Biomechanical analysis of pedicle screw thread differential design in an osteoporotic cadaver model

Mehta, Hitesh; Santos, Edward Rainier G; Ledonio, Charles Gerald T.; Sembrano, Jonathan N.; Ellingson, Arin M.; Pare, Philippe; Murrell, Brian; Nuckley, David J.

doi:10.1016/j.clinbiomech.2011.10.004

Cited by 54 publications

(41 citation statements)

References 16 publications

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“…A greater depth of thread and pitch leads to a higher pull-out strength of the screw which is due to greater holding capacity to the bones [36]. While the size of screw peak has no significant effect on the pullout strength [37], the screw length increases the pull-out strength due to higher contact or interface with the bone [38]. Therefore, the bone screw prototype in this work with a full length of 33 mm gives a high pull-out strength.…”

Section: Tensilementioning

confidence: 99%

Mechanical and corrosion properties of partially degradable bone screws made of pure iron and stainless steel 316L by friction welding

et al. 2017

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Section: Tensilementioning

confidence: 99%

Mechanical and corrosion properties of partially degradable bone screws made of pure iron and stainless steel 316L by friction welding

et al. 2017

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“…modified thread-design screw, 23 hydroxyapatite-coated screw, 29,32 and polymethylmethacrylate (PMMA) augmentation. 20,31 Among these approaches, the FPSs augmented by PMMA has achieved the highest fixation strength and best clinical outcomes 1,26 .…”

Section: 26mentioning

confidence: 99%

“…The protocol used was according to Mehta et al, 23 who performed their experiment based on the Standard Specification and Test Methods for Metallic Medical Bone Screws (ASTM F543-07). Briefly, the vertebra was fixed to a custom-made clamper subjected to load frame and the screw head was attached to the load fixture.…”

Section: Pullout Testmentioning

confidence: 99%

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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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“…Several solutions were studied to prevent screw pullout. These can be investigated under three main categories: screw design, expandable screws and cement augmentation [2][3][4][5][6][7][8][9][10][11][12]. Design studies on screw core geometry (cylindrical or conical), number of threads, flank overlap area, pitch diameter, dual lead and dual core were investigated by researchers.…”

Section: Introductionmentioning

confidence: 99%

Possible Usage of Cannulated Pedicle Screws without Cement Augmentation

Demir

2014

Applied Bionics and Biomechanics

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Abstract. 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.

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Biomechanical analysis of pedicle screw thread differential design in an osteoporotic cadaver model

Cited by 54 publications

References 16 publications

Mechanical and corrosion properties of partially degradable bone screws made of pure iron and stainless steel 316L by friction welding

Mechanical and corrosion properties of partially degradable bone screws made of pure iron and stainless steel 316L by friction welding

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

Possible Usage of Cannulated Pedicle Screws without Cement Augmentation

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