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Special issue on spinal biomechanics
ARTICLE IN PRESS
Journal of Biomechanics 37 (2004) 171
Editorial
Special issue on spinal biomechanics Many problems of the spine are now better understood because of biomechanical research. The Editors invited me to highlight this wide-ranging topic in this issue of the Journal. This issue contains 11 papers directed at problems in spinal biomechanics. For 10 of these articles, I supervised the peer review process, and one other (of which I am co-author) went through the normal review and editorial process. Spinal biomechanics has attracted the attention of biomechanics researchers for many reasons, notably its association with the huge medical and social problem of low back pain. In addition to work directed at this problem, papers in this Issue also address treatment of spinal deformities (Petit et al.), problems of loss of vertebral bone to osteoporosis and tumor (Haddock et al.) and remedial treatment for these conditions (Baroud et al.). Apart from the clinical importance of spinal biomechanics, there are many intriguing biomechanical questions about spinal and trunk function. The articulations are based around a flexible structure (the intervertebral disc), and the posterior elements interact in a complex way with the disc to transmit forces between the vertebrae (Pollentine et al.). The motion segment is the basic element of the spinal column, and its mechanical behavior varies with the testing conditions (Goertzen, et al., Gardner-Morse and Stokes). The intervertebral disc is a huge avascular structure whose viability depends on the transport of nutrients and metabolites over distances of several millimeters to the nearest blood supply. This transport may be beneficially altered by mechanical loading (Ferguson et al.). The disc annulus is a structurally highly organized tissue that undergoes large deformations, that also deform the cells within it (Bruehlmann et al.). The material properties of the disc annulus might be modified beneficially by novel physical means (Bass et al.). The vertebral column consists of over 20 articulations, each having six degrees of freedom, yet the number of muscles exceeds the total
0021-9290/$ - see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.jbiomech.2003.12.003
degrees of freedom. This provides the central nervous system with ‘choices’ about how to activate muscles for a specific tasks and in response to perturbations (Granata et al.). The interaction between muscles and spinal motion in real-world conditions and the work place appears to be partly but not entirely controlled to optimize defined biomechanical variables (Kingma and van Die.en). While they may not be a completely representative sample of current research topics in this field, in looking at the topics of these papers and the methodologies they employ, one factor is striking: almost every paper owes something (often a lot!) to the pioneering work on spinal biomechanics done by Albert B. Schultz. He, together with his students and colleagues, published 64 Medlinecited papers on spinal and trunk biomechanics (22 in the Journal of Biomechanics) during the period 1970–1997. (Then he shifted his attention to new challenges in the area of postural stability and falls.) His work on spinal biomechanics included finite element analyses of disc, scoliosis deformity and its treatment by braces and by surgery, simulation of spinal deformity surgery, motion segment properties and the role of the posterior elements, muscle force analyses, and neuromuscular control of trunk positioning. All of us who work in this area have a huge debt of gratitude to Professor Schultz for inspiring our work, and incidentally for leaving us a number of important yet unanswered questions. I encourage you to read the new papers published in this issue; and also to read Albert Schultz’ papers to find the origins of many of the advances in this field.
Ian A.F. Stokes (Guest Editor) University of Vermont, Department of Orthopaedics and Rehabilitation, Burlington, VT 05405-0084, USA E-mail address: [email protected]
Journal of Biomechanics 37 (2004) 171
Editorial
Special issue on spinal biomechanics Many problems of the spine are now better understood because of biomechanical research. The Editors invited me to highlight this wide-ranging topic in this issue of the Journal. This issue contains 11 papers directed at problems in spinal biomechanics. For 10 of these articles, I supervised the peer review process, and one other (of which I am co-author) went through the normal review and editorial process. Spinal biomechanics has attracted the attention of biomechanics researchers for many reasons, notably its association with the huge medical and social problem of low back pain. In addition to work directed at this problem, papers in this Issue also address treatment of spinal deformities (Petit et al.), problems of loss of vertebral bone to osteoporosis and tumor (Haddock et al.) and remedial treatment for these conditions (Baroud et al.). Apart from the clinical importance of spinal biomechanics, there are many intriguing biomechanical questions about spinal and trunk function. The articulations are based around a flexible structure (the intervertebral disc), and the posterior elements interact in a complex way with the disc to transmit forces between the vertebrae (Pollentine et al.). The motion segment is the basic element of the spinal column, and its mechanical behavior varies with the testing conditions (Goertzen, et al., Gardner-Morse and Stokes). The intervertebral disc is a huge avascular structure whose viability depends on the transport of nutrients and metabolites over distances of several millimeters to the nearest blood supply. This transport may be beneficially altered by mechanical loading (Ferguson et al.). The disc annulus is a structurally highly organized tissue that undergoes large deformations, that also deform the cells within it (Bruehlmann et al.). The material properties of the disc annulus might be modified beneficially by novel physical means (Bass et al.). The vertebral column consists of over 20 articulations, each having six degrees of freedom, yet the number of muscles exceeds the total
0021-9290/$ - see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.jbiomech.2003.12.003
degrees of freedom. This provides the central nervous system with ‘choices’ about how to activate muscles for a specific tasks and in response to perturbations (Granata et al.). The interaction between muscles and spinal motion in real-world conditions and the work place appears to be partly but not entirely controlled to optimize defined biomechanical variables (Kingma and van Die.en). While they may not be a completely representative sample of current research topics in this field, in looking at the topics of these papers and the methodologies they employ, one factor is striking: almost every paper owes something (often a lot!) to the pioneering work on spinal biomechanics done by Albert B. Schultz. He, together with his students and colleagues, published 64 Medlinecited papers on spinal and trunk biomechanics (22 in the Journal of Biomechanics) during the period 1970–1997. (Then he shifted his attention to new challenges in the area of postural stability and falls.) His work on spinal biomechanics included finite element analyses of disc, scoliosis deformity and its treatment by braces and by surgery, simulation of spinal deformity surgery, motion segment properties and the role of the posterior elements, muscle force analyses, and neuromuscular control of trunk positioning. All of us who work in this area have a huge debt of gratitude to Professor Schultz for inspiring our work, and incidentally for leaving us a number of important yet unanswered questions. I encourage you to read the new papers published in this issue; and also to read Albert Schultz’ papers to find the origins of many of the advances in this field.
Ian A.F. Stokes (Guest Editor) University of Vermont, Department of Orthopaedics and Rehabilitation, Burlington, VT 05405-0084, USA E-mail address: [email protected]