Research Topics
| I A F StokesSummaryAffiliation: University of Vermont Country: USA Publications
Research Grants
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Detail Information
Publications
Intervertebral disc changes in an animal model representing altered mechanics in scoliosisI A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, USA
Stud Health Technol Inform 140:273-7. 2008..Further studies are in progress to characterize gene expression, matrix protein synthesis and composition in these discs...- Measurement of a spinal motion segment stiffness matrixIan A Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
J Biomech 35:517-21. 2002..Results from a pig lumbar spinal motion segment in an isotonic bath, with and without a 500 N axial preload, showed a large stiffening effect with axial preload... 
Trunk muscular activation patterns and responses to transient force perturbation in persons with self-reported low back painIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
Eur Spine J 15:658-67. 2006..g., muscle atrophy) or reduced motivation (e.g., pain avoidance)...- Computer-assisted algorithms improve reliability of King classification and Cobb angle measurement of scoliosisIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405 0084, USA
Spine (Phila Pa 1976) 31:665-70. 2006..Interobserver and intraobserver reliability study of improved method to evaluate radiographs of patients with scoliosis... - Endochondral growth in growth plates of three species at two anatomical locations modulated by mechanical compression and tensionIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vermont 05405 0084, USA
J Orthop Res 24:1327-34. 2006..These data may be applicable to planning the management of progressive deformities in patients having residual growth... - Alterations in the growth plate associated with growth modulation by sustained compression or distractionIan A F Stokes
University of Vermont, Burlington, VT 05405 0084, USA
Bone 41:197-205. 2007..38 and 0.56 respectively). According to multiple linear regression coefficients for these two variables (0.72 and 1.39 respectively), chondrocytic enlargement made a greater contribution to altered growth rates... - Analysis and simulation of progressive adolescent scoliosis by biomechanical growth modulationIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, 434 Stafford Hall, Burlington, VT 05405 0084, USA
Eur Spine J 16:1621-8. 2007.... - Stature and growth compensation for spinal curvatureI A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
Stud Health Technol Inform 140:48-51. 2008..Spinal curvatures alter measured stature and may influence the evaluation of skeletal maturity and growth based on stature measurements... - Classification of scoliosis deformity three-dimensional spinal shape by cluster analysisIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
Spine (Phila Pa 1976) 34:584-90. 2009..Cluster analysis of existing database of spinal shape of patients attending a scoliosis clinic... - Limitation of finite element analysis of poroelastic behavior of biological tissues undergoing rapid loadingIan A Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405 0084, USA
Ann Biomed Eng 38:1780-8. 2010..Pressure instabilities may impose limitations on the use of the finite element method for simulating fluid transport behaviors of biological soft tissues at moderately rapid physiological loading rates... 
Intra-abdominal pressure and abdominal wall muscular function: Spinal unloading mechanismIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
Clin Biomech (Bristol, Avon) 25:859-66. 2010..Biomechanical analyses are needed to understand the function of intra-abdominal pressurization because of the anatomical and physiological complexity, but prior analyses have been over-simplified...- Refinement of elastic, poroelastic, and osmotic tissue properties of intervertebral disks to analyze behavior in compressionIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Stafford Hall, Burlington, VT 05405 0084, USA
Ann Biomed Eng 39:122-31. 2011..55 and 2.6. Force relaxation and time constants from the analytical simulations were most sensitive to values of fixed charge density and endplate porosity... - Abdominal muscle activation increases lumbar spinal stability: analysis of contributions of different muscle groupsIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, USA
Clin Biomech (Bristol, Avon) 26:797-803. 2011..This biomechanical analytical study addressed whether lumbar spinal stability is increased by such selective activation... - Modulation of vertebral and tibial growth by compression loading: diurnal versus full-time loadingIan A Stokes
Department of Orthopaedics and Rehabilitation, McClure Musculoskeletal Research Center, Robert T Stafford Hall, University of Vermont, Burlington, VT 05405 0084, USA
J Orthop Res 23:188-95. 2005..This study was designed to determine whether the amount of endochondral growth response to mechanical compression and the underlying growth mechanism differed with night-time or day-time loading, relative to full-time loading... - Relationships of EMG to effort in the trunk under isometric conditions: force-increasing and decreasing effects and temporal delaysIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Stafford Hall 434, Burlington, VT 05405 0084, USA
Clin Biomech (Bristol, Avon) 20:9-15. 2005.... - Identifying sources of variability in scoliosis classification using a rule-based automated algorithmIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vermont 05405, USA
Spine (Phila Pa 1976) 27:2801-5. 2002..Use of a rule-based automated algorithm to determine sources of variability in radiographic classification... - Surface EMG electrodes do not accurately record from lumbar multifidus musclesIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405 0084, USA
Clin Biomech (Bristol, Avon) 18:9-13. 2003..This study investigated whether electromyographic signals recorded from the skin surface overlying the multifidus muscles could be used to quantify their activity... - Spinal stiffness increases with axial load: another stabilizing consequence of muscle actionIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405 0084, USA
J Electromyogr Kinesiol 13:397-402. 2003.... - Muscle activation strategies and symmetry of spinal loading in the lumbar spine with scoliosisIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405 0084, USA
Spine (Phila Pa 1976) 29:2103-7. 2004..Biomechanical analysis of muscle and spinal forces in a lumbar spine with scoliosis... - Intervertebral disc changes with angulation, compression and reduced mobility simulating altered mechanical environment in scoliosisIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
Eur Spine J 20:1735-44. 2011..The purpose of this study was to document morphological and biomechanical changes in four different models of altered mechanical environment in intervertebral discs of growing rats and in a sham and control groups... - Motion segment stiffness measured without physiological levels of axial compressive preload underestimates the in vivo values in all six degrees of freedomMark G Gardner-Morse
Department of Orthopaedics and Rehabilitation, University of Vermont, Stafford Hall, Burlington, Vermont 05405-0084, USA
Stud Health Technol Inform 91:167-72. 2002..82, 0.97 and 0.98 at 0, 200 and 400 N axial compression respectively). Motion segment and disc load-displacement behaviors were stiffer, more linear and had greater hysteresis with axial compressive preloads... - Frequency-dependent behavior of the intervertebral disc in response to each of six degree of freedom dynamic loading: solid phase and fluid phase contributionsJohn J Costi
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington
Spine (Phila Pa 1976) 33:1731-8. 2008..Nondestructive displacement-controlled dynamic testing of cadaver material, with repeated measures design and randomized sequence of tests... - Physiological axial compressive preloads increase motion segment stiffness, linearity and hysteresis in all six degrees of freedom for small displacements about the neutral postureMack G Gardner-Morse
Department of Orthopaedics and Rehabilitation, University of Vermont, Stafford Hall, Burlington 05405 0084, USA
J Orthop Res 21:547-52. 2003..82, 0.97 and 0.98 at 0, 200 and 400 N axial compression respectively). Motion segment and disc load-displacement behaviors were stiffer, more linear and had greater hysteresis with axial compressive preloads... - Mechanical modulation of vertebral and tibial growth: diurnal versus full-time loadingIan A Stokes
Department of Orthopaedics and Rehabilitation University of Vermont, Burlington, VT 05405-0084, USA
Stud Health Technol Inform 91:97-100. 2002..The BrdU labeling index demonstrated an opposite trend, which was not statistically significant. In half-time loaded growth plates the proliferative zone cell count change predominated... - Growth plate chondrocyte enlargement modulated by mechanical loadingIan A Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
Stud Health Technol Inform 88:378-81. 2002..Thus mechanical loading of tail vertebrae modulated their growth rate, that in turn correlated with changes in the amount of hypertrophic chondrocyte height increase. The effects for compression were greater than for distraction... - Enlargement of growth plate chondrocytes modulated by sustained mechanical loadingIan A Stokes
University of Vermont, Burlington, Vermont 05405, USA
J Bone Joint Surg Am 84:1842-8. 2002.... - The role of remodeling and asymmetric growth in vertebral wedgingDavid D Aronsson
University of Vermont College of Medicine, Burlington, Vermont 05405, USA
Stud Health Technol Inform 158:11-5. 2010..We investigated whether vertebral wedging in scoliosis might involve both mechanisms... - On the implications of interpreting the stability index: a spine exampleMack G Gardner-Morse
J Biomech 39:391-2; author reply 393-4. 2006 - Mechanical conditions that accelerate intervertebral disc degeneration: overload versus immobilizationIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vermont 05405, USA
Spine 29:2724-32. 2004..Future studies will need to evaluate additional unquantified interactions between biomechanics and factors such as genetics and behavioral responses to pain and disability... - Intervertebral disc adaptation to wedging deformationIan A F Stokes
University of Vermont, Orthopaedics and Rehabilitation, Burlington, Vermont, 05405-0084, USA
Stud Health Technol Inform 123:182-7. 2006..This indicates that this animal model is suitable for studying adaptive wedging changes in human scoliosis... - Structural behavior of human lumbar spinal motion segmentsMack G Gardner-Morse
Department of Orthopaedics and Rehabilitation, University of Vermont, Stafford Hall, Burlington, VT 05405 0084, USA
J Biomech 37:205-12. 2004..These stiffness properties can be used in structural analyses of the lumbar spine... - Vertebral height growth predominates over intervertebral disc height growth in adolescents with scoliosisIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405 0084, USA
Spine (Phila Pa 1976) 31:1600-4. 2006..A cross-sectional study of spinal stereoradiographs of adolescents with scoliosis to measure growth... - Different effects of static versus cyclic compressive loading on rat intervertebral disc height and water loss in vitroKazunori Masuoka
University of Vermont, Burlington, VT 05405, USA
Spine (Phila Pa 1976) 32:1974-9. 2007..In vitro biomechanical study on rat caudal motion segments to evaluate association between compressive loading and water content under static and cyclic conditions... - Measurements of proteoglycan and water content distribution in human lumbar intervertebral discsJames C Iatridis
University of Vermont, Burlington, VT 05405, USA
Spine (Phila Pa 1976) 32:1493-7. 2007..Study of regional variations in composition in a sample of 9 mildly to moderately degenerated human intervertebral discs... - Mechanical modulation of spinal growth and progression of adolescent scoliosisIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405 0084, USA
Stud Health Technol Inform 135:75-83. 2008..Quantitative simulation of this mechanism demonstrates how therapeutic interventions to alter neuromuscular control of trunk muscles or otherwise modify spinal loading may alter the natural history of progression... - Rule-based algorithm for automated King-type classification of idiopathic scoliosisIan A F Stokes
Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VT 05405, USA
Stud Health Technol Inform 88:149-52. 2002..The algorithm overcame accuracy and reliability problems, except in rare cases when it was borderline whether or not a lumbar curve crossed the midline, when the apex level was ambiguous, or when a Cobb angle was close to 10 degrees...
Research Grants
- Progressive scoliosis deformity in intervertebral discIan Stokes; Fiscal Year: 2007..These approaches may include improvements in brace design, new possibilities for muscle rehabilitation, and surgical procedures aimed at early, minimally invasive modification of spinal growth. ..
- AN INTEGRATED MODEL OF INTERVERTEBRAL DISC FUNCTIONIan Stokes; Fiscal Year: 2006..and the local conditions that can influence its metabolism, eventual composition and function in three-dimensions. ..
- MECHANICAL MODULATION OF GROWTH IN PHYSESIan Stokes; Fiscal Year: 2003..abstract_text> ..
- STABILITY OF MUSCULAR LOADING OF THE LUMBAR SPINEIan Stokes; Fiscal Year: 2002..In addition, the specific roles of individual muscles will be better elucidated, which will be helpful in guiding therapy for people with low back dysfunction. ..
- Progressive scoliosis deformity in intervertebral discIan Stokes; Fiscal Year: 2009..These approaches may include improvements in brace design, new possibilities for muscle rehabilitation, and surgical procedures aimed at early, minimally invasive modification of spinal growth. ..