Comparison of the In Vitro Holding Strengths of Conical and Cylindrical Pedicle Screws in a Fully Inserted Setting and Backed Out 180°

Lill, C. A.; Schlegel, U.; Wahl, D.; Schneider, Erich

doi:10.1097/00002517-200006000-00011

Cited by 44 publications

(36 citation statements)

References 27 publications

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“…O desenvolvimento do parafuso com o diâmetro externo cônico foi a tentativa inicial (15) . No entanto, apesar dos bons resultados clínicos com a sua utilização, os parafusos com o desenho externo côni-co podem apresentar propriedades mecânicas inferiores aos parafusos cilíndricos (16) .…”

Section: A B a Bunclassified

Torque de inserção e resistência ao arrancamento dos parafusos vertebrais com alma cilíndrica e cônica

et al. 2008

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Section: A B a Bunclassified

Torque de inserção e resistência ao arrancamento dos parafusos vertebrais com alma cilíndrica e cônica

et al. 2008

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“…Similarly, screw pull-out with the calf model reports values from 747 to 7,300 N, depending on treatment (30,35). Polyurethane blocks have been reported in the literature and offer a wealth of data to compare against.…”

Section: Comparison To Existing Literaturementioning

confidence: 99%

“…Unfortunately, all samples were toggled and the effects of toggling, hubbing and bone density could not be individually assessed. Lill et al (35) tested screws in calf spines and removed the effect of thicker cortex, as compared to humans, by over-drilling the dorsal cortex to 8 mm diameter and a depth of 2 mm. Although this study did not state the intention to evaluate hubbing, the procedure was very similar.…”

Section: Comparison To Existing Literaturementioning

confidence: 99%

The contribution of the cortical shell to pedicle screw fixation

Pelletier¹,

Bertollo²,

Al-Khawaja³

et al. 2017

J. Spine Surg.

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Background: A pedicle screw insertion technique known as "hubbing" involves the removal of cortical bone around the screw insertion with the aim of improving fixation and decreasing screw loosening.However, the efficacy of this procedure relative to bone density and early loading have not been fully explored. The purpose of this study is to establish the contribution of the cortical layer (hubbing), cancellous density, early loading (toggling) in an idealised model. This is an in vitro laboratory study.Methods: Synthetic bone blocks with cancellous bulk and a simulated cortical shell were implanted with 6.5 mm pedicle screws. Three key variables were evaluated in this study; density of the simulated bone (10-20 lb/ft 3 ), toggling (±0.5 mm for 10,000 cycles), and the presence or absence of the surrounding cortex (hubbing). Pullout testing after toggling was performed to determine maximum load, stiffness and energy.Results were analyzed to assess interaction and main effects.Results: Removal of the cortex decreased the pullout loads by approximately 1,100 N after toggling.Toggling in the presence of the cortical shell had no effect. However, once the cortical shell is removed damage to the weaker cancellous bone accumulates and further compromises the fixation.Conclusions: The addition of a cortical layer in the Sawbone model is significant and provides a more realistic model of load sharing. The cortex plays a considerable role in the protection of underlying cancellous bone as well as contributing to initial pullout strength. The results of this study demonstrate a negative synergistic effect when both toggling and hubbing are applied to the weaker bone.

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“…However, the fact of the connection of the implants be internal hexagon, these procedure may have influenced on these superior strength results; and in the densities of 20 and 15 PCF, these conical implants had larger and statistically different results, from that cylindrical implants with external hexagon. Moreover, the conical implants had a smaller diameter than the cylindrical ones, due to the availability of the company; and it can have influenced the values of insertion torque and pullout strength as well as the study of Lill et al 24 , that showed the screws with conical design may present inferior mechanical properties when compared to machine screws in different sizes.…”

Section: Effect Of Implant Design and Bone Density In Primary Stabilitymentioning

confidence: 99%

Effect of implant design and bone density in primary stability

Oliscovicz¹,

Shimano²,

Marcantonio³

et al. 2013

Braz. J. Oral Sci.

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Aim: To evaluate the influence of the format and surface treatment of implants, as well as the substrate used in primary stability. Methods: Thirty-two Conexão ® implants were used: 8 conical (CC) (11.5 x 3.5 mm) and 24 cylindrical (11.5 x 3.75 mm) -8 external hexagon implants without surface treatment (MS), 8 external hexagon implants with double Porous treatment (MP), 8 internal hexagon implants with Porous treatment (CA). They were inserted in Nacional ® polyurethane in three densities (15, 20 and 40 PCF). The insertion torque (IT) (N.cm) was quantified using the digital Mackena ® torque meter, and the pullout force (PF) (N) by means of axial traction force with a 200 kg load cell, performed in a Universal Test Machine (Emic ® DL-10000) and the Tesc 3.13 software. Data were analyzed statistically by ANOVA and Tukey's test with a significance level of 5%. Results: Difference was observed between groups (p<0.05). Regarding the IT, MP and MS inserted to the substrate 40PCF showed higher values with statistically significant difference with all interactions implants x substrate; the 15 and 20PCF densities was not significant in all groups of implants. MP, MS, CC and CA did not differ significantly, even inserted in a lower density, where CC showed better IT compared with other densities. For PF, the best performance was the interaction implant CA x 40PCF substrate, showing a difference from the other implants inserted in all substrates. Conclusions: The higher bone density and cylindrical implants with surface treatment provides greater IT and PF.

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Comparison of the In Vitro Holding Strengths of Conical and Cylindrical Pedicle Screws in a Fully Inserted Setting and Backed Out 180°

Cited by 44 publications

References 27 publications

Torque de inserção e resistência ao arrancamento dos parafusos vertebrais com alma cilíndrica e cônica

Torque de inserção e resistência ao arrancamento dos parafusos vertebrais com alma cilíndrica e cônica

The contribution of the cortical shell to pedicle screw fixation

Effect of implant design and bone density in primary stability

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