ABSTRACT
The research progress in fatigue protocols and biomechanics of lower extremity and its relationship with injury induced by exercise-induced fatigue was reviewed in this paper. At present, fatigue protocols can be divided into the traditional fatigue-induced protocol and the functional fatigue-induced protocol under laboratory condition. The former mainly includes power-cycling model, treadmill run model and step-ups model, while the latter is closer to what is experienced during competition, which is usually shown as multidirectional movements. In addition, the biomechanical measures of exercise-induced fatigue mainly include kinematics, ground reaction force, joint mechanics and electromyography. Different fatigue protocols do not uniformly produce alterations in lower limb biomechanical factors. The refinement of fatigue protocols and specific indicators should be considered in future studies, in order to compare the induced effects of fatigue protocols and provide references for the selection of fatigue protocols in laboratory tests. Meanwhile, the relationship between the response of brain-nerve system and the activation of musculoskeletal system for specific athletic task should be focused, so as to understand the difference of biomechanical mechanisms between fatigue protocols and further explore the effect of exercise-induced fatigue on sports injuries.
ABSTRACT
PURPOSE: Chemically strong-acids (HF and HCl/H₂SO₄) dual etching implant surfaces have higher strengths of osseointegration than machined implant surfaces. However, the dual acid treatment deteriorates the physical properties of the titanium by weakening the fatigue resistance of the implant and causing microcracks. The removal torque comparison between the dual-acid etched (hydrochloric acid, sulfuric acid, HS) and single-acid etched implants (hydrochloric acid, H) could reveal the efficiency of implant surface acid treatment. MATERIALS AND METHODS: Nine 3.75 × 4 mm dual-acid etched SLA implants and nine single-acid etched SLA implants were inserted into New Zealand rabbit tibias. After 10 days, removal torque, roughness, and wetting angle were measured. RESULTS: Mean removal torque values were as follows: Mean removal torque were 9.94 Ncm for HS group and 9.96 Ncm for H group (P=.995). Mean surface roughness value were 0.93 µm for HS group and 0.84 µm for H group (P=.170). Root mean square roughness (RSq) values were 1.21 µm for HS group and 1.08 µm for H group (P=.294), and mean wetting angle values were 99° for HS group and 98° for H group (P=.829). Statistical analysis showed no significant difference between the removal torques, roughness, or wetting angles of the two groups. CONCLUSION: In this experiment, we found no significant difference in removal torque, roughness, or wetting angle between dual-acid etched and single-acid etched implants.
Subject(s)
Rabbits , Fatigue , Osseointegration , Sulfur , Tibia , Titanium , TorqueABSTRACT
ABSTRACT Introduction: the use of titanium miniplates is the gold standard in the treatment of facial fractures. A Colombian company has developed a system of osteosynthesis miniplates for the treatment of facial fractures, which was chemically and mechanically compared with an imported system. Methods: comparative in-vitro tests were carried out to analyze the chemical composition and the biomechanical behavior of the national and imported systems. A sample of 36 items was selected, including 24 miniplates and 12 screws, in order to mechanically assess their materials by means of tensile and flexural tests for the plates and torque strength tests for the screws, and to perform a microscopic analysis of the chemical composition of the plates of both brands by means of scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Results: The findings showed that there are no major differences in terms of the chemical composition and the biomechanical behavior of the implants of both brands (national and imported) when assessing plates and screws separately. Conclusions: the results showed a higher content of titanium in the material of national plates; however, the mechanical properties of both brands are very similar. Taking into account the material′s biomechanical characteristics, either system is a good choice when selecting a device for rigid internal fixation of facial fractures.
RESUMEN Introducción: el uso de miniplacas de titanio representa el estándar de oro en el tratamiento de las fracturas faciales. Una empresa colombiana desarrolló un sistema de miniplacas de osteosíntesis para el tratamiento de fracturas faciales, el cual fue comparado química y mecánicamente con un sistema importado. Métodos: se realizaron pruebas in vitro comparativas para analizar la composición química y el comportamiento biomecánico del sistema nacional y del importado. Se seleccionó una muestra total de 36 elementos de prueba, de los cuales 24 eran miniplacas y 12 tornillos, con el fin de evaluar el material mecánicamente por medio de pruebas de tracción y flexión para las placas y pruebas de resistencia al torque para los tornillos, y realizar un análisis microscópico y de la composición química de las placas de ambas marcas por medio de Microscopía Electrónica de Barrido (SEM) y Energy Dispersive Spectroscopy (EDS). Resultados: los hallazgos mostraron que no existen grandes diferencias en cuanto a la composición química y el comportamiento biomecánico entre los implantes de ambas marcas (nacional e importado), al evaluar las placas y los tornillos por separado. Conclusiones: los resultados mostraron un mayor contenido de titanio en el material de las placas nacionales; sin embargo, se encontró que las propiedades mecánicas de ambas marcas son muy similares. Teniendo en cuenta las características biomecánicas del material, cualquiera de los dos sistemas es una buena alternativa en el momento de elegir un dispositivo para la fijación interna rígida de fracturas faciales.