar force displacement recordings using the buoy approach with 2 separate hardware systems. Simultaneous imaging enabled geometrical and microstructural analysis of the sample. Murine bladder tissue was mechanically tested using two different hardware systems and testing protocols. The platform was able to accurately capture the nonlinear stress-stretch response, alongside expected strain-softening and preconditioning behavior. Stress-relaxation testing yielded results consistent with expected microstructural and viscoelastic responses of mouse bladder tissue. The versatility of the platform underscores the potential for it to integrate with various force measurement and actuator-based systems. In conclusion, this platform offers a new avenue for accurate measurement of tissue and hydrogel mechanics, facilitating mm-scale soft material research.

Finite element analysis (FEA) for mandibular fracture fixation in craniomaxillofacial surgery remains promising but has been restricted due to the absence of an authenticated FEA model. This study aims to create an authenticated FEA model. This model was verified through a series of 3D printed mandible mechanical testing (3D-MMT) in a universal tensile machine using an indistinguishable set-up. Non-comminuted mandibular symphysis, parasymphysis, and angle fracture fixation stability were evaluated using a 2.0 mm 4-hole miniplate in three different plate configurations. Both FEA and 3D-MMT outcomes were reproducible and in agreement with the present understanding of stable mandibular fracture treatment. The results show favourable fracture stability with the dual plating, followed by the superior border, with the least stability observed in the inferior border plating. Furthermore, the FEA and the 3D-MMT outcomes were consistently similar, with a systematic 0.56 ± 0.12 mm total displacement difference (standard deviation). An excellent interclass relation coefficient (0.93, 95% confidence interval: 0.80–0.96) was found between the FEA model and the 3D-MMT mechanical test, indicating that both results were consistent with each other. The authenticated FEA can accurately study the recognised biomechanical behaviour of non-comminuted mandibular fractures and shows a potential application for complex fracture fixation analysis.

Virtual mechanical testing on image-based bone models (digital twins) provides subject-specific insights about the mechanical behavior of a bone during fracture healing. However, the established workflows for these tests are limited by reliance on commercial software and time-consuming manual procedures needed to create the digital twins. To overcome these barriers to clinical adoption and scalability, we have developed methods for user-independent and automated model generation. This study aimed to: (1) compare four competing methods for digital twin creation (two manual versus two automated approaches), (2) assess the influence of model-creation procedures and choice of material model (single- and dual-zone) on the virtual test results, and (3) evaluate the accuracy of the model-creation techniques through experimental validation of the results. Digital twins were generated from 59 CT scans (33 operated osteotomy fractures, 26 contralateral intact bones). Torsional rigidities were compared between modeling workflows and validated using postmortem physical mechanical test data. There were no significant differences in torsional rigidity between any of the four virtual testing groups and physical testing when a dual-zone material model was implemented for bone and callus. These results confirm that virtual mechanical testing is a reliable alternative to physical mechanical testing for assessing intact and healing long bones, with resilience to variations in digital twin creation methods. Automated model creation was substantially faster than the manual approaches, suggesting that automatic digital twin analysis is the pathway toward future clinical scalability.

Bone fractures commonly repair by forming a bridging structure called callus, which begins as soft tissue and gradually ossifies to restore rigidity to the bone. Virtual mechanical testing is a promising technique for image-based assessment of structural bone healing in both preclinical and clinical settings, but its accuracy depends on the validity of the material model used to assign tissue mechanical properties. The goal of this study was to develop a constitutive model for callus that captures the heterogeneity and biomechanical duality of the callus, which contains both soft tissue and woven bone. To achieve this, a large-scale optimization analysis was performed on 2363 variations of 3D finite element models derived from computed tomography (CT) scans of 33 osteotomized sheep under normal and delayed healing conditions. A piecewise material model was identified that produced high absolute agreement between virtual and physical tests by differentiating between soft and hard callus based on radiodensity. The results showed that the structural integrity of a healing long bone is conferred by an internal architecture of mineralized hard callus that is supported by interstitial soft tissue. These findings suggest that with appropriate material modeling, virtual mechanical testing is a reliable surrogate for physical biomechanical testing.

Measuring interface pressure is currently used in a variety of settings, e.g., automotive or clinical, to evaluate pressure distribution at support surface interfaces. Commercial pressure sensing arrays are employed to monitor and visualise these pressure distributions to aid mattress or cushion selection by assessing their ability to redistribute the pressure magnitudes over vulnerable areas, e.g., the buttock. These technologies vary in configurations and measurement principles, with manufacturers supplying calibration and specifications. This study evaluated the performance of six commercial pressure sensing arrays, which differed in sensor type, configuration, and spatial resolution. Each system was subjected to mechanical compression loading on a standard cushion using a dual hemispherical ‘buttock shaped’ standard indenter. Pressure parameters were estimated, e.g., contact area, peak pressure index, from the sensing arrays and a comparison between measured and predicted pressure values was performed. The results showed that both contact area and pressures are influenced by the spatial resolution, with higher values associated with systems with the highest resolution. A high variability between systems was observed in the measured pressure, with sensor type driving difference between the observed and the predicted pressures. Further research is needed to establish standards and performance analysis of these technologies.

Companies developing automated driving system (ADS) technologies have spent heavily in recent years to conduct live testing of autonomous vehicles operating in real world environments to ensure their reliable and safe operations. However, the unexpected onset and ongoing resurgent effects of the Covid-19 pandemic starting in March 2020 has serve to halt, change, or delay the achievement of these new product development test objectives. This study draws on data obtained from the California automated vehicle test program to determine the extent that testing trends, test resumptions, and test environments have been affected by the pandemic. The importance of government policies to support and enable autonomous vehicles development during pandemic conditions is highlighted.

Background Acute tendon cut represents a great challenge both in human and veterinary medical practice. The current study aimed to compare the ultimate biomechanical properties (tensile strength, elongation, stress load, yield load and break load) of double strand, braided and knitted polyethylene suture in an ex vivo model of acute transverse section of the Achilles tendon in dog model using locking loop suture and three-loop pulley suture. Methods A-thirty-six Achilles tendon was transected from 18 dog cadavers. Tendon samples were randomly allocated (6 tendons/group) to be sutured either by double strand, braided and novel knitted formation techniques from polyethylene suture using either three-loop pulley suture or locking loop suture patterns. Biomechanical testing of different yarn for tensile strength, elongation, stress, yield load, break load was performed. Results Braided polyethylene sutures demonstrated superior biomechanical properties, showing the highest maximum tension, load, stress, and yield load, while knitted sutures exhibited the greatest strain and elongation due to their looped structure. Despite the knitted yarn’s high elongation, its tensile strength and load-bearing capabilities were significantly lower. Overall, yarn formation had a greater influence on biomechanical performance in association with suturing technique. The three-loop pulley suturing demonstrated significantly improved suturing outcomes. Conclusion Both novel knitted, and braided suture structure demonstrated improved biomechanical properties of tendon suturing by increasing the number of strands within the tendon, simplifying the suturing process, reducing the needle passes, and minimizing tendon punctures that may interfere with healing and the overall strength. Suturing technique had a major influence on the biomechanical properties where the three-loop pulley suture demonstrated superior biomechanical properties compared to locking loop suturing.

Background The displacement and rotation of the Kirschner wire (K-wire) in the traditional tension band wiring (TBW) led to a high rate of postoperative complications. The anti-rotation tension band wiring (ARTBW) could address these issues and achieve satisfactory clinical outcomes. This study aimed to investigate the biomechanical performance of the ARTBW in treating transverse patellar fracture compared to traditional TBW using finite element analysis (FEA) and mechanical testing. Methods We conducted a FEA to evaluate the biomechanical performance of traditional TBW and ARTBW at knee flexion angles of 20°, 45°, and 90°. Furthermore, we compared the mechanical properties under a 45° knee flexion through static tensile tests and dynamic fatigue testing. The K-wire pull-out test was also conducted to evaluate the bonding strength between K-wires and cancellous bone of two surgical approaches. Results The outcome of FEA demonstrated the compression force on the articular surface of ARTBW was 28.11%, 27.32%, and 52.86% higher than traditional TBW at knee flexion angles of 20°, 45°, and 90°, respectively. In mechanical testing, the mechanical properties of ARTBW were similar to the traditional TBW. In the K-wire pull-out test, the pull-out strength of ARTBW was significantly greater than the traditional TBW (111.58 ± 2.38 N vs. 64.71 ± 4.22 N, P  < 0.001). Conclusions The ARTBW retained the advantages of traditional TBW, and achieved greater compression force of articular surface, and greater pull-out strength of K-wires. Moreover, ARTBW effectively avoided the rotation of the K-wires. Therefore, ARTBW demonstrates potential as a promising technique for treating patellar fractures.

Background A new plate for the treatment of Pauwels type III femoral neck fractures was developed, and its biomechanical stability was analyzed by the finite element method. Method Using 3-matic and UG-NX software, we constructed models of Pauwels type III femoral neck fractures with angles of 50°, 60°, and 70°. Moreover, a new femoral neck plate (NFNP) fixation model and a Pauwels screw fixation model were developed. Under axial loads of 1400 N and 2100 N, von Mises stress (VMS) distribution on the screws, peak VMS, displacement between fracture fragments, and model principal strains in cancellous bone were recorded. Result The peak VMS of internal fixation in the two models was mostly located near the fracture line, and the screw closest to the femoral calcar experienced maximum stress. With a Pauwels angle of 50°, 60°, and 70°, the peak VMS values of the new plates were lower than in the Pauwels screw. The displacement of fracture fragments in the NFNP was smaller than in the Pauwels screw, and peak VMS values of cancellous bone in the NFNP were lower than in the Pauwels screw. Conclusion The newly developed plate provided excellent biomechanical stability for Pauwels type III femoral neck fractures.