A Novel Technique for Measuring Pedicle Screw Forces In Situ

Long posterior fusion constructs in the lumbar spine cause substantial posteriorly directed loading of the supporting pedicle screws, particularly during patient bending activities. Although there are numerous documented accounts of clinical failure at the pedicle screw-bone interface [1,2], the in situ pull-out strength of pedicle screws in long surgical constructs has not been characterized. Previous biomechanical studies have quantified pedicle screw pull-out force in cadaveric models through destructive testing or in nondestructive cases, through the use of custom-machined pedicle screws instrumented with strain gages [3–6]. However, these techniques involve altering screw geometry and may fail to properly simulate in vivo mechanical loading conditions. The goal of this study was to develop and validate a sensor system for measuring pedicle screw pull-out forces in long posterior constructs in situ during multi-segmental cadaveric testing.

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Correlation between the Computed Tomography Values of the Screw Path and Pedicle Screw Pullout Strength: An Experimental Study in Porcine Vertebrae

Asian Spine Journal ◽

10.31616/asj.2019.0170 ◽

2020 ◽

Vol 14 (3) ◽

pp. 265-272

Author(s):

Atsushi Ikeura ◽

Taketoshi Kushida ◽

Kenichi Oe ◽

Yoshihisa Kotani ◽

Muneharu Ando ◽

...

Keyword(s):

Computed Tomography ◽

Bone Mineral Density ◽

Pedicle Screw ◽

Bone Mineral ◽

Lumbar Vertebrae ◽

Pedicle Screws ◽

Mineral Density ◽

Screw Insertion ◽

Pull Out ◽

Pull Out Strength

Study Design: Biomechanical study.Purpose: To assess the correlation between the computed tomography (CT) values of the pedicle screw path and screw pull-out strength.Overview of Literature: The correlation between pedicle screw pull-out strength and bone mineral density has been well established. In addition, several reports have demonstrated a correlation between bone mineral density and CT values. However, no previous biomechanical studies investigated the correlation between CT values and pedicle screw pull-out strength.Methods: Sixty fresh-frozen lumbar vertebrae from 6-month-old pigs were used. Before screw insertion, the CT values of the screw path were obtained for each sample. Specimens were then randomly divided into three equal groups. Each group had one of three pedicle screws inserted: 4.0-mm LEGACY (4.0-LEG), 4.5-mm LEGACY (4.5-LEG), or 4.5-mm SOLERA (4.5-SOL) (all from Medtronic Sofamor Danek Inc., Memphis, TN, USA). Each screw had a consistent 30-mm thread length. Axial pull-out testing was performed at a rate of 1.0 mm/min. Correlations between the CT values and pedicle screw pull-out strength were evaluated using Pearson’s correlation coefficient analysis.Results: The correlation coefficients between the CT values of the screw path and pedicle screw pull-out strength for the 4.0-LEG, 4.5-LEG, and 4.5-SOL groups were 0.836 (p <0.001), 0.780 (p <0.001), and 0.873 (p <0.001), respectively. Greater CT values were associated with greater screw pull-out strength.Conclusions: The CT values of the screw path were strongly positively correlated with pedicle screw pull-out strength, regardless of the screw type and diameter, suggesting that the CT values could be clinically useful for predicting pedicle screw pull-out strength.

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The Role of Imaging and In Situ Biomechanical Testing in Assessing Pedicle Screw Pull-Out Strength

Spine ◽

10.1097/00007632-199609010-00004 ◽

1996 ◽

Vol 21 (17) ◽

pp. 1962-1968 ◽

Cited By ~ 57

Author(s):

Barry S. Myers ◽

Philip J. Belmont ◽

William J. Richardson ◽

James R. Yu ◽

Kristine D. Harper ◽

...

Keyword(s):

Pedicle Screw ◽

Biomechanical Testing ◽

Pull Out ◽

Pull Out Strength

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Comparison of Insertion Time, Pull-out Strength, and Screw-media Interface Area of Customized Pedicle Screw With Different Core and Thread Design Against Commercial Pedicle Screw

10.21203/rs.3.rs-429747/v1 ◽

2021 ◽

Author(s):

Rahadyan Magetsari ◽

Tedjo Rukmoyo ◽

Marda Ade Saputra ◽

Yudha Mathan Sakti

Keyword(s):

Pedicle Screw ◽

Pedicle Screws ◽

Insertion Time ◽

Control Group ◽

Interface Area ◽

Screw Design ◽

Pull Out ◽

Thread Diameter ◽

Screw Group ◽

Pull Out Strength

Abstract Objective: This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result: The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22,94 s) with commercially available pedicle screw (15.86 s) (p<0.05). The pull-out strength was significantly difference between commercially available pedicle screw (408.60 N) with square-thread conical pedicle screw (836.60 N) (p<0.05). The square-thread conical-core group have the highest interface area (1486.21 mm2). The data comparison showed that the square-thread conical-core customized pedicle screw group has comparable insertion time and has better pull-out strength than commercially available pedicle screw.

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Comparison of insertion time, pull-out strength, and screw-media interface area of customized pedicle screw with different core and thread design against commercial pedicle screw: a pilot study on Indonesian Population

BMC Research Notes ◽

10.1186/s13104-021-05803-5 ◽

2022 ◽

Vol 15 (1) ◽

Author(s):

Rahadyan Magetsari ◽

Tedjo Rukmoyo ◽

Marda Ade Saputra ◽

Yudha Mathan Sakti

Keyword(s):

Pedicle Screw ◽

Pedicle Screws ◽

Insertion Time ◽

Control Group ◽

Interface Area ◽

Screw Design ◽

Pull Out ◽

Indonesian Population ◽

Thread Diameter ◽

Pull Out Strength

Abstract Objective This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22.94 s) with commercially available pedicle screw (15.86 s) (p < 0.05). The pull-out strength was significantly difference between commercially available pedicle screw (408.60 N) with square-thread conical pedicle screw (836.60 N) (p < 0.05). The square-thread conical-core group have the highest interface area (1486.21 mm2). The data comparison showed that the square-thread conical-core customized pedicle screw group has comparable insertion time and has better pull-out strength than commercially available pedicle screw.

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Anterior transvertebral interbody cage with posterior transdiscal pedicle screw instrumentation for high-grade spondylolisthesis

Neurosurgical FOCUS ◽

10.3171/foc.2006.20.3.8 ◽

2006 ◽

Vol 20 (3) ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

Will Forest Beringer ◽

Jean-Pierre Mobasser ◽

Dean Karahalios ◽

Eric Alfred Potts

Keyword(s):

Pedicle Screw ◽

Degenerative Spondylolisthesis ◽

Pedicle Screws ◽

Pedicle Screw Fixation ◽

Technical Note ◽

Slip Angle ◽

Fibular Graft ◽

High Grade ◽

Shear Forces

✓Adult high-grade degenerative spondylolisthesis represents the extreme end of the spectrum for spondylolisthesis and is consequently rarely encountered. Surgical management of high-grade spondylolisthesis requires constructs capable of resisting the shear forces at the slipped L5–S1 interspace. The severity of the slip, sacral inclination, and slip angle may make conventional approaches to 360° fusion difficult or hazardous. Transdiscal pedicle screw fixation, transvertebral fibular graft fusion, and transvertebral cage fixation are techniques that have been developed to establish anterior column load sharing and to resist shear forces at the L5–S1 interspace, given the anatomical constraints accompanying high-grade spondylolisthesis. In this technical note the authors describe the procedure for implanting an in situ anterior L5–S1 transvertebral cage and performing L4–5 anterior lumbar interbody fusion, followed by placement of posterior S1–L5 vertebral body transdiscal pedicle screws for management of high-grade spondylolisthesis.

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Influence of novel design alteration of pedicle screw on pull-out strength: A finite element study

Journal of Orthopaedic Science ◽

10.1016/j.jos.2019.03.002 ◽

2020 ◽

Vol 25 (1) ◽

pp. 66-72 ◽

Cited By ~ 1

Author(s):

Shota Takenaka ◽

Takashi Kaito ◽

Ken Ishii ◽

Kota Watanabe ◽

Kei Watanabe ◽

...

Keyword(s):

Finite Element ◽

Pedicle Screw ◽

Finite Element Study ◽

Pull Out ◽

Novel Design ◽

Pull Out Strength ◽

Element Study

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Pull out strength calculator for pedicle screws using a surrogate ensemble approach

Computer Methods and Programs in Biomedicine ◽

10.1016/j.cmpb.2016.08.023 ◽

2016 ◽

Vol 137 ◽

pp. 11-22 ◽

Cited By ~ 12

Author(s):

Vicky Varghese ◽

Palaniappan Ramu ◽

Venkatesh Krishnan ◽

Gurunathan Saravana Kumar

Keyword(s):

Pedicle Screws ◽

Ensemble Approach ◽

Pull Out ◽

Pull Out Strength

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In vitro biomechanical study of pedicle screw pull-out strength based on different screw path preparation techniques

Indian Journal of Orthopaedics ◽

10.4103/0019-5413.177572 ◽

2016 ◽

Vol 50 (2) ◽

pp. 177 ◽

Cited By ~ 1

Author(s):

Mark Moldavsky ◽

Kanaan Salloum ◽

Brandon Bucklen ◽

Saif Khalil ◽

JwalantS Mehta

Keyword(s):

Pedicle Screw ◽

Biomechanical Study ◽

Pull Out ◽

Strength Based ◽

Preparation Techniques ◽

Pull Out Strength

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ANALYSIS ON THE EFFECT OF HALF ANGLE ON THE DISPLACEMENT OF PEDICLE SCREW DURING AXIAL PULL-OUT TEST IN CANCELLOUS BONE USING 2D AXISYMMETRIC FE MODEL

Biomedical Sciences Instrumentation ◽

10.34107/yhpn9422.04153 ◽

2021 ◽

Vol 57 (2) ◽

pp. 153-158

Author(s):

Harikrishna Makaram ◽

◽

Ramakrishnan Swaminathan ◽

Keyword(s):

Pedicle Screw ◽

High Stress ◽

Pedicle Screws ◽

Stress Transfer ◽

Von Mises Stress ◽

Fe Model ◽

Distal Half ◽

Proximal Half ◽

Pull Out ◽

Half Angle

Pedicle screw fixations are commonly used in the treatment of spinal pathologies. For effective treatment, stable anchorage between the screw and bone is necessary. In this study, the influence of proximal and distal half angle of the screw, on the displacement of fixation and stress transfer are simulated using a 2D axisymmetric finite element model. A parametric study was performed by varying the proximal half-angle between 0° and 60° in steps of 10° and the distal half angles are considered as 30° and 40°. The material properties and boundary conditions are applied based on previous studies. Frictional contact is considered between the bone and screw. Results show that, displacement of fixation is observed to be minimum at a proximal half angle of 0° and maximum at an angle of 60°. High stress concentration is observed in first few threads with highest maximum von Mises stress at an angle of 60°. High stress transfer was obtained for proximal half-angles of 40° and 50°. It is observed that, this method might aid to develop better pedicle screws for treatment of Scoliosis.

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