| Part One Micro-hardness distribution of humeral shaft in human skeletonObjective:To measure and analyze the distribution and significance of bone hardness at different levels and directions of humerus shaft.Methods:3 humeral shafts from fresh cadaver specimens were included in this study,and were cut with diamond saw in the vertical of shaft`s long axis horizontal equidistant exactly into 7 levels?3 mm specimen?,and each layer was divided into anterior,posterior,medial and lateral four areas.Vickers microhardness diamond pressure head was used in the specimen surface to achieve hardness measurement,HV?kgf/mm2?.The distribution of hardness was recorded and analyzed.Results:A total of 84 parts of humeral shaft were measured and 420measurements were made.The average hardness of humeral shaft was?47.52±6.01?HV,the medial part of middle shaft?hardness was biggest?53.77±8.70?HV;and the minimum hardness occurred in posterior part of shaft section??42.02±7.47 mm?HV.The overall hardness of the middle humeral shaft is greater than that of the upper and lower humeral shaft.?level of 7 horizontal layers has the maximum hardness?51.34±7.01?HV.Minimum hardness was?l evel?45.72±6.25?HV.The overall hardness of the posterior humerus?45.28±6.47?HV was lower than that of the lateral humerus?49.12±5.22?HV,the medial humerus?48.28±6.10?HV,and the anterior humerus?47.40±5.55?HV?P<0.005?.Conclusion:This study found that there were differences in the micro-hardness of the humerus diaphyseal cortex at different levels and in the orientation of the bone.The data of this distribution can be used to guide the design of 3D-printed implants adapted to the characteristics of bone stress conduction under physiological conditions.It can also provide data support for bone modeling and finite element analysis of bone biomechanical properties under simulated physiological state.Part two Micro-hardness distribution of clavicle in human skeletonObjective:The purpose of the study was to investigate the detailed hardness distribution of human clavicle by using the Vickers microhardness tester,and study its characteristics of the hardness.The digital basis was provided for the artificial bone with the same elastic modulus of the human clavicleMethods:Three fresh right clavicles taken from cadaver donors were excluded and divided into three segments in accordance with the Allman classification of the clavicle fracture:the proximal segment,the middle segment and the distal segment.15 3-mm thick bone specimens were prepared by cutting perpendicular to the lone axix,and a total of 45 specimens were produced from the three clavicles.At the same time,according to the anatomical location,the cortical bone shell of each bone specimen is further divided into four quadrants:anterior?A?,posterior?P?,superior?S?,inferior?I?directions.The hardness values of different quadrant regions were measured.Five effective hardness values were selected for each quadrant,and 20effective sites were selected for each bone specimen.The average value of all the effective values was used as the hardness value of the region and analyzed to research the characteristics of the hardness distribution.Results:A total of 180 sites and 900 effective indentations of cortical bone were performed on the three clavicles,and a total of 45 sites and 225effective indenations of cancellous bone were measured.We found:1.The overall hardness of the cortical bone on the clavicle were ranged from 14.30 to70.60 HV,with an average of 35.94±8.13 HV?the proximal:33.78±6.08HV,the middle:41.32±6.84HV,the distal:29.70±5.35HV?.2.The overall hardness of the cancellous bone was 30.74±6.17HV?the proximal:29.24±2.87HV,the middle:34.53±5.51HV,the distal:26.34±5.10HV?.3.The maximum hardness of the cortical bone was the 5 level of the middle clavicle;minimum hardness was the 4 level of the distal clavicle.4.The maximum hardness of the cancellous bone was the 5 level of the middle clavicle;minimum hardness was the 5 level of the distal clavicle.5.There was no statistically significant in hardness of different diractions.Conclusions:The hardness values of different anatomical locations of the clavicle are significantly different,but it maybe follow a certain rule.The hardness of the middle segment is significantly higher than the two ends of the clavicle.Part three Incidence of Low-energy Upper Extremity Fractures and its risk factors in Chinese Populations?50 yearsObjective:To investigate the incidence of low-energy upper extremity fracture and identify the associated risk factors in Chinese?50 yearsMethods:This study was a part of Chinese National Fracture Survey,which was performed between January and May 2015,which aimed to investigate the epidemiology of traumatic fracture in 2014 in China.The CNFS was registered with the Chinese Clinical Trial Registry,number ChiCTR-EPR-15005878.Stratified multistage cluster randomized sampling method was used to recruit subjects and the survey was made in habitants through the questionnaire survey manner.The relevant results have been published elsewhere.In the current study,154099 Chinese men and women aged 50 years or older were included for data collection and analysis.The low-energy fracture was defined as the fractures that were caused by simple fall from the standing height.Individuals who had low-energy upper extremity fractures were defined as case group and the remaining were defined as control group.Univariate and multivariate logistics regression analysis models were constructed to investigate the independent risk factors,after adjustment for confounding variables.Results:Totally,184 patients sustained low-energy upper extremity fractures in 2014,indicating the overall incidence was 119.4/100000 persons,with 57.4 and 180.9/100000 person-year in men and women.About 80%of fractures occurred at home and on the common road.In men,alcohol consumption,residence at?2nd floor without elevator,sleep duration<7h/d and history of past fracture were identified as significant risk factors.In women,obesity?BMI?28.0?,living in middle region,higher latitude zone?40-49.9°N?,alcohol consumption,more births,sleep duration<7h/d,and history of past fracture were identified as significant risk factors.Conclusion:Based on these results,health policies that focus on decreasing alcohol consumption and encouraging individuals to improve their sleep quality and duration should clearly be implemented in China.The significance of changing living place to a ground floor or to a building equipped with elevator for men,and maintaining a healthy bodyweight for women,should be emphasized to prevent upper extremity fractures.Part four Finite element analysis of anatomic locking plate and herbert screw for treating midshaft clavicle fracturesObjective:This study aimed to present a finite element analysis of biomechanical properties of midshaft clavicle fractures treated with Herbert screw and anatomic locking plate.Methods:The FE model of the intact clavicle was reconstructed from CT images of a young female volunteer.The midshaft clavicular fractures fixed with Herbert screw and anatomic locking plate were built.Axial compression,cantilever bending and axial torsion were applied at the distal end of the clavicle.Meanwhile,the clavicle displacement,stress distributions and peak stresses were calculated.Results:In present study,the anatomic locking plate exhibite enhanced cantilever bending stiffness,reduced axial compression stiffness.However,the Herbert screw represented an similar but less stiffness than those of the intact clavicle.The stress distributions of the Herbert screw fixation model which showed the greater peak bone and implant stresses in three loading modes were similar to those of the intact clavicle model.However,the stress distributions of the anatomic locking plate fixation model showed obvious stress shielding.The stress at the site where the implant and clavicle were in contact showed a smooth transition.The stresses were uniformly distributed on the Herbert screw and anatomic locking plate.Conclusions:Herbert screw is suitable for the treatment of simple displaced clavicluar fractures.Meanwhile,the shoulder excessive activities and weight bearing should be avoided after operation.Anatomic locking plate fixation showed greater stability,but had an obvious stress shielding.Therefore,anatomic locking plate fixation maybe preferred for patients who demands early return to activity.Summary:1.This study found that there were differences in the micro-hardness of the humerus diaphyseal cortex at different levels and in the orientation of the bone.The data of this distribution can be used to guide the design of3D-printed implants adapted to the characteristics of bone stress conduction under physiological conditions.It can also provide data support for bone modeling and finite element analysis of bone biomechanical properties under simulated physiological state.2.The hardness values of different anatomical locations of the clavicle are significantly different,but it maybe follow a certain rule.The hardness of the middle segment is significantly higher than the two ends of the clavicle.The microhardness distribution of the clavicle can provide a digital basis for the artificial bone with the same elastic modulus of the human clavicle,and can provide theoretical support for the basic research of clavicle injury and disease.3.Based on these results,health policies that focus on decreasing alcohol consumption and encouraging individuals to improve their sleep quality and duration should clearly be implemented in China.The significance of changing living place to a ground floor or to a building equipped with elevator for men,and maintaining a healthy bodyweight for women,should be empha-sized to prevent upper extremity fractures.4.Herbert screw is suitable for the treatment of simple displaced clavicluar fractures.Meanwhile,the shoulder excessive activities and weight bearing should be avoided after operation.anatomic locking plate fixation showed greater stability,but had an obvious stress shielding.Therefore,anatomic locking plate fixation maybe preferred for patients who demands early return to activity. |
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