Characteristics of immediate and fatigue strength of a dual-threaded pedicle screw in cadaveric spines

Brasiliense, Leonardo B.C.; Lázaro, Bruno C.R.; Reyes, Phillip M.; Newcomb, Anna G.; Turner, Joseph L.; Crandall, Dennis G.; Crawford, Neil R.

doi:10.1016/j.spinee.2013.03.010

Cited by 65 publications

(45 citation statements)

References 34 publications

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“…However, the dual-threaded screw achieved a pullout force 19% less than that of the single threaded screw when being tested in high porosity (low density) polyurethane foam models and performed only slightly better (7.8%) when tested in vertebrae with a bone density of less than 0.8 g/cm 2 . Both differences were determined to be statistically insignificant [37]. These results differ from those reported by Thompson et al [36], who stated that the surface area of the screw's thread was a good predictor of its fixation strength within bone.…”

Section: Basic Screw Designmentioning

confidence: 87%

“…Also hoping to increase the fixation of pedicle screws through the addition of more than one thread, Brasiliense et al [37] compared a standard single threaded screw with a pitch of 2.6 mm to a screw with a pitch of 4 mm and the addition of a second parallel thread in the proximal half. They hypothesized that while the standard screw had a larger overall FOA, the dual-threaded screw had a larger FOA in the region of the pedicle, which the majority of the pullout force is dependent upon [33, 59], and therefore should increase fixation within the bone.…”

Section: Basic Screw Designmentioning

confidence: 99%

See 1 more Smart Citation

Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status

Shea

Laun

Gonzalez-Blohm

et al. 2014

BioMed Research International

137

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Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g., spinal fusion) is needed after failure of conservative treatments. Different pedicle screw designs and instrumentation techniques have been explored to enhance spinal device fixation in bone of compromised quality. These include alterations of screw thread design, optimization of pilot hole size for non-self-tapping screws, modification of the implant's trajectory, and bone cement augmentation. While the true benefits and limitations of any procedure may not be realized until they are observed in a clinical setting, axial pullout tests, due in large part to their reproducibility and ease of execution, are commonly used to estimate the device's effectiveness by quantifying the change in force required to remove the screw from the body. The objective of this investigation is to provide an overview of the different pedicle screw designs and the associated surgical techniques either currently utilized or proposed to improve pullout strength in osteoporotic patients. Mechanical comparisons as well as potential advantages and disadvantages of each consideration are provided herein.

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Section: Basic Screw Designmentioning

confidence: 87%

Section: Basic Screw Designmentioning

confidence: 99%

Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status

Shea

Laun

Gonzalez-Blohm

et al. 2014

BioMed Research International

137

View full text Add to dashboard Cite

show abstract

“…The material in bone model failed primarily in the shearing of a thin region the size of outer diameter of the screw as observed in studies on synthetic, human, and animal bones [61][62][63] . The different design factors that effect the pullout strength of pedicle screws can be classified as by screw parameters, such as thread type [27,52,64] , outer diameter [9] , and inner diameter or by insertion technique, such as the effect of size of pilot holes [65] , tapping [66] , and insertion angle [23] , or by augmentation technique such as polymethylmethacrylate(PMMA) [16] , or calcium phosphate (CaP) [67] . A detailed discussion regarding these factors can be read in a review paper by Shea et al .…”

Section: Discussionmentioning

confidence: 99%

Effect of various factors on pull out strength of pedicle screw in normal and osteoporotic cancellous bone models

Varghese

Kumar

Krishnan

2017

Medical Engineering & Physics

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“…However, the demand for pullout force also decreased due to a less active lifestyle in the elderly. With the development of screw xations such as dual-threaded pedicle screws, which may have a stronger pullout force than their single-threaded counterparts (24), and minimally-invasive surgical technology that protects the back muscle better than open surgery (11), we hypothesized that patients with low BMD who underwent PSSF may attain stabilization following surgery. In this study, patients with BMD in their lumbar region between 1g/cm 2 and 0.5g/cm 2 and a de nite history of major trauma, which was distinguished from osteoporosis with pathological fractures, were enrolled.…”

Section: Discussionmentioning

confidence: 99%

Efficacy of percutaneous short segment fixation on the treatment of Magerl A3 thoracolumbar fractures: a retrospective study

lin

et al. 2020

Preprint

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BackgroundThis is a retrospective study to evaluate the efficacy of percutaneous short segment fixation (PSSF) with or without intermediate screws in Magerl A3 thoracolumbar (TL) fractures accompanied with low bone mineral density (BMD).Methods From January 2017 to December 2018, 30 patients diagnosed with Magerl A3 TL fractures having a BMD between 0.5/cm2 and 1g/cm2 in the lumbar vertebrae with intact neurological functions and a history of major trauma who underwent PSSF with or without intermediate screws were enrolled in this study. The patients were divided into two groups of those with intermediate screws (group F) or without (group S). The operation time and intra-operation blood loss were recorded. Oswestry disability index (ODI) questionnaire and visual analogue scale (VAS) were employed as clinical assessments and quantified. Radiographic follow-up assessed according to the Cobb angle (CA), Vertebral wedge angle (VWA), and anterior vertebral body height (AVBH).ResultsLoose screws were observed in 4 of the 30 enrolled patients. Significant differences were observed in operation time and intra-operative blood loss between the two groups. The enrolled patients’ clinical results (VAS and ODI scores) were good, however, no significant differences during all follow-up periods were present between the two groups. Radiographic evaluation (CA, VWA and AVBH) improved immediately after surgery, but significant correction loss was observed in the follow-up periods, especially in the first month. Radiographic evaluation demonstrated no significant differences between the two groups.Conclusion Although the patients’ clinical results were satisfactory, PSSF could not resist the correction loss in Magerl A3 TL fractures accompanied with BMD below 1g/cm2. Accordingly, the use of intermediate pedicle screws may be unnecessary due to their limited ability in resisting correction loss and increasing operation time as well as intra-operation blood loss.

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Characteristics of immediate and fatigue strength of a dual-threaded pedicle screw in cadaveric spines

Cited by 65 publications

References 34 publications

Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status

Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status

Effect of various factors on pull out strength of pedicle screw in normal and osteoporotic cancellous bone models

Efficacy of percutaneous short segment fixation on the treatment of Magerl A3 thoracolumbar fractures: a retrospective study

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