Fixation stability comparison of bone screws based on thread design: buttress thread, triangle thread, and square thread

Feng, Xiaoreng; Luo, Zhaopei; Li, Yupeng; Yao, Yanlai; Qi, Weichen; Chen, Bin; Liang, Hongfeng

doi:10.1186/s12891-022-05751-6

Cited by 3 publications

(1 citation statement)

References 37 publications

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“…We ensured that the screws and the pullout force were directed along the same axis by clamping the potted specimen in a way that enabled free rotation about the axis, and the direction of the pullout force could be adjusted through the polyaxial design of the adaptor. The screws were then loaded in displacement control mode at a constant displacement rate of 5 mm/min for a total displacement of 10 mm, which is in accordance with published literature on axial pull-out testing 42 – 44 . Data collection was set at 1 sample/0.05 mm.…”

Section: Methodsmentioning

confidence: 76%

Biomechanical evaluation of position and bicortical fixation of anterior lateral vertebral screws in a porcine model

Hsieh

Lee

et al. 2023

Sci Rep

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Although an anterior approach with anterior lateral screw fixation has been developed for stabilizing the thoracolumbar spine clinically, screw loosening still occurs. In this novel in vitro study, we attempted to elucidate the optimal screw position in the lateral lumbar vertebra and the effect of bicortical fixation. A total of 72 fresh-frozen lumbar vertebrae from L1–6 were harvested from 12 mature pigs and randomly assigned to two modalities: bicortical fixation (n = 36) and unicortical fixation (n = 36). Six groups of screw positions in the lateral vertebral body in each modality were designated as central-anterior, central-middle, central-posterior, lower-anterior, lower-middle, and lower- posterior; 6 specimens were used in each group. The correlations between screw fixation modalities, screw positions and axial pullout strength were analyzed. An appropriate screw trajectory and insertional depth were confirmed using axial and sagittal X-ray imaging prior to pullout testing. In both bicortical and unicortical fixation modalities, the screw pullout force was significantly higher in the posterior or middle position than in the anterior position (p < 0.05), and there was no significant differences between the central and lower positions. The maximal pullout forces from the same screw positions in unicortical fixation modalities were all significantly lower, decreases that ranged from 32.7 to 74%, than those in bicortical fixation modalities. Our study using porcine vertebrae showed that screws in the middle or posterior position of the lateral vertebral body had a higher pullout performance than those in the anterior position. Posteriorly positioned lateral vertebral screws with unicortical fixation provided better stability than anteriorly positioned screws with bicortical fixation.

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Section: Methodsmentioning

confidence: 76%

Biomechanical evaluation of position and bicortical fixation of anterior lateral vertebral screws in a porcine model

Hsieh

Lee

et al. 2023

Sci Rep

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3D printing of asymmetric buttress plate for posteromedial tibial plateau fracture using metal fused filament fabrication

Vijaya Kumar,

Velmurugan

2024

MMMS

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PurposeThis research addresses the challenges encountered when securing bone plates in the human body to treat tibial plateau fractures, specifically focusing on preventing posterolateral fractures. The goal is to develop a 3D buttress plate that offers better stability, facilitating anatomical reduction and rigid fixation. The newly fabricated T-buttress plate enables early knee motion and reduces postoperative complications, marking a significant advancement over existing internal fixation plates.Design/methodology/approachA new buttress plate model was designed using modeling software, featuring an asymmetric curved design with three fragments. Finite element analysis was used to simulate the biomechanical performance of this new model, comparing it with symmetric flat and symmetric curved plates. Accurately predicting the biomechanical behavior of the implant posed challenges, especially during extensive simulations. Optimal parameters for the asymmetric curved plate were identified from the simulation results, and the 3D buttress plate was then fabricated using the metal fused filament fabrication (MFFF) process. This process presents challenges due to the novel nature of the asymmetric design.FindingsThe results indicate that the newly developed buttress plate exhibits superior strength and performance compared to current internal fixation plates. Biomechanical simulations show that the asymmetric curved design provides better stability and support. Moreover, the yield and ultimate tensile strengths were found to be 685 MPa and 855 MPa, respectively.Research limitations/implicationsThe study’s finite element analysis model has limitations due to its reliance on assumptions about material properties, boundary conditions and loading scenarios. It also excludes biological factors, patient variability and the bone’s heterogeneous nature, which may affect the accuracy and applicability of the results in real-life situations.Originality/valueThe development of an asymmetric curved buttress plate using MFFF is a novel innovation aimed at improving biomechanical performance and patient outcomes in orthopedic surgery, offering significant potential impact in the medical field.

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Measurement of anatomical parameters of anterior transpedicular root screw intervertebral fusion system of cervical spine

Ye,

Zhao,

Hou

et al. 2023

BMC Musculoskelet Disord

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Objective This study aims to investigate the feasibility of the anterior transpedicular root screw (ATPRS) intervertebral fusion system for the cervical spine and provide a basis for the design of the ATPRS intervertebral fusion system. Methods A total of 60 healthy adult cervical spine CT images examined from our hospital were selected, including 30 males and 30 females, with an average age of 39.6 ± 4.8 years. The image data was imported into Mimics 21.0 software in DICOM format for 3D model reconstruction. Simulated screw insertion was performed on both sides of the midline of the intervertebral space. The entry point (P1) was determined when the upper and lower screw paths did not overlap. When the screw was tangent to the medial edge of the Luschka joint, the insertion point was determined as the entry point (P2). Measurements were taken and recorded for the following parameters: distance from the screw entry point to the midline of the intervertebral space (DPM), the simulated screw length, inclination angle, cranial/caudal tilted angle, the anterior–posterior (AP) and mediolateral (ML) diameters of the cervical intervertebral space, the heights of the anterior, middle, and posterior edges of the cervical intervertebral space, and the curvature diameter of the lower end plate of the cervical vertebral body. Statistical analysis was performed on the measurement results. Results The screw entry area (P1P2) showed an increasing trend from C3-C7 in both male (2.92–6.08 mm) and female (2.32–5.12 mm) groups. There were statistical differences between men and women at the same level (P < 0.05). The average screw length of men and women was greater than 20 mm, and the upper and lower screw lengths showed an increasing trend from C3 to C7. In the area where screws could be inserted, the range of screw inclination was as follows: male group upper screw (47.73–66.76°), lower screw (48.05–65.35°); female group upper screw (49.15–65.66°) and lower screw (49.42–63.29°); The range of cranial/caudal tilted angle of the screw was as follows: male group upper screw (32.06–39.56°), lower screw (29.12–36.95°); female group upper screw (30.97–38.92°) and lower screw (27.29–37.20°). The anterior–posterior diameter and mediolateral diameter of the cervical intervertebral space showed an increasing trend from C3 to C7 in both male and female groups. The middle height (MH) of the cervical intervertebral space was greater than the anterior edge height (AH) and posterior edge height (PD), with statistical differences (P < 0.05). Conclusions Through the study of CT images of the cervical spine, it was determined that the ATPRS intervertebral fusion system has a feasible area for screw insertion in the cervical intervertebral space.

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Fixation stability comparison of bone screws based on thread design: buttress thread, triangle thread, and square thread

Cited by 3 publications

References 37 publications

Biomechanical evaluation of position and bicortical fixation of anterior lateral vertebral screws in a porcine model

Biomechanical evaluation of position and bicortical fixation of anterior lateral vertebral screws in a porcine model

3D printing of asymmetric buttress plate for posteromedial tibial plateau fracture using metal fused filament fabrication

Measurement of anatomical parameters of anterior transpedicular root screw intervertebral fusion system of cervical spine

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