group 1: supervisor: michael lasagadr. ted hubbard andrew allanclients: riley wilsondr. michael...

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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 Gear

An

gle

Ach

ieve

d (

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 Gear

An

gle

Ach

ieve

d (

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

120

Six Primary Joints Outside of Bone

Trial 1 Trial 2

Number of Turns on Worm Gear

An

gle

Ach

ieve

d (

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