pptx - Research
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Trey DeLong
Lacey Gorochow
Brian Rappa
Adam Vandergriff
Sandra Wadeer
Advisor: Dave Martinez
VP of Sales at Zimmer, Inc.
Surgical Consult:
Dr. Michael Christie, M.D.
Southern Joint Replacement Institute
Problem Statement
Current tissue retractors are narrow, multiple
retractors are required especially in obese
patients
NY times reports 34% adults are obese
+Surgical Techs($20.00/hr*2-4hr/surgery*200k
surgeries/year)
Time of surgery increases as well
Previous team designed an adjustable
retractor
Complex and impractical for industrial
production
Prototype could not be used in
surgery
Mechanism & Consequences
Mechanism causing the problem
Physical properties of adipose tissue allow it to wrap around
narrow retractors
Consequences of unresolved problem
Poor surgical field of vision
Increase cost for additional materials and personnel
Surgery Experience
4-5 in (6 in in bigger patient)
3 in
wide
Depth can range from
1-6 inches depending
(Patient Size)
Fat tissue getting in the way
Dr. Christie’s Perspective
Functions of retractor:
Orient the incision
Keep tissue from falling into
surgical window
Disposabile vs. Non
Not “green”
Strength concerns
Ideal Device:
Robust
Simple
Movable window
Design Requirements &
Objectives
Keep back adipose tissue
Fit multiple patient sizes and provide a clear view
of the surgical site
Must be cost efficient
Simple manufacturing
cheap material
Ready for use in surgery
Easily attached
Easily sterilized
Strong enough to hold back fat tissue
Design
• Lofted feature-rounded to keep back tissue
• Curvature based on angle of known
measurements in surgery video
Material of Attachment Piece
17-4 Precipitation Hardening Stainless
Steel
Composition: 15.5% Chromium, 4.5%
Nickel, 3.5%Copper
Ultimate Tensile Strength: 1000-1340 Mpa
High strength maintained up to 600°F
Corrosion resistance superior
Readily welded-preheating not usually
required
Stainless Steel Model
Weld rods onto existing retractor
to provide rails
Attachment made in machine
shop using CAD design
Goals
Reduce total hip replacement surgery
cost
Less personnel in the operating room
Less retractors needed for surgery
Increase vision and work room for the
surgeon
Increase efficiency of the surgery
Reduce surgery time
Performance Metrics
Retractor system work on 95% of
patients
Different size attachments for non-
disposable.
Costs
Keep production costs minimal
○ Mass production
○ Readily machined
Predicted to be ~$300 for retractor and
attachments (non-disposable)
System and Environment
Role in surgery
Increase view of region and allows access
Why its beneficial to the surgeon
Reduce people near patient
Reduce number of retractors
Make surgery easier
Testing Methods
Verification and Validation
Hardware Testing
Stress Testing
Sterilization Testing
Verification and Validation
Verification: ensuring that all of the
parts of the device work together
Obtained a model made of ABS plastic
made from an FDM process
Validation: making sure that the device
satisfies specified requirement
Taking the actual prototype into surgery for
Dr. Christie to use
Hardware Testing Protocol
Use of mechanical equipment to test strength
of device
Take retractor with similar properties to testing labs
Apply a load using a compression/ tensile machine
to the device
Hold the load over the device for several minutes
Observe the deformation of the device over time
Mechanically test ability of steel to get the
properties
Stress Testing Protocol
Computer Modeling
Use PDE Toolbox
(MATLAB) to analyze
tissue
Obtain force load on
the retractor from
tissue data
Model stress on the
retractor using force
loads
Analyze model during
normal use
Sterilization Testing
Use in surgery
Run through Autoclave to test resilience
and observe any remaining tissue
Run through multiple cycles and
observe the number of cycles until
completely clean.
Next Steps…
Obtain a completed prototype to be
shown in the final presentation
Conduct testing methods
Verification
Validation
Hardware Testing
Stress Testing
Sterilization Testing
Present our final project
References
http://www.bls.gov/bls/blswage.htm
http://www.innomed.net/hip_rets_mis.htm#
Anchor-APC-49575
http://www.nytimes.com/2010/01/14/health/
14obese.html
http://www.orthosupersite.com/view.aspx?ri
d=1889
http://www.zimmer.com/z/ctl/op/global/actio
n/1/id/8140/template/PC/navid/10427