Transcript Femoral Fracture Reduction Device

Femoral Fracture
Reduction Device
1
GROUP 1:
MICHAEL LASAGA
ANDREW ALLAN
RILEY WILSON
XIANG GONG
SUPERVISOR:
DR. TED HUBBARD
CLIENTS:
DR. MICHAEL DUNBAR
DAVE WILSON
Presentation Outline
2
 Problems with Current Surgery
 Design Requirements
 Final Design
 Test Procedure and Results
 Strengths and Weaknesses
 Final Budget
 Conclusions and Recommendations
Red Line 1 inch
Problem with Current Surgery
3
 Time in the Operating
Room


Huge cost
Huge health risk
 Difficult Procedure
 Only skilled surgeons
capable
 Possibility for infection
 Forces on the Patient
 Manual Fracture
Reduction
Problematic Step
4
Design Requirements (General)
5
 To bridge femoral gap
 To reduce femoral fracture
Design Requirements (General)
6
Design Requirements (Specific)
7
 Must be able to be sterilized or be disposable
 Must fit in medullar canal (avg. diameter of 12mm)
 Must be greater than 480 mm in length
 Must be able to bend 30 degrees
 Must have separate tip control
 Must be hollow through center (intermediate wire
2.5mm)
 Must be able to apply 75Nm moment about the knee
joint
Final Design Concept
8
 “Snake Rod” Design
Final Design Components
9
 Proximal Rod
 Tensioning Mechanism
 Ball Joints
 Stainless Steel Wires
Final Design (Proximal Rod)
10
 Immobile part of device
 Stainless 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
holes
 Ball joint at tip
Final Design (Ball Joints)
11
 Allow mobility of the device
 Matching holes compared to proximal rod
 Each joint has a ball or socket on either end
Final Design (Ball Joints)
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 Section 1 – 9 large
primary joints
 Section 2 – 3 small
primary joints

Allow better range of
motion
 Section 3 – 4 small
secondary joints

Section 3 controlled
independently from 1 and
2
Final Design (End Control)
13
 Independent control of
secondary joints allows
formation of S-shape
 Allows device to steer
across most common
fractures
Final Design (Stainless Steel Wiring)
14
 Four wires in total
 Two 0.70mm diameter (Black)


Control Primary Joints
Two 0.35mm diameter (Green)

Control Secondary Joints
Final Design (Tensioning Mechanism)
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 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
General Testing Procedures
16
 Mobility
 Forces
Testing Procedure (Mobility)
17
 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
Testing Procedure (Mobility)
18
Testing Results (Mobility)
Angle Achieved (degrees)
19
80
Secondary Segments Outside of Bone
70
60
50
40
30
20
10
0
1
1.5
2
2.5
3
3.5
4
Number of Turns on Worm Gear
Trial 1
Trial 2
4.5
5
Testing Results (Mobility)
Angle Achieved (degrees)
20
100
90
80
70
60
50
40
30
20
10
0
Three Primary Joints Outside of Bone
1
1.5
2
2.5
3
3.5
4
Number of Turns on Worm Gear
Trial 1
Trial 2
4.5
5
Testing Results (Mobility)
Angle Achieved (degrees)
21
120
Six Primary Joints Outside of Bone
100
80
60
40
20
0
1
1.5
2
2.5
3
3.5
4
Number of Turns on Worm Gear
Trial 1
Trial 2
4.5
5
Testing Procedure (Forces)
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 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
Testing Results (Forces)
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 7.5lbs of force achieved at the tip
Testing Procedure (Failure)
24
 The worm gear failed at low force
 The worm gear should be redesigned
 Calculations were done to extrapolate forces of
stronger gear
Testing Results (Failure)
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 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
Results
26
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 primary
75° for secondary
Wire Insertion
Room for 2.5mm wire Bored out 3.43mm
through center
Yes
Forces
Apply 75 Nm about
knee
No
10 Nm about knee
(43 Nm ?)
Yes
Performance
27
Performance
28
Strengths
29
 Failure occurs outside of patient
instead of inside
 Sufficient mobility between
joints
Primary deflection angle can
reach 100 degree
2. Perfect S-shape can be created
1.
 High durability with stainless
steel wires and parts
Strengths
30
 Ease of manipulation
Only two turning controllers
2. Moderate linear-turning speed
3. 30 degree of clearance
1.
 Cost-$2,300
Large saving on the operation procedure
2. Major cost is the machining spending
3. Multiple use
1.
Weaknesses
31
 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
Final Budget
32
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
Conclusions and Recommendations
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 Design meets all requirements other than force
 Surgeon can apply lacking force
 Excellent mobility
 Can be applied for most common fractures
 Will reduce time and cost in OR
 Stronger worm gears
 More practical method of tying wires
 Should see a tool in the future
Questions?
34
 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 Precision
o Orthopedic Research
Group
o Mark
o Angus
o Albert
o Craig