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BACKGROUND: In the treatment of osteoporotic vertebral compression fracture, bone-filling mesh container has a significant curative effect. Considering the operation time, lateral leakage of bone cement and the number of radiation exposure, unilateral approach is better. However, no study compared unilateral bone-filling mesh container and bilateral bone-filling mesh container from the perspective of biomechanics, lacking certain theoretical data support. OBJECTIVE: To investigate the biomechanical characteristics and clinical effects of unilateral and bilateral bone-filling mesh container approaches in the treatment of osteoporotic vertebral compression fracture. METHODS: (1) A finite element model was established to simulate the treatment of osteoporotic vertebral compression fracture with unilateral and bilateral bone-filling mesh container. The displacement and stress changes of the whole finite element model of thoracolumbar segment in the unilateral bonefilling mesh container group and bilateral bone-filling mesh container group were compared and analyzed under 400 N vertical downward loading force and 7.5 N·m bending moment load under four working conditions. (2) A retrospective analysis was performed on 99 patients with osteoporotic vertebral compression fracture who were treated with bone-filling mesh container from January 2018 to August 2020 in Wuhan Puren Hospital. Of them, 49 patients were treated with unilateral bone-filling mesh container and 50 patients were treated with bilateral bone-filling mesh container. Bone cement leakage rate, visual analogue scale score, and Cobb angle change were analyzed between the two groups. RESULTS AND CONCLUSION: (1) Finite element model: There was no significant difference in the maximum displacement between unilateral group and bilateral group under axial, forward flexion, left bending, and left rotation conditions (P > 0.05). There was no significant difference in the maximum stress between unilateral group and bilateral group under axial, forward flexion, left bending, and left rotation conditions (P > 0.05). (2) Clinical trial: The bone cement leakage rates in the unilateral and bilateral approach groups were 12% and 16%, respectively, and the visual analogue scale score and scoliosis angle at 6 months after surgery were significantly improved compared with those before operation in both groups (P < 0.001). There was no significant difference in visual analogue scale score and scoliosis angle between the two groups at 6 months after operation (P > 0.05). (3) From the perspective of biomechanics and clinical efficacy, unilateral bone-filling mesh container approach is more effective than bilateral bone-filling mesh container approach in treating osteoporotic vertebral compression fracture. [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]