ABSTRACT
The aim of the present study was to evaluate the biomechanical mechanism of injuries of the thoracolumbar junction by the methods of a backward fall simulation experiment and finite element (FE) analysis (FEA). In the backward fall simulation experiment, one volunteer was selected to obtain the contact force data of the sacrococcygeal region during a fall. Utilizing the fall data, the FEA simulation of the backward fall process was given to the trunk FE model to obtain the stress status of local bone structures of the thoracolumbar junction during the fall process. In the fall simulation test, the sacrococcygeal region of the volunteer landed first; the total impact time was 1.14±0.58 sec, and the impact force was up to 4,056±263 N. The stress of thoracic (T)11 was as high as 42 MPa, that of the posterior margin and the junction of T11 was as high as 70.67 MPa, and that of the inferior articular process and the superior articular process was as high as 128 MPa. The average stress of T12 and the anterior margin of lumbar 1 was 25 MPa, and that of the endplate was as high as 21.7 MPa, which was mostly distributed in the back of the endplate and the surrounding cortex. According to the data obtained from the fall experiment as the loading condition of the FE model, the backward fall process can be simulated to improve the accuracy of FEA results. In the process of backward fall, the front edge of the vertebral body and the root of vertebral arch in the thoracolumbar junction are stress concentration areas, which have a greater risk of injury.
ABSTRACT
BACKGROUND: Cervical tuberculosis accounts for only 4.2%-12% of the total incidence of spinal tuberculosis cases. Although antituberculosis drugs have been the mainstay treatment of cervical tuberculosis, they have been ineffective against the symptoms of existing spinal deformities and spinal cord compression, which often require surgical intervention. The conventional surgical methods have been anterior debridement and titanium mesh, cage bone graft fusion and internal fixation. However, all have certain deficiencies regarding the stability of fixation. CASE DESCRIPTION: We have presented the case of a 41-year-old Chinese man who had been experiencing neck pain and stiffness for 1 month. The symptoms had been accompanied by low-grade fever and repeated night sweats. The purified protein derivative test result was positive and the antituberculosis test result was negative. Imaging examination showed destruction of the C5 and C6 vertebral bodies and C5 andC6 intervertebral discs, with an intensive abscess at the C5-C6 vertebral level. After 3-dimensional printing-assisted anterior debridement and artificial vertebral body replacement, his preoperative symptoms of neck pain and stiffness had been alleviated. Also, his symptoms of numbness in both upper limbs had disappeared completely. At the last follow-up examination, he had recovered well and the tuberculosis focus had been completely cured. CONCLUSION: To the best of our knowledge, we have reported the first clinical application of 3-dimensional printing-assisted cervical anterior bilateral pedicle screw fixation of an artificial vertebral body. We accomplished ultrashort segment fixation, with excellent clinical outcomes obtained, which were maintained at the recent 2-year follow-up examination.
