Updated Design Night Presentation
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Transcript of Updated Design Night Presentation
D.I.S.C.Decompressive Intervertebral Spine Chair Sponsored by Entrepreneur: Sheel Gardner
Advised by Dr. James Iatridis, PhD
The Objective: Proof of Concept
• Find a method and create a non-invasive device that will effectively mitigate low back pain
• Primary Goals:– A) Do No Harm– B) Relieve short-term pain– C) Contribute to long-term health
The Need Immediate : A) Sponsor presented with ruptured disc
Broad Implications: 1) Total direct and indirect costs for treatments
of LBP are estimated to be $100 billion annually in the U.S.1
2) The lifetime prevalence of LBP in the United States is 60-80%2
1 - Bigos SJ, Boyer OR, Braen GR. Acute Low Back Problems in Adults. Clinical Practice Guideline, Quick Reference Guide Number 14. Public Health Agency, Agency for Health Care Policy and Research. Rockville, Md:. Department of Health and Human Services;1994.2 - http://www.ninds.nih.gov/disorders/backpain/detail_backpain.htm
General Approach
• 1) Preliminary Research: anatomy, pathologies, routes to health, working with Cadavers
• 2) Consulting Experts: Orthopaedic Spine Surgeon, Spine Researcher, Physical Therapist, Chiropractors
• 3) Evaluate successful treatments• 4) Existing products and technologies? • 5) Brainstorm, Evaluate, Calculate, Design• 6) Repeat #4-5• 7) Fabricate• 8) Test and Analyze
Understanding the Spine: Basic Anatomy
Healthy Spinal Unit
Side View
http://sobrien2000-ivil.tripod.com/sitebuildercontent/sitebuilderpictures/hs2fig1.gif
Preliminary Research: Spine Pathology
http://emedicine.medscape.com/article/310353-overview
- Because they are avascular, discs rely on pressure gradients to obtain nutrients
- When under compression, a negative pressure gradient cannot be established
Various Pathologies
• Healthy• Small tears in
annulus• Nucleus begins
bulging out annulus, impinging on nerve
• Nucleus escapes via tear or burst through annulus
Why Do Discs Degenerate?
Natural Causes
• Aging – Natural process of
wear and tear over time
• Genetics– Predispositions to
degeneration
Habits• Nutrition
– Vitamins– Fluids
• Lifestyle– Sitting all day– Exercise– Sleep
• Posture– Musculature
Decompress the discAllows diffusion to occurNutrients can replenish the discFacilitates self-repair over timeApproaches the fundamental problem
Intervertebral Decompression (ID)
Challenges Inducing ID
• How to grab vertebrae in a non-invasive way?
• While being comfortable?
• What about muscle resistance (cadaver lab)?
• What already exists?• What target user?• Options: Mechanical
Manipulation, Electrostimulation, Posture Aid
Initial Concept
DISC Solutions
• Work with gravity instead of against it– Lower user instead of
raising them• Comfort provided by
uniquely molded orthotic splint pads
• Seating is a naturally relaxed position, solving the tightening musculature issue
• Many massage chairs exist, but none focus on effective decompression
Demonstration: Final Design Concept
How it WorksWeight compressing discs
Reactant forces from chair
How it Works
Friction
AppliedForce
AppliedForce
Normal Force
After Deflation
Friction and Normal Force Resultant
Weight
Design Evolution
• Decided on an office chair as the platform
– Easier to obtain controlled leverage
– Large market
• This particular chair– Highly adjustable– Modifiable– Solid Steel Frame
Staples® Acadia™ Multi-Function Mesh Task Chair
Design Constraints
• Based on structural anatomy: best contact point was determined
• Contact Area 1.5” governed lead screw choice
• Lead Screw design– Strength was
overdesigned for safety and conformance to contact area
– Negligible deflection
Lumbar Saddles
• Contoured• ThermoPlast• Traction is
obtained at desired location
• Lumbar back support
• Approximately 90 degree coverage, allowing fit for range of users
• Through 5 iterations
• Stiffness design
Saddle Iterations
Connection to Lumbar Saddles
- Steel leveling feet bolted to saddles
- Ball joint to allow degrees of freedom for comfort
- Countersunk bolts into saddle construction
- 5cm into lead screw, other connection
Lead Screw, Frame, Forcepath
- Lead screw connected through threaded bolt support
- Welded to steel base plate
- Bolted to original chair frame
- Transfers force from human through all elements to ground
Seat Cushion Assembly
- Pneumatic cushion- Designed for
immobile users- 3” deflation
capability
- Foam layers for comfort at full deflation
- Supporting wood for enclosed seat cushion assembly
- Connected to Steel base plate
Testing and Analysis
Partial Deflation (5 second intervals)
Load Reduction
(lbs)
Quantitative: Load Reduction on Lumbar Spine
0 1 2 3 4 5 6 7 8 9 10
0
20
40
60
80
100
120
140
160
Testing and Analysis
Partial Deflation (5 second intervals)
Comfort Level
Qualitative: Comfort Levels Throughout Cycle
0 1 2 3 4 5 6 7 8 9 10
0
1
2
3
4
5
6
7
8
9
10
Results
• Average maximum unloading of lumbar spine: 44.7% of body weight
• Average comfort @44.7% unloading : 7.5/10 → MAXIMUM UNLOADING
• Average initial comfort (1-10(good)) : 8.25/10• Average comfort @38.3% unloading : 9.25/10 → OPTIMAL
COMFORT• 5 minute comfort level (@38.3%) : 8.5/10• 10 minute comfort level (@38.3%) : 8/10
Conclusions
- Quantitative– Unloading does take place
• Isolating the lumbar area• Proof of concept successful
- Qualitative– Improved posture
• Muscle training– Higher comfort level needed
• The main deterrent for devices is comfort
Future of DISC
• More comprehensive testing– More diverse subjects– Long term results– Invasive measurement of disc height
• Determine whether customization vs. sizes for saddles
• Refine product now that there is proof that lumbar unloading occurs
Acknowledgments
• Dr. Sharon Henry PhD, Physical Therapy• Dr. Robert Monsey MD, Orthopaedics and
Rehabilitation• Erik Hemmit DC, Chiropractor• Dr. Jean Szilva MD, Gross Anatomy and
Neuroscience• Corey Berman Physical Plant• Dr. Mike Rosen PhD, Engineering• Floyd Vilmont Machine Shop• Dr. James Iatridis PhD, Spine Bionengineering• Sheel Gardner Sponsor, Entrepreneur