Analysis of infection related factors and clinical characteristics after percutaneous vertebral augmentation procedures

Objective Based on the clinical study of patients infected after percutaneous vertebral augmentation procedures (PVAP), the infection related factors and clinical characteristics were analyzed to provide basis for early prevention and diagnosis. Methods A retrospective study was conducted to analyze the diagnosis and treatment process and prognosis of 5 patients with infection after PVAP in Shanghai Ninth Peaple's Hospital from December 2017 to November 2023. Results There were 3 males and 2 females, aged 68-81 years, with an average age of 74.8 years. The time from operation to infection was 5-24 months. All patients presented with low back pain, the visual analogue scale (VAS) score was 7-8. All patients had imited thoracolumbar movement, local tenderness and percussion pain. Four patients had nerve symptoms such as decreased muscle strength in both lower limbs to varying degrees, 2 of which accompanied by defecation disorder. In laboratory tests, white blood cell (WBC) count was (4.0-7.3）×109/L, C-reactive protein (CRP) was 1.51-66.00 mg/dL, erythrocyte sedimentation rate (ESR) was 2-94 mm/1 h, and procalcitonin (PCT) was 0.10-0.40 ng/mL. X-ray, CT and MRI indicated the manifestations of infection, etiology and pathology confirmed 4 cases of Mycobacterium tuberculosis, of which 1 case was complicated with Acinetobacter baumannii, and the other case was diagnosed with Staphylococcus epidermidis. At the last follow-up, 2 patients died of complications, 3 patients were relieved of low back pain after surgery combined with drug treatment, body temperature was normal and inflammatory indicators were within the normal reference value range, and imaging examination showed no signs of infection. Conclusion Adequate preoperative assessment， symptomatic treatment of complications, and standard operation during the operation can reduce the incidence of infection after PVAP. If infection occurs, early diagnosis and systematic treatment can obtain good results

Finite element analysis of displacement actuator based on giant magnetostrictive thin film

With the rapid development of science and technology, mechanical and electrical equipment become more and more miniature. In order to achieve precise control in less than 1cm3, the giant magnetostrictive thin film has become a research hotspot. The micro displacement actuator with planar and arc film is designed by the dynamic coupling model based on J-A model and magneto-mechanical effect method which is proposed in this paper. The different structure and thickness of films are analyzed by COMSOL Multiphysics software when the current flows through driving coil. After comparing the simulation results with the test ones, it can be seen that the coupling model is accurate and the structure is reliable. At the same time, MATLAB is used to fit the current density-displacement curve and higher order equation is obtained, and then the feasibility of design can be verified. The actuator with arc structure had advantages of small volume, fast response, high precision, easy integration, etc., which has a broad application prospect in the field of vibration control, micro positioning, robot and so on