Hydrogel Composites for Spinal Disc Replacement

1
Hydrogel Composites for Spinal Disc Replacement
Objective
Properties Analysis
China Lim, Paul Cary and Greg Newbloom Chemical,
Biological and Environmental Engineering, Oregon
State University
To evaluate the effects of micro-crystalline
cellulose filler in a hydrogel matrix as a
potentially injectable nucleus pulposus
replacement.
Mechanical Testing
Current Solutions
Compression Modulus, K
Lumbar Spinal Fusion
Lumbar Decompression

• Immobilization of spinal bones via screws to
  reduce movement related pain
• This can hasten the degeneration of adjacent
  intevertebral discs and reduce daily mobility

• Laminectomy Relieves pressure on nerve root
• Discectomy Removal of the nucleus pulposus to
  relieve pressure on spinal chord

Who Cares?
where F applied force A initial
cross-sectional area ?h change in
height ho initial height

• A 2002 National Health Survey reported that 34
  million Americans over 18 have lower back pain.
• 80 of people will have some form of back pain in
  their lives, many of them with extruded discs.
• People with lower back pain are often less
  productive and have large medical expenses.
• Disc or nucleus pulposus replacement attempts to
  remove debilitating pain and restore
  functionality.

http//catalog.nucleusinc.com/imagescooked/9122W.j
pg
http//brispine.com.au/images/ posterior_fusion_x_
ray.jpg
Initial Peak Breaking Point
Total Disc Replacement
Nucleus Pulposus Replacement

• An invasive surgery that eliminates all damaged
  disc tissue
• It restores function, but without properly
  imitating the actual function

• Replaces only the central cushion and restores
  disc height
• However, this requires a fully functional annulus
  fibrosus

http//www.usc.edu/schools/medicine/departments/ne
urological_surgery/clinical/spina/artdisc.html
http//www.discdyn.com/procedure.html
Rheological Testing
Composite Perspective
The Problem
Agarose
Micro-crystalline Cellulose (MCC)

• A polymer extracted from red algae
• Forms a gel network in water when heated and then
  cooled
• Is inexpensive and biocompatible

BIO-BASED NANOCOMPOSITES CHALLENGES AND
OPPORTUNITIES - John Simonsen , OSU Wood Science
and Engineering

• Structural component in the cell wall of green
  plants
• Is non-soluble in water and highly hydrophilic

Synthesis Procedure
Methods

• The compressive and rheological properties of a
  native disc may be achieved by varying the matrix
  and filler to water ratios.
• The MCC has a tensile strength of 7.5 GPa and was
  used to increase the toughness of the gel.
• 1 Agarose-gel composites were created in 0.00,
  0.04, 0.08, and 0.30 ratios of microcrystalline
  cellulose to water.
• Trends were analyzed to predict the effect of
  cellulose filler on gel strength.

• Agarose is dissolved in water.
• Microcrystalline cellulose is added and sonicated
  to disrupt aggregates.
• The mixture is heated by microwave, and quickly
  poured into chilled molds to prevent filler
  settling.

At Rest Breathing Walking
Driving
Acknowledgements
http//biology.clc.uc.edu/
http//www.pontinaelettronica.com/