Lakemeier, Stefan

[["dc.bibliographiccitation.firstpage","473"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Biomedical Engineering / Biomedizinische Technik"],["dc.bibliographiccitation.lastpage","480"],["dc.bibliographiccitation.volume","57"],["dc.contributor.author","Foelsch, Christian"],["dc.contributor.author","Goost, Hans"],["dc.contributor.author","Figiel, Jens"],["dc.contributor.author","Paletta, Juergen R. J."],["dc.contributor.author","Schultz, Wolfgang"],["dc.contributor.author","Lakemeier, Stefan"],["dc.date.accessioned","2018-11-07T09:02:38Z"],["dc.date.available","2018-11-07T09:02:38Z"],["dc.date.issued","2012"],["dc.description.abstract","Background: Cement augmentation of pedicle screws increases fixation strength in an osteoporotic spine. This study was designed to determine the cement distribution and the correlation between the pull-out strength of the augmented screw and the cement volume within polyurethane (PU) foam. Methods: Twenty-eight cannulated pedicle screws (6 x 45 mm) (Peter Brehm, Erlangen, Germany) with four holes at the distal end of the screw were augmented with the acrylic Stabilit ER Bone Cement Vertebral Augmentation System (DFine Inc., San Jose, CA, USA) and implanted into open-cell rigid PU foam (Pacific Research Laboratories, Vashon Island, WA, USA) with a density of 0.12 g/cm(3), resembling severe osteoporosis. Volumetric measurement of the cement with consideration of the distribution around the screws was done with multislice computed tomography scan (Somatom Definition, Siemens, Erlangen, Germany). Pull-out strength was tested with a servohydraulic system (MTS System Corporation, Eden Prairie, MN, USA), and nonaugmented screws served as control. Pearson ' s correlation coefficient with significance level a = 0.05 and one-way analysis of variance test were used. Results: We found a high (r = 0.88) and significant (p < 0.01) correlation between the cement volume and the pull-out strength, which increased by more than 5-fold with a volume of 3 ml. The correlation appeared linear at least up to 4 ml cement volume and failure always occurred at the cement-bone interface. The cement distribution was symmetric and circular around the most proximal hole, with a distance of 14 mm from the tip, and nearly 90% of the cement was found 6 mm distal and cranial to it. The 95% confidence interval for the relative amount of cement was 37% -41% within 2 mm of the most proximal hole. Conclusion: Compared with the control, a cement volume between 2.0 and 3.0 ml increased the pull-out strength significantly and is relevant for clinical purposes, whereas a volume of 0.5 ml did not. A cement volume beyond 3.0 ml should further increase the pull-out strength because the correlation was linear at least up to 4.0 ml, but the possibility of in vivo cement leakage with increasing volume has to be considered. Pressure-controlled cement application might be a tool to avoid this complication. The cement almost completely penetrated the most proximal perforation."],["dc.identifier.doi","10.1515/bmt-2012-0012"],["dc.identifier.isi","000312707900007"],["dc.identifier.pmid","23152399"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10598"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/24730"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Walter De Gruyter & Co"],["dc.relation.issn","0013-5585"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Correlation of pull-out strength of cement-augmented pedicle screws with CT-volumetric measurement of cement"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","359"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Acta Neurochirurgica"],["dc.bibliographiccitation.lastpage","365"],["dc.bibliographiccitation.volume","154"],["dc.contributor.author","Lakemeier, Stefan"],["dc.contributor.author","Schmid, Raphael"],["dc.contributor.author","Foltz, Lisa"],["dc.contributor.author","Rohlfs, Jochen"],["dc.contributor.author","Fuchs-Winkelmann, Susanne"],["dc.contributor.author","Efe, Turgay"],["dc.contributor.author","Foelsch, Christian"],["dc.contributor.author","Paletta, Jürgen R. J."],["dc.date.accessioned","2019-07-09T11:54:37Z"],["dc.date.available","2019-07-09T11:54:37Z"],["dc.date.issued","2011"],["dc.description.abstract","Background The most common spinal disorder in the elderly is lumbar spinal stenosis (LSS), which results in part from ligamentum flavum (LF) hypertrophy. Although prior histologic and immunochemical studies have been performed in this area, the pathophysiology of loss of elasticity and hypertrophy is not completely understood. The purpose of this immunohistological study is to elucidate the role of CD44 and its splice variants CD44v5 and CD44v6 in the hypertrophied LF obtained from patients with lumbar spinal stenosis (LSS). Materials and methods LF samples of 38 patients with LSS were harvested during spinal decompression. Twelve LF samples obtained from patients with disc herniation and no visible degeneration on preoperative MRI were obtained as controls. Samples were dehydrated and embedded in paraffin. For immunohistochemical determination, slices were stained with antibodies against CD44, Cd44v4, and CD44v6 stained with DAB. LF hypertrophy and cross-sectional area (CSA) were measured with T1-weighted MRI. Results CD44 and CD44v5 expression were significantly increased in the hypertrophy group (p<0.05). CD44v6 expression was not significantly increased. The number of elastic fibers was significantly higher in the hypertrophy group. In the hypertrophy group, LF thickness was significantly increased while CSA was significantly decreased. There was a statistical correlation between LF thickness, CSA, CD44, and CD44v5 expression in the hypertrophy group (p<0.05). Conclusions LF hypertrophy is accompanied by increased CD44 and CD44v5 expression. CD44v6 expression is not enhanced in LF hypertrophy."],["dc.format.extent","7"],["dc.identifier.doi","10.1007/s00701-011-1206-z"],["dc.identifier.fs","593532"],["dc.identifier.pmid","22052472"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9467"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/60696"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","0942-0940"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Increased expression of CD44 in hypertrophied ligamentum flavum and relevance of splice variants CD44v5 and CD44v6"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]