scholarly journals Comparison of the Pull‐Out Strength between a Novel Micro‐Dynamic Pedicle Screw and a Traditional Pedicle Screw in Lumbar Spine

2020 ◽  
Vol 12 (4) ◽  
pp. 1285-1292 ◽  
Author(s):  
Lei Qian ◽  
Weidong Chen ◽  
Peng Li ◽  
Dongbin Qu ◽  
Wenjie Liang ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Pedicle Screw ◽  
Pull Out ◽  
Pull Out Strength

Assessment of Pedicle Bone Strength in the Lumbar Spine Using a “Smart” Ball Tip Probe

2013 ◽  
Vol 7 (4) ◽  
Author(s):  
Kate D. Liddle ◽  
Michael A. Tufaga ◽  
Glenn Diekmann ◽  
Jenni M. Buckley ◽  
Viva Tai ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Pedicle Screw ◽  
Bone Strength ◽  
Insertion Torque ◽  
Mineral Density ◽  
Line Load ◽  
Pull Out ◽  
Screw Augmentation ◽  
Local Bone ◽  
Pull Out Strength

Preoperative assessment of bone mineral density (BMD) via dual X-ray absorptiometry (DEXA) has been shown to help determine the need for screw augmentation, particularly in the pedicle. However, patients frequently present without preoperative DEXA scans, especially in trauma situations. We developed a “smart” probe for intra-operative assessment of local bone strength in the pedicle. A standard ball tip probe was instrumented with an in-line load cell and was used to test the bone strength of fresh-frozen human cadaveric lumbar spine. Local bone crush strength was assessed using the probe at five locations within the centrum and the pedicle. The contralateral pedicle was outfitted with a standard pedicle screw and insertion torque and pull-out force of the screw were measured. Correlation was found between PS-centrum (probe strength-centrum) and screw pull-out strength (adj. R2 = 0.42). A stepwise linear regression revealed that when considering BMD, insertion torque, and PS-centrum, pull-out strength could be predicted based on PS-centrum and insertion torque (adj. R2 = 0.51, p < 0.01, Fisher test). The results suggest that use of the new probe may be a more quantitative measurement of screw purchase when DEXA is unavailable, such as in spinal trauma cases. Furthermore, when used in conjunction with DEXA, the “smart” ball tip probe may improve assessment of the strength of pedicle screw purchase.

A Novel Technique for Measuring Pedicle Screw Forces In Situ

2008 ◽  
Author(s):  
Samuel Q. Tia ◽  
Jennifer M. Buckley ◽  
Thuc-Quyen Nguyen ◽  
Jeffrey C. Lotz ◽  
Shane Burch
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Clinical Failure ◽  
Strain Gages ◽  
Destructive Testing ◽  
Novel Technique ◽  
Pull Out ◽  
Pull Out Strength

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.

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

2020 ◽  
Vol 25 (1) ◽  
pp. 66-72 ◽  
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

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

2016 ◽  
Vol 50 (2) ◽  
pp. 177 ◽  
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

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

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 (<i>p</i> <0.001), 0.780 (<i>p</i> <0.001), and 0.873 (<i>p</i> <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.

scholarly journals Quantitative comparison of a laterally misplaced pedicle screw with a re-directed screw. How much pull-out strength is lost?

2018 ◽  
Vol 52 (6) ◽  
pp. 459-463 ◽  
Author(s):  
Murat Korkmaz ◽  
Kerim Sarıyılmaz ◽  
Okan Ozkunt ◽  
Halil Can Gemalmaz ◽  
Turgut Akgül ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Quantitative Comparison ◽  
Pull Out ◽  
Pull Out Strength

Novel Support Device Improves Pedicle Screw Retention

2020 ◽  
Author(s):  
Lucas J Ray ◽  
Jonathan N Sembrano ◽  
David S Nedrelow
Keyword(s):  
Pedicle Screw ◽  
Orthopedic Surgery ◽  
Triple Helix ◽  
Osteoporotic Bone ◽  
Industry Standard ◽  
Pull Out ◽  
Support Device ◽  
Improved Performance ◽  
Pullout Failure ◽  
Pull Out Strength

Abstract Osteoporosis is one of the most challenging diseases facing orthopedic surgery. Implants may exhibit poor bone retention due to the decreased density of osteoporotic bone, leading to mechanical failure. Our study aimed to design a pedicle screw for vertebral implantation that exhibited pullout strengths that were higher than the current industry standard screw. We created three prototypes to address pullout failure with varying numbers of helices and one design that was a two-part hybrid (triple helix and pedicle screw). Each screw was subjected to pull-out testing in foam blocks (n=3). Ultimate pull-out load, ultimate extension, and screw removal energy were determined based on testing results. Based on the results, the two-part assembly demonstrated significantly improved pull-out strength to 102.76 ± 2.52 N (P &gt; 0.0002), ultimate extension to 8.787 ± 0.242 (P &gt; 0.002), and screw removal energy of 2.37 ± 0.03 kJ (P &gt; 0.0003) vs 1.66 ± .08 kJ in the control screw, and the other two screw designs. It is noteworthy that the flexible and stiff helix designs by themselves did not exhibit improved performance, but when combined into a dual-threaded screw the helix features improved performance. The results for the two-part design suggested that there is utility in this design or variations thereof for improving screw-to-bone retention in osteoporotic patients.

Quantitative dual-energy CT for phantomless evaluation of cancellous bone mineral density of the vertebral pedicle: correlation with pedicle screw pull-out strength

2014 ◽  
Vol 25 (6) ◽  
pp. 1714-1720 ◽  
Author(s):  
Julian L. Wichmann ◽  
Christian Booz ◽  
Stefan Wesarg ◽  
Ralf W. Bauer ◽  
J. Matthias Kerl ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Pedicle Screw ◽  
Bone Mineral ◽  
Cancellous Bone ◽  
Dual Energy ◽  
Dual Energy Ct ◽  
Mineral Density ◽  
Pull Out ◽  
Pull Out Strength
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