Objectives: To investigate foot transverse arch biomechanical stability contributed by the second metatarsal and the three ligaments connecting medial cuneiform to the second metatarsal base.Methods: Six fresh-frozen ...Objectives: To investigate foot transverse arch biomechanical stability contributed by the second metatarsal and the three ligaments connecting medial cuneiform to the second metatarsal base.Methods: Six fresh-frozen cadaveric lower extremities were dissected to expose the展开更多
Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply...Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure.展开更多
The majority of foot deformities are related to arch collapse or instability,especially the longitudinal arch.Although the relationship between the plantar fascia and arch height has been previously investigated,the s...The majority of foot deformities are related to arch collapse or instability,especially the longitudinal arch.Although the relationship between the plantar fascia and arch height has been previously investigated,the stress distribution remains unclear.The aim of this study was to explore the role of the plantar ligaments in foot arch biomechanics.We constructed a geometrical detailed three-dimensional (3-D) finite element (FE) model of the human foot and ankle from computer tomography images.The model comprised the majority of joints in the foot as well as bone segments,major ligaments,and plantar soft tissue.Release of the plantar fascia and other ligaments was simulated to evaluate the corresponding biomechanical effects on load distribution of the bony and ligamentous structures.These intrinsic ligaments of the foot arch were sectioned to simulate different pathologic situations of injury to the plantar ligaments,and to explore bone segment displacement and stress distribution.The validity of the 3-D FE model was verified by comparing results with experimentally measured data via the displacement and von Mise stress of each bone segment.Plantar fascia release decreased arch height,but did not cause total collapse of the foot arch.The longitudinal foot arch was lost when all the four major plantar ligaments were sectioned simultaneously.Plantar fascia release was compromised by increased strain applied to the plantar ligaments and intensified stress in the midfoot and metatarsal bones.Load redistribution among the centralized metatarsal bones and focal stress relief at the calcaneal insertion were predicted.The 3-D FE model indicated that plantar fascia release may provide relief of focal stress and associated heel pain.However,these operative procedures may pose a risk to arch stability and clinically may produce dorsolateral midfoot pain.The initial strategy for treating plantar fasciitis should be non-operative.展开更多
A good knowledge of midfoot biomechanics is important in understanding the biomechanics of the entire foot,but it has never been investigated thoroughly in the literature.This study carried out in vitro experiments an...A good knowledge of midfoot biomechanics is important in understanding the biomechanics of the entire foot,but it has never been investigated thoroughly in the literature.This study carried out in vitro experiments and finite element analysis to investigate the midfoot biomechanics.A foot-ankle finite element model simulating the mid-stance phase of the normal gait was developed and the model validated in in vitro experimental tests.Experiments used seven in vitro samples of fresh human cadavers.The simulation found that the first principal stress peaks of all midfoot bones occurred at the navicular bone and that the tensile force of the spring ligament was greater than that of any other ligament.The experiments showed that the longitudinal strain acting on the medial cuneiform bone was-26.2±10.8μ-strain,and the navicular strain was-240.0±169.1μ-strain along the longitudinal direction and 65.1±25.8μ-strain along the transverse direction.The anatomical position and the spring ligament both result in higher shear stress in the navicular bone.The load from the ankle joint to five branches of the forefoot is redistributed among the cuneiforms and cuboid bones.Further studies on the mechanism of loading redistribution will be helpful in understanding the biomechanics of the entire foot.展开更多
Foot plantar fascia is a kind of important tissue in stabilizing the longitudinal arch of human foot. Direct measurement to monitoring the mechanical situation of plantar fascia at human locomotion is very difficult. ...Foot plantar fascia is a kind of important tissue in stabilizing the longitudinal arch of human foot. Direct measurement to monitoring the mechanical situation of plantar fascia at human locomotion is very difficult. The purpose of this study is to construct a three-dimensional finite element model of the foot to calculate the internal stress/strain value of plantar fascia during different stages of the gait. The simulated stress distribution of plantar fascia was the lowest at heel-strike,which concentrated on the medial side of calcaneal tubercle. The peak stress of plantar fascia was appeared at push-off,and the value was more than 5 times of the heel-strike position. Current FE model was able to explore the plantar fascia tension trend at the main subphases of the foot. More detailed fascia models and intrinsic muscle forces could be developed in the further study.展开更多
基金National Natural Science Foundation #30801163,year2008,and#30640058
文摘Objectives: To investigate foot transverse arch biomechanical stability contributed by the second metatarsal and the three ligaments connecting medial cuneiform to the second metatarsal base.Methods: Six fresh-frozen cadaveric lower extremities were dissected to expose the
文摘Simply-supported tied arch is a zero-thrust arch bridge with clear structural force,large stiffness,low height,beautiful appearance and economic efficiency.In Xuzhou-Shanghai section of Beijing-Shanghai HSR,the simply-supported tied arch is systematically studied and widely applied for the first time.A total of 21 simplysupported tied arch bridges with the spans of 96 m,112 m and 128 m respectively are constructed for the route.The simply-supported tied arch is an external static and internal super-static parallel arch or basket arch of Nielsen system in structure;single-box,threechamber and equal-height prestressed concrete box girder is adopted for the tie beam;dumbbell steel pipe concrete section is adopted for the arch rib;PES(FD)low-stress anticorrosion cable body is adopted for the suspender.The rational structural form is determined by comparative study on the key technical parameters such as the layout form of suspender,rise-span ratio and arch axis alignment.This paper summarizes the optimization of simplysupported tied arch structure and looks forward to the development of bridge structure.
基金supported by the National Natural Science Foundation of China(Grant No. 30801163)
文摘The majority of foot deformities are related to arch collapse or instability,especially the longitudinal arch.Although the relationship between the plantar fascia and arch height has been previously investigated,the stress distribution remains unclear.The aim of this study was to explore the role of the plantar ligaments in foot arch biomechanics.We constructed a geometrical detailed three-dimensional (3-D) finite element (FE) model of the human foot and ankle from computer tomography images.The model comprised the majority of joints in the foot as well as bone segments,major ligaments,and plantar soft tissue.Release of the plantar fascia and other ligaments was simulated to evaluate the corresponding biomechanical effects on load distribution of the bony and ligamentous structures.These intrinsic ligaments of the foot arch were sectioned to simulate different pathologic situations of injury to the plantar ligaments,and to explore bone segment displacement and stress distribution.The validity of the 3-D FE model was verified by comparing results with experimentally measured data via the displacement and von Mise stress of each bone segment.Plantar fascia release decreased arch height,but did not cause total collapse of the foot arch.The longitudinal foot arch was lost when all the four major plantar ligaments were sectioned simultaneously.Plantar fascia release was compromised by increased strain applied to the plantar ligaments and intensified stress in the midfoot and metatarsal bones.Load redistribution among the centralized metatarsal bones and focal stress relief at the calcaneal insertion were predicted.The 3-D FE model indicated that plantar fascia release may provide relief of focal stress and associated heel pain.However,these operative procedures may pose a risk to arch stability and clinically may produce dorsolateral midfoot pain.The initial strategy for treating plantar fasciitis should be non-operative.
基金supported by the National Natural Science Foundation of China(11302154,11272273)China Postdoctoral Science Foundation(2013M530211)+1 种基金Opening Project of Shanghai Key Laboratory of Orthopaedic Implants(KFKT2013002)Fundamental Research Funds for the Central Universities
文摘A good knowledge of midfoot biomechanics is important in understanding the biomechanics of the entire foot,but it has never been investigated thoroughly in the literature.This study carried out in vitro experiments and finite element analysis to investigate the midfoot biomechanics.A foot-ankle finite element model simulating the mid-stance phase of the normal gait was developed and the model validated in in vitro experimental tests.Experiments used seven in vitro samples of fresh human cadavers.The simulation found that the first principal stress peaks of all midfoot bones occurred at the navicular bone and that the tensile force of the spring ligament was greater than that of any other ligament.The experiments showed that the longitudinal strain acting on the medial cuneiform bone was-26.2±10.8μ-strain,and the navicular strain was-240.0±169.1μ-strain along the longitudinal direction and 65.1±25.8μ-strain along the transverse direction.The anatomical position and the spring ligament both result in higher shear stress in the navicular bone.The load from the ankle joint to five branches of the forefoot is redistributed among the cuneiforms and cuboid bones.Further studies on the mechanism of loading redistribution will be helpful in understanding the biomechanics of the entire foot.
文摘Foot plantar fascia is a kind of important tissue in stabilizing the longitudinal arch of human foot. Direct measurement to monitoring the mechanical situation of plantar fascia at human locomotion is very difficult. The purpose of this study is to construct a three-dimensional finite element model of the foot to calculate the internal stress/strain value of plantar fascia during different stages of the gait. The simulated stress distribution of plantar fascia was the lowest at heel-strike,which concentrated on the medial side of calcaneal tubercle. The peak stress of plantar fascia was appeared at push-off,and the value was more than 5 times of the heel-strike position. Current FE model was able to explore the plantar fascia tension trend at the main subphases of the foot. More detailed fascia models and intrinsic muscle forces could be developed in the further study.
