Comparison of eight published static finite element models of the intact lumbar spine : predictive power of models improves when combined together

Finite element (FE) model studies have made important contributions to our understanding of functional biomechanics of the lumbar spine. However, if a model is used to answer clinical and biomechanical questions over a certain population, their inherently large inter-subject variability has to be considered. Current FE model studies, however, generally account only for a single distinct spinal geometry with one set of material properties. This raises questions concerning their predictive power, their range of results and on their agreement with in vitro and in vivo values. Eight well-established FE models of the lumbar spine (L1-5) of different research centres around the globe were subjected to pure and combined loading modes and compared to in vitro and in vivo measurements for intervertebral rotations, disc pressures and facet joint forces. Under pure moment loading, the predicted L1-5 rotations of almost all models fell within the reported in vitro ranges, and their median values differed on average by only 2° for flexion-extension, 1° for lateral bending and 5° for axial rotation. Predicted median facet joint forces and disc pressures were also in good agreement with published median in vitro values. However, the ranges of predictions were larger and exceeded those reported in vitro, especially for the facet joint forces. For all combined loading modes, except for flexion, predicted median segmental intervertebral rotations and disc pressures were in good agreement with measured in vivo values. In light of high inter-subject variability, the generalization of results of a single model to a population remains a concern. This study demonstrated that the pooled median of individual model results, similar to a probabilistic approach, can be used as an improved predictive tool in order to estimate the response of the lumbar spine.

Learning from Eames : six lessons

"Eventually everything connects—people, ideas, objects. The quality of the connections is the key toquality per se.” (Charles Eames) On 8 November, 2007, in a moment charged with serendipity, an Exhibition titled ‘The Gifted Eye of Charles Eames—A Portfolio of 100 images’ was opened exclusively to Brisbane. The Artisan Gallery in Fortitude Valley became the launch point for an international orbit of Fringe locations hosting one of 18 sets of 100 images each...

Perfect start to a river cruise

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Kari Gislason's response to the Ottoman Motel by Christopher Currie [The Art of Vanishing Parents]

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Popular Science

Review of The Anatomist by Bill Hayes (Scribe, 2008). Bill Hayes wanted to write about Henry Gray, the author of Gray's Anatomy (1858), which at least until the television series connoted a standard text for anatomy students. Perhaps even more seductive for the biographer than the book's enduring appeal was a sense that Gray himself had partly disappeared from the historical record. Here was a scientist with the sort of brilliant young mind that seemed a specialty of the Victorian Age, and yet one who had not benefited from that period's compulsive documenting of the men of the moment and their deeds. Surely in that mystery there lay a narrative...