Effect of the Degree of Osteoporosis on the Biomechanical Anchoring Strength of the Sacral Pedicle Screws

Zhuang, Xiaoxi; Yu, Bo; Zheng, Zhaomin; Zhang, Jia-Fang; Lu, William W.

doi:10.1097/brs.0b013e3181c5fb21

Cited by 61 publications

(21 citation statements)

References 28 publications

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“…In osteoporotic patients, the abnormal bone mass can affect the mechanical properties of the bone (23) and may lead to low back pain, disc degeneration or wedge fracture of the vertebral body (45678). Moreover, the decreased bone mass of the cervical vertebrae is closely related to loosening of the spinal surgical implant screws and the artificial inter-vertebral disc substitutes (910). …”

Section: Introductionmentioning

confidence: 99%

Population-Stratified Analysis of Bone Mineral Density Distribution in Cervical and Lumbar Vertebrae of Chinese from Quantitative Computed Tomography

Zhang

Zhou

et al. 2016

Korean J Radiol

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ObjectiveTo investigate the bone mineral density (BMD) of cervical vertebrae in a population-stratified manner and correlate with that of the lumbar vertebrae.Materials and MethodsFive hundred and ninety-eight healthy volunteers (254 males, 344 females), ranging from 20 to 64 years of age, were recruited for volumetric BMD (vBMD) measurements by quantitative computed tomography. Basic information (age, height, weight, waistline, and hipline), and vBMD of the cervical and lumbar vertebrae (C2–7 and L2–4) were recorded. Comparisons among sex, age groups and different levels of vertebrae were analyzed using analysis of variance. Linear regression was performed for relevance of different vertebral levels.ResultsThe vBMD of cervical and lumbar vertebrae was higher in females than males in each age group. The vBMD of the cervical and lumbar vertebrae in males and the vBMD of lumbar vertebrae in females decreased with aging. In each age group, the vBMD of the cervical vertebrae was higher than that of the lumbar vertebrae with gradual decreases from C2 to C7 except for C3; moreover, the vBMD of C6 and C7 was significantly different from that of C2–5. Correlations of vBMD among different cervical vertebrae (females: r = 0.62–0.94; males: r = 0.63–0.94) and lumbar vertebrae (males: r = 0.93–0.98; females: r = 0.82–0.97) were statistically significant at each age group.ConclusionThe present study provided normative data of cervical vertebrae in an age- and sex-stratified manner. Sex differences in vBMD prominently vary with age, which can be helpful to design a more comprehensive pre-operative surgical plan.

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Section: Introductionmentioning

confidence: 99%

Population-Stratified Analysis of Bone Mineral Density Distribution in Cervical and Lumbar Vertebrae of Chinese from Quantitative Computed Tomography

Zhang

Zhou

et al. 2016

Korean J Radiol

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“…A variety of designs and surgical techniques have been implemented, both clinically and in laboratory settings, in an attempt to enhance the amount of fixation possible between the pedicle screw and the surrounding bone of osteoporotic patients. One method includes augmenting the screw with a bone cement, such as polymethylmethacrylate (PMMA), calcium phosphate (CaP), and hydroxyapatite (HA), which can dramatically increase the purchase of screws in the vertebral body [11, 13, 15–29]. Another approach for improving the screw fixation is design alteration, which includes modifications to the diameter [30–32], length [32, 33], thread design [34–38], and tapering of the inner diameter of the screw [17, 30, 38, 39].…”

Section: Introductionmentioning

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

136

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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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“…Our review of the literature found that most of the current research on pedicle screw pullout has been performed with cylindrically shaped pedicle screws [4,5,7,18-20]. Cross sections of pedicles at the lumbar spine have an elliptical shape.…”

Section: Introductionmentioning

confidence: 99%

Pullout strength of pedicle screws with cement augmentation in severe osteoporosis: A comparative study between cannulated screws with cement injection and solid screws with cement pre-filling

Chen

Tai

Lee

et al. 2011

BMC Musculoskelet Disord

115

110

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BackgroundPedicle screws with PMMA cement augmentation have been shown to significantly improve the fixation strength in a severely osteoporotic spine. However, the efficacy of screw fixation for different cement augmentation techniques, namely solid screws with retrograde cement pre-filling versus cannulated screws with cement injection through perforation, remains unknown. This study aimed to determine the difference in pullout strength between conical and cylindrical screws based on the aforementioned cement augmentation techniques. The potential loss of fixation upon partial screw removal after screw insertion was also examined.MethodThe Taguchi method with an L8 array was employed to determine the significance of design factors. Conical and cylindrical pedicle screws with solid or cannulated designs were installed using two different screw augmentation techniques: solid screws with retrograde cement pre-filling and cannulated screws with cement injection through perforation. Uniform synthetic bones (test block) simulating severe osteoporosis were used to provide a platform for each screw design and cement augmentation technique. Pedicle screws at full insertion and after a 360-degree back-out from full insertion were then tested for axial pullout failure using a mechanical testing machine.ResultsThe results revealed the following 1) Regardless of the screw outer geometry (conical or cylindrical), solid screws with retrograde cement pre-filling exhibited significantly higher pullout strength than did cannulated screws with cement injection through perforation (p = 0.0129 for conical screws; p = 0.005 for cylindrical screws). 2) For a given cement augmentation technique (screws without cement augmentation, cannulated screws with cement injection or solid screws with cement pre-filling), no significant difference in pullout strength was found between conical and cylindrical screws (p >0.05). 3) Cement infiltration into the open cell of the test block led to the formation of a cement/bone composite structure. Observations of the failed specimens indicated that failure occurred at the composite/bone interface, whereas the composite remained well bonded to the screws. This result implies that the screw/composite interfacial strength was much higher than the composite/bone interfacial strength. 4) The back-out of the screw by 360 degrees from full insertion did not decrease the pullout strength in any of the studied cases. 5) Generally, larger standard deviations were found for the screw back-out cases, implying that the results of full insertion cases are more repeatable than those of the back-out cases.ConclusionsSolid screws with retrograde cement pre-filling offer improved initial fixation strength when compared to that of cannulated screws with cement injection through perforation for both the conically and cylindrically shaped screw. Our results also suggest that the fixation screws can be backed out by 360 degrees for intra-operative adjustment without the loss of fixation strength.

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Effect of the Degree of Osteoporosis on the Biomechanical Anchoring Strength of the Sacral Pedicle Screws

Cited by 61 publications

References 28 publications

Population-Stratified Analysis of Bone Mineral Density Distribution in Cervical and Lumbar Vertebrae of Chinese from Quantitative Computed Tomography

Population-Stratified Analysis of Bone Mineral Density Distribution in Cervical and Lumbar Vertebrae of Chinese from Quantitative Computed Tomography

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

Pullout strength of pedicle screws with cement augmentation in severe osteoporosis: A comparative study between cannulated screws with cement injection and solid screws with cement pre-filling

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