Pedicle screw fixation strength: pullout versus insertional torque

İnceoğlu, Serkan; Ferrara, Lisa; McLain, Robert F.

doi:10.1016/j.spinee.2004.02.006

Cited by 143 publications

(99 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Histomorphometric evaluation is more frequently reported for coated or expandable pedicle screws. Although the quantity and quality of bone between screw threads are important factors concerning screw pullout strength [10] and screw pullout strength is reportedly proportional to the volume of bone between the screw threads [3], the pullout test is the standard and more commonly used method to evaluate the mechanical properties of the bone-screw interface [22,23]. The need to use living animals in the acute phase of the study for A significant difference (p \ 0.01) was observed in the acute and chronic phases histomorphometric investigation of the screw-bone interface was based on the results of the pilot study.…”

Section: Discussionmentioning

confidence: 99%

Effect of pilot hole on biomechanical and in vivo pedicle screw–bone interface

et al. 2013

View full text Add to dashboard Cite

Purpose To experimentally study the influence of pilot hole diameter (smaller than or equal to the internal (core) diameter of the screw) on biomechanical (insertion torque and pullout strength) and histomorphometric parameters of screw-bone interface in the acute phase and 8 weeks after pedicle screw insertion. Methods Fifteen sheep were operated upon and pedicle screws inserted in the L1-L3 pedicles bilaterally. The pilot hole was smaller (2.0 mm) than the internal diameter (core) of the screw on the left side pedicle and equal (2.8 mm) to the internal diameter (core) of the screw on the right side pedicle. Ten animals were sacrificed immediately (five animals were assigned to pullout strength tests and five animals were used for histomorphometric bone-screw interface evaluation). Five animals were sacrificed 8 weeks after pedicle screw insertion for histomorphometric bonescrew interface evaluation. Results The insertion torque and pullout strength were significantly greater in pedicle screws inserted into pilot holes smaller than internal (core) diameter of the screw. Histomorphometric evaluation of bone-screw interface showed that the percentage of bone-implant contact, the area of bone inside the screw thread and the area of bone outside the screw thread were significantly higher for pilot holes smaller than the internal (core) diameter of the screw immediately after insertion and after 8 weeks. Conclusion A pilot diameter smaller than the internal (core) diameter of the screw improved the insertion torque and pullout strength immediately after screw insertion as well the pedicle screw-bone interface contact immediately and 8 weeks after screw placement in sheep with good bone mineral density.

show abstract

Section: Discussionmentioning

confidence: 99%

Effect of pilot hole on biomechanical and in vivo pedicle screw–bone interface

et al. 2013

View full text Add to dashboard Cite

show abstract

“…As the pilot hole's diameter increases, a larger amount of bone is removed, and a smaller amount of bone is available to be compacted around the implant, thus reducing the insertion torque. The correlation between insertion torque and implants' pullout resistance has been presented as a controversial subject in literature reports addressing the matter, where reports exist on the correlation between insertion torque and pullout resistance (1,5,(9)(10)(11)(12) next to other reports not finding such correlation (13,14) . Screws' resistance to pullout is a complex phenomenon and dependant on a number of factors (2,15) .…”

Section: Discussionmentioning

confidence: 99%

Estudo da influência do torque de inserção na resistência ao arrancamento dos parafusos pediculares

et al. 2008

View full text Add to dashboard Cite

Foram realizados ensaios mecânicos para avaliação do torque de inserção na resistência ao arrancamento dos parafusos pediculares. Foram utilizadas no estudo 30 vértebras de suínos da raça Landrace, nas quais parafusos de 5mm foram inseridos nos pedículos vertebrais. O orifício piloto foi realizado com brocas de 2,5mm, 3,8mm e 4,5mm. Foram realizados ensaios mecânicos de arrancamento dos implantes em máquina universal de testes. Foi observado aumento do torque de inserção dos parafusos com a perfuração do orifício piloto com diâmetro menor que o diâmetro interno do parafuso, e redução com o orifício piloto maior que o diâmetro interno do parafuso. Foi observada diferença estatística entre os valores do torque de inserção. A resistência ao arrancamento dos implantes aumentou com a perfuração do orifício piloto com valores menores que o diâmetro interno do parafuso e diminuiu com a perfuração com diâmetro maior que o diâmetro interno do parafuso. Foi observada diferença estatística dos valores da resistência ao arrancamento dos implantes apenas com a perfuração do orifício piloto com diâmetro maior que o diâmetro interno do parafuso.

show abstract

“…This feature was structurally significant and added approximately 1,100 N to the pullout load. Caudo-cephalad loading in an in vitro setting (10) is well established and can be used as a preconditioning step prior to pullout or can itself be an endpoint for loosening (41)(42)(43)(44)(45)(46). Toggling generally decreases the stability of the screw/bone construct (11,32), however, this is not always the case.…”

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.

View full text Add to dashboard Cite

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.

show abstract

Pedicle screw fixation strength: pullout versus insertional torque

Cited by 143 publications

References 22 publications

Effect of pilot hole on biomechanical and in vivo pedicle screw–bone interface

Effect of pilot hole on biomechanical and in vivo pedicle screw–bone interface

Estudo da influência do torque de inserção na resistência ao arrancamento dos parafusos pediculares

The contribution of the cortical shell to pedicle screw fixation

Contact Info

Product

Resources

About