Spine
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Destructive compression tests and finite element analyses were conducted to investigate the biomechanical strength at the graft-endplate interface in anterior cervical fusion. ⋯ Results of this study suggest that it is important to preserve the endplate as much as possible to prevent graft subsidence into the vertebral body, particularly in patients with poor bone quality. It is preferable to make one central hole rather than multiple smaller holes in the endplate for vascularity of the bone graft because it reduces the surface area exposed to fracture stresses.
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It is always gratifying to be acknowledged by a colleague and asked to give a talk in a faraway land about a topic of one's particular interest. To be invited, however, to give the Harry Farfan Presidential Lecture at the 27th Meeting of the International Society for the Study of the Lumbar Spine is, for me, a special honor and privilege. Too many years ago, when I was a very junior faculty member at the School of Physical and Occupational Therapy at McGill University in Montreal, Canada, we offered our students a course in Orthopedic Conditions. ⋯ Harry Farfan graciously agreed and provided several lectures for our students. He told them about the surgical management of problems of the lumbar spine and the necessity of treating the "whole" patient, as well as about his theory as to the cause of low back pain. At that point in time, we were not talking about quality of life as an outcome of care for our patients, but I cannot help but believe that he would keenly approve of the subject of this presentation.
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A biomechanical investigation using indentation tests in a human cadaveric model to seek variation in the structural properties across the lower lumbar and sacral endplates. ⋯ Highly significant regional strength and stiffness variations were identified in the lumbar and sacral endplates. The center of the bone, where implants are currently placed, is the weakest part of the lumbar endplates and is not the strongest region of the sacral endplate.
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A biomechanical and anatomic study with human cadaveric lumbar spine. ⋯ This study showed that the intervertebral foramen of the lumbar spine changed significantly not only on flexion-extension but also on lateral bending and axial rotation. The percent change in cross-sectional foraminal area was correlated with the amount of segmental motion except for extension motions. Further studies are needed to assess the morphologic changes in the intervertebral foramen in vivo and to correlate clinically.
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Using human cadaver spines, the authors investigated mechanical properties of the interface between titanium mesh cage and vertebra in respect to vertebral bone mineral density. ⋯ A titanium mesh cage with larger diameter and/or augmentation of internal end ring produces a significant increase of the interface strength between the cage and the vertebra. A positive correlation between the interface strength and vertebral bone mineral density suggests that vertebral bone mineral density is an important parameter for successful spinal reconstruction, and also implies that in severe osteoporotic spine the stability of the cage is declined, and other instrumentation should be combined.