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How evolutionary changes in body size are brought about by variance in developmental timing and/or growth rates (also known as heterochrony) is a topic of considerable interest in evolutionary biology. In particular, extreme size change leading to gigantism occurred within the dinosaurs on multiple occasions. Whether this change was brought about by(More)
OBJECTIVE To determine whether the human Achilles tendon has higher material properties than other tendons and to test for strain rate sensitivity of the tendon. DESIGN Mechanical testing of excised tendons. BACKGROUND While the human Achilles tendon appears to experience higher in vivo stresses than other tendons, it is not known how the Achilles(More)
Did dinosaurs grow in a manner similar to extant reptiles, mammals or birds, or were they unique? Are rapid avian growth rates an innovation unique to birds, or were they inherited from dinosaurian precursors? We quantified growth rates for a group of dinosaurs spanning the phylogenetic and size diversity for the clade and used regression analysis to(More)
STUDY DESIGN The range of motion (ROM) of lumbar cadaver spines was measured during flexion, extension, axial rotation, and lateral bending following graded facetectomies and implantation of an X STOP interspinous spacer implant. OBJECTIVE The study was performed undertaken to understand better the influence of the interspinous spacer implant on the(More)
BACKGROUND Adjacent segment disease is a recognized consequence of fusion in the spinal column. Fusion of the sacroiliac joint is an effective method of pain reduction. Although effective, the consequences of sacroiliac joint fusion and the potential for adjacent segment disease for the adjacent lumbar spinal levels is unknown. The objective of this study(More)
INTRODUCTION Sacroiliac (SI) joint pain has become a recognized factor in low back pain. The purpose of this study was to investigate the effect of a minimally invasive surgical SI joint fusion procedure on the in vitro biomechanics of the SI joint before and after cyclic loading. METHODS SEVEN CADAVERIC SPECIMENS WERE TESTED UNDER THE FOLLOWING(More)
We studied cadaveric motion segments instrumented with unique pedicle screw transducers and loaded in a corpectomy model. We hypothesized that the pedicle screw bending moments could be characterized using a mathematical model. Previous studies have estimated the loading characteristics of pedicle screws either by finite element analysis or by(More)
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