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Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Stress shielding can lead to the failure of implant prostheses to repair bone defects, mainly due to the fact that the elastic modulus of the implant is greater than that of the surrounding bone tissues. OBJECTIVE: To explore methods for eliminating the stress shielding by analyzing the influence of the elastic modulus of the implanted prosthesis on the stress distribution. METHODS: The bone tissue models of experimental canine and human bone tissues were obtained by CT scanning, and then were optimized. The gradient assignment was performed to establish a reliable bone mechanics model, and the finite element simulation was performed after the combination with the implanted prosthesis. First, the finite element simulation of experimental canine and human bone tissues and the corresponding implanted prosthesis was performed to simulate the distribution of stress and displacement of prosthesis with different elastic moduli after prosthesis implantation. Second, the reasons for the stress shielding even with small elastic modulus differences were analyzed. The bone and implant prosthesis models were established, and a method for assigning material properties was established. Finally, the feasibility of the model and material property assignment method was verified, and the influence of the relationship between the elastic modulus of the implanted prosthesis and the elastic modulus of the bone on the formation of stress shielding was quantitatively analyzed by randomly selecting the stress points. RESULTS AND CONCLUSION: The mechanical properties of bone models of experimental canine and human bone tissues established by gradient assignment method are close to the actual bones. The finite element simulation mechanics test proved that the implantation of different elastic modulus had less effect on the relative displacement between the prosthesis itself and the surrounding bones. Moreover, quantifying the effects of elastic moduli on the stress distribution after implantation of the prosthesis into the bone will contribute to the research in the future. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: How to improve the accuracy of puncture, reduce surgical damage, and improve surgical efficiency during vertebroplasty is currently one of the focuses of exploration and improvement in vertebroplasty techniques. OBJECTIVE: To explore the clinical significance of application of mixed reality technology in percutaneous vertebroplasty for spinal fractures. METHODS: Two patients with osteoporotic vertebral compression fracture in Dalian Second People’s Hospital in June 2023 were selected. Before operation, 128-row CT scanning of the lumbar spine was performed and the original data of digital imaging and communications in medicine (DICOM) were obtained. Visual Volume software was used to build the three-dimensional network model of vertebral compression fracture. Holographic imaging glasses were used to accurately map 3D network model images to the real world, assist the surgeon in completing preoperative simulation, explaining preoperative conditions and treatment plans, and guiding puncture and bone cement injection during surgery. RESULTS AND CONCLUSION: (1) Precise puncture was achieved with the assistance of a mixed reality technology. Postoperative imaging examination showed good bone cement filling and no obvious leakage. The postoperative symptoms of the patient were alleviated well, and they were able to move to the ground on the same day after surgery. (2) It is concluded that a mixed reality technology is helpful for preoperative surgical design and communication efficiency with patients and their families. Assisting with precise puncture during surgery, shortening surgical time, and reducing side injuries is a new and effective clinical diagnosis and treatment model, which has development potential in minimally invasive, precise, and personalized treatment of spinal surgery. [ABSTRACT FROM AUTHOR]

BACKGROUND: Sacral lumbarization will lead to changes in spinal segments, so that mechanical structure of spine is going to change, more likely to cause spinal lesions. OBJECTIVE: To analyze statics difference between the sacral lumbarization model and the normal model. METHODS: According to principle of reverse engineering and data based on CT, lumbosacral geometric models were set up. The sacral lumbarization model was in the experimental group and normal model was in the control group. Gradient was attributed to the material based on gray value of CT data and ligament model was set up. A concentrated force of 200 N was applied to the L4 vertebral body surface to simulate gravity. Simultaneously, a moment of 2 N·m was applied to the positive and negative directions of the X axis, Y axis and Z axis to simulate six conditions of sports: anteflexion and posterior extension, right and left lateral flexion and rotation. The stress distribution of the model, the deflection angle of the vertebral body, and the stress distribution between the intervertebral disc L5 and the sacrum were analyzed. RESULTS AND CONCLUSION: (1) Under six conditions, the stress concentration of sacral lumbarization model obviously occurred at the contact of the articular processes of S1 and S2 in the experimental group. Deflection angle was significantly larger in the experimental group than that in the control group. (2) From the stress nephogram of intervertebral disc distribution, the stress distribution area of experimental group and control group was close, which was fit for the stress characteristics of the spine. However, the stress of intervertebral disc in the experimental group was significantly higher than that in the control group. The max value of 2.480 MPa appeared in the experimental group under the anteflexion condition. The max intervertebral disc stress difference value between experimental group and control group was 1.722 5 MPa. (3) To sum up, the overall structure of sacral lumbarization is more unstable. Especially, the stress concentration is more obvious at the junction of transitional vertebra and sacral vertebra, thereby affects the stability of the whole spinal force line, and then leads to the occurrence of spinal diseases. [ABSTRACT FROM AUTHOR]

BACKGROUND: Human bones are characterized by strong nonlinearity and uneven bone distribution. Different elastic modulus assignments lead to great differences in static results. OBJECTIVE: To analyze differences of the three material attribute assigning methods in the numerical simulation analysis of vertebral body. METHODS: Based on the principle of reverse engineering, lumbar L4, L5 and intervertebral disc models were established through image segmentation, and three material attributes were assigned to the vertebral body models: (1) Gray value assignment: Gradient value was assigned by using gray value through Mimics. (2) Homogeneous and gray value mixed assignment: A single elastic modulus was given to the anterior cortical bone of the vertebral body, and gray values were used to give to the cancellous bone of the front end and the pedicle, transverse process and spinous process of the posterior end. (3) Cortical bone and cancellous bone assignment: Two elastic moduli of cortical bone and cancellous bone were used. The finite element model under the three assignment methods was loaded with an axial load of 100-500 N. The bending moments of 2, 4, 6, 8, and 10 N·m were applied to simulate the vertebral body to perform forward flexion, backward extension, left and right lateral bending and left and right rotation. RESULTS AND CONCLUSION: Vertebral body under different loading conditions had obvious differences in axial displacement and deflection angle. Root mean square error analysis showed that compared with the other two methods, data obtained by grey value assignment method were more close to the real experimental data. It did not produce obvious stress step phenomenon in material assignment junction, and could not produce obvious stress concentration phenomenon, was more in line with the mechanical properties of vertebral body. Thus, more accurate statics analysis of the spine can be carried out. [ABSTRACT FROM AUTHOR]

BACKGROUND: Paravertebral muscles play an important role in maintaining spinal balance. The finite element model of skeletal muscle is more close to the biomechanical environment of human body. However, the muscle modeling in the finite element analysis of the spine is more complex or the muscle force is simplified in the current finite element analysis of the spine. OBJECTIVE: To quickly establish the paravertebral muscle model and analyze loading of muscle force. METHODS: Based on the principle of reverse engineering, the three-dimensional reconstruction of the spine model was carried out through CT image data. The spring stiffness of the longest lumbar muscle and ligament in the erector spinalis muscle was calculated through the elastic modulus, muscle crosssectional area and average length of muscle line. The muscle modeling was carried out through the upper and lower attachment points, and the biomechanical verification of the established finite element model was carried out. The lumbar spine was simulated by applying a bending moment of 4 N•m for flexion and extension, left and right lateral bending, left and right rotation. RESULTS AND CONCLUSION: (1) Biomechanical verification showed that L4-L5 showed elastic properties under axial load. (2) Through the analysis of lumbar flexion and extension, left-right lateral bending and left-right rotation, a finite element model of skeletal muscle was established, which was consistent with the range of motion of lumbar spine. (3) The finite element model of lumbar spine with muscle tissue conforms to the biomechanical characteristics of human body, which provides a reference for analyzing the changes of the spine under orthopedic force. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shenzhen University Science & Engineering is the property of Editorial Department of Journal of Shenzhen University Science & Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: In recent years, artificial intelligence technology has been widely used in various fields of the medical industry, effectively assisting doctors in the diagnosis and treatment of patients. In the conservative treatment of adolescent idiopathic scoliosis, artificial intelligence technology can be applied to the design of adolescent idiopathic scoliosis orthosis, thereby shortening the manufacturing cycle of adolescent idiopathic scoliosis orthosis. OBJECTIVE: To design and implement an adolescent idiopathic scoliosis orthosis design expert system based on fuzzy logic. With the help of the expert system, it can help physicians to design adolescent idiopathic scoliosis orthosis quickly and effectively. METHODS: The adolescent idiopathic scoliosis orthosis design expert system is developed through the hybrid programming of C Language Integrated Production System and C++. The main function modules of adolescent idiopathic scoliosis orthosis design expert system include fuzzy inference engine, agenda, knowledge base management system, knowledge base, fact base, interpreter, and human-computer interface. Aiming at the uncertain information in the design of scoliosis orthosis, the knowledge representation of adolescent idiopathic scoliosis orthosis design is realized by fuzzy set theory, and the reasoning of adolescent idiopathic scoliosis orthosis design is realized by fuzzy reasoning based on certainty factor. The feasibility of the design method of adolescent idiopathic scoliosis orthosis design expert system based on fuzzy logic was verified by the treatments of two cases of adolescent idiopathic scoliosis patients. RESULTS AND CONCLUSION: (1) The adolescent idiopathic scoliosis orthosis design expert system improved the design efficiency of scoliosis orthosis by 50% and the deviation rates between the reasoning values and the actual operation values of experts were less than 10%. (2) Therefore, the adolescent idiopathic scoliosis orthosis design expert system can assist physicians to design adolescent idiopathic scoliosis orthosis quickly and effectively. [ABSTRACT FROM AUTHOR]

BACKGROUND: The design and manufacture of traditional spinal brace have the disadvantages of poor fit and long processing cycle. The use of computer-aided design and 3 D printing of the spinal brace has the advantages of individualization, accurate correction position and short design time.OBJECTIVE: This study combines computer aided engineering, biomechanical analysis and fused deposition modeling technology to propose a feasible scheme of 3 D printing for spine brace. METHODS: A finite element model of an adolescent idiopathic scoliosis patient based on human anatomy was constructed in volunteers with idiopathic scoliosis. Based on patient profile information and three-point stress principle, brace model was parameterized and its biomechanical properties were analyzed. The patient signed the informed consent. This study was approved by the Hospital Ethics Committee. The brace was optimized by finite element analysis to obtain the optimal brace model. The brace model was printed by 3 D printing technology. Finally, the wearing evaluation of patients was carried out. RESULTS AND CONCLUSION:(1) The biomechanical properties of wearing brace were analyzed by finite element method to predict its corrective effect. Ten groups of different sizes of tightening force were applied to the position of thoracic and lumbar scoliosis. The maximum correction rates of thoracic and lumbar scoliosis were 78% and 82%, respectively.(2) Topology optimization analysis of brace was carried out by setting 10 groups of optimization parameters. According to the results, the brace was reduced properly, and then the model was transferred to a 3 D printer to print the brace quickly.(3) The patient wore brace and gave feedback. According to the feedback of evaluation, the spine brace designed digitally is more suitable for patients and has higher correction rate.(4) The scheme of making spine brace by using 3 D printing is feasible, and it can provide reference for the follow-up application of 3 D printing brace in clinical rehabilitation. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)