[Pedestrian head injury biomechanics and damage mechanism. Pedestrian protection automotive regulation assessment]. / Biomecánica y mecanismo de producción del traumatismo cráneo-encefálico en el peatón atropellado. Evaluación de la normativa actual en la automoción.

INTRODUCTION: Pedestrian-vehicle collisions are a leading cause of death among motor vehicle accidents. Recently, pedestrian injury research has been increased, mostly due to the implementation of European and Japanese regulations. This research presents an analysis of the main head injury vehicle sources and injury mechanisms observed in the field, posteriorly the data are compared with the current pedestrian regulations. METHODS: The analysis has been performed through an epidemiologic transversal and descriptive study, using the Pedestrian Crash Data Study (PCDS) involving 552 pedestrians, sustaining a total of 4.500 documented injuries. RESULTS: According to this research, the hood surface is responsible for only 15,1% of all the head injuries. On the other hand, the windshield glazing is responsible for 41,8%. In case of sedan vehicles the head impact location exceeds what is expected in the current regulation, and therefore no countermeasures are applied. From all the head injuries sustained by the pedestrians just 20% have the linear acceleration as isolated injury mechanism, 40% of the injuries are due to rotational acceleration. CONCLUSIONS: In this research, the importance of the rotational acceleration as injury mechanism, in case of pedestrian-vehicle collision is highlighted. In the current pedestrian regulation just the linear acceleration is addressed in the main injury criteria used for head injury prediction.

Anatomical and biomechanical factors of osteoporotic vertebral fracture and the occurrence of cascade fractures. / Factores anatómicos y biomecánicos de la fractura vertebral osteoporótica y la aparición de las fracturas en cascada.

Osteoporosis weakens the structural strength of bone to such an extent that normal daily activity may exceed the capacity of the vertebra to bear this load. Vertebral fracture and deformity is a hallmark of osteoporosis. The detriment of trabecular bone properties alone cannot explain the occurrence of osteoporotic vertebral fracture. The ability of the spine to bear and resist loads depends on the structural capacity of the vertebrae, but also on loading conditions arising from activities of daily living or low-energy trauma. This review describes the mechanical properties of the vertebral bone, the structural load-bearing capacity of the various elements forming the spine, the neuromuscular control of the trunk, as well as the biomechanics of the loads to which the spine is subjected in relation to the presence of osteoporosis and the risk of vertebral fracture. A better understanding of biomechanical factors may help to explain both the high incidence of osteoporotic vertebral fractures and their mechanism of production. Consideration of these issues may be important in the development of prevention and management strategies.

[Translated article] Anatomical and biomechanical factors of osteoporotic vertebral fracture and the occurrence of cascade fractures.

Osteoporosis weakens the structural strength of bone to such an extent that normal daily activity may exceed the capacity of the vertebra to bear this load. Vertebral fracture and deformity is a hallmark of osteoporosis. The detriment of trabecular bone properties alone cannot explain the occurrence of osteoporotic vertebral fracture. The ability of the spine to bear and resist loads depends on the structural capacity of the vertebrae, but also on loading conditions arising from activities of daily living or low-energy trauma. This review describes the mechanical properties of the vertebral bone, the structural load-bearing capacity of the various elements forming the spine, the neuromuscular control of the trunk, as well as the biomechanics of the loads to which the spine is subjected in relation to the presence of osteoporosis and the risk of vertebral fracture. A better understanding of biomechanical factors may help to explain both the high incidence of osteoporotic vertebral fractures and their mechanism of production. Consideration of these issues may be important in the development of prevention and management strategies.

Finite element analysis evaluation of hypothetical alternative treatment scenarios for neglected developmental dysplasia of the hip.

OBJECTIVE: The study aimed to evaluate three different degrees of correction in the surgical treatment of neglected developmental dysplasia of the hip (DDH) using finite element models based on computed tomography. METHOD: Three tridimensional FEA models of hypothetical post-operative (PO) outcomes were developed, based on three tridimensional CT of a pediatric patient diagnosed with luxated neglected DDH: One with the acetabular index of the contralateral hip (CLAT); another based on a theoretical Bombelli biomechanical model (BMB); and another recreating the patient's actual PO. RESULTS: The stresses in the affected hip were greater than those in the unaffected hip. CLAT showed the greatest stress and the smallest loading zone (LZ). In contrast, BMB showed the smallest stress and the biggest LZs. CONCLUSIONS: The approach based on the BMB gave the best results in terms of the distribution of the stresses over the hip, whereas the worst was CLAT. Qualitatively, estimating the stability and range of movement of the hip, the PO case was considered the best.

OBJETIVO: Evaluar tres diferentes grados de corrección en el tratamiento quirúrgico de la displasia del desarrollo de la cadera (DDH) inveterada mediante modelos de elementos finitos basados en tomografía computarizada. MÉTODO: Se desarrollaron tres modelos tridimensionales de elementos finitos de resultados posoperatorios hipotéticos, basados en tres tomografías computarizadas tridimensionales de un paciente pediátrico diagnosticado de displasia del desarrollo de la cadera luxada inveterada: uno con el índice acetabular de la cadera contralateral (CLAT), otro basado en un modelo biomecánico teórico de Bombelli (BMB) y otro recreando el posoperatorio real (PO) del paciente. RESULTADOS: Los esfuerzos en la cadera afectada fueron mayores que en la cadera no afectada. El CLAT mostró el mayor esfuerzo y la menor zona de carga. Por el contrario, el BMB mostró el menor esfuerzo y las mayores zonas de carga. CONCLUSIONES: La propuesta basada en el BMB dio los mejores resultados en cuanto a la distribución de los esfuerzos sobre la cadera, mientras que la peor fue el CLAT. Cualitativamente, estimando la estabilidad y la amplitud de movimiento de la cadera, el caso PO se consideró el mejor.

Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study. / [Artículo traducido] Configuración y localización óptima de los tornillos posteriores en las fracturas de calcáneo Sanders 2B: estudio biomecánico.

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5 cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4 mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7 mm cannulated partially threaded CharlotteTM (Wright Medical Technology, Memphis, USA) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5 N, 10 N and 20 N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88 ± 0.390 at 5 N and 1.7 ± 1.251 at 20 N) and the most stable construct (p < 0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04 ± 0.971 at 5 N and 11.24 ± 7.590 at 20 N) (p < 0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.

Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study.

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04±0.971 at 5N and 11.24±7.590 at 20N) (p<0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.

Comparison of three different minimally invasive intramedullary screw for proximal phalanx fractures. A biomechanical study. / Comparación de tres técnicas de tornillo endomedular mínimamente invasivo para fracturas de falange proximal. Estudio biomecánico.

BACKGROUND AND OBJECTIVE: Phalangeal fractures are the most common hand fractures. In the last years, intramedullary compression screw (IMHCS) for instable transverse or short oblique proximal P1 fractures have been described. Although both anterograde (intraarticular or trans-articular) and retrograde IMHCS techniques have shown good results, no comparison between anterograde and retrograde screw in P1 fractures has been published. We sought to determine stability with retrograde IMHCS and anterograde IMHCS, both trans-articular and intra-articular technique, in a cadaveric transverse proximal P1 fracture model, at two different levels. MATERIAL AND METHODS: We performed a biomechanical study in 30 fresh-frozen human cadaveric P1 fracture model. Fracture was performed at 9-mm from the metacarpo-phalangeal (MCP) joint in 15 specimens, whereas it was done at 15 mm in the other 15. In turn, in each group, five fractures were stabilized with an anterograde intra-articular IMHCS, five with anterograde trans-articular IMHCS and other five with retrograde IMHCS. RESULTS: Anterograde IMHCS fixation in 9-mm P1 fractures (both trans- and intra-articular technique, 62.74 N and 70.86 N, respectively) was found to be more stable than retrograde IMHCS one (32.72 N) (p = 0.022). Otherwise, retrograde IMHCS fixation was found to be more stable in more distal P1 fractures (90.52 N retrograde vs. 57.64 N trans-articular vs. 42.92 N intra-articular; p = 0.20). CONCLUSIONS: Anterograde IMHCS fixation in proximal transverse P1 bone cut in a cadaveric model provides more stability than retrograde IMHCS, while retrograde screw provides more stability when the bone cut is located more distal.

[Translated article] Comparison of three different minimally invasive intramedullary screw for proximal phalanx fractures. A biomechanical study.

BACKGROUND AND OBJECTIVE: Phalangeal fractures are the most common hand fractures. In the last years, intramedullary compression screw (IMHCS) for instable transverse or short oblique proximal P1 fractures have been described. Although both anterograde (intraarticular or trans-articular) and retrograde IMHCS techniques have shown good results, no comparison between anterograde and retrograde screw in P1 fractures has been published. We sought to determine stability with retrograde IMHCS and anterograde IMHCS, both trans-articular and intra-articular technique, in a cadaveric transverse proximal P1 fracture model, at two different levels. MATERIAL AND METHODS: We performed a biomechanical study in 30 fresh-frozen human cadaveric P1 fracture model. Fracture was performed at 9-mm from the metacarpo-phalangeal (MCP) joint in 15 specimens, whereas it was done at 15mm in the other 15. In turn, in each group, five fractures were stabilised with an anterograde intra-articular IMHCS, five with anterograde trans-articular IMHCS and other five with retrograde IMHCS. RESULTS: Anterograde IMHCS fixation in 9-mm P1 fractures (both trans- and intra-articular technique, 62.74N and 70.86N, respectively) was found to be more stable than retrograde IMHCS one (32.72N) (p=0.022). Otherwise, retrograde IMHCS fixation was found to be more stable in more distal P1 fractures (90.52N retrograde vs. 57.64N trans-articular vs. 42.92N intra-articular; p=0.20). CONCLUSIONS: Anterograde IMHCS fixation in proximal transverse P1 bone cut in a cadaveric model provides more stability than retrograde IMHCS, while retrograde screw provides more stability when the bone cut is located more distal.

Importance and use of corneal biomechanics and its diagnostic utility.

The study of corneal biomechanics has become relevant in recent years due to its possible applications in the diagnosis, management, and treatment of various diseases such as glaucoma, keratorefractive surgery and different corneal diseases. The clinical biomechanical investigation has become of great importance in the setting of refractive surgery to identify patients at higher risk of developing iatrogenic ectasia. This review focuses on two of the technologies available for clinical use, the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY, USA) and the Corvis ST (Oculus Optikgergäte GmbH, Wetzlar, Germany). Both are non-contact tonometers that provided a clinical evaluation of corneal biomechanics. The fundamentals and main parameters of each device are described, as well as their use in eye surgery and the corneal biomechanical behavior in eye diseases. Finally, we will discuss the more recent Brillouin microscopy biomechanical analysis, and the integration Scheimpflug-based corneal tomography and biomechanical data with artificial intelligence to increase accuracy to detect risk of ectasia.

El estudio de la biomecánica corneal ha cobrado relevancia en los últimos años debido a sus posibles aplicaciones en el diagnóstico, el manejo y el tratamiento de diversas enfermedades, como glaucoma, cirugía queratorrefractiva y diferentes enfermedades corneales. La investigación de la biomecánica corneal es de mucha importancia en el contexto de cirugía refractiva, pues podría identificar pacientes en riesgo de desarrollar una ectasia corneal iatrogénica. Esta revisión se centra en dos de las tecnologías disponibles para uso clínico: el Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY, EE. UU.) y el Corvis ST (Oculus Optikgergäte GmbH, Wetzlar, Alemania). Ambos son tonómetros de no contacto que proporcionan una evaluación clínica de la biomecánica corneal. Se describen los fundamentos y los principales parámetros de cada dispositivo, así como su uso en cirugía ocular y el comportamiento biomecánico corneal en las enfermedades oculares. Finalmente, se mencionan los dispositivos más recientes de análisis biomecánico, como la microscopía de Brillouin, así como la integración de los datos biomecánicos y topográficos basados en Scheimpflug con la inteligencia artificial para aumentar la precisión en la detección del riesgo de ectasias.

Comparative clinical and biomechanical study of different types of osteosynthesis in the treatment of distal femur fractures. / Estudio comparativo clínico y biomecánico de distintos tipos de osteosíntesis en el tratamiento de fracturas distales de fémur.

INTRODUCTION AND OBJECTIVES: Distal femoral fractures represent a problem due to their high number of complications. The aim was to compare the results, complications and stability achieved with retrograde intramedullary nailing and the angular stable plate in the treatment of distal femoral diaphyseal fractures. MATERIAL AND METHOD: A clinical and experimental biomechanical study was carried out using finite elements. The results of the simulations allowed us to obtain the main results related to the stability of osteosynthesis. For clinical follow-up data, frequencies were used for qualitative variables, and Fisher's exact test and χ2 test were used to evaluate the significance of the different factors, with the condition of P<.05. RESULTS: In the biomechanical study, the retrograde intramedullar nails demonstrated superiority, obtaining lower values in terms of global displacement, maximum tension, torsion resistance, and bending resistance. In the clinical study, the rate of consolidation of the plates was lower than nails (77% vs. 96%, P=.02). The factor that most influenced the healing of fractures treated with plate were the central cortical thickness (P=.019). The factor that most influenced the healing of nail-treated fractures was the difference between the diameter of the medullary canal and the nail. CONCLUSIONS: Our biomechanical study shows that both osteosynthesis provide sufficient stability, but biomechanically behaves differently. Nails provide greater overall stability being preferable the use of long nails adjusted to the diameter of the canal. Plates form less rigid osteosynthesis, with little resistance to bending.

[Translated article] Comparative clinical and biomechanical study of different types of osteosynthesis in the treatment of distal femur fractures.

INTRODUCTION AND OBJECTIVES: Distal femoral fractures represent a problem due to their high number of complications. The aim was to compare the results, complications and stability achieved with retrograde intramedullary nailing and the angular stable plate in the treatment of distal femoral diaphyseal fractures. MATERIAL AND METHOD: A clinical and experimental biomechanical study was carried out using finite elements. The results of the simulations allowed us to obtain the main results related to the stability of osteosynthesis. For clinical follow-up data, frequencies were used for qualitative variables, and Fisher's exact test and χ2 test were used to evaluate the significance of the different factors, with the condition of P<.05. RESULTS: In the biomechanical study, the retrograde intramedullar nails demonstrated superiority, obtaining lower values in terms of global displacement, maximum tension, torsion resistance, and bending resistance. In the clinical study, the rate of consolidation of the plates was lower than nails (77% vs. 96%, P=.02). The factor that most influenced the healing of fractures treated with plate were the central cortical thickness (P=.019). The factor that most influenced the healing of nail-treated fractures was the difference between the diameter of the medullary canal and the nail. CONCLUSIONS: Our biomechanical study shows that both osteosynthesis provide sufficient stability, but biomechanically behaves differently. Nails provide greater overall stability being preferable the use of long nails adjusted to the diameter of the canal. Plates form less rigid osteosynthesis, with little resistance to bending.

[Bibliometric analysis of the thematic evolution in fibromyalgia and biomechanics (1985-2021)]. / Análisis bibliométrico de la evolución temática en fibromialgia y biomecánica (1985-2021).

The main objective of the study is to analyse the scientific evolution of the research field of fibromyalgia and biomechanics. A search was carried out in Web of Science, from 1985 to 2021. With those results, a bibliometric map of keywords was created with VOSviewer. On top of that, scientific mapping and performance analysis were also conducted using SciMAT. A total of 233 articles from around the world were analysed, highlighting the production of the USA and Spain. The results show great diversity in topics with 54 different topics and 33 keywords. Although most of the topics found are not widely developed except the topics of physical activity and symptomatology. In conclusion, the study of fibromyalgia and biomechanics has generally grown over time.

[Low-cost virtual reality. A new application for upper extremity motor rehabilitation in neurological pathology: Pilot study]. / Realidad virtual de bajo coste. Una nueva aplicación para rehabilitación motora de los miembros superiores en patología neurológica: Estudio piloto.

BACKGROUND AND OBJECTIVES: The aim of this study is to present a new virtual reality (VR) low cost application based on Leap Motion Controller (LMC) device for upper extremity motor rehabilitation after neurological pathology and to demonstrate its clinical feasibility by carrying out a pilot experience. MATERIAL AND METHODS: The LMC allows the interaction with virtual applications by capturing the patient's hand movements. A pilot study was carried out with 4 patients with upper limb impairment reflected with Upper Extremity Motor Score (UEMS) greater than 10. They were assessed using the Box and Block (BBT) and the writing task within the Jebsen-Taylor Hand Function (JTHF) before and after the intervention. RESULTS: All patients completed the 9-session, 30-min protocol divided into 3 sessions per week. They went from an average result of 38 (SD 20) blocks in BBT before the intervention to 44 (SD 21.72) after it. They went from 28.25 s (SD 8.61) to 26.75 s (SD 21.72) in the JTHF. Statistically significant differences were no found. The device usability was assessed by the QUEST scale, being the security, effectiveness and ease to use the aspects that patients considered to be a priority. CONCLUSIóN: A new VR development based on the LMC device is presented and the clinical feasibility of its application in neurological patients with upper limb involvement has been proven. A clinical study with a large sample size is needed to assess its potential clinical effectiveness as a treatment element.

Biomechanical study of autograft anatomic reconstruction in lateral ankle instability. / Estudio biomecánico de la reconstrucción ligamentosa anatómica con autoinjerto en la inestabilidad lateral de tobillo.

INTRODUCTION: The purpose of this work is perform a biomechanical comparison of anatomic reconstruction of the anterior talofibular ligament (ATFL) with the intact ATFL. MATERIALS AND METHODS: We studied 18 fresh cadaveric ankles with intact ATFL. Each specimen was clinically assessed with the anterior drawer (AD) and varus tilt (VT) tests and the angular movement in the three spatial planes (axial, coronal and sagittal) was measured with an arthrometer using a sensor located in the talus. RESULTS: Statistically significant differences were found in the axial plane, between the intact ATFL versus the sectioned ATFL for AD test with p = 0.012, and for VT test with p = 0.013. Regarding the coronal plane, we also observed a statistically significant difference for VT test with p = 0.016. In the sagittal plane, there are no statistically significant differences in both maneuvers. No statistically significant differences were found when comparing the biomechanics of anatomic ligament reconstruction versus the intact ATFL. CONCLUSION: Autograft anatomic reconstruction of the ATFL showed biomechanical properties similar to those of the native ATFL, at the zero moment in a cadaveric model.

Biomechanical behavior of bone tissue in spine instrumentation.

BACKGROUND: The mechanical fixation of the spine in patients with osteoporotic vertebral degeneration is a challenge for surgeons, the vertebrae selected to insert the screws may fail, endangering health and even patient's life. OBJECTIVE: The objective of the study was to study the effect of the variation of the bone density in the bone-screw interface from a three-dimensional model of the lumbar section. MATERIALS AND METHODS: The finite element method was used to model the behavior of the lumbar vertebral section when applying compression loads. RESULTS: The stresses between 2 and 3 MPa were located on the contact surface with the screw, both in the vertebral body and in the apophysis, being slightly higher in the vertebral body. CONCLUSIONS: Regardless of bone density, the contact zones between the screws are susceptible to bone tissue failure. The posterior half of the vertebral body was the most sensitive to high values of stress, while in the areas furthest from the axis of the screw stress tended to their minimum.

INTRODUCCIÓN: La fijación mecánica de la columna en pacientes con degeneración vertebral osteoporótica es un reto para los cirujanos, pues las vértebras seleccionadas para insertar los tornillos pueden fallar, poniendo en peligro la salud y la vida del paciente. OBJETIVO: Estudiar el efecto de la variación de la densidad ósea en la interfase hueso-tornillo, a partir de un modelo tridimensional de la sección lumbar. MATERIALES Y MÉTODOS: Se emplea el método de los elementos finitos para modelar el comportamiento de la sección vertebral lumbar al aplicar cargas de compresión. RESULTADOS: Los esfuerzos entre 2 y 3 MPa se ubicaron en la superficie de contacto con el tornillo, tanto en el cuerpo vertebral como en la apófisis, siendo ligeramente superiores en el cuerpo vertebral. CONCLUSIONES: Independientemente de la densidad ósea, las zonas de contacto entre el tornillo son susceptibles al fallo del tejido óseo, debido a que están próximos al esfuerzo de fallo óseo de 2.37 ± 1.14 MPa reportado en la literatura. La mitad posterior del cuerpo vertebral fue la más sensible a sufrir valores altos de esfuerzos, mientras que en las zonas más alejadas del eje del tornillo los esfuerzos tendieron a su magnitud mínima.

Descemet membrane endothelial keratoplasty and corneal biomechanics. / Queratoplastia endotelial de la membrana de Descemet y biomecánica corneal.

OBJECTIVE: To study the behaviour of the biomechanical properties of the cornea in DMEK (Descemet membrane endothelial keratoplasty). METHOD: Prospective longitudinal observational study. 21 pre and post-DMEK eyes. 3-month follow-up with the dynamic Scheimpflug Analyzer (Corvis ST, Oculus; Wetzlar, Germany). The following parameters were measured: IOPnc: non-corrected intraocular pressure (IOP), IOPb: IOP corrected by biomechanics, maximum deflection amplitude (DefA), CCT: central corneal pachymetry, flattening speed 1 and 2, peak distance, HC deformation amplitude: deformation amplitude in maximum concavity, integrated inverse concave radius, DAR 1 and 2: deformation amplitude at 1mm and 2mm from the corneal apex, respectively. ARTh: Ambrosial pachymetric ratio, SP1: stiffness parameter, CBI: Corvis Biomechanical index and the maximum inverse radius. Pre-operative and post-operative measurements were performed with a 3-month follow-up and compared with a paired sample t-test. RESULTS: There was a significant decrease in the IOPnc of 1.54±3mmHg (p<0.05), a significant increase in the post-surgical IOPb of 3.79±3.18mmHg (p<0.001), a significant pachymetric decrease of 164.4±91.35µm (p<0.001) after the intervention. All dynamic parameters of the Scheimpflug analyzer changed significantly after surgery (p<0.05), except the ARTh and IWC variables. CONCLUSIONS: Variables indicate a decrease in corneal strength post-DMEK, with an increase in IOPb, at least the first 3 months after surgery. This finding is especially relevant in the follow-up of patients with coexisting glaucoma.

Variables biomecánicas del penalti en futbolistas de las categorías sub-12 y sub-17

Introducción: El estudio de los patrones del movimiento técnico deportivo implica analizar sus componentes biomecánicos, teniendo en cuenta el carácter multifactorial del rendimiento deportivo. Objetivo: Describir la mecánica del movimiento del tiro penalti en futbolistas categorías sub-12 y sub-17. Métodos: Estudio cuasi experimental de orden correlativo. Se estudiaron ocho variables biomecánicas: centro de gravedad en sus dos ejes, inclinación corporal, ángulos femorotibial antes del contacto, ángulos femorotibial luego del contacto, velocidad, aceleración y acierto. Se seleccionaron dos grupos independientes de 30 futbolistas del género masculino, se clasificaron por categorías sub-12 y sub-17, y se analizó su rendimiento mediante videoanálisis. Resultados: Hubo diferencias significativas a favor de la categoría sub-17 en las variables centro de gravedad en el eje X (p = 0,000), en inclinación corporal (p = 0,000), en velocidad (p = 0,000), y en aceleración y acierto (p = 0,000); y diferencias no significativas en el resto (centro de gravedad eje Y: p = 0,267; ángulos femorotibial antes del contacto: p = 0,459; ángulos femorotibial luego del contacto: p = 0,446; y aciertos: p = 0,226). Conclusiones: Todos los rangos promedios sobresalieron en la categoría sub-17, excepto en la variable aciertos, lo que implicó una mayor velocidad y aceleración del pie durante la ejecución del tiro a penal. Sin embargo, la precisión, como componente coordinativo, resultó fundamental en la efectividad del disparo.

Introduction: The study of the patterns of technical sports movement involves analyzing its biomechanical components, taking into account the multifactorial nature of sports performance. Objective: To describe the mechanics of the movement of the penalty kick in U-12 and U-17 football players. Methods: Quasi-experimental study of a correlative order. Eight biomechanical variables were studied: center of gravity in its two axes, body inclination, femorotibial angles before contact, femorotibial angles after contact, speed, acceleration and success. Two independent groups of 30 male footballers were selected, classified by U-12 and U-17 categories, and their performance was analysed through video analysis. Results: There were significant differences in favor of the sub-17 category in the variables center of gravity on the X axis (p = 0.000), body inclination (p = 0.000), speed (p = 0.000), and acceleration and accuracy (p = 0.000); and non-significant differences in the rest (center of gravity Y-axis: p = 0.267; femorotibial angles before contact: p = 0.459; femorotibial angles after contact: p = 0.446; and correct answers: p = 0.226). Conclusions: All the average ranges stood out in the U-17 category, except in the variable hits, which implied a greater speed and acceleration of the foot during the execution of the penalty kick. However, accuracy, as a coordinating component, was fundamental in the effectiveness of the shot.

Plataforma cone morse, a melhor opção para a biomecânica e estética em próteses sobre implante: uma revisão de literatura / Conemorse platform, the best option for biomechanics and aesthetics in implant-supported prostheses: a literature review

A escolha da plataforma protética em implantodontia é fundamental para garantir o sucesso a longo prazo dos procedimentos. Todos os tipos de conexão protética apresentam vantagens e desvantagens, cabendo ao cirurgião-dentista optar pelo o que melhor se adepta ao seu caso. Uma revisão de literatura foi realizada, abrangendo estudos relevantes que compararam essas duas plataformas protéticas em termos de biomecânica e estética. Foram analisadas revisões de literatura e estudos in vitro, sob as palavras-chave "cone morse", "biomechanics", "abuptment". As pesquisas foram feitas nas bases de dados Scielo e PubMed, e os artigos escolhidos deveriam abordar a estabilidade das conexões, a preservação óssea e a estética peri-implantar. Os resultados da revisão demonstram que a plataforma Cone Morse oferece uma interface mais estável, reduz o afrouxamento de parafusos e minimiza a infiltração bacteriana. Com isso, o Cone Morse contribui para a preservação das estruturas ósseas e gengivais ao redor do implante, tornando-se uma escolha valiosa, especialmente em procedimentos de reabilitação estética.

A choice of the prosthetic platform in implant dentistry is fundamental to ensure long-term success of procedures. All types of prosthetic connections have their advantages and disadvantages, and it's up to the dentist to choose what best suits their case. A literature review was conducted, encompassing relevant studies comparing these two prosthetic platforms in terms of biomechanics and aesthetics. Literature reviews and in vitro studies were analyzed using keywords such as "Cone Morse," "biomechanics," and "abutment." The research was conducted on Scielo and PubMed databases, and the selected articles should address connection stability, bone preservation, and peri-implant aesthetics. The review results demonstrate that the Cone Morse platform offers a more stable interface, reduces screw loosening, and minimizes bacterial infiltration. As a result, Cone Morse contributes to the preservation of bone and gingival structures around the implant, making it a valuable choice, especially in aesthetic rehabilitation procedures.

Examining the Impact of Acute Binge Alcohol Consumption on Trabecular Morphometry and Tensile Strength in Adolescent Sprague Dawley Rat Mandibles / Análisis del Impacto del Consumo Excesivo de Alcohol en la Morfometría Trabecular y la Resistencia a la Tracción en Mandíbulas de Ratas Adolescentes Sprague Dawley

SUMMARY: Underage drinking has become a major public concern having a negative impact on the growth and development of the skeleton. Peak bone mass is attained during adolescence hence the aim of the study was to investigate the effect of acute binge alcohol consumption on trabecular morphometry and tensile strength of the adolescent mandible in the Sprague Dawley (SD) rat. The study comprised of 24 SD rats, aged 7 weeks, placed into either the alcohol-exposed [n=12 (6 males and 6 female)] or pair-fed control group [n=12 (6 male and 6 female)]. The treatment of the groups was as follows; the alcohol exposed group and the pair-fed control were administered a single daily dose of 3 g/kg of 20 % alcohol 3 days a week (alternate days) for 7 days and a caloric equivalent dose of maltose dextrin via oral gavage, respectively. The animals were terminated on day 7 via pentobarbital injection. The mandibles were harvested and scanned using a Nikon XTH 255L 3D-microCT scanner (Nikon Metrology, Leuven, Belgium), and biomechanical tests were done using a Shimadzu universal tensile strength testing machine (China). Following scanning and reconstruction, the trabecular morphometry was assessed using Volume Graphics Studio® software. A 3-point bending test was used to evaluate the tensile strength of the bone. Findings from our study showed changes in some trabecular parameters in the female alcohol-exposed group, while the male groups remained unaffected. No changes in tensile strength were seen when comparing male pair-fed control and alcohol-exposed groups and when comparing female pair-fed control and alcohol-exposed groups. Trabecular and tensile strength differences were observed between the sexes when comparing male pair-fed control and alcohol-exposed groups to female pair-fed control and alcohol-exposed groups. These findings do suggest that acute binge alcohol consumption has detrimental effects on the bone micro-architecture in female alcohol-exposed rats and that differences are seen between the sexes.

El consumo de alcohol entre menores de edad se ha convertido en una importante preocupación pública que tiene un impacto negativo en el crecimiento y desarrollo del esqueleto. La masa ósea máxima se alcanza durante la adolescencia, por lo que el objetivo del estudio fue investigar el efecto del consumo excesivo de alcohol en forma aguda sobre la morfometría trabecular y la resistencia a la tracción de la mandíbula en ratas adolescente Sprague Dawley (SD). El estudio estuvo compuesto por 24 ratas, de 7 semanas de edad, colocadas en el grupo control expuesto al alcohol [n=12 (6 machos y 6 hembras)] y alimentado en parejas [n=12 (6 machos y 6 hembras)]. El tratamiento de los grupos fue el siguiente; al grupo expuesto al alcohol y al control alimentado en parejas se les administró una dosis única diaria de 3 g/kg de alcohol al 20 % 3 días a la semana (días alternos) durante 7 días y una dosis equivalente calórica de maltosa dextrina mediante sonda oral, respectivamente. Los animales fueron sacrificados el día 7 mediante inyección de pentobarbital. Las mandíbulas se recolectaron y se escanearon utilizando un escáner 3D-microCT Nikon XTH 255L (Nikon Metrology, Lovaina, Bélgica), y las pruebas biomecánicas se realizaron utilizando una máquina de prueba de resistencia a la tracción universal Shimadzu (China). Después del escaneo y la reconstrucción, la morfometría trabecular se evaluó utilizando el software Volume Graphics Studio®. Se utilizó una prueba de flexión de 3 puntos para evaluar la resistencia a la tracción del hueso. Los hallazgos de nuestro estudio mostraron cambios en algunos parámetros trabeculares en el grupo de hembras expuestas al alcohol, mientras que los grupos de machos no se vieron afectados. No se observaron cambios en la resistencia a la tracción al comparar los grupos control de machos alimentados en parejas y los grupos expuestos al alcohol y al comparar los grupos control de las hembras alimentadas en parejas y los grupos expuestos al alcohol. Se observaron diferencias trabeculares y de resistencia a la tracción entre los sexos al comparar los grupos control de los machos alimentados en parejas y expuestos al alcohol con los grupos de control de hembras alimentadas en parejas y expuestas al alcohol. Estos hallazgos sugieren que el consumo excesivo de alcohol tiene efectos perjudiciales sobre la microarquitectura ósea en ratas hembras expuestas al alcohol y que se observan diferencias entre los sexos.

Effects of Biomimetic Shoes on Healthy Young Children's Gait / Efeitos do uso de calçado biomimético na marcha de crianças típicas

Abstract Objective To compare the spatial-temporal parameters and walking kinematics of toddlers wearing biomimetic shoes, regular shoes (daily use owned shoes), and barefoot. Methods Spatial-temporal parameters (speed, step length, and stride width), the mean vertical displacement of the center of mass (COM), knee flexion peak, and maximal foot height were analyzed. Results Children were not different in biomimetic shoes and barefoot conditions on speed, step length, and COM vertical displacement. There was no difference among conditions on stride width and foot height. The knee flexion peak was greater in shod conditions than barefoot. The regular shoes showed greater COM vertical displacement than biomimetic shoes and barefoot. Conclusion The findings showed that shoes affected the walking pattern in young children, but a shoe with a biomimetic design had a lesser effect on the walking pattern.

Resumo Objetivo O objetivo deste trabalho foi comparar os parâmetros espaço temporais e cinemáticos da marcha de crianças típicas em três condições: descalças, usando calçados biomiméticos e, calçados de uso diário (não biomiméticos - próprios das crianças). Métodos Foram analisadas variáveis espaço temporais (velocidade, comprimento e largura da passada), deslocamento vertical do centro de massa (CM), pico de flexão do joelho e altura máxima do pé, coletados via avaliação tridimensional do movimento. Resultados Comparado com a condição descalça, o uso do calçado biomimético não foi estatisticamente diferente em relação a velocidade da marcha, comprimento da passada e altura do pé. A largura da passada e a altura do pé não foi diferente estatisticamente entre as condições estudadas. O pico de flexão do joelho foi maior nas condições com calçados comparado a condição descalça. Os calçados de uso diário apresentaram maior deslocamento vertical do COM do que nas condições com o calçado biomimético e descalço. Conclusão Os achados deste trabalho reafirmam que o uso do calçado influencia a marcha de crianças, especificamente na fase de desenvolvimento da marcha mas, que calçados com um design biomimético tem menores impactos no padrão de marcha das crianças.