Biomechanical analysis of different types of pedicle screw augmentation: A cadaveric and synthetic bone sample study of instrumented vertebral specimens

Chao, Kuo-Hua; Lai, Yu‐Shu; Chen, Wen-Chuan; Chang, Chia‐Ming; McClean, Colin J.; Fan, Chang-Yuan; Chang, Chia‐Hao; Lin, Leou-Chyr; Cheng, Cheng‐Kung

doi:10.1016/j.medengphy.2013.04.007

Cited by 62 publications

(57 citation statements)

References 30 publications

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“…1,7,14,17,21,24 The main difference among these FPSs is the number of side perforations. Regardless of the different number of perforations, the pullout strength of PMMA-augmented FPSs is greater than that of nonaugmented conventional screws 3,5,9,10,12,26 or cannulated screws 8,16,18 in the osteoporotic condition. In the present study, compared with the nonaugmented CPS group, FPS-A1.0, 1.5, and 2.0 achieved 137%, 207%, and 265% increased pullout strengths, respectively, and FPS-B1.0, 1.5, and 2.0 achieved 166%, 232%, and 269% increased pullout strengths, respectively.…”

Section: Discussionmentioning

confidence: 95%

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Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations

Tan

Peng

et al. 2016

SPI

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OBJECTIVE This study investigated the optimum injection volume of polymethylmethacrylate (PMMA) to augment a novel fenestrated pedicle screw (FPS) with diameter-tapered perforations in the osteoporotic vertebral body, and how the distribution characteristics of PMMA affect the biomechanical performance of this screw. METHODS Two types of FPSs were designed (FPS-A, composed of 6 perforations with an equal diameter of 1.2 mm; and FPS-B, composed of 6 perforations each with a tapered diameter of 1.5 mm, 1.2 mm, and 0.9 mm from tip to head. Each of 28 human cadaveric osteoporotic vertebrae were randomly assigned to 1 of 7 groups: FPS-A1.0: FPS-A+1.0 ml PMMA; FPS-A1.5: FPS-A+1.5 ml PMMA; FPS-A2.0: FPS-A+2.0 ml PMMA; FPS-B1.0: FPS-B+1.0 ml PMMA; FPS-B1.5: FPS-B+1.5 ml PMMA; FPS-B2.0: FPS-B+2.0 ml PMMA; and conventional pedicle screws (CPSs) without PMMA. After the augmentation, 3D CT was performed to assess the cement distribution characteristics and the cement leakage rate. Axial pullout tests were performed to compare the maximum pullout force thereafter. RESULTS The CT construction images showed that PMMA bone cement formed a conical mass around FPS-A and a cylindrical mass around FPS-B. When the injection volume was increased from 1.0 ml to 2.0 ml, the distribution region of the PMMA cement was enlarged, the PMMA was distributed more posteriorly, and the risk of leakage was increased. When the injection volume reached 2.0 ml, the risk of cement leakage was lower for screws having diameter-tapered perforations. The pullout strengths of the augmented FPS-A groups and FPS-B groups were higher than that of the CPS group (p < 0.0001). All FPS-B groups had a higher pullout strength than the FPS-A groups. CONCLUSIONS The diameter of the perforations affects the distribution of PMMA cement. The diameter-tapered design enabled PMMA to form larger bone-PMMA interfaces and achieve a relatively higher pullout strength, although statistical significance was not reached. Study results indicated 1.5-ml of PMMA was a conservative volume for PMMA augmentation; more cement injection would significantly increase the risk of cement leakage.

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Section: Discussionmentioning

confidence: 95%

“…Recently, FPSs with different designs have been studied in vitro [3][4][5][8][9][10]12,16,18,26 and in vivo. 1,7,14,17,21,24 The main difference among these FPSs is the number of side perforations.…”

Section: Discussionmentioning

confidence: 99%

Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations

Tan

Peng

et al. 2016

SPI

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“…Screw pull-out studies using human cadaveric tissues report a wide range of values from 102 to 1,741 N (15,26,28,(31)(32)(33)(34). Similarly, screw pull-out with the calf model reports values from 747 to 7,300 N, depending on treatment (30,35).…”

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.

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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.

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“…They also found that the failure rate of CPS can be reduced by reducing the number of the radial hole. Although the effect of parameters of the radial holes (diameter and position of radial holes) on failure rate of CPS have been proof experimentally and numerically by several researchers [4][5][6][7][8][9][10], the optimum position and diameter of radial holes still becoming one of the gap in this research field. Thus, the aim of this paper is to propose the design optimization of cannulated pedicle screw which focuses more on optimization of diameter and position of radial holes.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Position and Different Size of Radial Hole on Performance of Cannulated Pedicle Screw

et al. 2017

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Abstract. Cannulated Pedicle Screw (CPS) is the instrumentation that has been introduced in Biomedical field in order to stabilize the spine structure and also to enhance the pullout strength in osteoporotic patient. The cement is injected through the CPS which is flow from the screw head to the radial hole and then distributed around the CPS to give higher performance of pullout strength. However, the fracture still reported to happened around the radial hole. This paper is aim to focus on the effect of the position and different diameter of radial hole on the CPS. Three designs were constructed using SolidWork software where two of it are the current models whereas the third was the proposed design which the radial holes were position differently (skewed to each other) and its size is smaller than the current model, 1.0 mm and 1.5mm respectively. The software used for Finite Element Analysis (FEA) is Ansys workbench 16.0. The Finite Element Models were verified with FEA result of the previous research. The FEA results of torsional stress for current and proposed design were then compared to obtain the maximum torque that both designs are able to resist before fracture. It can be concluded that the performance of CPS can be improved by the proposed design which is 2 radial hole skewed to each other and smaller radial hole diameter (1.0mm) than the current cannulated pedicle screw (1.5mm).

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Biomechanical analysis of different types of pedicle screw augmentation: A cadaveric and synthetic bone sample study of instrumented vertebral specimens

Cited by 62 publications

References 30 publications

Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations

Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations

The contribution of the cortical shell to pedicle screw fixation

The Effect of Position and Different Size of Radial Hole on Performance of Cannulated Pedicle Screw

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