1. Prosthesis Design and Control
Introduction
Fall 2014

2. Stump, or residual limb
Earliest amputation recorded by Herodotus, Greek historian, 480 BC Persian soldier Hegesistratus arrested by Spartans, facing torture and execution, one foot in stocks, cut off foot to escape, later obtained a prosthetic (wooden) foot

3. Disarticulation: Amputation between bone surfaces
Upper limb amputations: 7% 2%
33% 1%
54% 3%

4. Disease or infection – 74%
Causes of amputation
Accident – 23%
Disease or infection – 74%
Cancer – 2%
Vascular (circulatory) – 54%
Diabetes – 70%
Tripled between 1980 and 2005
Diabetic survival rate is improving
1/3 of adults diabetic by 2050
Birth defect – 3%
Paralysis – less than 1%

5. As of 2014:
2 million people with limb loss in the United States
185,000 amputations in the United States each year
In 2009, hospital costs associated with amputation totaled more than $8.3 billion
African‐Americans are four times more likely to have an amputation than white Americans
Nearly half of those who have an amputation due to vascular disease die within 5 years
Diabetics who have a leg amputation have a 55% of a second amputation within 3 years

6. Amputations by age
Below 10 years old: 3%
11-20 years old: 7%
21-30 years old: 7%
31-40 years old: 7%
41-50 years old: 9%
51-60 years old: 18%
61-70 years old: 28%
71-80 years old: 17%
Over 80 years old: 4%
A Primer on Limb Prosthetics, p. 9

7. Corset-style interface, pre-1960s
Patellar-tendon-bearing socket, introduced in the 1960s

8. (Silesia is a region in Poland) Total elastic suspension belt
Silesian bandage
(Silesia is a region in Poland)
Total elastic suspension belt
Pelvic belt
amhs.org.au/Virtual Museum/Surgery/orthopedics/Limb-prostheses

9. Socket Knee Shank Ankle Foot
Socket interfaces
Liner / lock – low activity
Suction – medium activity
Vacuum – high activity
Socket Knee Shank Ankle Foot
Mechanical interfaces between leg components are standard, which provides a “plug and play” prosthesis.

10. Gait Cycle: 2 steps = 1 stride
Heel strike
Heel strike
12%
50%

11. Lower limb amputee activity levels
Does not have the ability or potential to ambulate safely and a prosthesis does not enhance their quality of life or mobility.
Level 1
The ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed pace. This prosthesis is typical for the household ambulator.
Level 2
The ability or potential for ambulation with the ability to traverse low-level environmental barriers such as curbs, stairs, or uneven surfaces. This prosthesis is typical for the limited community ambulator.
Level 3
The ability or potential for ambulation with variable pace, with the ability to traverse most environmental barriers while participating in activities of daily living that require prosthetic use beyond simple locomotion.
Level 4
The ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, or energy levels. This prosthesis is typical of the child or active adult functioning in the community.

12. More than 50 models available today Some design for special activities
Prosthetic Feet
More than 50 models available today
Some design for special activities
Feet with no hinged parts: Low activity level
Solid ankle cushioned heel (SACH)
Elastic keel: more flexible

13. Flex foot
Oscar Pistorius, 2012 South African Olympic sprinter

14. Articulated Prosthetic Feet
iWalk product BiOM
Hugh Herr’s company
Google “Hugh Herr TED”

15. Odyssey – motorized
1 KHz control
JackSpring – motorized
Thomas Sugar, Professor
Arizona State University

16. Prosthetic Knees More than 100 models available
Single axis or polyaxial
Passive: no electronics
Mechanical friction
Constant
Variable
Hydraulic
Pneumatic
Active: motor control
Semi-active: computer control but no motors
Ottobock, Ossur, Trulife, Freedom Innovations, Endolite (Dayton, Ohio), …
medi OHP3/KHP3

17. Mauch SNS (swing and stance)
Ossur
Passive
Hydraulic
$5,000
Hans Adolph Mauch ( )
German engineer until the end of WW II
Jet engine and prosthesis development in Germany
Moved to USA in 1945

18. C-Leg Ottobock Semi-active Hydraulic Introduced in 1997
First microprocessor leg
$50,000 retail
Otto Bock,
German prosthetist

19. Rheo Knee Ossur Semi-active Hydraulic Introduced in 2005 $17,000
Magnetorheological fluid has viscosity that depends on the surrounding magnetic field

20. Plie Knee Freedom Innovations Semi-active: 100 Hz Hydraulic

21. Integrated knee and ankle motors Currently in testing
Vanderbilt Leg
(aka bionic leg, or
Goldfarb leg)
Freedom Innovations
Integrated knee and ankle motors
Currently in testing
Controller gain scheduling depending on “walking phase”
Image: National Institute of Biomedical Imaging and Bioengineering
F. Sup et al., “Self-Contained Powered Knee and Ankle Prosthesis”

22. First active transfemoral prosthesis
Power Knee
Ossur
First active transfemoral prosthesis
Introduced in 2009
$60,000
proklinik.com.tr

23. Increase in energy consumption Amputee with walker or crutches – 65%
Below-knee unilateral amputee – 15%
Below-knee bilateral amputee – 30%
Above-knee unilateral amputee – 65%
Three times normal hip power on amputated side
Above-knee bilateral amputee – 200%
“Microprocessor Prosthetic Knees,” by D. Berry
“Self-contained power knee and ankle prosthesis,” by F. Sup et al.

24. Coordinate system Z Y, right to left X Thigh angle (positive as shown)
Direction of walking Z
Y, right to left X
Knee angle (positive)
Thigh angle (positive as shown)

25. Able-Bodied Gait Data
Heel Strike
Toe Off
Flexion
Extension
Stance Phase
Swing Phase
Gait_Data_Sub3.xls, Normal Walk (Cleveland Clinic)

26. Able-Bodied Gait Data Positive: Power Generated by the Joint
Negative: Power Absorbed
by the Joint
Does not match published data well
Gait_Data_Sub3.xls, Normal Walk (Cleveland Clinic) kg subject

27. Power = Torque * (Angular Velocity) Normal walking speed
Toe
Off
“Energy generation and absorption at the ankle and knee during fast, natural, and slow cadences,” by D. Winter, 1983
Figure 3 and Table 1
Able-Bodied Gait Data
Power = Torque * (Angular Velocity)
Normal walking speed
104.4 steps/minute (52.2 strides/minute)
Ankle work = – = 17.8 J
Knee work = – – 9.6 – 8.4 = –20.6 J
The ankle requires energy
The knee absorbs energy
The net work done by the knee/angle combination is negative
Discriminating age and disability effects in locomotion: neuromuscular adaptations in musculoskeletal pathology, by Chris A. McGibbon and David E. Krebs

28. Control group: dotted line More hip power required for amputees
Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg® and Mauch SNS® prosthetic knees, by Ava D. Segal et al. 2 1 4 3
Prosthetic Limb
C-leg: solid line
Mauch leg: dashed line
Control group: dotted line
More hip power required for amputees
No stance knee flexion in prostheses
More negative knee power in prostheses
No ankle push-off with prostheses

29. C-leg users: solid line Mauch leg users: dashed line
Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg® and Mauch SNS® prosthetic knees, by Ava D. Segal et al. 1 2 3
Intact Limb
C-leg users: solid line
Mauch leg users: dashed line
Control group: dotted line
Limping (shorter steps) by amputees
More hip power in amputees
More ankle push-off by amputees
ancillary health issues

30. Prosthetics Research at CSU
Fall 2009 – Davis and van den Bogert (CC) contact Simon about hydraulic prosthesis control
Spring 2010 – CC provides funding to CSU
Summer 2010 – Davis leaves CC for Austen BioInnovation
Fall 2010 – van den Bogert leaves CC for self-employment
Fall 2011 –Richter begins design of hip robot
Spring 2012 – Richter completes hip robot
Fall 2012 – CC project concludes
Fall 2012 – van den Bogert moves to CSU
Summer 2013 – Wright Center funds CSU for 1 year
Fall 2013 – NSF funds CSU for 4 years