scholarly journals A Biomechanical Comparison of Expansive Pedicle Screws for Severe Osteoporosis: The Effects of Screw Design and Cement Augmentation

PLoS ONE ◽  
2015 ◽  
Vol 10 (12) ◽  
pp. e0146294 ◽  
Author(s):  
Ching-Lung Tai ◽  
Tsung-Ting Tsai ◽  
Po-Liang Lai ◽  
Yi-Lu Chen ◽  
Mu-Yi Liu ◽  
...  
Keyword(s):  
Pedicle Screws ◽  
Cement Augmentation ◽  
Severe Osteoporosis ◽  
Screw Design ◽  
Biomechanical Comparison

scholarly journals Possible Usage of Cannulated Pedicle Screws without Cement Augmentation

2014 ◽  
Vol 11 (3) ◽  
pp. 149-155 ◽  
Author(s):  
Teyfik Demir
Keyword(s):  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
Cement Augmentation ◽  
Control Group ◽  
Pullout Strength ◽  
Screw Design ◽  
Pullout Tests ◽  
Pu Foam ◽  
Common Problems ◽  
Testing Protocols

Background: The use of pedicle screws is becoming increasingly popular for spinal surgery practice as the technology advances. Screw pullout due to bone quality and loading conditions is one of the most common problems observed after pedicle screw fixation. Several solutions were studied to prevent screw pullout. These can be investigated under three main categories: screw design, expandable screws and cement augmentation.Objective: This study aimed to investigate the pullout performance of cannulated screws without cement augmentation on synthetic foams.Methods: Artificial fusion process for PU is described and validated in our previous studies. For this study six newly designed cannulated pedicle screws were artificially fused to PU foam and pullout test were conducted according to ASTM F543 standard testing protocols.Results: According to the results of post-fusion pullout tests, worst performed cannulated screw design was S3H on healthy bone simulating PU foam. However, pullout strength of unilaterally three holes including (S3H) design was purchased with two times higher loads when compared to control group. Solid cored screws were purchased with 671 N where this value was 1450 N for S3H design.Conclusions: This study provided that using cannulated pedicle screws without cement augmentation for the cases with healthy bone can be a reliable alternative to classical screws. To the knowledge of the authors this is the first post-fusion study investigating cannulated pedicle screws without cement augmentation.

scholarly journals The effect of cement augmentation on pedicle screw fixation under various load cases

2021 ◽  
Vol 10 (12) ◽  
pp. 797-806
Author(s):  
Yan Chevalier ◽  
Maiko Matsuura ◽  
Sven Krüger ◽  
Hannes Traxler ◽  
Christoph Fleege† ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Bone Quality ◽  
Pedicle Screws ◽  
Bending Stiffness ◽  
Cement Augmentation ◽  
Fixation Strength ◽  
Screw Design ◽  
Pull Out ◽  
Local Bone ◽  
Significant Difference

Aims Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques. Methods Micro-finite element (µFE) models were created from micro-CT (μCT) scans of vertebrae implanted with two types of pedicle screws (L: Ennovate and R: S4). Simulations were conducted for a 10 mm radius region of interest (ROI) around each screw and for a full vertebra (FV) where different cementing scenarios were simulated around the screw tips. Stiffness was calculated in pull-out and anterior bending loads. Results Experimental pull-out strengths were excellently correlated to the µFE pull-out stiffness of the ROI (R2 > 0.87) and FV (R2 > 0.84) models. No significant difference due to screw design was observed. Cement augmentation increased pull-out stiffness by up to 94% and 48% for L and R screws, respectively, but only increased bending stiffness by up to 6.9% and 1.5%, respectively. Cementing involving only one screw tip resulted in lower stiffness increases in all tested screw designs and loading cases. The stiffening effect of cement augmentation on pull-out and bending stiffness was strongly and negatively correlated to local bone density around the screw (correlation coefficient ( R) = -0.95). Conclusion This combined experimental, µCT and µFE study showed that regional analyses may be sufficient to predict fixation strength in pull-out and that full analyses could show that cement augmentation around pedicle screws increased fixation stiffness in both pull-out and bending, especially for low-density bone. Cite this article: Bone Joint Res 2021;10(12):797–806.

Pullout strength for cannulated pedicle screws with bone cement augmentation in severely osteoporotic bone: Influences of radial hole and pilot hole tapping

2009 ◽  
Vol 24 (8) ◽  
pp. 613-618 ◽  
Author(s):  
Lih-Huei Chen ◽  
Ching-Lung Tai ◽  
Po-Liang Lai ◽  
De-Mei Lee ◽  
Tsung-Tin Tsai ◽  
...  
Keyword(s):  
Bone Cement ◽  
Pedicle Screws ◽  
Cement Augmentation ◽  
Osteoporotic Bone ◽  
Pullout Strength ◽  
Pilot Hole

Biomechanical analysis of stiffness and fracture displacement after using PMMA-augmented sacroiliac screw fixation for sacrum fractures

2017 ◽  
Vol 62 (4) ◽  
pp. 421-428 ◽  
Author(s):  
Andreas Höch ◽  
Richard Schimpf ◽  
Niels Hammer ◽  
Stefan Schleifenbaum ◽  
Michael Werner ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Pedicle Screws ◽  
Osteoporotic Fractures ◽  
Fragility Fractures ◽  
Cement Augmentation ◽  
Biomechanical Analysis ◽  
Human Donor ◽  
Sacroiliac Screw ◽  
Fracture Stabilization ◽  
Sacroiliac Screw Fixation

AbstractCement augmentation of pedicle screws is the gold standard for the stabilization of osteoporotic fractures of the spine. In-screw cement augmentation, in which cement is injected through the cannula, is another option for fracture stabilization of fragility fractures of the sacrum. However, biomechanical superiority of this technique compared to conventional sacroiliac screw fixation has not been tested. The present study compares the stability of cement-augmented and non-cement-augmented sacroiliac screw fixation in osteoporotic sacrum fractures under cyclic loading. Eight human donor pelvises with intact ligaments and 5

Modeling NiTi Superelastic-Shape Memory Antagonistic Beams: A Finite Element Analysis

2009 ◽  
Author(s):  
Majid Tabesh ◽  
Mohammad Elahinia ◽  
Mehdi Pourazady
Keyword(s):  
Finite Element ◽  
Body Temperature ◽  
Shape Memory ◽  
Pedicle Screws ◽  
Experimental Tests ◽  
Element Analysis ◽  
Major Drawback ◽  
Screw Design ◽  
Finite Element Software ◽  
Engineering Sciences

Shape memory alloys (SMA) have received widespread attention from researchers in various fields of engineering sciences due to their exceptional properties of shape memory and superelasticity. NiTi equiatomic alloys among other SMA, show acceptable biocompatibility to be implemented in biomedical applications. Applications of NiTi in biomedical areas specifically orthopedics, demonstrate its unique performance which is not achievable with conventional materials. Pedicle screws, which are used as an anchoring point for implanting spinal instrumentations in spinal fracture and deformity treatments, entail a major drawback; i.e. loosening and back-out. The strength of screw contact with the surrounding bone diminishes as the bone degrades due to osteoporosis. A “Smart” pedicle screw design was developed to address this issue which uses NiTi superelastic-shape memory coils wrapped around it. The smart assembly consists of external superelastic tubing which is responsible for expanding the designed protrusions when they reach body temperature; also an internal shape memory wire inserted into the tubing is sought to retract the assembly when locally heated to above body temperature. The whole assembly was modeled as a beam structure in COMSOL Multiphysics Finite Element software. The behavior of shape memory alloy was defined in the software via its Partial Differential Equation (PDE) module. The SMA model has is a Tanaka-based model and is capable of capturing shape memory effect, superelasticity and hysteresis behavior, and partial transformation in both positive and negative directions. This 1D model was further modified to be included in a 3D framework such that it makes it possible for simulation of a beam under bending. The functionality of the smart screw design can be studied via this FEM model as a future work and the outcomes of the simulation can be compared with experimental tests on the prepared sample of the screw comprising NiTi tubing and wires.

scholarly journals Evaluation of the Intrinsic Properties of Pedicle Screws: Do Diameter, Manufacturing and Screw Design Affect Resistance and/or Resistivity

2009 ◽  
Vol 9 (1) ◽  
pp. S77-S82 ◽  
Author(s):  
Worawat Limthongkul ◽  
Jason Savage ◽  
Emmanuel K. Nenonene ◽  
Eldin E. Karaikovic
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Constant Current ◽  
Intrinsic Properties ◽  
Measurement Variability ◽  
Screw Design ◽  
Measured Voltage ◽  
Lower Resistance ◽  
Screw Diameter ◽  
Lower Resistivity

The pedicle screw diameter, composite and design are variables that can affect the threshold of intraoperative electromyographic monitoring. Even though we know that larger diameter objects tend to have less resistance, no study documented the effect that this variable could have on pedicle screw resistance. Using high quality equipment, resistance and resistivity of ten pedicle screws (from four manufacturers) were calculated based on known constant current and measured voltage. Voltage was measured three times for each screw to determine intraobserver measurement variability. Resistance of all screws ranged from 1.4 to 3.9 m ohm (mean = 2.69+/-0.71 m ohm). The screw with largest diameter (7.75 mm) had lower resistance than screws with other diameters. Resistivity of screws ranged from 7.12 to 12.63 micro ohm*m (mean = 9.9+/-1.82 micro ohm*m). Based on the screw design, one manufacturer's pedicle screws (A) had significantly lower resistivity compared to three other manufacturers (p<0.01). Larger diameter screws (7.75 mm in diameter) had lower resistance. Screw design (polyaxial or monoaxial) had no effect on its resistance. Screws of one manufacturer (A) showed lower resistivity compared to those manufactured by other three companies.

Effect of Fenestrated Pedicle Screws with Cement Augmentation in Osteoporotic Patients Undergoing Spinal Fusion

2020 ◽  
Vol 143 ◽  
pp. e351-e361
Author(s):  
Yamaan S. Saadeh ◽  
Kevin N. Swong ◽  
Timothy J. Yee ◽  
Michael J. Strong ◽  
Osama N. Kashlan ◽  
...  
Keyword(s):  
Spinal Fusion ◽  
Pedicle Screws ◽  
Cement Augmentation

scholarly journals Rescue Augmentation: Increased Stability in Augmentation After Initial Loosening of Pedicle Screws

2020 ◽  
pp. 219256822091912
Author(s):  
Lukas Weiser ◽  
Gerd Huber ◽  
Kay Sellenschloh ◽  
Klaus Püschel ◽  
Michael M. Morlock ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Bone Density ◽  
Fatigue Testing ◽  
Quantitative Computed Tomography ◽  
Pedicle Screws ◽  
Fatigue Loading ◽  
Cement Augmentation ◽  
Fatigue Load ◽  
The Impact

Study Design: Biomechanical study. Objectives: Failure of pedicle screws is a major problem in spinal surgery not only postoperatively, but also intraoperatively. The aim of this study was to evaluate whether cement augmentation may restore mounting of initially loosened pedicle screws. Methods: A total of 14 osteoporotic or osteopenic human cadaveric vertebral bodies (L2)—according to quantitative computed tomography (QCT)—were instrumented on both sides by conventional pedicle screws and cement augmented on 1 side. In vitro fatigue loading (cranial-caudal sinusoidal, 0.5 Hz) with increasing peak force (100 N + 0.1 N/cycles) was applied until a screw head displacement of 5.4 mm (∼20°) was reached. After loosening, the nonaugmented screw was rescue augmented, and fatigue testing was repeated. Results: The fatigue load reached 207.3 N for the nonaugmented screws and was significantly ( P = .009) exceeded because of initial cement augmentation (300.6 N). The rescue augmentation after screw loosening showed a fatigue load of 370.1 N which was significantly higher ( P < .001) compared with the nonaugmented screws. The impact of bone density on fatigue strength decreased from the nonaugmented to the augmented to the rescue-augmented screws and shows the greatest effect of cement augmentation on fatigue strength at low bone density. Conclusions: Rescue augmentation leads to similar or higher fatigue strengths compared with those of the initially augmented screws. Therefore, the cement augmentation of initially loosened pedicle screws is a promising option to restore adequate screw stability.

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