Influência da superfície dos parafusos pediculares no torque de inserção e resistência ao arrancamento

Fleury, Rodrigo Barra Caiado; Shimano, Antonio Carlos; Matos, Thiago Dantas; Teixeira, Kelsen de Oliveira; Romero, Valéria; Defino, Helton Luíz Aparecido

doi:10.1055/s-0040-1710072

Cited by 2 publications

(1 citation statement)

References 14 publications

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“…In the bilateral screw-rod system, reinsertion also has no significant effect on pullout strength 35 . A new research suggested that the roughness of surface is another important factor for insertion torque 36 . Incidence of screw breakage ranges between 2.6 and 60% 8 – 10 and its occurrence represents a serious problem.…”

Section: Discussionmentioning

confidence: 99%

Stress distribution of different lumbar posterior pedicle screw insertion techniques: a combination study of finite element analysis and biomechanical test

Song

Sun

Zong

et al. 2021

Sci Rep

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At present, the pedicle screw is the most commonly used internal fixation device. However, there are many kinds of common posterior pedicle screw insertion techniques performed to reconstruct the lumbar stability. Therefore, spinal surgeons often face a difficult choice. The stress distribution of internal fixation system is an important index for evaluating safety. Unfortunately, little had been known about the difference of stress distribution of screw-rod systems that established by Roy-Camille, Magerl and Krag insertion techniques. Here, combination of finite element analysis and model measurement research was adopted to evaluate the difference of stress. Following different pedicle screw insertion techniques, three lumbar posterior surgery models were established after modeling and validation of the L1–S1 vertebrae finite element model. By analyzing the data, we found that stress concentration phenomenon was in all the postoperative models. Roy-Camille and Magerl insertion techniques led to the great stress on screw-rod systems. Then, fresh frozen calf spines were selected as a model for subsequent measurements. Fitted with a specially designed test pedicle screw, L5–L6 vertebrae were selected to repeat and verify the results of the finite element analysis. With the aid of universal testing machine and digital torque wrench, models simulated flexion, extension, lateral bending and rotation. Finally, the strain value was captured by the strain gauge and was then calculated as the stress value. Krag and Magerl were found to be the safer choice for pedicle screw insertion. Overall, our combination method obtained the reliable result that Krag insertion technique was the safer approach for pedicle screw implantation due to its relatively dispersive stress. Therefore, without the consideration of screw size, pedicle fill, bone density, and bone structures, we recommend the Krag insertion technique as the first choice to reconstruction of lumbar stability. Additionally, the combination method of finite element analysis and strain gauge measurement can provide a feasible way to study the stress distribution of spinal internal fixation.

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Section: Discussionmentioning

confidence: 99%

Stress distribution of different lumbar posterior pedicle screw insertion techniques: a combination study of finite element analysis and biomechanical test

Song

Sun

Zong

et al. 2021

Sci Rep

View full text Add to dashboard Cite

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Cutting Flute and Thread Design on Self-Tapping Pedicle Screws Influence the Insertion Torque and Pullout Strength

Hsieh

Kuo

et al. 2022

Applied Sciences

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Self-tapping screws are commonly used in trauma and maxillofacial surgery and are increasingly used for pedicle screw insertions. In order to evaluate how the quantity and length of cutting flutes on self-tapping pedicle screws affect the insertion torque and pullout strength, eight different self-tapping pedicle screw designs were evaluated. All screws had a threaded length of 35 mm and featured variations in the number of leads, as well as the length and quantity of cutting flutes. Five samples of each design were inserted into pre-drilled, untapped holes (ø2.7 mm, length 35 mm) in sawbone blocks of density 20 PCF. The insertion torque and pullout strength were measured according to ASTM F543. The results showed that screws with a longer cutting flute of 9.5 mm had a lower mean maximum insertion torque than screws with shorter 2.9 mm cutting flutes. Pedicle screws with a double-lead thread design had a greater insertion torque than their single-lead counterparts, and the use of three cutting flutes produced a lower torque than two cutting flutes. The results demonstrated a greater pullout strength in screws with a single-lead thread rather than a double-lead, three cutting flutes instead of two, and a longer length for the cutting flute. In conclusion, to provide immediate stability and reduce the surgical insertion time, a single-lead, self-tapping pedicle screw incorporating three long cutting flutes is recommended because of the significantly greater pullout strength. This design could also reduce the risk of implant loosening in comparison to double-lead, self-tapping pedicle screw designs.

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Influência da superfície dos parafusos pediculares no torque de inserção e resistência ao arrancamento

Cited by 2 publications

References 14 publications

Stress distribution of different lumbar posterior pedicle screw insertion techniques: a combination study of finite element analysis and biomechanical test

Stress distribution of different lumbar posterior pedicle screw insertion techniques: a combination study of finite element analysis and biomechanical test

Cutting Flute and Thread Design on Self-Tapping Pedicle Screws Influence the Insertion Torque and Pullout Strength

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