| Long spiral femoral shaft fracture,which the length of the ramp is more than two times longer than the diameter of the femoral at the level of the fracture,is a special type of fracture that unstable length as the main feature.It frequently due to some type of high-energy violence.With the promotion of social economic level,children's travel and activities increased.The rate of children's long spiral femoral shaft fracture caused by high-energy trauma such as traffic accidents increased year by year.How to treat long spiral femoral shaft fracture is becoming a hot issue in pediatric orthopedic research.Benefiting from the breakthrough of surgery and fixed technology,the treatment of femoral shaft fractures in children is no longer confined to traction and cast,resulting in faster and more reliable treatment.In particular,the elastic intramedullary nail(ESIN)invented by France doctor Metaizeau and Prévot,was recognized as the golden standard treatment of children fracture after nearly 40 years worldwide proved.However,most of studies suggest that this method applies only to the 7-14 ys children's transverse fractures or short oblique fractures of femoral shaft,is not recommended for long spiral fracture,which is length-unstable.There are two main reasons: First,because of the strong capability of younger children,ESIN does not show obvious advantages comparing with non-surgical treatments.Secondly,long spiral fracture can easily lead to the occurrence of angular deformity or shorteningmay,which causes higher rate of complication.But we believe that pre-school children(2-7 years old)also need a fast recovery.Reviewing the literature,we found that it is lack of specific studies at present using elastic intramedullary nail in the treatment of long spiral femoral shaft fracture of preschool children.Clinical study trials have been done in our hospital.ESIN obtained satisfactory therapeutic effect,but lacking theoretical basis.This study is to explore the feasibility and use points of ESIN in the treatment of preschool children in long spiral fracture of femoral shaft by "simulation-biomechanical experiment in vitro-in vivo clinical studies" method.Objective:With the adoptions of such methods as “finite element simulation” and “In vitro biomechanical experiments”,this research compared the influences of the nailing methods of different bent nails on the integral dynamic performances of the post-treatment femur,and analyzed the fixation mechanism of ESIN and optimized the nailing method;through the retrospective comparisons and analysis of the cases,and compared the clinical efficacies and the complication status of the treatments of two kinds of fractures(long spiral fracture vs transverse/short oblique fractures),and analyzed the clinical efficacies of the treatment of femoral long spiral fractures in preschool children,thus providing the applications of this technique with experimental data.Methods:1.Finite element simulation research of the two kinds of ESIN nailing modes for bent nails for the treatments of the femoral long spiral fractures.(1)The digital models of the Long spiral fracture of femur,and after they were combined with the ESIN,they were subject to grid partitioning;(2)Abaqus was adopted for the comparisons of the stress distributions and their characteristics of “fracture vertex nailing” and “symmetrical nailing” at the static condition and at the standing by a single foot;(3)By adopting simulating such loads as the four-point bends,rotation and loads,the anti-bending,anti-rotation and anti-compression stiffness.2.The biomechanics study of the two different kinds of ESIN bent nailing modes and end cap for the treatments of femoral long spiral fracture.(1)24 pieces of standardized artificial femurs for femoral long spiral fractures were randomly divided into 4 experiment groups(n=6),3 were artificial femurs for transverse fractures,which were divided into the Controls;(2)The fixation methods of “fracture vertex nailing(Vertex Nailing,VN)”,“Vertex Nailing with End Cap,VN+EC”,“Symmetrically Nailing,SN”,“Symmetrically Nailing with End Cap,SN+EC” were respectively adopted by the experiment groups,while the conventional symmetrical nailing fixation was conducted on the Control of the transverse fractures without the additions of the end caps;(3)Repeated Measures were adopted for respectively conducting the experiments of four-pint bending,twisting and 0° and 9° compression;(4)The anti-bending strength,rotational stiffness and compression stiffness in the various directions of the intra-group whole femurs were observed and compared.3.The clinical comparisons and studies of the treatments of the two kinds of fractures of the femoral shafts in preschool children(long spiral fracture vs horizontal form/short oblique fractures).Follow-ups were conducted on the 21 cases of the treatments of ESIN in the long spiral fracture of femoral shaft in preschool children(aged 2-7)from January to march,2015,and they were compared with the 59 cases of children patients of transverse/short oblique fractures who were admitted in the same period and treated with ESIN and the general data,surgery time,bleeding during operation,hospitalization charges,fracture healing time,loading time and complication condition of the cases in the two groups were analyzed.Results:1.The convergence test and the model verification proved that the established models were effective.It was revealed by the stress cloud that at the loading positions,in contrast to the symmetric nailing group,the group of fracture vertex nailing provided a bigger force of support at the contact location of with the elastic intramedullary nail(7.54 MPa vs5.33 MPa);meanwhile,the stress distributions in the surroundings of the fracture lines were even,but the residual stress of end of the elastic intramedullary nail was also bigger(177.29 MPa vs156.22MPa).It was indicated by the loading results of the finite element simulation that in contrast to the symmetrical nailing the fracture vertex nailing could effectively elevate the anti-rotation capacity,among which the internal rotation stiffness was elevated by 175%(0.22 Nm/° vs 0.08 Nm/°),and the internal rotation stiffness was elevated by 92%(0.27 Nm/°vs 0.14 Nm/°);in addition,the anti-compression properties of the fracture vertex nailing also feature advantages.2.It was revealed by the in vitro biomechanical experiments that VN+EC group resistance to recurvatu,and the anti-varus stiffness was 1.79±0.19 Nm/mm and 1.12±0.22 Nm/mm,and are more advantageous then various other groups.In comparison to the symmetric nailing group and the Control,the fracture vertex nailing featured stronger anti-rotation capacity(P<0.05);in addition,to the adding of the end cap,such a function was further enhanced.During the 9° physiological positions and 0° axial compression,the treatments of the EN+EC group for the treatment of femoral long spiral fracture could provide the anti-compression stiffness similar to that of the Control of the transverse fractures(514.70±32.86 vs 504.55±25.22,294.99±23.91 vs 298.18±17.33,Nm/mm,P>0.05).3.In this research,80 cases(81 limbs)of the ESIN treatments of long spiral fractures of femur in preschool children,among which 21 cases(22limbs)were long spiral fractures,with an average age of 4.0±1.37 y,and an average follow-up period of 17 months(12~30 months).The average fracture clinical healing time was 7.6±1.4w,and the average complete weight-bearing time 12.1±1.6w.In all the cases,elastic intramedullary nails were removed after 6~10 months after the operation when fractures were healed.Most of the patient children had equal lengths of the double lower limbs,with normal treads,the knee joints had normal mobility and were free of pains;8 cases(long spiral fracture 3 cases)experienced the “irritation” featuring the needle tail skin allergy,which were rapidly healed when the nails were removed;3 cases(1 in long spiral fractures)occured overgrowth more than 1cm of the affected limbs.All cases had no such phenomena as breakage of nails,nails backout,osteomyelitis,epiphyseal injury,post-operative re-displacement,refracture or non-union.Conclusion:In the treatments of the long spiral fractures of femur in preschool children using ESIN,the fixation method of “Vertex Nailing with End Cap,VN+EC” featured properties of higher resistance to recurvatu,anti-varus,anti-rotation and anti-compression than the symmetrically niling method,and the stresses on the fracture site were more even.Cinical research verified that there were no substantial differences in the clinical healing time and complete loading time with both "long spiral" and "transverse/short oblique" fracture patients,and it is a safe and effective way for the treatment of the long spiral fractures of femur in preschool children.However,since ESIN is not a rigid fixation,it is recommended that it should be aided by casting or brace at an early stage after operation. |
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