The Influence of the Insertion Technique on the Pullout Force of Pedicle Screws

Chatzistergos, Panagiotis; Sapkas, George; Kourkoulis, Stavros K.

doi:10.1097/brs.0b013e3181ba0b0c

Cited by 42 publications

(49 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Unlike the vertebral cancellous bone, the use of a pilot hole smaller than the internal (core) screw diameter should be avoided in cortical bone because it causes cortical bone fissures and microcraks that lead to bone fixation failure [39]. The increased pullout strength effect of cancellous bone compression around the pedicle screw was also observed using a tap smaller than the screw diameter or untapped screw pedicle screw insertion [7]. In our study, the pilot hole smaller (2.0 mm) than the internal diameter of the screw (2.8 mm) was randomly chosen.…”

Section: Discussionmentioning

confidence: 99%

“…It is well established in the literature that the holding power of the pedicle screw is influenced by bone mineral density [5], geometry of the screw [1,20,[25][26][27] and the screw insertion technique employed by the surgeon [5,14,33,38]. It has been reported that the holding power of the pedicle screw is significantly influenced by the size and technique of the pilot hole [5,7,14,15,33]. For selftapping cylindrical pedicle screws, reduction of the pilot hole diameter in relation to the screw outer diameter increases screw pullout force; however, the correlation of the pilot hole with screw internal (core) diameter was not mentioned [4,6,12,15,16].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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%

Section: Introductionmentioning

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

“…Preliminary results indicated that the above mentioned numerical procedure can satisfactory simulate the influence of radial compaction as this is realized by undertapping [32].…”

Section: Discussionmentioning

confidence: 99%

A parametric study of cylindrical pedicle screw design implications on the pullout performance using an experimentally validated finite-element model

Chatzistergos

Magnissalis

Kourkoulis

2010

Medical Engineering & Physics

Self Cite

View full text Add to dashboard Cite

Abstract:The present study aims to the design of a finite-element model simulating accurately the pullout behaviour of cylindrical pedicle screws and predicting their pullout force. Three commercial pedicle screws, subjected to pure pullout from synthetic bone, were studied experimentally. The results were used for the design, calibration and validation of a finite-element model. Special attention was paid to the accurate simulation of the failure inside the host material. For this purpose a bilinear cohesive zone material model was adopted to control mode-II debonding of neighbouring elements in the vicinity of the screw and simulate this way the failure in shear of the hosting material. Comparison between experimental and numerical results proved that the implementation of this method can significantly enhance the accuracy of the numerical simulation of a screw's mechanical behaviour under pure pullout loads. The numerical model was used for the parametric study of various factors affecting the pullout performance of a cylindrical pedicle screw. It was concluded that the major parameters influencing the pullout force is the outer radius and purchase length of the screw. Significantly weaker was the dependence of the screw's pullout force on its thread inclination, depth and pitch.

show abstract

“…Existing experimental studies indicate that a screw's pullout force increases linearly with increasing Title shear strength of its hosting material (Chapman et al, 1996). The fixation strength of a screw is also influenced by the design of the screw (Krenn et al, 2008, Inceoglu et al, 2008, Gefen, 2002, Chatzistergos et al, 2010a) and the insertion technique used by the surgeon (Conrad et al, 2005, Chatzistergos et al, 2010b). …”

Section: Introductionmentioning

confidence: 99%