Ian A.F. Stokes, Ph.D.

Ian A.F. Stokes, Ph.D.

Research Professor
Orthopaedics and Rehabilitation
434 Stafford Hall,
Burlington, Vermont 05405-0084, USA
Phone : (802) 656-2250
Fax: (802) 656-4247

Email: Ian.Stokes@uvm.edu

Ian Stokes' Research

Description of Research Program
Stability of muscular loading of the lumbar spine
Predictive model of progression of spinal deformity
Analysis and simulation of surgical spinal fusion
Spinal motion segment mechanical behavior
Address / Contact
Recent Publications - go to CV

Curriculum Vitae

Ian Stokes' CV

Academic Links

Department of Orthopaedics and Rehabilitation, University of Vermont
International Research Society of Spinal Deformities
Scoliosis Research Society Glossaries

Links to Machines for burning fossil fuels

Douglas Motorcycle Mk III (1948)
Citroën 'Traction avant' 7C (1936)

Other Links

End the Occupation - Electronic Intifada
Hendrix Quote
Quotes - Hermann  Goering and others - on war
 

Description of Research Program

Dr Stokes' primary research interest is in problems of the spine, including muscle function around the lumbar spine and spinal deformity and growth plate biomechanics, with an emphasis on using biomechanical modelling and simulation. He has close collaborative ties with the Department of Mechanical Engineering, and Department Physical Therapy (University of Vermont), the Sainte-Justine Hospital and the École Polytechnique (Montréal), Cornell University (Veterinary medicine) and the École Nationale Supérieure d'Arts et Metiers (Paris).
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A. Stability of muscular loading of the lumbar spine.

This work examines the idea that the spine might be 'self-injured' during buckling events resulting from unstable equilibrium under the action of muscular forces. Results to date confirm that muscular stiffness (which depends on muscle activation) is required normally for stability. Analytical modeling is used to determine conditions under which the spine is at risk for such 'self-injury', and experimental (EMG) measurements of human subjects are used to compare model predictions with the theoretical predictions. This work also involves experimental studies of the spinal motion segment stiffness with axial preload.

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B. Mechanical modulation of growth and progression of spinal deformity.

Experimental (animal) models are used to determine sensitivity of growth plates in long bones and vertebrae to mechanical load. Quantitative histology (fluorescent labelling, cellular morphology, BrDU labelling, etc.) is used to investigate cellular responses mechanical forces in growth plates of different species and anatomical locations, having different base-line growth velocities.

This is combined with analytical determinations of the loading asymmetry of vertebrae in spines with scoliosis in order to make a predictive model of the progression of deformity. Results are compared with clinical (radiographic) studies of patients during the adolescent growth period.

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C. Analysis and simulation of surgical spinal fusion.

Model the effects of spinal surgery on spinal and ribcage deformity using finite element and other techniques. This involves individualized simulations of patients based on pre- and post-operative stereo x-ray photogrammetry. Also, in a collaborative arrangement, intra-operative measurements of surgical manoeuvres to correct spinal deformity are being made for comparison with the model predictions. (Collaboration with Sainte-Justine Hospital and the École Polytechnique, Montreal)
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D. Spinal motion segment mechanical behavior.

This work involved development of a six-degree of freedom linear and non-linear stiffness representation of spinal motion segments, based on experimental measurements with and without physiological axial loading. A purpose-built hexapod robotic device is used in this research. Results are used in a number of spinal modelling applications, including stability studies of the spine, simulations of surgical correction of deformity and analytical studies of the structural behavior of various spinal implant devices.
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