Simulated versus physical bench tests: The economic evaluation of the InSilc platform for designing, developing, and assessing vascular scaffolds.

BACKGROUND: In silico medicine allows for pre-clinical and clinical simulated assessment of medical technologies and the building of patient-specific models to support medical decisions and forecast personal health status. While there is increasing trust in the potential central role of in silico medicine, there is a need to recognize its degree of reliability and evaluate its economic impact. An in silico platform has been developed within a Horizon 2020-funded project (In-Silc) for simulations functional to designing, developing, and assessing drug-eluting bioresorbable vascular scaffolds.The main purpose of this study was to compare the costs of 2 alternative strategies: the adoption of In-Silc platform versus the performance of only physical bench tests. METHODS: A case study was provided by a medical device company. The values of the model parameters were principally set by the project partners, with use of interviews and semi-structured questionnaires, and, when not available, through literature searches or derived by statistical techniques. An economic model was built to represent the 2 scenarios. RESULTS: The InSilc strategy is superior to the adoption of physical bench tests only. Ceteris paribus, the costs are 424,355€ for the former versus 857,811€ for the latter. CONCLUSIONS: In silico medicine tools can decrease the cost of the research and development of medical devices such as bioresorbable vascular scaffolds. Further studies are needed to explore the impact of such solutions on the innovation capacity of companies and the consequent potential advantages for target patients and the healthcare system.

Design, optimisation and testing of a compact, inexpensive elastic element for series elastic actuators.

This paper presents the development of a compact torsion spring for use as an elastic element in a lightweight series elastic actuator for an active orthosis. This orthosis is going to be utilised as an assistive device for motorically impaired stroke-patients. In the design a two-step optimisation strategy was implemented to meet all requirements for the torsion spring. The first step was to identify a promising topology for the element. In the second step, the shape was optimised based on a finite element model using two different optimisation methods in order to minimise the von Mises equivalent stresses. Four promising variants of the identified topology were extracted from these calculations, one of which was then chosen as the final design. A prototype was manufactured by a laser cutting process, which is a new procedure in the context of elastic elements for series elastic actuators. The calculation results were validated successfully by measurement of the spring properties of this prototype.

An experimental approach to determining fatigue crack size in polyethylene tibial inserts.

A major limiting factor to the longevity of prosthetic knee joints is fatigue crack damage of the polyethylene tibial insert. Existing methods to quantify fatigue crack damage have several shortcomings, including limited resolution, destructive testing approach, and high cost. We propose an alternative fatigue crack damage visualization and measurement method that addresses the shortcomings of existing methods. This new method is based on trans-illumination and differs from previously described methods in its ability to non-destructively measure subsurface fatigue crack damage while using a simple and cost-effective bench-top set-up. We have evaluated this method to measure fatigue crack damage in two tibial inserts. This new method improves on existing image-based techniques due to its usability for subsurface damage measurement and its decreased reliance on subjective damage identification and measurement.

Unconstrained testing of spine with bi-axial universal testing machine.

BACKGROUND: In-vitro biomechanical assessment of the spine reveals significant information on the mechanics of spinal disorders, treatment methods, and surgical implants. Specialized devices for the evaluation of spine biomechanics have thus become popular. However, these devices might not be affordable for all research groups. PURPOSE: The purpose of this study was to describe an apparatus to be attached to a standard bi-axial universal testing machine that would make unconstrained testing of the spine possible. STUDY DESIGN/SETTING: A technical note on the definition of a spinal testing fixture with validation. METHODS: Intact lumbosacral spines (T12-S1) were tested in sagittal and lateral bending and axial rotation. Three-dimensional interlevel rotations at each level (L1-4) were analyzed. RESULTS: By comparison with the literature, we found that the new fixture was able to successfully produce reasonable relative rotation values for the lumbar spine. CONCLUSIONS: We demonstrated that the low cost fixture allowed unconstrained (six degree of freedom, 6 DOF) testing of fresh-frozen cadaveric lumbar spine.

A new approach to determine ligament strain using polydimethylsiloxane strain gauges: exemplary measurements of the anterolateral ligament.

A thorough understanding of ligament strains and behavior is necessary to create biomechanical models, comprehend trauma mechanisms, and surgically reconstruct those ligaments in a manner that restores a physiological performance. Measurement techniques and sensors are needed to conduct this data with high accuracy in an in vitro environment. In this work, we present a novel sensor device that is capable of continuously recording ligament strains with high resolution. The sensor principle of this biocompatible strain gauge may be used for in vitro measurements and can easily be applied to any ligament in the human body. The recently rediscovered anterolateral ligament (ALL) of the knee joint was chosen to display the capability of this novel sensor system. Three cadaver knees were tested to successfully demonstrate the concept of the sensor device and display first results regarding the elongation of the ALL during flexion/extension of the knee.

Evaluation of hydrogels for bio-printing applications.

In the United States alone, there are approximately 500,000 burn injuries that require medical treatment every year. Limitations of current treatments necessitate the development of new methods that can be applied quicker, result in faster wound regeneration, and yield skin that is cosmetically similar to undamaged skin. The development of new hydrogel biomaterials and bioprinting deposition technologies has provided a platform to address this need. Herein we evaluated characteristics of twelve hydrogels to determine their suitability for bioprinting applications. We chose hydrogels that are either commercially available, or are commonly used for research purposes. We evaluated specific hydrogel properties relevant to bioprinting applications, specifically; gelation time, swelling or contraction, stability, biocompatibility and printability. Further, we described regulatory, commercial and financial aspects of each of the hydrogels. While many of the hydrogels screened may exhibit characteristics suitable for other applications, UV-crosslinked Extracel, a hyaluronic acid-based hydrogel, had many of the desired properties for our bioprinting application. Taken together with commercial availability, shelf life, potential for regulatory approval and ease of use, these materials hold the potential to be further developed into fast and effective wound healing treatments.

Wound dressing absorption: a comparative study.

The purpose of this study was to compare absorption properties of a variety of wound dressing products that are available on the market. A simple, inexpensive method of evaluation was utilized so that new dressings could easily be tested and added to the data set.

A novel, inexpensive and easy to use tendon clamp for in vitro biomechanical testing.

Frozen clamps can hold tendons and ligaments tightly and transmit high loads, from 4 kN to 13 kN, without slippage, yet they are complex and expensive. The existing non-frozen serrated jaw clamp is simple to fabricate and use, but the maximal tensile force it can sustain is only about 2.5 kN, which is not enough in many biomechanical tests. In this study, a new type of non-frozen clamp, which has lateral block boards and asymmetrical teeth jaws, was designed. The lateral block boards made of titanium alloy were used to prevent the soft tissues from being squeezed out during compressing, while the asymmetrical teeth jaws made of nylon were used to grip and keep holding soft tissues. The capability of this new type of clamp was tested by stretching five cattle tendons to failure on the tensile and compression testing machine, none of them displayed any slippage before rupture, the maximum tension force was 6.87 kN. This non-frozen asymmetrical teeth jaw clamp was designed for gripping tendons in foot and ankle dynamic simulation test, but it can also be applied to other in vitro tests, such as hip and knee dynamic tests.

Development of a cost-effective torsional unit for rodent long bone assessment.

Thorough mechanical testing of rodent bones requires an understanding of bone behavior in a variety of loading modes including tension, compression, bending and shear. While these tests are easily conducted with single axis mechanical testing machines, it may also be desirable to determine torsional properties of bone. Although higher-end materials testing machines will enable torsional and/or rotational testing, simpler, less expensive systems rarely offer these capabilities. In this work, we illustrate the development of a torsional system that uses a simple rack and pinion concept to deliver a rotary motion to bones given the linear motion of a testing machine. As the bone field becomes increasingly interdisciplinary, more biologists and non-test engineers need cost-effective mechanical testing capabilities and the torsional system described here has proven to be more than adequate for standard biomechanical testing requirements. Furthermore, given the small-scale size of rodent long bones, a series of potting/testing fixtures were developed that enabled preparation and handling of the specimens without incurring damage to the bone shafts. Once fabricated the system was used to destructively load mice humeri and femurs and quantify torsional properties.

Enhancement of tensile strength of lignocellulosic jute fibers by alkali-steam treatment.

The physico-chemical properties of jute fibers treated with alkali (NaOH) solution have been investigated in this study. The treatments were applied under ambient and elevated temperatures and high pressure steaming conditions. To the knowledge of these authors the influence of alkali-steam treatment on the uniaxial tensile strength of natural ligno-cellulosic fibers, such as jute, has not been investigated earlier. The results from this investigation indicate that a 30 min dipping of the fibers in 0.5% alkali solution followed by 30 min alkali-steam treatment leads to an increase in the tensile strength of up to 65%. The increase appears to be due to fiber separation and removal of non-cellulosic materials, which, in turn, resulted in an increased crystallinity.

Tissue reaction to new scalp clips.

Animal testing was used to observe skin reaction to plastic hair clips. The results were similar to the reaction caused by standard Raney scalp clips, indicating that this hair clip may be a useful local alternative to imported scalp clips. Clinical trials confirmed the safety of this type of clip in a series of craniotomy procedures.

Product quality-based eco-efficiency applied to digital cameras.

When calculating eco-efficiency, there are considerable confusion and controversy about what the product value is and how it should be quantified. We have proposed here a quantification method for eco-efficiency that derives the ratio of the multiplication value of the product quality and the life span of a product to its whole environmental impact based on Life Cycle Assessment (LCA). In this study, product quality was used as the product value and quantified by the following three steps: (1) normalization based on a value function, (2) determination of the subjective weighting factors of the attributes, and (3) calculation of product quality of the chosen products. The applicability of the proposed method to an actual product was evaluated using digital cameras. The results show that the eco-efficiency values of products equipped with rechargeable batteries were higher than those products that use alkaline batteries, because of higher quality values and lower environmental impacts. The sensitivity analysis shows that the proposed method was superior to the existing methods, because it enables to identify the quality level of the chosen products by considering all products that have the same functions in the market and because, when adding a new product, the calculated quality values in the proposed method do not have to be changed.

Comparison of the ovine and porcine animal models for biocompatibility testing of vascular prostheses.

OBJECTIVE: Evaluation of the pig and sheep models for biocompatibility investigations of vascular prostheses (VP). DESIGN: Comparative analysis of animal experimental investigations involving two different animal models. MATERIALS AND METHODS: Commercially available polyester vascular prostheses (PET-VP) were implanted into two different animal models (infrarenal porcine aorta and ovine carotid artery). The costs, surgical handling, patency rate, and healing on the basis of macroscopic, microscopic, and immunohistochemical criteria were analyzed over a period of 3 months. RESULTS: Handling and operating times (63 +/- 10 versus 76 +/- 16 min; P = 0.125) did not differ significantly. The cost of the two animal models was comparable. Integration of the VP was complete in the sheep model, but varied in the pig model (two complete, four incomplete). Complete endothelialization of all VPs was observed in the pig, which contrasted with the sheep with complete (circular) endothelialization only in the region of the anastomosis. The thickness of neointima in the region of the anastomosis differed insignificantly; immunohistochemically, only periprosthetic Ki67 was significantly reduced (28.7 +/- 9.9 versus 6 +/- 0.9%; P = 0.002) in the sheep. CONCLUSIONS: In the porcine model, extremely good endothelialization of the VP was observed, with formation of a rapid neointimal hyperplasia. The ovine model was characterized by the fact that postoperative follow-up investigations were easy to perform. Complete endothelialization was not observed.

[A new method for small displacement test and measurement based on the light reflection theory].

A new idea for small displacement test and measurement system based on light reflection is presented in this paper. Some theoretical researches using the method and experiments in practice were carried out. The results proved that the theory is feasible and efficient. Compared with the traditional small displacement test and measurement system, such as mechanical displacement magnifier; resistance strain test and measurement method; piezoelectric material strain test and measurement system and so on, this method has the following advantages: it creates little disturbance of the test and measurement system; the displacement magnification coefficient is high and is convenient for user to adjust; the test and measurement precision is high and is very easy for its realization; and the cost is low. It fits a lot of test and measurement situations.

[Insulating polymeric film in comprehensive prevention of complications of mandibular fractures]. / Ispol'zovanie izoliruiushchei polimernoi plenki v kompleksnoi profilaktike vospalitel'nykh oslozhnenii perelomov nizhnei cheliusti.

A method for prevention of inflammatory complications of mandibular fractures making use of insulating polymer-based bioactive film was studied on 48 mice. Antibacterial and osteoregeneratory activities of the therapeutic film were assessed.

Inexpensive, semi-automated system for measuring mechanical properties of soft tissues.

Stiffness and strength are important properties of many tissues, but standard material-testing equipment is expensive, often ill-suited for testing soft tissues, and rarely accessible to biologists. We describe a system built around a microcomputer and an electronic balance which is particularly well-suited for measuring stress and strain in small samples of soft tissue. We use a discarded floppy disk drive as a linear actuator to strain the sample, while an electronic balance measures the tension (used to calculate stress). We give an algorithm for a program to drive a microcomputer which controls the floppy disk drive via its parallel port and records the balance measurements via its serial port. We used this system to obtain stress-strain curves from a sample of latex rubber and a sample of soft insect cuticle. Three tests of the rubber sample gave nearly identical results, with smooth, J-shaped stress-strain curves. The stress-strain curves gave a modulus elasticity value of 1.72 Mpa over the steep, straight region, well within the range for natural latex rubber. We also tested a sample of abdominal cuticle from a caterpillar (Manduca sexta). The caterpillar cuticle had a J-shaped stress-strain curve with a modulus of elasticity of 2.11 Mpa over the steep part of the curve. J. Exp. Zool. 284:374-378, 1999.