Browsing by Author "Bagley, Carlos A"

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    Comparison of superior-level facet joint violations during open and percutaneous pedicle screw placement.
    (Neurosurgery, 2012-11) Babu, Ranjith; Park, Jong G; Mehta, Ankit I; Shan, Tony; Grossi, Peter M; Brown, Christopher R; Richardson, William J; Isaacs, Robert E; Bagley, Carlos A; Kuchibhatla, Maragatha; Gottfried, Oren N

    Background

    Superior-level facet joint violation by pedicle screws may result in increased stress to the level above the instrumentation and may contribute to adjacent segment disease. Previous studies have evaluated facet joint violations in open or percutaneous screw cases, but there are no reports describing a direct institutional comparison.

    Objective

    To compare the incidence of superior-level facet violation for open vs percutaneous pedicle screws and to evaluate patient and surgical factors that affect this outcome.

    Methods

    We reviewed 279 consecutive patients who underwent an index instrumented lumbar fusion from 2007 to 2011 for degenerative spine disease with stenosis with or without spondylolisthesis. We used a computed tomography grading system that represents progressively increasing grades of facet joint violation. Patient and surgical factors were evaluated to determine their impact on facet violation.

    Results

    Our cohort consisted of 126 open and 153 percutaneous cases. Percutaneous procedures had a higher overall violation grade (P = .02) and a greater incidence of high-grade violations (P = .006) compared with open procedures. Bivariate analysis showed significantly greater violations in percutaneous cases for age < 65 years, obesity, pedicle screws at L4, and 1- and 2-level surgeries. Multivariate analysis showed the percutaneous approach and depth of the spine to be independent risk factors for high-grade violations.

    Conclusion

    This study demonstrates greater facet violations for percutaneously placed pedicle screws compared with open screws.
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    Experience with intrawound vancomycin powder for spinal deformity surgery.
    (Spine, 2014-01) Martin, Joel R; Adogwa, Owoicho; Brown, Christopher R; Bagley, Carlos A; Richardson, William J; Lad, Shivanand P; Kuchibhatla, Maragatha; Gottfried, Oren N

    Study design

    Retrospective cohort study.

    Objective

    To evaluate the ability of local vancomycin powder to prevent deep wound infection after thoracolumbar and lumbar spinal fusion for open deformity cases.

    Summary of background data

    Recent studies report that local delivery of vancomycin powder is associated with a decrease in spinal surgical site infection (SSI). This study compares deformity fusion cases before and after the routine application of spinal vancomycin powder.

    Methods

    Posterior spinal deformity surgical procedures by a single institution were reviewed from January 2011 to April 2013. Routine application of vancomycin powder started in April 2012. Inclusion criteria included adult patients who underwent posterior fusion for deformity pathologies, including spondylolisthesis, kyphosis, sagittal imbalance, and scoliosis. Each cohort's baseline characteristics including infection risk factors, operative data, and rates of wound infection were compared. Associations between infection and vancomycin powder, with and without propensity score adjustment for risk factors were determined using logistic regression.

    Results

    A total of 306 patients were included in the study. All measured baseline and operative variables were statistically similar between untreated (n = 150) and those who received vancomycin powder (n = 156). No significant change in deep wound infection rate was seen between the control (5.3%) and intervention group (5.1%, P = 0.936). Logistic regression with and without propensity score adjusted for risk factors demonstrated that the use of vancomycin powder did not impact the development of SSI (odds ratio [95% confidence interval]: 1.01 [0.36-2.79], P = 0.9910) and (odds ratio [95% confidence interval]: 0.87 [0.31-2.42], P = 0.7876), respectively.

    Conclusion

    The local application of powdered vancomycin was not associated with a significant difference in the rate of deep SSI after spinal deformity surgery, and other treatment modalities are necessary to limit infection for this high-risk group. This study is in contrary to prior studies, which have reported a decrease in SSI with vancomycin powder.

    Level of evidence

    2.
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    Molecular characterization of chordoma xenografts generated from a novel primary chordoma cell source and two chordoma cell lines.
    (J Neurosurg Spine, 2014-09) Karikari, Isaac O; Gilchrist, Christopher L; Jing, Liufang; Alcorta, David A; Chen, Jun; Richardson, William J; Gabr, Mostafa A; Bell, Richard D; Kelley, Michael J; Bagley, Carlos A; Setton, Lori A
    OBJECT: Chordoma cells can generate solid-like tumors in xenograft models that express some molecular characteristics of the parent tumor, including positivity for brachyury and cytokeratins. However, there is a dearth of molecular markers that relate to chordoma tumor growth, as well as the cell lines needed to advance treatment. The objective in this study was to isolate a novel primary chordoma cell source and analyze the characteristics of tumor growth in a mouse xenograft model for comparison with the established U-CH1 and U-CH2b cell lines. METHODS: Primary cells from a sacral chordoma, called "DVC-4," were cultured alongside U-CH1 and U-CH2b cells for more than 20 passages and characterized for expression of CD24 and brachyury. While brachyury is believed essential for driving tumor formation, CD24 is associated with healthy nucleus pulposus cells. Each cell type was subcutaneously implanted in NOD/SCID/IL2Rγ(null) mice. The percentage of solid tumors formed, time to maximum tumor size, and immunostaining scores for CD24 and brachyury (intensity scores of 0-3, heterogeneity scores of 0-1) were reported and evaluated to test differences across groups. RESULTS: The DVC-4 cells retained chordoma-like morphology in culture and exhibited CD24 and brachyury expression profiles in vitro that were similar to those for U-CH1 and U-CH2b. Both U-CH1 and DVC-4 cells grew tumors at rates that were faster than those for U-CH2b cells. Gross tumor developed at nearly every site (95%) injected with U-CH1 and at most sites (75%) injected with DVC-4. In contrast, U-CH2b cells produced grossly visible tumors in less than 50% of injected sites. Brachyury staining was similar among tumors derived from all 3 cell types and was intensely positive (scores of 2-3) in a majority of tissue sections. In contrast, differences in the pattern and intensity of staining for CD24 were noted among the 3 types of cell-derived tumors (p < 0.05, chi-square test), with evidence of intense and uniform staining in a majority of U-CH1 tumor sections (score of 3) and more than half of the DVC-4 tumor sections (scores of 2-3). In contrast, a majority of sections from U-CH2b cells stained modestly for CD24 (scores of 1-2) with a predominantly heterogeneous staining pattern. CONCLUSIONS: This is the first report on xenografts generated from U-CH2b cells in which a low tumorigenicity was discovered despite evidence of chordoma-like characteristics in vitro. For tumors derived from a primary chordoma cell and U-CH1 cell line, similarly intense staining for CD24 was observed, which may correspond to their similar potential to grow tumors. In contrast, U-CH2b tumors stained less intensely for CD24. These results emphasize that many markers, including CD24, may be useful in distinguishing among chordoma cell types and their tumorigenicity in vivo.