The Specialized Transfemoral External Prosthetic Support team's presentation on the progress made over a year of exploring the possibilities of a mechanical external support for a transfemoral prosthetic. The presentation describes the effort put into concepts and prototypes that would be utilized with a prosthesis which includes background information, initial prototype, final prototype, tests performed, results obtained, and the overall outcome of the project. Note: Download if you want to view all animations and videos to enhance the knowledge about the team's prosthetic support.

1. Spring Semester Presentation
April 27, 2017
SpecializedTransfemoral External Prosthetic Support

2. 2
Dr. Kotaro Sasaki
FacultyAdvisor
Sonia Sosa Saenz
Team Lead
BME
Joshua Kucera
Design Lead
BME
Anna Steege
Testing Lead
BME
Dolores Henson
Public Relations
BME
Raul Saldana
Data Processing
BME
Jessanne Lichtenberg
Documentation
BME
JosephWilcox
Mechanical Lead
ME
Aaron Conrad
Financial Manager
ME
AndrewAdamo
Design Support
BME
Garret Senti
CAD & Simulations
ME
Aaron Panagotopulos
TestingVolunteer
BME
Michael Hildebrant
Design Junior Member
BME

3. Outline
•Background
•Device Specifications
•STEPS Device
•DeviceTesting
•Results
•Next STEPS 3

4. Background
Mechanical vs. Active
Prosthetic Knees
Problems: Knee Stabilization
and Energy Expenditure
4
30,000 transfemoral (above-knee) amputations are performed
each year in the United States.1
1 - Sup, F.,Varol, H.A., Mitchell, J.,Withrow,T.J., and Goldfarb, M. (2009). Self-Contained Powered Knee andAnkle Prosthesis:
Initial Evaluation on aTransfemoral Amputee. IEEE Int.Conf. Rehabil. Robot. Proc. 2009, 638–644.
2 -Transfemoral & Knee DisarticulationTreatment - P&O Care. http://www.pandocare.com/transfemoral-knee-disarticulation/
Parts of transfemoral prosthesis2
Socket
Knee Joint
Pylon
Foot

5. Knee Prosthesis: Lock at full extension 5
http://4.bp.blogspot.com/-6zWt3HtHcZ0/UXC7_wdjHZI/AAAAAAAAA8w/F7zrQdyjIrs/s1600/thegaitcycle.gif
Stance Phase Swing Phase
Gait Cycle

6. Background
Low-Resource Settings
•Low-cost prosthetics are passive
•Microprocessor prosthetics
•Expensive
•Not suitable for the environment1
High-Income Countries
•Active Prosthetic Knee $70,000+2
6
1 -Ayers, S., Gonzalez, R., and Minelga, E. (2006). Development of a low cost, easily manufactured, prosthetic knee
technology with improved functionality outcomes for trans-femoral amputees in developing nations.
J. Biomech. 39, S500.
2 - Harkins, C.S., McGarry, A., and Buis, A. (2013). Provision of prosthetic and orthotic services in low-income countries:
a review of the literature. Prosthet. Orthot. Int. 37, 353–361.

7. Project Goal
Develop an external prosthesis support device
for mechanical prosthetic knees
•Add-on device
•Prevent unwanted knee flexion during stance phase
•Improve gait
7

8. Device Specifications
Goal Description
Adaptable Compatible with different mechanical knees
External from
prosthesis
Coexist and not suppress the function
of the prosthesis
Cost-efficient Necessary for distribution to larger population
Lightweight The weight should not inhibit prosthesis function
and not increase energy expenditure
Low-maintenance Minimal maintenance and adjustment for user
8

9. Comparable Alternatives
Knee-Ankle-Foot Orthosis (KAFO) Brace for Orthosis - Deharde
9
1. Shlomovitz,Tal, and Ronny Shelly. Knee-ankle-foot Orthotic Device.Tal Shlomovitz, Ronny Shelly, assignee. Patent US 7462159
B1. 24 July 2007. Print.
2. Deharde, Mark. Bi-Directional Dampening andAssistingUnit. Ultraflex Systems, Inc., assignee. Patent US 20140308065 A1. 10
Apr. 2013. Print.

10. Transfemoral Prosthetic Gait (TPG)
Simulator
Allow able-bodied subjects to simulate
transfemoral amputee gait
to test prototypes
•Adaptable
•Multiple users
•Multiple knees
10
Frame
Foot*
Pylon*
Knee*
Brace
*LIMBS International

11. STEPS Device
11

12. Alpha Prototype
12

13. FOOT SWITCH
Function: Engages the ratchet mechanism
on heel strike
Solution: Compression spring
Alpha Prototype
RATCHET
Function: Lock for stance, unlock for swing
Solution: Modified ratchet mechanism
13

14. Alpha Improvements
• ReduceWeight
• Increase Reliability of Activation
• Reduce Instability
• Design for Repeatability
14

15. Beta Prototype
15

16. 16
Switch Comparison
Alpha Beta

17. Ankle Switch
• Concept: Intercept all linear force in the pylon
• Embodiment: Compressive element mounted above the foot
17

18. Flange Comparison
Alpha Beta
18

19. 19
Pawl Comparison
Alpha Beta

20. Ratchet Adaptations
• Single-Piece Upper Flange
• Linear Pawl
• Smaller GearTeeth  Enhanced Angular Resolution
20

21. 21

22. 22

23. Future DesignWork
•EnhanceAdaptability for Other Knees
•ReduceWeight
•ReduceTuning Required by User 23

24. DeviceTesting
24

25. Variables
•Metabolic Energy
Expenditure
Oxygen Consumption at
Anaerobic Threshold
•Joint Angles
Hip, Knee, and Ankle
•Ground Reaction
Forces
•Muscle Activation
(EMG)
• Rectus Femoris
• Semitendinosus
• Gluteus Medius
• Tensor Fasciae Latae
25
Adapted from Marieb, Elaine N, and Katja Hoehn. Human Anatomy & Physiology. Boston: Pearson, 2013.

26. Conditions
•Control
•TPG Simulator
•TPG Simulator + STEPS Device 26

27. Results
27

28. Energy Expenditure Results
28Parameters: 1.3 mph and 5° incline
15.4
19.7 20.3
CONTROL TPG SIMULATOR TPG SIMULATOR
+ STEPS DEVICE
mL/kg/min
Steady-State Oxygen Consumption
4%
32%

29. Joint Angle Results
29
*Gait cycle corresponding to Right/Affected limb
Control
TPG Simulator
TPG Simulator
+ device
0 20 40 60 80 100
-20
0
20
40
FlexionAngle(deg)
% Gait cycle
(a) Hip Angle Right/Affected Leg
0 20 40 60 80 100
-20
0
20
40
60
80
FlexionAngle(deg)
% Gait cycle
(c) Knee Angle Right/Affected Leg
0 20 40 60 80 100
-40
-20
0
20
40
FlexionAngle(deg)
% Gait cycle
(b) Hip Angle Left/Intact Leg
0 20 40 60 80 100
-20
0
20
40
60
80
FlexionAngle(deg)
% Gait cycle
(d) Knee Angle Left/Intact Leg
0 20 40 60 80 100
-40
-20
0
20
DorsiFlexionAngle(deg) % Gait cycle
(e) Ankle Angle Left/Intact Leg
Control
TPG Simulator
TPG Simulator + STEPS Device
0 20 40 60 80 100
-20
0
20
40
FlexionAngle(deg)
% Gait cycle
(a) Hip Angle Right/Affected Leg
0 20 40 60 80 100
-20
0
20
40
60
80
FlexionAngle(deg)
% Gait cycle
(c) Knee Angle Right/Affected Leg
0 20 40 60 80 100
-40
-20
0
20
40
FlexionAngle(deg)
% Gait cycle
(b) Hip Angle Left/Intact Leg
0 20 40 60 80 100
-20
0
20
40
60
80
FlexionAngle(deg)
% Gait cycle
(d) Knee Angle Left/Intact Leg
0 20 40 60 80 100
-40
-20
0
20
DorsiFlexionAngle(deg) % Gait cycle
(e) Ankle Angle Left/Intact Leg
Control
TPG Simulator
TPG Simulator + STEPS Device

30. Joint Angle Results
30
Control TPG Simulator TPG Simulator + device
*Gait cycle corresponding to Right/Affected limb
0 20 40 60 80 100
-20
0
20
FlexionAn
% Gait cycle
0 20 40 60 80 100
-20
0
20
FlexionAn
% Gait cycle
0 20 40 60 80 100
-40
-20
0
20
DorsiFlexionAngle(deg)
% Gait cycle
(e) Ankle Angle Left/Intact Leg
Control
TPG Simulator
TPG Simulator + STEPS Device
0 20 40 60 80 100
-20
Fle
% Gait cycle
0 20 40 60 80 100
-20
Fle
% Gait cycle
0 20 40 60 80 100
-40
-20
0
20
DorsiFlexionAngle(deg)
% Gait cycle
(e) Ankle Angle Left/Intact Leg
Control
TPG Simulator
TPG Simulator + STEPS Device
0 20 40 60 80 100
-20
Flex
% Gait cycle
0 20 40 60 80 100
-20
Flex
% Gait cycle
0 20 40 60 80 100
-40
-20
0
20
DorsiFlexionAngle(deg)
% Gait cycle
(e) Ankle Angle Left/Intact Leg
Control
TPG Simulator
TPG Simulator + STEPS Device

31. Ground Reaction Force Results
31
Control TPG Simulator TPG Simulator + device
Right/Affected Leg Left/Intact Leg

32. Muscle Activation Results
32
Control
TPG Simulator
TPG Simulator
+ device

33. Muscle Activation Results
33
Control
TPG Simulator
TPG Simulator
+ device
Adapted from Marieb, Elaine N, and Katja Hoehn. Human Anatomy & Physiology. Boston: Pearson, 2013.

34. Testing Conclusions for Device
•Energy Expenditure
Did not significantly increase the subject’s oxygen consumption
•Joint Angles
Improved the angles of the right knee and left ankle
•Ground Reaction Forces
Extended stance phase and reduced instability
•MuscleActivation
Improved pattern of gluteus medius 34

35. Next STEPS
Increase
sample
size
35
Goal Level of
Achievement
Adaptable
External from
prosthesis
Cost-efficient
Lightweight
Low-
maintenance
One Knee
Achieved!
1.22 kg
Simplified
design
~$220

36. Conference Presentation in August
36
http://asb2017.org/

37. Audience Questions
37

38. Fall Schedule
38
8/22/2016 9/11/2016 10/1/2016 10/21/2016 11/10/2016 11/30/2016
Literature Review Research
Master Project Plan Development
Master Project Plan Final Draft
Develop STEPS Specifications
Final STEPS Design
Construct Alpha Prototype
Alpha Prototype Completed
Prepare for Presentation
Finish Final Documentation
Fall Semester Final Presentation

39. Spring Schedule
39
1/1/2017 1/29/2017 2/26/2017 3/26/2017 4/23/2017
Documentation
Final Report Development
Final Report Due
Data Collection
Simulator Proficiency
Preliminary EMG Trials
Healthy Trials
Literature Review and Citations
TPG Simulator Trials
TPG Simulator + Device Trials
Foot Switch Selection
First TPG Simulator
TPG Simulator Testing
CAD Modeling Focus
Upper Connector Selection
Lower Connector Selection
Parts Delivery
Beta Prototype Construction

40. Priced Bill of Materials
Part No.: Part Name: Net: Part No.: Part Name: Net: Part No.: Part Name: Net:
1 Bike Clamp, 1 $ 29.99 9 Accordion Pipe, 1 $ 35.83 17 Cotter Pin, 1 $ 0.54
2 Pawl Springs, 2 $ 4.50 10 Pins, 12 $ 16.56 18 Linear Guides, 4 $ 8.00
3 Pylon Spring, 1 $ 4.00 11 Rotary Shaft, 6 $ 0.39 19 Linear Pawl, 2 $ 18.00
4 Slotted pylon, 1 $ 17.35 12 Set Screw, 1 $ 5.13 20 Upper Flange, 1 $ 16.00
5 Cable Crimps, 2 $ 1.18 13 Sleeve Bearing, 6 $ 0.51 21
Pylon Bushing
Adapter, 2 $ 0
6 Eyebolt, L, 4 $ 1.32 14 Socket Head Cap Screw, 1 $ 12.02 22 Top Block, 2 $ 0
7 Outer Lock Nuts, 6 $ 1.02 15 Spacers, 4 $ 6.11 23 Ankle BushingAdapter, 2 $ 0
8 TensionCable, 1 $ 8.84 16 Threaded Rod, 2 $ 6.11 Total: $ 217.17
40

41. Budget
41
Category Expected Spent Remaining
Gait Simulator $ 100.00 $ 65.14 $ 34.86
Testing $ 100.00 $ 61.08 $ 38.92
Alpha Prototype $ 250.00 $ 210.88 $ 39.12
Beta Prototype $ 500.00 $ 462.90 $ 37.10
Marketing $ 300.00 $ 276.00 $ 24.00
Incidentals $ 100.00 $ 91.55 $ 8.45
Total $ 1,350.00 $ 1,167.55 $ 182.45

42. Supplementary Information
42
Ankle Switch Spring Stiffness:
This equation calculates the maximum spring stiffness needed at the ankle to
consistently compress during stance phase.
The average walking force applied to the foot during stance phase is 150 lb.
The clutch should engage at 70% of the maximum force applied.
The maximum travel at the ankle spring is 1 inch.
Favg = 150 lb.
Fapplied = Favg * percentage
Fapplied = 150 lb. * 0.7 = 105 lb. = 467 N
Lspring = 25.4 mm
Spring constant, k =
Fapplied
Lspring
k =
467 N
25.4 mm
= 18.4
N
mm

43. Number ofTeeth σmax (MPa) Usable
1 889.9 No
2 444.9 No
3 269.9 No
4 222.5 No
5 178 Yes
6 148.3 Yes
7 127.1 Yes
Supplementary Information
Yield strength of stainless steel: 215 Mpa
Maximum stress buildup based on number of engaged teeth:
* calculated with safety factor of 2.5 * 43

44. Testing Equipment
44
DelsysTrigno
Muscle Activation
VICON/Nexus
Joint Angles &
Ground Reaction Forces
http://www.gdmedical.ch/de/produkte/diagnostik/31/ergospirometrie/fitmate-pro/
http://www.delsys.com/products/emg-auxiliary-sensors/std-sensor/
http://dmnnewswire.digitalmedianet.com/article/UC-Merced-Adopts-VICON-F40-Motion-Capture-System-643459
COSMED
Fitmate PRO
Oxygen Consumption

45. Testing
45