Liraglutide improves bone mineral density in osteoporotic rats by mediating O3a/Wnt signaling / 中华内分泌外科杂志

Objective:To study the effect of liraglutide on the forkhead box O3a (forkhead box O3a, FoxO3a) /Wnt signaling pathway and vertebral bone density in osteoporotic rats.Methods:Female Sprague-dawley rats were divided into sham operation group, model group, and liraglutide intervention group according to the random number table method, with 10 rats in each group. Both the model group and the intervention group used bilateral oophorectomy to establish an osteoporosis model. The intervention group was injected subcutaneously with liraglutide every day, and the sham operation group and the model group were given an equal volume of normal saline. After 12 weeks of continuous administration, the bone mineral density and bone biomechanics were measured, the serum osteoprotegerin, anti-tartrate acid phosphatase, and osteocalcin levels were detected by enzyme-linked immunosorbent assay, and the O3a/Wnt pathway was detected by Real-time PCR technology. The expression level of mRNA was detected by Western blot to detect the expression level of related proteins in the O3a/Wnt pathway.Results:The bone mineral density levels of L4,5 (0.33±0.04 vs 0.18±0.03) and left and right femurs (0.37±0.05 vs 0.23±0.04 0.35±0.04 vs 0.24±0.03) of the successfully modeled rats were significantly lower than those of the sham operation group ( P<0.05) . After 12 weeks of treatment, the differences in the maximum bone load, three-point bending stress, bone density and elastic modulus of the three groups of rats were statistically significant. Among them, the sham operation group had the highest level of each index (36.53±5.23, 154.13±6.27, 0.34±0.04, 3 102.34±160.44) , followed by the intervention group (19.37±4.32, 141.54±6.58, 0.18±0.03, 2 270.18±145.53) and the model group in turn (26.17±4.68, 147.56±5.84, 0.28±0.03, 2 804.24±140.42) ( P<0.05) . There were statistically significant differences in the levels of serum osteoprotegerin, anti-tartrate acid phosphatase and osteocalcin among the three groups. Among them, the osteoprotegerin (Sham operation group vs model group vs intervention group: 7.53±0.63 vs 4.57±0.42 vs 6.15±0.61) of the sham operation group was significantly higher than that of the intervention group and the model group. The anti-tartrate acid phosphatase (Sham operation group vs model group vs intervention group: 14.34±2.87 vs 19.53±3.52 vs 15.96±3.14) and osteocalcin levels (Sham operation group vs model group vs intervention group: 0.84±0.09 vs 1.13± 0.12 vs 0.95± 0.08) of rats The factor was significantly lower than that of the intervention group and model group ( P<0.05) . The mRNA and protein expression levels of FoxO3a, Wnt2, and β-catenin in the three groups of rats were significantly different. Among them, Wnt2 and β-catenin in the sham operation group were significantly higher than the intervention group and model group, and FoxO3a was significantly lower than the intervention group and model Group ( P<0.05) . Conclusion:Liraglutide can increase bone density and improve bone biomechanics by activating O3a/Wnt signal, thereby effectively treating osteoporosis.

El peroné: mal alumno, pero buen profesor. (¿Qué tiene prioridad biológica: la integridad, o la supervivencia?) / Fibula: a bad pupil but a good profesor. (What comes first, integrity or survival?)

La concepción original del mecanostato como un regulador de la rigidez estructural ósea orientado a mantener un determinado 'factor de seguridad' en todos los esqueletos parece no corresponder por igual a cualquier hueso y para cualquier tipo de estímulo. Hemos descubierto que la estructura cortical diafisaria del peroné humano manifiesta un comportamiento ambiguo del sistema, referido al uso del pie. La diáfisis peronea, además de ser insensible al desuso, se rigidiza, como sería de esperar, por entrenamientos en disciplinas deportivas que rotan o revierten el pie (hockey, fútbol, rugby); pero, llamativamente, se flexibiliza en su mitad proximal por entrenamiento en carrera larga, que optimiza el rendimiento del salto que acompaña a cada paso. La referida rigidización robustecería la región peronea de inserción de los músculos que rotan o revierten el pie, favoreciendo la locomoción sobre terrenos irregulares o 'gambeteando', propia de especies predadoras como los leopardos. La 'inesperada' flexibilización proximal, pese a reducir la resistencia a la fractura por flexión lateral (poco frecuente en el hombre), favorecería la absorción elástica de la energía contráctil de la musculatura inserta, optimizando el rendimiento del salto al correr, condición vital para especies presas como las gacelas. La falta de analogía de estas respuestas de la estructura peronea a distintos entrenamientos, incompatible con el mantenimiento de un factor de seguridad, sugiere su vinculación preferencial con la optimización de aptitudes esqueléticas con valor selectivo. Esto ampliaría el espectro regulatorio del mecanostato a propiedades esqueléticas 'vitales', más allá del control de la integridad ósea. Su manifestación en el hombre, ajena a connotaciones selectivas (quizá resultante del mantenimiento de genes ancestrales), permitiría proponer la indicación de ejercicios orientados en direcciones preferenciales a este respecto, especialmente cuando estas coincidieran con las de las fuerzas que podrían fracturar al hueso. (AU)

The original notion of the mechanostat as a regulator of bone structural rigidity oriented to maintain a certain 'safety factor' in all skeletons does not seem to correspond equally to every bone and for any type of stimulus. We have discovered that the diaphyseal cortical structure of the human fibula shows an ambiguous behavior of the system, with reference to the use of the foot. The peroneal shaft, in addition to being insensitive to disuse, becomes stiffened, as might be expected, by training in sport disciplines that involve rotating or reversing the foot (hockey, soccer, rugby); but, remarkably, it becomes more flexible in its proximal half by long-distance running training, which optimizes the performance of the jump that accompanies each step. The stiffening would strengthen the peroneal region of insertion of the muscles that rotate or reverse the foot, favoring locomotion on uneven terrain or 'dribbling', typical of predatory species such as leopards. The 'unexpected' proximal flexibilization, despite reducing the resistance to lateral flexion fracture (rare in human), would favor the elastic absorption of contractile energy from the inserted muscles, optimizing jumping performance when running, a vital condition for prey species such as gazelles. The lack of analogy of these responses of the peroneal structure to different training, incompatible with the maintenance of a safety factor, suggests its preferential link with the optimization of skeletal aptitudes with selective value. This would expand the regulatory spectrum of the mechanostat to 'vital' skeletal properties, beyond the control of bone integrity. Its manifestation in humans, oblivious to selective connotations (perhaps resulting from the maintenance of ancestral genes), would make it possible to propose the indication of exercises oriented in preferential directions, especially when they coincide with the direction of the forces that could fracture the bone. (AU)

Demostración original de la interferencia de los efectos modeladores corticales expansivos de un entrenamiento sobre los de otro ulterior: (la modelación 'marca el terreno' para la remodelación) / Original demonstration of the interference of the expansive cortical modeling effects of one training on those of another further training: (modeling "sets limits" for remodeling)

La expansión modeladora de la geometría cortical de un hueso inducida por su entorno mecánico podría ser difícil de modificar por estímulos ulteriores con diferente direccionalidad. Este estudio, que por primera vez combina datos tomográficos del peroné (pQCT) y dinamométricos de la musculatura peronea lateral, intenta demostrar que, en individuos jóvenes no entrenados, el entrenamiento en fútbol produce cambios geométricos peroneos expansivos, similares a los del rugby, que podrían interferir en los efectos de un entrenamiento ulterior direccionalmente diferente (carrera larga). Confirmando la hipótesis, los resultados indican, con evidencias originales, 1) la relevancia creciente del uso del pie (rotación externa y eversión provocadas por los peroneos laterales) para la determinación de la geometría peronea (incremento del desarrollo de los indicadores de masa y de diseño óseos), evidenciada por la secuencia creciente de efectos: carrera < fútbol < rugby; 2) la predominancia de esos efectos sobre el desarrollo centro-proximal del peroné para resistir a la flexión lateral, y en la región distal para resistir el buckling (principal sitio y causa de fractura del hueso) y 3.) la relevancia de la anticipación de esos efectos para interferir en la manifestación de los cambios producidos por un entrenamiento ulterior (carrera), cuando los del primero (fútbol) afectan la modelación cortical de modo expansivo. Esta última deducción demuestra, en forma inédita, que un cambio modelatorio expansivo tempranamente inducido sobre la estructura cortical ósea 'delimitaría el terreno'para la manifestación de cualquier otro efecto ulterior por estímulos de distinta direccionalidad. (AU)

The modeling-dependent, geometrical expansion of cortical bone induced by the mechanical environment could be hard to modify by subsequent stimulations with a different directionality. The current study aimed to demonstrate that in young, untrained individuals, training in soccer or rugby enhances the geometric properties of the fibula cortical shell in such a way that the geometrical changes could interfere on the effects of a second training in which the loads are induced in a different direction, e.g. long-distance running. The original findings reported herein confirm our hypothesis and support 1) The relevance of the use of the foot (external rotation and eversion produced by peroneus muscles) to determine fibula geometry (improved development of indicators of bone mass and design) as evidenced by the increasing nature of the effects induced by running < soccer < rugby trainings; 2) The predominance of those effects on the ability of the fibula to resist lateral bending in the centralproximal region (insertion of peroneus muscles), and to resist buckling in the distal region (the main cause and site of the most frequent bone fractures), and 3) The interaction of the effects of a previous training with those of a subsequent training with a different orientation of the loads when the former induced a modeling-dependent expansion of the cortex. Our results support the proposed hypothesis with original arguments by showing that a first, expansive effect induced on cortical bone modeling would set the stage the manifestation of any subsequent effect derived from mechanical stimuli. (AU)

¿A qué pregunta responde "el hueso"?: una cuestión de direccionalidad estructural y organización biológica (hueso y huesos, del big-bang a la osteoporosis) / To which question is 'bone' the answer?: a matter of structural directionality and biological organization (bone and bones, from the big bang to osteoporosis)

La "razón de ser" de nuestros huesos y esqueletos constituye un dilema centralizado en los conceptos biológicos de "estructura" y "organización", cuya solución necesitamos comprender para interpretar, diagnosticar, tratar y monitorear correctamente las osteopatías fragilizantes. Últimamente se ha reunido conocimiento suficiente para proponer aproximaciones razonables a ese objetivo. La que exponemos aquí requiere la aplicación de no menos de 6 criterios congruentes: 1) Un criterio cosmológico, que propone un origen común para todas las cosas; 2) Un criterio biológico, que explica el origen común de todos los huesos; 3) Un enfoque epistemológico, que desafía nuestra capacidad de comprensión del concepto concreto de estructura y del concepto abstracto de organización, focalizada en la noción rectora de direccionalidad espacial; 4) Una visión ecológica, que destaca la importancia del entorno mecánico de cada organismo para la adecuación de la calidad mecánica de sus huesos a las "funciones de sostén" que les adjudicamos; 5) Una correlación entre todo ese conocimiento y el necesario para optimizar nuestra aptitud para resolver los problemas clínicos implicados y 6) Una jerarquización del papel celular en el manejo de las interacciones genético-ambientales necesario para asimilar todo el problema a una simple cuestión de organización direccional de la estructura de cada hueso. Solo aplicando estos 6 criterios estaríamos en condiciones de responder a la incógnita planteada por el título. La conclusión de esta interpretación de la conducta y función de los huesos debería afectar el fundamento de la mayoría de las indicaciones farmacológicas destinadas al tratamiento de la fragilidad ósea. (AU)

The nature of the general behavior of our bones as weight-bearing structures is a matter of two biological concepts, namely, structure and organization, which are relevant to properly interpret, diagnose, treat, and monitor all boneweakening diseases. Different approaches can be proposed to trace the corresponding relationships. The one we present here involves six congruent criteria, namely, 1) a cosmological proposal of a common origin for everything; 2) a biological acknowledgement of a common origin for all bones; 3) the epistemological questioning of our understanding of the concrete concept of structure and the abstract notion of organization, focused on the lead idea of directionality; 4) the ecological insight that emphasizes the relevance of the mechanical environment of every organism to the naturally-selected adjustment of the mechanical properties of their mobile bones to act as struts or levers; 5) The clinical aspects of all the alluded associations; 6) The central role of bone cells to control the genetics/ environment interactions of any individual as needed to optimize the directionality of the structure of each of his/her bones to keep their mechanical ability within physiological limits. From our point of view, we could only solve the riddle posed by the title by addressing all of these six criteria. The striking conclusion of our analysis suggests that the structure (not the mass) of every bone would be controlled not only to take care of its mechanical ability, but also to cope with other properties which show a higher priority concerning natural selection. The matter would be that this interpretation of bone behavior and 'function' should affect the rationales for most pharmacological indications currently made to take care of bone fragility. (AU)

De la osteología a la osteomiología: tres décadas de aportes originales continuos al análisis biomecánico osteomuscular / From osteology to osteo-myology: three decades of continuous, original contributions to musculoskeletal biomechanical analysis

En consonancia con la orientación tradicional de nuestras investigaciones, la Osteología está incorporando progresivamente el análisis estructural-biomecánico óseo y las interacciones músculo-esqueléticas. En este artículo se sintetizan los aportes originales del CEMFoC a la Osteología moderna en el terreno biomecánico en forma didáctica, para que el lector aprecie sus posibles aplicaciones clínicas. Los hallazgos aportaron evidencias sucesivas en apoyo de dos proposiciones fundamentales: a) los huesos deben interpretarse como estructuras resistivas, biológicamente servocontroladas ("Los huesos tienden siempre a mantener un factor de seguridad que permite al cuerpo trabajar normalmente sin fracturarse" ­ Paradigma de Utah) y b) los huesos interactúan con su entorno mecánico, determinado principalmente por las contracciones musculares, en forma subordinada al entorno metabólico ("Los huesos son lo que los músculos quieren que sean, siempre que las hormonas lo permitan"). Los avances producidos se refieren, tanto cronológica como didácticamente, al conocimiento osteológico en general y al desarrollo de recursos novedosos para el diagnóstico no invasivo de fragilidad ósea, para distinguir entre osteopenias y osteoporosis, y para discriminar entre sus etiologías 'mecánica' y 'sistémica'. Finalmente, el nuevo conocimiento se integra en la proposición de un algoritmo diagnóstico para osteopenias y osteoporosis. El espíritu general de la presentación destaca que la evaluación osteomuscular dinámicamente integrada genera un nuevo espacio de análisis personalizado de los pacientes para la atención de cualquier osteopatía fragilizante con criterio biomecánico. (AU)

In consonance with the traditional spirit of our studies, skeletal research is being progressively focused on the structural-biomechanical analysis of bone and the muscle-bone interactions. In this article, the CEMFoC's members summarize their original findings in bone biomechanics and their potential clinical applications. These findings provided evidence supporting two fundamental hypotheses, namely, A. bones constitute resistive structures, which are biologically servo-controlled ('Bones tend to maintain a safety factor which allows the body to function normally avoiding fractures' ­ the 'Utah paradigm'), and B. the interactions of bones with their mechanical environment mainly are determined by the contraction of local muscles - 'bone-muscle units'), and are subordinated to the control of the metabolic environment ('Bones are what muscles wish them to be, provided that hormones allow for it'). The achievements in the field are presented in a chronological and didactical sequence concerning the general knowledge in Osteology and the development of novel resources for non-invasive diagnosis of bone fragility, aiming to distinguish between osteopenias and osteoporosis and the 'mechanical' and 'metabolic' etiology of these conditions. Finally, the integrated new knowledge is presented as supporting for a proposed diagnostic algorithm for osteopenias and osteoporosis. In general terms, the article highlights the dynamic evaluation of the musculoskeletal system as a whole, opening a new diagnostic field for a personalized evaluation of the patients affected by a boneweakening disease, based on functional and biomechanical criteria. (AU)

Pulsed electromagnetic field therapy can be used to treat osteoporosis / 中华物理医学与康复杂志

Objective To observe the effect of a pulsed electromagnetic field (PEMF) on the bone structure and metabolism of rats with disuse osteoporosis (DOP).Methods One hundred 4-month-old female Sprague-Dawley rats were randomly divided into a control group (INT group),an osteoporosis model group (DOP group),a sodium alendronate group (ALN group) and a pulsed electromagnetic field group (PEMF group),each of 25.The right hind-limbs of the rats in the DOP,ALN and PEMF groups were immobilized by tibia-tail fixation for two weeks to establish a DOP model.The rats in the ALN group were given 1 mg/kg of sodium alendronate once a day,while those in the PEMF group received PEMF at 3.82 mT and 10 Hz with a pulse time of 8 ms for 40 min/d.Five rats in each group were sacrificed at the 2nd,4th,8th and 12th week and their right hind-limbs were separated to measure the bone mineral density (BMD),structural mechanics indexes (the maximum load,maximum displacement and rupture energy) and material mechanics indexes (maximum stress,maximum strain and modulus).Moreover,the expression of tumor necrosis factor alpha (TNF-α) and bone morphogenetic protein 2 (BMP-2) were detected using immunohistochemical methods.Results The average BMD of the model group was significantly lower than that of the ALN group after 2 weeks,and lower than that of the PEMF group after 4 and 8 weeks.After 12 weeks the average BMD of the PEMF group was significantly higher than that of the ALN and model groups.After two and four weeks,all the structural and material mechanics measurements had decreased significantly compared with those of the control group.The average maximum displacement and load of the ALN group had increased significantly compared with the model group after 4 weeks of treatment.After 8 weeks the average maximum load,maximum displacement,rupture energy and maximum stress of the ALN and PEMF groups had increased significantly compared with the model group.Compared with the model group,the average level of TNF-α decreased gradually in both the ALN and PEMF groups from the 2nd week on,while that of BMP-2 increased from the same time point.However,at the 8th week the expression of BMP-2 protein in the PEMF group was on average significantly higher than in the ALN group.Conclusion Both PEMF and sodium alendronate can increase bone density,but PEMF has more persistent effects.

Study on the Effects of New Xianling Gubao Capsule on Fracture Healing in Rats / 中国药房

OBJECTIVE:To study the effects of new Xianling gubao capsule on fracture healing in rats,and to provide reference for seeking new formula of"to reduce stockpiles and increase efficiency(to reduce stockpiles and constant efficiency)".METHODS:Rats were randomly divided into sham operation group(distilled water),model group(distilled water),Xianling gubao capsule group (350 mg/kg),new Xianling gubao capsule low-dose,medium-dose and high-dose groups (53,105,210 mg/kg),with 14 rats in each group. Except for sham operation group,right middle femur fracture model was established under the anesthetic state. Rats were given relevant medicine 10 mL/kg intragastrically after woken,once a day,for consecutive 4 weeks.After last administration,body weights of rats were determined;the formation of callus and histopathological changes in fracture were observed;biomechanics of fracture side(fracture stress and bone crushing force)was measured. The levels of inflammatory factors (TNF-α ,IL-1 β) in serum were detected by ELISA. RESULTS:Compared with sham operation group,body weight,fracture stress and bone crushing force of fracture side were decreased significantly(P<0.05 or P<0.01),while the serum levels of TNF-α and IL-1 β were increased significantly(P<0.01). In model group,the scab was visible around the fracture,and the trabecular bone was not mature and arranged in confusion. Compared with model group,body weights of rats were increased significantly in new Xianling gubao capsule high-dose group and Xianling gubao capsule group (P<0.05);fracture stress of fracture side were increased significantly in new Xianling gubao capsule medium-dose and high-dose groups and Xianling gubao capsule group(P<0.05 or P<0.01). The serum levels of TNF-α and IL-1β were decreased significantly(P<0.01). There was no statistical significance in above indexes among new Xianling gubao capsule groups and Xianling gubao capsule group(P>0.05).The area of the callus in each group was smaller;the fracture line became blurred;the fracture trace disappeared and the number of bone trabeculae increased. The cortical layer was thickened,and a large number of capillary implants were found in the bone marrow cavity. CONCLUSIONS:New Xianling gubao capsule has a significant role in promoting fracture healing,and can effectively improve the strength of bone biomechanics and inhibit the inflammatory reaction.

Effects of ossotide injection on bone mineral density (BMD) , bone microstructure and biomechanical properties in ovariectomized rats / 中国比较医学杂志

Objective To observe the effect of ossotide injection on bone mineral density (BMD), bone microstructure and biomechanical properties and mRNA expression of small intestinal calcium binding protein (CaBp-D9K), and to study the mechanism of ossotide injection in the treatment of ovariectomized osteoporosis. Methods Forty-eight 3-month old SPF male rats with successful modeling (excision of bilateral ovaries) were randomly divided into the observation group and model group, 24 normal rats were divided into sham operation group (excised part of the mesenteric membrane), and 24 normal blank group. The blank group, sham operation group and model group were given normal saline, and the observation group was intragastrically given 1. 1 mg/kg ossotide. Two months after intervention, the bone volume (BV), trabecular bone volume (Tb. Th), trabecular number (Tb. N), trabecular separation (Tb. Sp), bone mineral density, bone biomechanics, serum 1,25(OH)2D3 levels and CaBp-D9K mRNA expression levels of small intestine were assessed and statistically analyzed. Results The bone mineral density, maximum load, fracture load, BV, Tb. Th, Tb. N, serum 1, 25 (OH ) 2D3 and intestinal CaBp-D9K mRNA expression level in the model group were significantly lower than those of the control group and sham operation group (P＜ 0. 05), Tb. Sp of the model group was significantly higher than that of the control group and sham operation group (P ＜ 0. 05 ). The bone mineral density, maximum load, fracture load, BV, Tb. Th, Tb. N, serum 1,25(OH)2D3 and intestinal CaBp-D9K mRNA expression level in the observation group were significantly higher than those of the model operation group, and the Tb. Sp of the observation group was lower than that of the model group (P ＜ 0. 05). Conclusions Ossotide injection treatment can reduce the degree of osteoporosis in ovariectomized rats, increasing intestinal CaBp-D9k mRNA expression and promoting intestinal calcium absorption may be its important mechanisms of action.

Effects of Huangqi Powder on femur and tibia in rats with glucocorticoid-induced osteoporosis / 中成药

AIM To study the influence of Huangqi Powder (Puerariae lobatae Radix,Astragali Radix,Mori Cortex) on femur and tibia in rats with glucocorticoid-induced osteoporosis (GIOP).METHODS Thirty one-month-old male SD rats were divided into three groups by randomized block design,which were control group (normal saline),prednisone group (3.5 mg/kg prednisone acetate),Huangqi Powder group (clinical adult dosage).Experimental test was maintained for one hundred and twenty days.Double fluorochrome labeling with calcein was performed before necropsy;bone resorption and bone formation index were determined by using blood serum;the femur structural and material mechanics were analyzed by using bone biomechanics method.The cancellous bone of proximal tibial and the cortical bone of tibial shaft static parameter and dynamic parameter were analyzed by bone histomorphometry method.RESULTS Huangqi Powder had no obvious improving effects on bone biomechanics and bone static parameter,but could increas the area,width and number of the proximal tibia bone trabecular.Mark perimeter percentage and mineralization rate of deposition could be increased.CONCLUSION Huangqi Powder can significantly increase proximal tibia cancellous bone mass and enhance bone trabecula structure of glucocorticoid-induced osteoporosis rats.

Application of CFD mesh generation technology in finite element modeling of skeleton / 医用生物力学

Objective To study high-quality and high efficient meshing methods for skeleton. Methods Based on characteristics of bone structure, the mesh generation technology of computational fluid dynamics (CFD) was applied in mesh generation for bone biomechanics. Hexahedron elements and tetrahedron elements were used to simulate cortical bone and cancellous bone, respectively. Results By using CFD mesh generation technology, high-quality hexahedral elements could be obtained, the structure characteristics of skeleton could be preferably simulated, and computer automatic meshing could be implemented. The amount of time for meshing bones by the new method was only about 1/5 of that by the traditional method, and the calculation results obtained from the finite element model were basically consistent with the results from the cadaver experiment. Conclusions The CFD mesh generation technology can be applied in the field of bone biomechanics, which provides an effective approach to reconstruct complex human skeleton.

Development of new loading device for establishment of stress fracture animal models / 医疗卫生装备

Objective To develop a novel stress fracture animal model system based on dynamic cyclic mechanical loading.Methods Ulnae and tibiae of rats were respectively fixed using differently shaped fixtures (including a fixed holder and a movable holder).The axial mechanical loading was applied via a linear actuator based on LabVIEW control program.During the loading process,a load cell and a laser displacement transducer were used to detect the force and displacement changes in the limbs,respectively.The two signals were sampled at real time by PC-based LabVIEW data acquisition program.A compressive loading test (peak force of 50 N) was conducted to examine the consistency and reliability of cyclic loads after completing the loading system.The loading system and an ElectroForce 3220 mechanical testing machine were respectively used to measure and compare the Young's modulus of a standard ultra-high molecular weight polyethylene (UHMWPE)cylinder to calibrate the loading system.Results The compressive loading test (peak force of 50 N) demonstrated that the mechanical loading system was able to apply consistent loads with controllable intensity and time.The calibration experiment indicated the accuracy of the loading system.Conclusion The novel mechanical loading device has characteristics of precision,scientificity and reliability,and it is approaching the real development situation of stress fracture,which may provide a reliable experimental base for exploring the precautionary measures of stress fracture.

Application of CFD mesh generation technology in finite element modeling of skeleton / 医用生物力学

Objective To study high-quality and high efficient meshing methods for skeleton.Methods Based on characteristics of bone structure,the mesh generation technology of computational fluid dynamics (CFD) was applied in mesh generation for bone biomechanics.Hexahedron elements and tetrahedron elements were used to simulate cortical bone and cancellous bone,respectively.Results By using CFD mesh generation technology,high-quality hexahedral elements could be obtained,the structure characteristics of skeleton could be preferably simulated,and computer automatic meshing could be implemented.The amount of time for meshing bones by the new method was only about 1/5 of that by the traditional method,and the calculation results obtained from the finite element model were basically consistent with the results from the cadaver experiment.Conclusions The CFD mesh generation technology can be applied in the field of bone biomechanics,which provides an effective approach to reconstruct complex human skeleton.

Biomecánica de las fracturas por stress / Biomechanical features of stress fractures

Se define como estrés (stress) tanto la fuerza que una carga externa ejerce sobre un cuerpo sólido como la fuerza reactiva que acompaña a la primera (Ley de Newton), por unidad de área imaginaria transversal a su dirección. Las cargas internas reactivas inducen deformaciones proporcionales del cuerpo. La resistencia del cuerpo a deformarse se llama rigidez. La deformación puede resquebrajar el cuerpo y, eventualmente, producir una fractura por confluencia de trazos. La resistencia del cuerpo a separarse en fragmentos por esa causa se llama tenacidad. La resistencia del cuerpo a la fractura es proporcional al stress que puede soportar sin separarse en fragmentos por deformación (no hay fractura sin deformación y sin stress previo). El stress máximo que un cuerpo puede soportar sin fracturarse resulta de una combinación de ambas propiedades: rigidez y tenacidad, cada una con distintos determinantes biológicos. Una o varias deformaciones del cuerpo pueden provocarle resquebrajaduras sin fracturarlo. La acumulación de resquebrajaduras determina la "fatiga" del material constitutivo del cuerpo, que reduce su rigidez, tenacidad y resistencia a la fractura para la próxima ocasión ("fragilidad por fatiga"). En el caso de los huesos, en general, los términos stress y fatiga tienen las connotaciones amplias referidas, respecto de todas las fracturas posibles. La fatiga predispone a fracturas a cargas bajas, que se denominan (correctamente) "fracturas por fatiga" y también (incorrectamente) "fracturas por stress", para distinguirlas de las que ocurren corrientemente, sin resquebrajaduras previas al trauma, que se denominan (incorrectamente) "fracturas por fragilidad, o por insuficiencia". En realidad, todas las fracturas se producen por stress y por fragilidad o insuficiencia (en conjunto); pero la distinción grosera entre fracturas "por fatiga, o por stress", por un lado, y "por fragilidad" o "por insuficiencia", por otro, aceptando las amplias connotaciones referidas antes, tiene valor en la práctica clínica. Este artículo intenta explicar esas particularidades biomecánicas y describir las distintas condiciones que predisponen a las fracturas "por fatiga o por stress" en la clínica, distinguiéndolas de las fracturas "por fragilidad o por insuficiencia" (manteniendo estas denominaciones) y detallando las características de interés directo para su diagnóstico y tratamiento. (AU)

The term "stress" expresses the force exerted by an external load on a solid body and the accompanying, opposed force (Newton's Law), expressed per unit of an imaginary area perpendicular to the loading direction. The internal loads generated this way deform (strain) proportionally the body's structure. The resistance of the body to strain expresses its stiffness. Critical strain magnitudes may induce micro-fractures (microdamage), the confluence of which may fracture the body. The body's resistance to separation into fragments determines its toughness. Hence, the body's resistance to fracture is proportional to the stress the body can support (or give back) while it is not fractured by the loadinduced strain (no stress, no strain -> no fracture). Therefore, the maximal stress the body can stand prior to fracture is determined by a combination of both, its stiffness and its toughness; and each of those properties is differently determined biologically. One or more deformations of the body may induce some microdamage but not a fracture. Microdamage accumulation determines the fatigue of the material constitutive of the body and reduces body's toughness, leading to a "fatigue-induced fragility". In case of bones, in general, both stress and fatigue have the referred, wide connotations, regarding any kind of fractures. In particular, bone fatigue predisposes to low-stress fractures, which are named (correctly) "fatigue fractures" and also misnamed "stress fractures", to distinguish them from the current fractures that occur without any excess of microdamage, that are named (wrongly) "fragility" or "insufficiency" fractures. In fact, all fractures result from all stress and fragility or insufficiency as a whole; however, the gross distinction between "fatigue or stress fractures", on one side, and "fragility or insufficiency fractures", on the other, accepting the wide connotations of the corresponding terminology, is relevant to clinical practice. This article aims to explain the above biomechanical features and describe the different instances that predispose to "fatigue or stress fractures" in clinical practice, as a different entity from "insufficiency or fragility fractures" (maintaining this nomenclature), and describe their relevant features to their diagnosis and therapy. (AU)

Preventive effect of Polygonum Multiflorum on deteriorated micro-structure and biomechanical properties induced by prednisone / 中国药理学通报

Aim To investigate the preventive effect of Polygonum Multiflorum (PM)on the deteriorated mi-cro-structure and biomechanical properties induced by prednisone.Methods Ninety 6-month-old male Sprague-Dawley rats were randomly divided into nine groups,which were control,prednisone,CAL,30%ethanol eluent of the PM(H,M,L),PM(H,M,L). Prednisone was gavaged to rat for 21 weeks as model group of osteoporosis.Meanwhile,tested herbal ab-stract were orally administrated to the modeled rats in-duced by prednisone.At the end of the experiment, the right femur was collected for micro-CT scanning, three-dimensional reconstruction and biomechanical test.Results Compared with the control group,mod-el group showed destruction of bone microarchitecture, BV /TV fell 28.6%(P <0.05),bone biomechanical parameters decreases,and stiffness fell 29.7%(P <0.01 ). Compared with the model group, positive group had significantly improved effect on bone micro-architecture,and biomechanical parameters,BV /TV increased 46.7%(P <0.01 ),and stiffness increased 25.9%(P <0.01 ).30% ethanol eluent of the PM (M,L)dose may improve bone microstructure by in-creasing BV /TV 46.7% (P <0.01 ),40.0% (P <0.05)respectively,PM(H)may improve the biome-chanical parameters by increasing stiffness 24.7%(P<0.05),and 30% ethanol eluent of the PM(H)and PMhigh-dose may improve the biomechanical parame-ters,but not as positive group.Conclusions Predni-sone reduces biomechanical properties of rat femur and deteriorates femoral microstructure.30% ethanol eluent of the PM(M,L)and PM(H)plays a preventive role in the changes of micro-structural and biomechanical properties by prednisone,and increases BMD,whereas other groups have no significant preventive effect.

Estudio biomecánico de resistencia en fémur porcino y predictibilidad de zona de fractura / Biomechanical study of porcine femur resistance and predictability of fracture zone

During everyday activities, bones are submitted to the action of different strengths. While walking, the femur must support loads up to 3 times the body weight. It is for this that the need of knowing the mechanical behavior of the femur submitted to different loads and the place where the fracture would occur is born. This study analyzes, through experimental testing, the maximum resistance of the porcine femur, mechanically comparable to the human femur, submitted to different strengths, to obtain the location of fracture and compare the results obtained with computational simulation and with information described for human femur.

Durante actividades de la vida diaria, los huesos se ven sometidos a la acción de diferentes fuerzas. En la marcha, el fémur debe soportar cargas de hasta 3 veces el peso corporal. Es por esto que nace la inquietud de conocer el comportamiento mecánico del fémur sometido a distintos tipos de cargas, y el lugar de falla donde se produciría una fractura. Este estudio analiza, mediante ensayo experimental, la resistencia máxima del fémur porcino, mecánicamente comparable al fémur humano, frente a distintas cargas, para obtener así el sitio de fractura y luego comparar los resultados obtenidos con simulación computacional y con datos descritos para el fémur humano.

Effects of Chinese Medicine Compound on Bone Loss of Weightlessness Rats Simulated by Suspension / 中国中医药信息杂志

Objective To study the effects of Chinese medicine compound on bone density, biomechanics, histomorphometry of weightlessness rats simulated by tail suspension. Methods Fifty Wistar rats were randomly divided into 5 groups with 10 rats each group:control group, model group, and low dose, medium dose and high dose Chinese medicine compound treated suspension group, the experiment period was 21 days. BMD of femur and lumbar vertebrae were detected by dual energy X-ray absorptiometry. The femoral biomechanics parameters and anti-compress ability of lumbar vertebrae were measured by three-point assay and compress test respectively. The quantitative structures of non- decalcified bone tissue sections were analyzed by histomorphometry. Result Compared with control group, BMD of femur and lumbar of model group decreased remarkably (P

Preventive effect of the supplemental dietary boron on bone damage of rats with excess fluoride ingestion / 西安交通大学学报(医学版)

Objective To explore the preventive effect of the supplemental dietary boron on bone damage of rats with excess fluoride (EF) ingestion. Methods Twenty-four Sprague-Dawley rats aged 4-5 weeks old were divided into the control (C group, treated with distilled water and the elementary dietary), the excessive fluoride dose group (EF group, treated with distilled water with 100mg/L F-from 221.0g NaF per liter and the elementary dietary) and the boron prevention group (P group, treated with 100mg/L F-distilled water and the supplemental boron dietary). Three months after the experiment, fluorine, boron contents and AKP activities in serum, total RNA and fluorine contents in bone, vertical and transverse diameter and dry weight of tibias of rats were assayed, and bone biomechanics of femur and bone mineral density (BMD) were determined. Results Compared with those in the C group, fluorine contents in serum and bone, AKP activities in serum of rats in the EF group significantly increased; total RNA in bone and BMD of the bone of whole body and tibia decreased, vertical and transverse diameter of tibias was shortened, dry weight was decreased; peak load of femur increased but maximum deformation decreased. Compared with those in EF group, fluorine contents in serum and bone, AKP activities in serum of rats in the P group obviously decreased; total RNA in bone and BMD of whole body, lumbar vertebrae and tibias notably increased, vertical and transverse diameters and dry weight of tibia were enhanced, peak load of femur was obviously raised. Boron contents in serums of rats in three groups had no significant differences. Conclusion Bone damage obviously occurred in rats with EF intake, and the supplemental dietary boron had a preventive effect on these changes.

Effects of ?-3 polyunsaturated fatty acids on bone biomechanics in ovariectomized rats / 肠外与肠内营养

Objective:To explore the benefit effects of ?-3 polyunsaturated fatty acids on bone biomechanics in ovariectomized(OVX) rats.Methods: 60 virgin female Sprague-Dawley rats were randomized by the stratified weight method into 6 groups: ① Sham group:deionized water 2 mL/d;②OVX group:deionized water 2 mL/d;③E2 group: OVX +17?-ethinylestradiol 0.1 mg/(kg?d);④ A group: OVX+?-3 PUFAs 75 mg/(kg?d);⑤B group: OVX+?-3 PUFAs 150 mg/(kg?d);⑥ C group: OVX+?-3 PUFAs 300 mg/(kg?d).Each group had 10 rats.After feeding for 90 days,the rats were killed and femur were separated.The maximum load,maximum deformation,elastic load,elastic deformation and energy absorption were measured from three point bending test.Bone wet weights were measured.Result: The femur biomechanics markers of OVX group decreased obviously,while that of all medicated group increased obviously(P