Biological Activities of Citrus-Derived Extracellular Vesicles on Human Cells: The Role of Preservation.

Extracellular vesicles (EVs) have been identified as important mediators for cell-to-cell communication. Citrus-based EVs in particular offer an excellent platform for nutraceutical delivery systems, as their endemic cargo includes micronutrients (e.g., ascorbic acid), which contribute to their antioxidant capacity. Despite being extensively investigated as to their therapeutic and diagnostic potential, their cargo is inherently unstable and thus directly affected by their storage and preservation. In this study, EVs were isolated from citrus fruit using tangential flow filtration and evaluated for their physicochemical characteristics, antioxidant activity and effects on human cells. To assess how their isolation and preservation methods affect these properties, the EVs were tested immediately after isolation (from fresh and freeze-thawed juices) or following freeze-drying. A measurable biological effect of cryoprotection on citrus-derived EVs was evident, whether during or after isolation. This was more pronounced in the cell-based assays, ranging from -4% to +32% in human skin fibroblast proliferation. Nevertheless, the effects on human cancer cells varied depending on the cell line. Although these results should be considered preliminary observations, subject to further investigation, it is safe to state that any type of preservation is expected to impact the EVs' biological activity.

Antibacterial Activity of Copper Nanoparticles against Xanthomonas campestris pv. vesicatoria in Tomato Plants.

Copper-based bactericides have appeared as a new tool in crop protection and offer an effective solution to combat bacterial resistance. In this work, two copper nanoparticle products that were previously synthesized and evaluated against major bacterial and fungal pathogens were tested on their ability to control the bacterial spot disease of tomato. Growth of Xanthomonas campestris pv. vesicatoria, the causal agent of the disease, was significantly suppressed by both nanoparticles, which had superior function compared to conventional commercial formulations of copper. X-ray fluorescence spectrometry measurements in tomato leaves revealed that bioavailability of copper is superior in the case of nanoparticles compared to conventional formulations and is dependent on synthesis rather than size. This is the first report correlating bioavailability of copper to nanoparticle efficacy.

Plant-Derived Extracellular Vesicles as Therapeutic Nanocarriers.

Mammalian exosomes have emerged as a promising class of functional materials, inspiring novel applications as therapeutic vehicles and nutraceutical compounds. Despite this, their immunogenicity has been an issue of controversy within the scientific community. Although, exosome-like vesicles, innately formed in plants and inherent to eukaryotic cell-derived vesicles, could soothe most of the concerns, they are notably underutilized as therapeutic modalities. This review highlights all efforts published so far, on the use of plant-derived extracellular vesicles (EVs) as therapeutic delivery systems. A summary of the physicochemical characteristics of plant-derived EVs is provided along with their main biological composition and in vitro/in vivo evidence of their therapeutic efficacy provided where available. Despite only a hand full of clinical trials being underway, concerning these vesicles, they arguably possess significant potential as nanodelivery systems of natural origin.

Notch Signaling Pathway in Tooth Shape Variations throughout Evolution.

Evolutionary changes in vertebrates are linked to genetic alterations that often affect tooth crown shape, which is a criterion of speciation events. The Notch pathway is highly conserved between species and controls morphogenetic processes in most developing organs, including teeth. Epithelial loss of the Notch-ligand Jagged1 in developing mouse molars affects the location, size and interconnections of their cusps that lead to minor tooth crown shape modifications convergent to those observed along Muridae evolution. RNA sequencing analysis revealed that these alterations are due to the modulation of more than 2000 genes and that Notch signaling is a hub for significant morphogenetic networks, such as Wnts and Fibroblast Growth Factors. The modeling of these tooth crown changes in mutant mice, via a three-dimensional metamorphosis approach, allowed prediction of how Jagged1-associated mutations in humans could affect the morphology of their teeth. These results shed new light on Notch/Jagged1-mediated signaling as one of the crucial components for dental variations in evolution.

A finite element model technique to determine the mechanical response of a lumbar spine segment under complex loads.

This study presents a CT-based finite element model of the lumbar spine taking into account all function-related boundary conditions, such as anisotropy of mechanical properties, ligaments, contact elements, mesh size, etc. Through advanced mesh generation and employment of compound elements, the developed model is capable of assessing the mechanical response of the examined spine segment for complex loading conditions, thus providing valuable insight on stress development within the model and allowing the prediction of critical loading scenarios. The model was validated through a comparison of the calculated force-induced inclination/deformation and a correlation of these data to experimental values. The mechanical response of the examined functional spine segment was evaluated, and the effect of the loading scenario determined for both vertebral bodies as well as the connecting intervertebral disc.

Posterior spinal stabilization: A biomechanical comparison of Laminar Hook Fusion to a Pedicle Screw System.

BACKGROUND: Several spine instrumentation techniques have been introduced to correct inter-segmental alignment, or provide long-term stability. Whilst pedicle screws are considered the intervention of reference, we hypothesize that the week hold of osteoporotic bone, might be a clinical indicator for an alternative surgical approach. METHODS: To put this to the test, a non-linear Finite Element model, of a ligamentous lumbosacral spine, was employed to examine a stabilization spanning over L3-L5. Two different immobilization techniques (a Pedicle Screw System and Laminar Hook Fusion) are compared as to their biomechanical response during 7.5 Nm flexion, lateral flexion and torsion, while considering a 280 N follower load. Fifteen analyses performed in total, simulating patients of healthy and osteoporotic Bone Mineral Density. FINDINGS: Range of Motion was significantly reduced after instrumentation for both implant systems. This trend was more pronounced in the Pedicle Screw models, which were stressed to a higher degree. To evaluate implant loosening risk, we introduce the consideration of strain energy patterns around the screw tract. The notably higher intensity of these, for the osteoporotic model, taken into consideration with the weaker strength of the tissue and inconsistencies in the stress allocation between implant and bone, affirmed an increased risk for loosening of the Pedicle Screws in osteoporotic patients. INTERPRETATION: The analysis provided refined insight as to the treatment of osteoporotic patients as well as to their postoperative care, as restriction of specific movements (e.g. through bracing), could significantly restrict the stress values in the bone-implant interface and thus, reduce implant failure.

A finite element model of an osteoblast to quantify the transduction of exogenous forces to cellular components.

Encouraged by recent advances of biophysical and biochemical assays we introduce a 3D finite element model of an osteoblast, seeking an analogue between exogenous forces and intracellularly activated sensory mechanisms. The cell was reverse engineered and the dimensions of the internal cellular structures were based on literature data. The model was verified and validated against atomic force microscopy experiments and four loading scenarios were considered. The stress distributions developing on the main cellular components were calculated along with their corresponding strain values. The nucleus and mitochondria exhibited similar loading trends, with the mitochondria being stressed by an order of magnitude higher than the nucleus (e.g. 1.4 vs. 0.16 MPa). Equivalent stiffness was determined to increase by almost 50%, from the apex to the cell's periphery, as was the cell's elasticity, which was lowest when the load was exerted directly above the nucleus. The assessment of how extrinsic loads are propagated to a cell's internal structures is inherently a problem of high complexity. The findings presented in this study can provide important insight into biophysical and biochemical responses elicited in cells through mechanical stimulus. This was evident in both the nuclear and mitochondrial loading and would stipulate the important contribution of even more accurate models in the interpretation of cellular events. One Sentence Summary: The results of this numerical biomechanical study demonstrated that even minor extrinsic loads irrespective of the application site, are transduced by a fraction of the cytoskeleton to its internal structure (primarily to its mitochondria and secondary to the cell's nucleus), indicating mechanical stimulus as the dominant pathway to cell expression.

Antibacterial Effect of Colloidal Suspensions Varying in Silver Nanoparticles and Ions Concentrations.

A lot of effort has been dedicated recently to provide a better insight into the mechanism of the antibacterial activity of silver nanoparticles (AgNPs) colloidal suspensions and their released silver ionic counterparts. However, there is no consistency regarding whether the antibacterial effect displayed at cellular level originates from the AgNPs or their ionic constitutes. To address this issue, three colloidal suspensions exhibiting different ratios of AgNPs/silver ions were synthesized by a wet chemistry method in conjunction with tangential flow filtration, and were characterized and evaluated for their antimicrobial properties against two gram-negative, Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), and two gram-positive, Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis), bacterial strains. The produced samples contained 25% AgNPs and 75% Ag ions (AgNP_25), 50% AgNPs and 50% Ag ions (AgNP_50), and 100% AgNPs (AgNP_100). The sample AgNP_100 demonstrated the lowest minimum inhibitory concentration values ranging from 4.6 to 15.6 ppm for all four bacterial strains, while all three samples indicated minimum bactericidal concentration (MBC) values ranging from 16.6 ppm to 62.5 ppm against all strains. An increase in silver ions content results in higher bactericidal activity. All three samples were found to lead to a significant morphological damage by disruption of the bacterial cell membranes as analyzed by means of scanning electron microscopy (SEM). The growth kinetics demonstrated that all three samples were able to reduce the bacterial population at a concentration of 3.1 ppm. SEM and growth kinetic data underline that S. epidermidis is the most sensitive among all strains against the investigated samples. Our results showed that all three AgNPs colloidal suspensions exhibited strong antibacterial properties and, thus, they can be applied in medical devices and antimicrobial control systems.

Synthesis and Characterization of Novel Copper Nanoparticles for the Control of Leaf Spot and Anthracnose Diseases of Olive.

Olive crop is frequently treated with copper fungicides to combat foliar and fruit diseases such as olive leaf spot caused by Fusicladium oleagineum and anthracnose caused by Colletotrichum spp. The replacement of copper-based products with more eco-friendly alternatives is a priority. Metal nanoparticles synthesized in several ways have recently revolutionized crop protection with applications against important crop pathogens. In this study, we present the development of four copper-based nanoparticles (CuNP Type 1 to 4) synthesized with a wet chemistry approach. The CuNPs were characterized using Transmission Electron Microscopy, Dynamic Light Scattering, Laser Doppler Electrophoresis, and Attenuated Total Reflection measurements. In addition, the activity of the four CuNP types was tested in vitro and in planta against F. oleagineum and Colletotrichum spp. In vitro sensitivity measurements showed that for both pathogens, mycelial growth was the most susceptible developmental stage to the tested compounds. Against both pathogens, CuNP Type 1 and Type 2 were found to be more active in reducing mycelial growth compared to the reference commercial compounds of copper oxide and copper hydroxide. In planta experiments showed that CuNP Type 3 and CuNP Type 4 exhibited a strong protectant activity against both F. oleagineum and Colletotrichum acutatum with control efficacy values significantly higher than those achieved by the applications of either reference product.

Bactericides Based on Copper Nanoparticles Restrain Growth of Important Plant Pathogens.

Copper nanoparticles (CuNPs) can offer an alternative to conventional copper bactericides and possibly slow down the development of bacterial resistance. This will consequently lower the accumulation rate of copper to soil and water and lower the environmental and health burden imposed by copper application. Physical and chemical methods have been reported to synthesize CuNPs but their use as bactericides in plants has been understudied. In this study, two different CuNPs products have been developed, CuNP1 and CuNP2 in two respective concentrations (1500 ppm or 300 ppm). Both products were characterized using Dynamic Light Scattering, Transmission Electron Microscopy, Attenuated Total Reflection measurements, X-ray Photoelectron Spectroscopy, X-ray Diffraction and Scattering, and Laser Doppler Electrophoresis. They were evaluated for their antibacterial efficacy in vitro against the gram-negative species Agrobacterium tumefaciens, Dickeya dadantii, Erwinia amylovora, Pectobacterium carotovorum, Pseudomonas corrugata, Pseudomonas savastanoi pv. savastanoi, and Xanthomonas campestris pv. campestris. Evaluation was based on comparisons with two commercial bactericides: Kocide (copper hydroxide) and Nordox (copper oxide). CuNP1 inhibited the growth of five species, restrained the growth of P. corrugata, and had no effect in X. c. pv campestris. MICs were significantly lower than those of the commercial formulations. CuNP2 inhibited the growth of E. amylovora and restrained growth of P. s. pv. savastanoi. Again, its overall activity was higher compared to commercial formulations. An extensive in vitro evaluation of CuNPs that show higher potential compared to their conventional counterpart is reported for the first time and suggests that synthesis of stable CuNPs can lead to the development of low-cost sustainable commercial products.

Gait-Specific Optimization of Composite Footwear Midsole Systems, Facilitated through Dynamic Finite Element Modelling.

OBJECTIVE: During the last century, running shoes have been subject to drastic changes with incremental however improvements as to injury prevention. This may be, among others, due to the limited insight that experimental methodologies can provide on their 3D in situ response. The objective of this study was to demonstrate the effectiveness of finite element (FE) modelling techniques, in optimizing a midsole system as to the provided cushioning capacity. METHODS: A commercial running shoe was scanned by means of micro computed tomography and its gel-based midsole, reverse-engineered to a 200 µm accuracy. The resulting 3D model was subjected to biorealistic loading and boundary conditions, in terms of time-varying plantar pressure distribution and shoe-ground contact constraints. The mesh grid of the FE model was verified as to its conceptual soundness and validated against velocity-driven impact tests. Nonlinear material properties were assigned to all entities and the model subjected to a dynamic FE analysis. An optimization function (based on energy absorption criteria) was employed to determine the optimum gel volume and position, as to accommodate sequential cushioning in the rear-, mid-, and forefoot, of runner during stance phase. RESULTS: The in situ developing stress fields suggest that the shock dissipating properties of the midsole could be significantly improved. Altering the position of the gel pads and varying their volume led to different midsole responses that could be tuned more efficiently to the specific strike and pronation pattern. CONCLUSIONS: The results suggest that midsole design can be significantly improved through biorealistic FE modelling, thus providing a new platform for the conceptual redesign and/or optimization of modern footwear.

A Bio-Realistic Finite Element Model to Evaluate the Effect of Masticatory Loadings on Mouse Mandible-Related Tissues.

Mice are arguably the dominant model organisms for studies investigating the effect of genetic traits on the pathways to mammalian skull and teeth development, thus being integral in exploring craniofacial and dental evolution. The aim of this study is to analyse the functional significance of masticatory loads on the mouse mandible and identify critical stress accumulations that could trigger phenotypic and/or growth alterations in mandible-related structures. To achieve this, a 3D model of mouse skulls was reconstructed based on Micro Computed Tomography measurements. Upon segmenting the main hard tissue components of the mandible such as incisors, molars and alveolar bone, boundary conditions were assigned on the basis of the masticatory muscle architecture. The model was subjected to four loading scenarios simulating different feeding ecologies according to the hard or soft type of food and chewing or gnawing biting movement. Chewing and gnawing resulted in varying loading patterns, with biting type exerting a dominant effect on the stress variations experienced by the mandible and loading intensity correlating linearly to the stress increase. The simulation provided refined insight on the mechanobiology of the mouse mandible, indicating that food consistency could influence micro evolutionary divergence patterns in mandible shape of rodents.

New Ti-Alloys and Surface Modifications to Improve the Mechanical Properties and the Biological Response to Orthopedic and Dental Implants: A Review.

Titanium implants are widely used in the orthopedic and dentistry fields for many decades, for joint arthroplasties, spinal and maxillofacial reconstructions, and dental prostheses. However, despite the quite satisfactory survival rates failures still exist. New Ti-alloys and surface treatments have been developed, in an attempt to overcome those failures. This review provides information about new Ti-alloys that provide better mechanical properties to the implants, such as superelasticity, mechanical strength, and corrosion resistance. Furthermore, in vitro and in vivo studies, which investigate the biocompatibility and cytotoxicity of these new biomaterials, are introduced. In addition, data regarding the bioactivity of new surface treatments and surface topographies on Ti-implants is provided. The aim of this paper is to discuss the current trends, advantages, and disadvantages of new titanium-based biomaterials, fabricated to enhance the quality of life of many patients around the world.

The Influence of Bone Quality on the Biomechanical Behavior of a Tooth-Implant Fixed Partial Denture: A Three-Dimensional Finite Element Analysis.

PURPOSE: The purpose of this study was to evaluate whether or not bone quality has an effect on the biomechanical behavior of a tooth connected to an implant, when a rigid and a nonrigid attachment are used. MATERIALS AND METHODS: Models of fixed partial dentures supported by a tooth and an implant were developed. These models were then imported into finite element analysis software to study the impact of forces on different types of attachments (rigid vs nonrigid) and bones (types 1 to 4). Each fixed partial denture was subjected to a vertical load of 200 N on the premolars and 230 N on the molar. The materials were considered linear, isotropic, and homogenous. Eight different scenarios were tested. The von Mises criterion was used to display the stress in five structures: fastening screw, implant, attachment, cortical, and trabecular bone. The displacements of the tooth and the implant were also examined. RESULTS: The calculated maximum observed stress values differed among the simulated scenarios. The biggest values of stress concentrations were observed at the lingual cervical areas, the implant-cortical bone interface, the implant-crown interface, the butt-joint contact of the implant-abutment screw, and the apical parts of the tooth and implant. The main difference between the rigid and nonrigid connection was observed between the natural tooth retainer and the pontic. In the rigid connection, the movement of the natural tooth retainer was smooth. In the nonrigid connection, the attachment exhibited a partial buccal displacement. Von Mises stresses among the different tested structures ranged between 24 and 840 MPa. CONCLUSION: The quality of the bone and the rigidity of the connection between a natural tooth and an implant influence both the generated stresses and the displacement of the tooth and the implant. The highest stresses for the implant-trabecular bone interface, the neck of the implant, and the fastening screw were observed in type 3 bone when a rigid connection was used. The lowest stresses for the implant-cortical bone interface, the neck of the implant, and the connector were registered in type 1 bone, when a rigid connection was used. The smallest tooth and implant displacement was observed in type 1 bone, when a rigid connection was used, while the biggest tooth and implant displacement was registered in type 4 bone when a nonrigid connection was used.

The effect of pedicle screw implantation depth and angle on the loading and stiffness of a spinal fusion assembly.

BACKGROUND: The increasing prevalence of spine disorders in industrialized environments has impaired the quality of life in the elder population. In an effort to relieve pain, physicians strive to improve treatment through the consideration of patient specific characteristics during preoperative planning of procedures such as spinal fusion. OBJECTIVE: This study aims at quantifying aspects of spondylodesis to the loading and mobility of the utilized instrumentation, as the use of rigid vs. motion sparing materials as well as implantation angle and depth of the pedicle screws are still subject to controversy among surgeons. METHODS: A fixation assembly was reverse engineered based on µCT measurements of the involved instrumentation. Two pedicle screws were connected with a rod, thus representing a mono-segmental fixation device. The pedicle screws were embedded in hexahedral structures simulated by bone properties. Upon validation and verification, the response of the model to a compressive and a torsional load was simulated in ANSYS 14, while altering the implantation depth and insertion angle of the pedicle screws along with the rod material. RESULTS: The mobility of the instrumentation was drastically increased (by up to 390%) when PEEK rods were used in place of traditional Ti ones, a tendency observed at varying extent for all simulated scenarios. Shallow implantation induced a slight stress increase (∼21%) on the implant and a notable distressing of the bony tissue (∼44%), whereas inclined screw positioning was overall beneficial to the developing stress fields in both, with bone profiting a max. stress release of ∼15% during the application of torsion. CONCLUSIONS: The investigation presented refined insight into the biomechanical response of a spinal fusion device. As expected, rigid fixation seems preferable in fusion oriented instrumentation whereas semi rigid devices should be employed for non-fusion applications. Shallow implantation resulted in a slight posterior offset of the stabilization device, which could be beneficial in the treatment of osteoporotic patients.

Anisotropic post-yield response of cancellous bone simulated by stress-strain curves of bulk equivalent structures.

During the last decade, finite element (FE) modelling has become ubiquitous in understanding complex mechanobiological phenomena, e.g. bone-implant interactions. The extensive computational effort required to achieve biorealistic results when modelling the post-yield behaviour of microstructures like cancellous bone is a major limitation of these techniques. This study describes the anisotropic biomechanical response of cancellous bone through stress-strain curves of equivalent bulk geometries. A cancellous bone segment, reverse engineered by micro computed tomography, was subjected to uniaxial compression. The material's constitutive law, obtained by nano-indentations, was considered during the simulation of the experimental process. A homodimensionally bulk geometry was employed to determine equivalent properties, resulting in a similar anisotropic response to the trabecular structure. The experimental verification of our model sustained that the obtained stress-strain curves can adequately reflect the post-yield behaviour of the sample. The introduced approach facilitates the consideration of nonlinearity and anisotropy of the tissue, while reducing the geometrical complexity of the model to a minimum.

Assessment of stress patterns on a spinal motion segment in healthy versus osteoporotic bony models with or without disc degeneration: a finite element analysis.

BACKGROUND CONTEXT: With an increasing prevalence of low back pain, physicians strive to optimize the treatment of patients with degenerated motion segments. There exists a consensus in literature that osteoporotic patients exhibit nonphysiologic loading patterns, while degenerated intervertebral discs (IVDs) are also believed to alter spine biomechanics. PURPOSE: To evaluate alterations occurring in lumbosacral spine biomechanics of an osteoporotic model, with or without IVD degeneration, when compared with a healthy spine segment. STUDY DESIGN: The investigation was based on finite element (FE) analysis of a patient-specific lumbosacral spine model. METHODS: A biorealistic model of a lumbosacral spine segment is introduced to determine the morbidity of disc degeneration and osteoporosis. The model was verified and validated for the purpose of the study and subjected to a dynamic FE analysis, considering anisotropic bone properties and solid ligamentous tissue. RESULTS: The yielded results merit high clinical interest. Osteoporosis resulted in a nonuniform increase of facet joint loading, which was even more pronounced in the scenario simulating a degenerated disc. The results also revealed an enslavement of intradiscal pressure to the disc state (in the degenerated and superior adjacent level). CONCLUSIONS: The investigation presented refined insight into the dynamic biomechanical response of a degenerated spine segment. The increase in the calculated occurring stresses was considered as critical in the motion segment adjacent and superior to the degenerated one. This suggests that prevalent trauma in a motion segment may be a symptomatic condition of a poorly treated formal pathology in the inferior spine level.

Influence of Alveolar Bone Loss and Different Alloys on the Biomechanical Behavior of Internal-and External-Connection Implants: A Three-Dimensional Finite Element Analysis.

PURPOSE: The purpose of this study was to evaluate the stress distribution during application of occlusal loads to maxillary anterior single external- and internal-connection implant-supported restorations with different amounts of bone loss and with the use of different metal alloys for restorations and fixation screws. MATERIALS AND METHODS: Models of external- and internal-connection implants, corresponding abutments/crowns, and fixation screws were developed. These models were then imported into finite element analysis software to study the impact of forces on different implant connections and materials. Each prosthesis was subjected to a 200-N compressive shear force applied at 130 degrees relative to the long axis of the implant. The materials were considered linear, isotropic, and homogenous. The parameters changed for each connection type included: bone resorption in relation to the prosthetic platform (no, 2 mm, or 4 mm of resorption); alloys of the restorations (nonprecious vs precious); and alloys of the abutment screws (titanium vs gold). Von Mises stresses were used to display the stress in five models: implant, restoration, screw, cancellous bone, and cortical bone. RESULTS: Statistically significant differences in the stresses of all involved structures occurred when the bone level decreased by 2 mm and by 4 mm. The connection type contributed to statistically significant differences in the stresses in both the restoration and the screw. The alloy type resulted in statistically significant differences in the implant, the superstructure, and the cortical bone stresses. CONCLUSION: As bone resorbed, the stresses generated within the internal-connection implant were greater than those generated in the external-connection implant. The same findings applied for the restoration and for cancellous and cortical bone. The stresses generated in the fixation screw were greater in the external-connection implant than in the internal-connection implant for all bone resorption scenarios.

A new, low cost, locking plate for the long-term fixation of a critical size bone defect in the ratfemur: in vivo performance, biomechanical and finite element analysis.

BACKGROUND: The optimum fixation device for the critical size bone defect is not established yet. OBJECTIVE: A reliable, feasible and low-cost fixation device for the long-term maintenance of a critical bone defect. METHODS: A custom-made plate made of poly-methyl-methacrylate was used for the fixation of a critical defect of rats' femurs. The screws were securely fixing both on the plate and the bone. A three point bending test, aimed to resemble the in vivo loading pattern, a Finite Element Analysis and a 24-week in vivo monitoring of the integrity of the plate fixation were utilized. RESULTS: The plate has linear and reproducible behavior. It presents no discontinuities in the stress field of the fixation. Its properties are attributed to the material and the locking principle. It fails beyond the level of magnitude of the normal ambulatory loads. In vivo, 100% of the plates maintained the bone defect intact up to 12 weeks and 85% of them at 24 weeks. CONCLUSION: This novel locking plate shows optimal biomechanical performance and reliability with high long-term in vivo survival rate. It is fully implantable, inexpensive and easily manufactured. It can be qualified for long term critical defect fixation in bone regeneration studies.

The effect of kyphoplasty parameters on the dynamic load transfer within the lumbar spine considering the response of a bio-realistic spine segment.

BACKGROUND: With an increasing prevalence of osteoporosis, physicians have to optimize treatment of relevant vertebral compression fractures, which have significant impact on the quality of life in the elder population. Retrospective clinical studies suggest that kyphoplasty, despite being a procedure with promising potential, may be related to an increased fracture risk of the adjacent untreated vertebrae. METHODS: A bio-realistic model of a lumbar spine is introduced to determine the morbidity of cemented augmentation. The model was verified and validated for the purpose of the study and subjected to a dynamic finite element analysis. Anisotropic bone properties and solid ligamentous tissue were considered along with α time varying loading scenario. FINDINGS: The yielded results merit high clinical interest. Bi-pedicular filling stimulated a symmetrically developing stress field, thus comparing favourably to uni-pedicular augmentation which resulted in a non-uniform loading of the spine segment. An enslavement of the load transfer was also found to both patient bone mineral density and reinforcement-nucleous pulpous superimposition. INTERPRETATION: The investigation presented refined insight into the dynamic biomechanical response of a reinforced spine segment. The increase in the calculated occurring stresses was considered as non-critical in most cases, suggesting that prevalent fractures are a symptomatic condition of osteoporosis rather than a sequel of efficiently preformed kyphoplasty.