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GROUP 1 : SUPERVISOR:MICHAEL LASAGA DR. TED HUBBARDANDREW ALLAN CLIENTS: RILEY WILSON DR. MICHAEL DUNBARXIANG GONG DAVE WILSON
Femoral FractureReduction Device
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Presentation Outline
Problems with Current SurgeryDesign RequirementsFinal DesignTest Procedure and ResultsStrengths and WeaknessesFinal BudgetConclusions and Recommendations
Red Line 1 inch
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Problem with Current Surgery
Time in the Operating Room Huge cost Huge health risk
Difficult Procedure Only skilled surgeons
capable Possibility for infection
Forces on the PatientManual Fracture
Reduction
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Problematic Step
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Design Requirements (General)
To bridge femoral gap
To reduce femoral fracture
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Design Requirements (General)
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Design Requirements (Specific)
Must be able to be sterilized or be disposableMust fit in medullar canal (avg. diameter of
12mm)Must be greater than 480 mm in lengthMust be able to bend 30 degreesMust have separate tip controlMust be hollow through center (intermediate
wire 2.5mm) Must be able to apply 75Nm moment about
the knee joint
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Final Design Concept
“Snake Rod” Design
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Final Design Components
Proximal Rod Ball Joints
Tensioning Mechanism
Stainless Steel Wires
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Final Design (Proximal Rod)
Immobile part of deviceStainless steel 450mm long x 9.5mm
diameter 3.4mm diameter center hole
Required 6 holes to run wires 6 x 1.25mm diameter holes
10mm deep at each end 6 slots that extend between
these holesBall joint at tip
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Final Design (Ball Joints)
Allow mobility of the deviceMatching holes compared to proximal rodEach joint has a ball or socket on either end
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Final Design (Ball Joints)
Section 1 – 9 large primary joints
Section 2 – 3 small primary joints Allow better range of
motionSection 3 – 4 small
secondary joints Section 3 controlled
independently from 1 and 2
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Final Design (End Control)
Independent control of secondary joints allows formation of S-shape
Allows device to steer across most common fractures
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Final Design (Stainless Steel Wiring)
Four wires in total Two 0.70mm diameter (Black)
Control Primary Joints Two 0.35mm diameter (Green)
Control Secondary Joints
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Final Design (Tensioning Mechanism)
Two C-Channels welded at 120o angle
Wires are counter wrapped onto worm gears
Left worm gear controls primary joints
Right worm gear controls secondary joints Intuitive Controls
Proximal rod fastened using threaded collar and two nuts
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General Testing Procedures
Mobility
Forces
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Testing Procedure (Mobility)
Device was passed through femoral canal until a specific number of joints were exposed
Range of motion was determined using a protractor
Tested range with 4 secondary segments out of Saw Bone
Tested range with 3 primary joints out of Saw Bone
Tested range with 6 primary joints out of Saw Bone
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Testing Procedure (Mobility)
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Testing Results (Mobility)
1 1.5 2 2.5 3 3.5 4 4.5 50
1020304050607080
Secondary Segments Outside of Bone
Trial 1 Trial 2
Number of Turns on Worm GearAng
le A
chie
ved
(deg
rees
)
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Testing Results (Mobility)
1 1.5 2 2.5 3 3.5 4 4.5 50
20
40
60
80
100
Three Primary Joints Outside of Bone
Trial 1 Trial 2
Number of Turns on Worm GearAng
le A
chie
ved
(deg
rees
)
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Testing Results (Mobility)
1 1.5 2 2.5 3 3.5 4 4.5 50
20406080
100120
Six Primary Joints Outside of Bone
Trial 1 Trial 2
Number of Turns on Worm GearAng
le A
chie
ved
(deg
rees
)
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Testing Procedure (Forces)
Used broken Saw Bone to model femur
Proximal end of bone clamped to table
Distal end of bone mounted so that it can pivot at the knee
Distal end of fracture site tied to spring scale
Bone is positioned to imitate a typical misalignment
Measured forces produced by device in an effort to reduce the fracture
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Testing Results (Forces)
7.5lbs of force achieved at the tip
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Testing Procedure (Failure)
The worm gear failed at low force
The worm gear should be redesigned
Calculations were done to extrapolate forces of stronger gear
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Testing Results (Failure)
Calculated forces needed to fail 0.7 mm wire: 1144 N 1.0 mm wire: 2356 N
Worm gear failure occurred at 10 Nm of moment about the knee
Max moment with new wire and worm gear: 43 Nm
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Results
Parameter Design Requirement
Actual Performance
Achievement
Sterilization Cleanable/disposable
Disposable Yes
Diameter Under 12mm 9.52mm Yes
Length At least 480mm Over 600mm Yes
Steering Separate tip control
Separate tip control
Yes
Mobility 30° bend in each direction
100° for primary75° for secondary
Yes
Wire Insertion
Room for 2.5mm wire through center
Bored out 3.43mm
Yes
Forces Apply 75 Nm about knee
10 Nm about knee(43 Nm ?)
No
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Performance
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Performance
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Strengths
Failure occurs outside of patient instead of inside
Sufficient mobility between joints
1. Primary deflection angle can reach 100 degree
2. Perfect S-shape can be created High durability with stainless
steel wires and parts
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Strengths
Ease of manipulation1. Only two turning controllers2. Moderate linear-turning speed3. 30 degree of clearance
Cost-$2,3001. Large saving on the operation procedure 2. Major cost is the machining spending3. Multiple use
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Weaknesses
Insufficient forces produced at tip 10 Nm produced in the
test, about 15% of moment required about the knee
Inefficiency on wire tying Counter-wrapping stiff
wires Hard to tie tightly
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Final Budget
Nature Company Description Price
Part Eagle Stainless SS Tubing $144.00
Part McMaster Carr SS Wiring $525.16
Part McMaster Carr SS C Channel $122.10
Part Music World Brass Worm Gears
$45.19
Service Dalhousie University
Rapid Prototyping
$69.92
Service Priority Precision
Machining $1460.82
Total Cost: $2,367.19
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Conclusions and Recommendations
Design meets all requirements other than forceSurgeon can apply lacking forceExcellent mobilityCan be applied for most common fracturesWill reduce time and cost in OR
Stronger worm gearsMore practical method of tying wires
Should see a tool in the future
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Questions?
Group 1 Michael Lasaga Andrew Allan Riley Wilson Xiang Gong
Supervisor Dr. Ted Hubbard
Clients Dr. Michael Dunbar Dave Wilson
Special thanks to:o Priority Precisiono Orthopedic
Research Groupo Marko Anguso Alberto Craig