Prosthesis Design and Control

Introduction Fall 2014

Stump, or residual limb www.vitalitymedical.com

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 2

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

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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%

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• • • • • • 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 www.amputee-coalition.org

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• • • • • • • • • 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

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Corset-style interface, pre-1960s http://www.studyblue.com/notes/note/n/ rehab-prosthortho-pictures/deck/6884210 Patellar-tendon-bearing socket, introduced in the 1960s 7

Silesian bandage http://oandplibrary.com

(Silesia is a region in Poland) Total elastic suspension belt http://www.ortho europe.com/prosthetics/Liners Pelvic belt amhs.org.au/Virtual Museum/Surgery/orthopedics/ Limb-prostheses 8

www.ottobockus.com

Socket

Socket interfaces Liner / lock – low activity Suction – medium activity Vacuum – high activity

Knee Shank Ankle Foot

Mechanical interfaces between leg components are standard, which provides a “plug and play” prosthesis.

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Gait Cycle: 2 steps = 1 stride

Heel strike 12% 50% www.jaaos.org/content/15/2/107/F1.large.jpg

Heel strike 10

• • • • • Lower limb amputee activity levels Level 0 – 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.

www.health.alberta.ca/documents/AADL-Manual-P-Products.pdf

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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 www.willowwoodco.com/products and-services/feet/low-activity/sach www.heritage-medical.com/foot-prosthetics 12

Flex foot

http://www.ossur.com/prosthetic solutions/products/feet/feet/flex foot-assure Oscar Pistorius, 2012 South African Olympic sprinter http://www.dailymail.co.uk

http://www.telegraph.co.uk

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Articulated Prosthetic Feet

http://www.amputee-coalition.org/military instep/feet.html

iWalk product BiOM Hugh Herr’s company http://blog.amsvans.com

Google “Hugh Herr TED” www.newscientist.com

www.businessinsider.com

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Odyssey – motorized 1 KHz control www.springactive.com

Thomas Sugar, Professor Arizona State University JackSpring – motorized www.springactive.com

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Prosthetic Knees

More than 100 models available Single axis or polyaxial Passive: no electronics – Mechanical friction • Constant • Variable – Hydraulic – Pneumatic Active: motor control

medi OHP3/KHP3

www.medi.de/en/international/products/leg-prostheses Semi-active: computer control but no motors Ottobock, Ossur, Trulife, Freedom Innovations, Endolite (Dayton, Ohio), … 16

Mauch SNS (swing and stance)

– Ossur – Passive – Hydraulic – $5,000 Hans Adolph Mauch (1906-1984) German engineer until the end of WW II Jet engine and prosthesis development in Germany Moved to USA in 1945 www.ossur.com

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C-Leg

– Ottobock – Semi-active – Hydraulic – Introduced in 1997 – First microprocessor leg – $50,000 retail Otto Bock, 1881-1960 German prosthetist www.ottobockus.com

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

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Plie Knee Freedom Innovations Semi-active: 100 Hz Hydraulic

www.freedom-innovations.com

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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” 21

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Power Knee Ossur First active transfemoral prosthesis Introduced in 2009 $60,000

proklinik.com.tr

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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.

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Coordinate system

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

Heel Strike 80

Able-Bodied Gait Data

Knee Angle Toe Off 60 40 Flexion Extension Flexion Extension 20 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 Thigh Angle 40 30 20 10 0 -10 -20 -30 Stance Phase Swing Phase 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 Hip Position 900 850 800 750 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 Time (Sample Number) Gait_Data_Sub3.xls, Normal Walk (Cleveland Clinic) 25

Able-Bodied Gait Data

Knee Power (W/kg) 2 1,5 1 0,5 Positive: Power Generated by the Joint 0 -0,5 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 -1 -1,5 -2 -2,5 Negative: Power Absorbed by the Joint Ankle Power (W/kg) 2,5 2 1,5 1 0,5 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 -0,5 -1 Does not match published data well -1,5 Gait_Data_Sub3.xls, Normal Walk (Cleveland Clinic) -113.8 kg subject 26

Toe Off Discriminating age and disability effects in locomotion: neuromuscular adaptations in musculoskeletal pathology, by Chris A. McGibbon and David E. Krebs “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 = –7.8 + 25.6 = 17.8 J Knee work = –6.3 + 3.7 – 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 27

2 Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg ® and Mauch SNS ® prosthetic knees, by Ava D. Segal et al.

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Prosthetic Limb

C-leg: solid line Mauch leg: dashed line Control group: dotted line 1. More hip power required for amputees 2. No stance knee flexion in prostheses 3. More negative knee power in prostheses 4. No ankle push-off with prostheses 28

1 Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg ® and Mauch SNS ® prosthetic knees, by Ava D. Segal et al.

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Intact Limb

C-leg users: solid line Mauch leg users: dashed line Control group: dotted line 1. Limping (shorter steps) by amputees 2. More hip power in amputees 3. More ankle push-off by amputees ancillary health issues 29

• • • • • • • • • • 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 30