Influence of cement-augmented pedicle screws with different volumes of polymethylmethacrylate in osteoporotic lumbar vertebrae over the adjacent segments: A 3D finite element analysis

Abstract

Background: Polymethylmethacrylate (PMMA) is commonly used for cement-augmented pedicle screw instrumentation (CAPSI) to improve the fixation stability and reduce the risk of screw loosening in the osteoporotic thoracolumbar spine. Biomechanical researches have shown that various dose of cement (1-3ml) can be injected to enhance screw stability. To date, there have been no studies on the relationship between adjacent segment degeneration and the volume of PMMA. This study aimed to explore the influence of CAPSI with different volumes of PMMA in osteoporotic lumbar vertebrae over adjacent segments by using finite element analysis.Methods: Seven different finite element models were reconstructed and simulated under different loading conditions, including (1) an intact model, (2) three single-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml), and (3) three double-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml). To improve the accuracy of the finite element analysis, the models of the injectable pedicle screw and bone cement were created by using a three-dimensional scanning machine and the CAPSI patient’s CT data, respectively. The range of motion (ROM), the stress of intervertebral discs, and the stress of facet in the adjacent segment were comparatively analysed among the different models.Results: The ROMs of the different segments were compared with experimental data, with good agreement under the different load conditions. Compared with the intact model, the ROM, disc stresses, and facet stress in adjacent segments were found to be higher in the six operative models. Otherwise, with a larger volume of PMMA injected, the ROM, disc stresses, and facet stress slightly increased at the adjacent segment. However, the differences among the augmented models were insignificant for all loading cases.Conclusions: CAPSI could increase the incidence of disk degeneration in the adjacent segment, while within a certain range, different volumes of PMMA provided an approximate impact over the adjacent segment degeneration.

Risk Factors for Pulmonary Cement Embolism (PCE) After Polymethylmethacrylate Augmentation: Analysis of 32 PCE Cases

“…38 Based on the above risk factors and our experience, we recommend injecting cement with a toothpaste-like viscosity in small doses multiple times (0.1 mL-0.2 mL for each injection) and under continuous fluoroscopic monitoring. 2,39,40 Some measures, including keeping the tip of screw/puncture needle away from the midline of the vertebral body, 5 reduce the volume of cement, 13 and limit the number of augmented vertebral body, 40 could also be useful to prevent cement leakage and to contribute to reductions in the incidence of PCE. Additional risk factors for PCE have also been reported in the literature.…”

“…Since Galibert and Deramond first described the use of percutaneous vertebroplasty (PVP) for the treatment of symptomatic vertebral hemangioma in 1984, 1 cement augmentation with polymethylmethacrylate (PMMA) has been widely used in the treatment of painful vertebral fractures and osteoporosis-relat-ed degenerative spine disorders. 2 PMMA bone cement is heavily used in PVP, percutaneous kyphoplasty (PKP), and cementaugmented pedicle screw instrumentation (CAPSI) owing to the rapid and durable stability improvements of the fracture area and bone-screw interface. 3,4 However, these surgical procedures also bear a high risk of cement leakage into the vertebral venous system and fracture gaps.…”

Finite element analysis of proximal femoral nail anti-rotation in the treatment of osteoporotic AO3.3 intertrochanteric fracture

“…We perform a biomechanical study to determine which treatment is better amongst the available treatment options for type A3.3 intertrochanteric fractures with different degrees of osteoporosis using the finite element method, thereby providing reference information for clinical treatment. STL files for smooth optimization, surface mesh reconstruction, and surface fitting [8]. After this, a 3D smooth right femur model was obtained.…”