| In recent years,the incidence of adolescent idiopathic scoliosis has been increasing year by year.For light and moderate scoliosis,orthosis therapy is the most commonly used treatment.At present,the design and manufacture of orthosis still mainly depends on the experience of orthopedists.The research on the mechanism and digital manufacture of scoliosis orthosis has not been fully developed.There are still some problems in the design and manufacture of scoliosis orthosis,such as large error,low precision,and poor correction effect.Therefore,it is very urgent to investigate the scientific design method of scoliosis orthosis,define the trunk orthosis force,and guide the research of orthosis design and 3D printing technology.To solve the above problems,this paper combines digital imaging technology,reverse engineering,finite element method,and fused deposition molding technology to carry out the design of scoliosis orthosis.This paper is the first to propose the elastic foundation beam theory to analyze the simplified model of the human spine muscles,and a design method of orthotics based on the mechanical model is realized.The current clinical experience-oriented artificial manufacturing orthosis was adjusted to a 3D printing orthosis guided by the numerical theory,and a scoliosis orthosis with the characteristics of personalization,precision,universality,and lightweight was designed and manufactured.The wearing study of 31 scoliosis patients(26 girls and 5 boys)was carried out,and good clinical correction effect and high patient satisfaction were obtained,which provided a clear idea and method for the design of scoliosis orthosis.The detailed research contents are as follows:(1)Based on the biomechanical characteristics of human bone,muscle,and other tissue structures,the elastic foundation beam theory is introduced in this paper.The soft tissue such as body surface,muscle,and viscera are characterized as elastic foundation structure,and the spine is characterized as beam structure.A simplified mechanical model of human spinal muscle tissue is constructed.In this paper,a design method of orthosis based on a mechanical model is proposed.According to this method,the functional relationship between trunk correction force and spinal displacement is obtained.Combined with the offset distance between the vertebrae of patients with scoliosis and the physiological curve of the normal spine,the corresponding trunk correction force of the corresponding vertebrae is obtained,which provides a theoretical basis for applying accurate correction force during the spine correction process.(2)Based on human anatomy and human characteristics of adolescent scoliosis patients,a full spine finite element model of musculoskeletal biomechanics patient with scoliosis with detailed anatomical structure was established.Considering the deformity of scoliosis in three-dimensional space,this paper proposes a set of three-dimensional correction objective functions.Considering the deformity of scoliosis in three-dimensional space,this paper proposes a set of three-dimensional correction objective functions.Through the numerical simulation of biomechanics,the three-dimensional correction force based on the optimal correction objective function is obtained,and the accuracy of the correction force calculated by the elastic foundation beam theory is verified.This method provides theoretical guidance for the quantitative and personalized design of the orthosis.(3)Based on the mechanical model of elastic foundation beam,bone functional adaptation and the finite element numerical calculation,a model design and optimization method for scoliosis orthosis was proposed.Using the three-point force correction principle and the trunk correction force function curve,combined with the patient’s scoliosis,the initial model of the orthosis was constructed.Considering the influencing factors of the orthosis structure,the numerical calculation of the orthosis wear under 13 cross factors is carried out to solve the optimal personalized orthosis model.Moreover,based on the topology optimization technology,the structure of the orthosis was optimized,and rapid prototyping manufacturing was carried out.The practicality model of the high-precision orthosis was printed in 3D technology,and the correction effect was compared by wearing the practicality orthosis.The orthosis designed in this paper has the advantages of high correction rate,high accuracy,lightweight,and good air permeability,which verifies the feasibility of the digital design method of the scoliosis orthosis proposed in this paper.(4)Thirty-one adolescent patients with scoliosis were selected,and the orthosis model was designed for each patient in combination with the orthosis design method proposed in this paper.Meantime,the orthosis was processed by 3D printing to obtain the practicality model.The film pressure acquisition system was used to collect the pressure values of each contact position of the trunk and the orthosis when the patient wears the orthosis in six daily activities.The changes of the patient’s scoliolosis correction index were statistics.The experimental results can achieve the expected effect.Based on the fuzzy analytic hierarchy process,a satisfaction evaluation system including the structure,material,environment,and motion characteristics of the orthosis was established,and the patients ’ satisfaction was higher.The results show that the design and manufacturing method of scoliosis orthosis proposed in this paper is reasonable and effective,which provides a new design method for the design of scoliosis orthosis.Based on the theoretical analysis of elastic foundation beam,bone functional adaptation,finite element numerical calculation,3D printing,and experimental measurement,the design and manufacture method of scoliosis orthosis proposed in this paper,which improves the shortcomings in the design and manufacture of traditional scoliosis orthosis.It is of great significance and clinical promotion value for improving the correction effect and research level of scoliosis. |
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