Cervical Spine Research

A three-dimensional parametric model of the cervical spine for finite element analysis.

Carlos G. Lopez-Espina, F. Amirouche PhD.

More information on: http://www2.uic.edu/~clopez17

Pro Engineer Model of Cervical Spine

Objectives
The main objective of this project is to produce a sufficiently accurate parametric model of a human cervical vertebrae and the intervertebral disc.

 

• Based on a limited number of parameters that reflect the differences between the different vertebras.
• Modeling of each vertebrae by changing these parameters and making the least possible changes in the model.
• The reconstruction of cervical segments of the cervical spine by using the generated vertebras.

• Need for a simplified model that could be used for further Finite Element studies.
• Several recent studies have used CT scans to recreate the geometry, which produces a better and more accurate geometry, but lacks flexibility to perform further studies based on geometry variation.

Guarantee that the produced geometry could be loaded and easily handled with this ANSYS.

• Simple model
• Accurate to reflect the geometry of the vertebrae.
• Not compromising the fuctionalities that this geometry accomplishes.

Animations.

FE Model of Cervical Spine

Biomechanical Analysis And Evaluation Of Load Sharing And Stiffness In Static And Dynamic Cervical Plates

Carlos G. Lopez-Espina, F. Amirouche PhD.

Constrained Plate

Cervical plates for single and multilevel anterior surgery have been accepted as the standard procedure to improve initial stability and decrease complications from graft dislocation, endplate fracture, and late kyphotic collapse. It has been suggested in current literature that the rigid fixation of the cervical plates may be responsible for the elimination of the mechanical loads that are important in graft healing. The rigid fixation may also prevent gap closures between bone graft and endplates when contact is eliminated resulting in graft subsidence and osteolysis. Recently, dynamic cervical plates have been introduced that allow for axial settling to accommodate a potential biologic or mechanical shortening of the anterior strut graft. The dynamic plate in essence allows for movement along the vertical axis and therefore raises an issue of concern in terms of load sharing properties and overall stiffness characteristics of the cervical plates. The objective of this research is to evaluate the Synthes static plate using a validated cervical Finite Element Spine Model. The procedure will based on clinical data and a protocol which includes 1) Full length intact graft, 2) bone graft subsidence of 5, 10, and 20% shortening of the graft, and 3) complete graft removal or expulsion. The dynamic analysis will be based on a simulated condition, which allows for a vertical travel of a limited movement constrained by the proposed design. The model will simulate conditions, which allows the screw-plate interface to have two degrees of freedom a translation and a rotation. Furthermore the investigation should focus on the evaluation of load transmitted by simply allowing translation, only rotation or both. What is crucial in this research is this project is the development of a model where the dynamic plate rotation and translation at the screw –plate interface is studied and quantified in terms of how much movement should be allowed. Since most of the construct are dependent on the pathological conditions each patient present. We should allow certain flexibility in allowing these joint motions to lock when needed. The analysis will be repeated and the load sharing, stiffness and deformation of all attributes will be computed and analyzed. The results will provide an assessment of the advantages and disadvantages of both methods. 

Publications

Carlos Lopez, F.M.L.Amirouche, Franklin Wagner, Kern Guppy. “A Three dimensional parametric model of the cervical spine for finite element analysis” World congress of biomechanics – 2002

Carlos Lopez, F.M.L.Amirouche, Franklin Wagner, Kern Guppy. “A validated three dimensional parametric model of the cervical spine for finite element analysis” ASME – Bioengineering division – 2002

Carlos Lopez, F.M.L. Amirouche, Franklin Wagner, Kern Guppy” A three dimensional parametric model of cervical spine for analysis of fusion and instrumentation techniques” Congress of neurological surgeons – 2002

Carlos Lopez, F.M.L.Amirouche, Franklin Wagner, Kern Guppy. Applications of a three-dimensional parametric model of the cervical spine:  An evaluation of load-sharing and stiffness in fixed and dynamic plates during cervical spine fusion. Fifth International Conference on Simulations in Biomedicine (April 2003)

Carlos Lopez, F.M.L.Amirouche, Franklin Wagner, Kern Guppy. Evaluation of load-sharing and stiffness in fixed and dynamic plates during cervical spine fusion. 49th Orthopaedic Research Society Meeting. (Februery 2003)

Carlos Lopez, F.M.L.Amirouche, Franklin Wagner. Development and validation of a three-dimensional parametric model of the cervical spine. Clinical Biomechanics (Review)