Lars G. Gilbertson

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STUDY DESIGN This study analyzed interlaminar shear stresses across the laminae of a ligamentous L3-L4 motion segment. A three-dimensional finite element model of the motion segment was developed and its response in axial compression mode was predicted. OBJECTIVES The contributions of "mechanical" factors in producing laminae separation in a disc are not(More)
STUDY DESIGN A nonlinear three-dimensional finite element model of the osteoligamentous L3-L4 motion segment was used to predict changes in posterior element loads as a function of disc implantation and associated surgical procedures. OBJECTIVES To evaluate the effects of disc implantation on the biomechanics of the posterior spinal elements (including(More)
STUDY DESIGN In vivo studies using a rabbit model to determine the biologic effects of direct, adenovirus-mediated transfer of a therapeutic gene to the intervertebral disc. OBJECTIVES 1) To deliver an exogenous therapeutic gene to rabbit lumbar intervertebral discs in vivo, 2) to quantify the resulting amount of gene expression, and 3) to determine the(More)
STUDY DESIGN The progression of intervertebral disc degeneration following anterolateral "stab" of adult rabbit lumbar discs by 16-gauge hypodermic needle to a limited (5-mm) depth was studied for up to 24 weeks using magnetic resonance imaging, radiograph, and histologic outcome measures. OBJECTIVES To develop a slowly progressive, reproducible rabbit(More)
Bone remodeling theory based on strain energy density (SED) as the feedback control variable was used in conjunction with the finite element method to analyze the shape of the vertebral bodies within the ligamentous motion segment. The remodeling theory was once again applied to the altered two motion segments model to predict the Young's modulus(More)
STUDY DESIGN A cohort of young, healthy New Zealand White rabbits was followed longitudinally with serial magnetic resonance imaging (MRI) analysis and terminal analysis of histologic changes and gene expression. OBJECTIVE To examine the changes observed during normal aging in the intervertebral disc. SUMMARY OF BACKGROUND DATA Although there is a(More)
The finite element method has been used in spine biomechanics research for nearly a quarter of a century. Recent developments have made it possible to simulate a variety of clinical situations in an increasingly realistic manner, and have elevated the finite element method into a fully complementary partnership with experimental approaches for investigating(More)
BACKGROUND CONTEXT Serial analysis of gene expression during the course of intervertebral disc degeneration (IDD) could elucidate valuable insight into pathophysiology and provide a basis for identification of potential targets for the development of novel cellular- and gene-based therapies. However, very few previous studies described the changes in gene(More)
BACKGROUND CONTEXT Different strategies to supplement/replenish the disc cell population have been proposed. Recently, adult stem cells have shown promise as a cell source for a variety of tissue engineering and cell therapy applications. A stem cell can renew itself through cell division and can be induced to develop into many different specialized cell(More)
STUDY DESIGN Changes in gene expression profile and cell fusion of mesenchymal stem cells (MSC) and nucleus pulposus cells (NPC) after coculture were analyzed. OBJECTIVE To investigate the mechanisms of the interaction between NPC and MSC such us differentiation, stimulatory effect, and cell fusion. SUMMARY OF BACKGROUND DATA Introduction of exogenous(More)