prostetic limbs and uses

1. Bionics 4
Kevin Warwick

2. Artificial Limbs
• An artificial limb usually replaces a
missing limb, such as an arm or leg.
• The type of artificial limb used is
determined largely by the extent of
amputation of the missing extremity –
each one is a little different.
• Reasons include disease, accidents, and
congenital (birth) defects.

3. Geography
• Likely reasons for an amputation depend
on location.
• In USA & Europe circulatory disease,
cancer and infection are the leading
causes.
• In Africa the most likely causes are
industrial, vehicular, or a war related
accidents – again infection is a problem.

4. This Presentation
• More interested in the legs and arms
themselves
• Neuroprosthetics & Enhancements etc are
mostly a separate lecture

5. History
• Two artificial toes have been found on Egyptian
mummies – these date back to 1,000BC.
However it is not known if they were actually
used in life.
• The first artificial leg, from archaeology, is the
Roman Capua Leg. This was found in a tomb in
Capua, Italy, and dates back to 300BC. It was
made of wood and copper.
• In the 15th century artificial limbs were often
made out of iron for soldiers and sailors.
However wood came to be used much more,
simply because of its weight.

6. Wooden Legs
• Such a wooden leg
could be simply
fixed.
• Or it could be
hinged at the knee
to assist walking
• No hinge – possible
strange gait

7. Developments
• In the 19th century, artificial limbs became more
widespread due to the large number of amputees from
wars.
• Helped by the discovery of anesthetics.
• In the 20th century scientific research and commercial
possibilities opened the field further.
• In recent years, a great deal of emphasis has been
placed on developing artificial limbs that look and move
more like actual human limbs.
• General new technology (plastics, CAD, manufacturing,
medicine) have all improved the end results.

8. Types of Prosthetic
• Transtibial Prosthesis replaces a leg missing below the knee. Such
amputees can regain normal movement more readily than those with a
transfemoral amputation - retaining the knee allows for easier
movement.
• Transfemoral Prostheses replaces a leg missing above the knee. Such
amputees can have a very difficult time regaining normal movement. A
transfemoral amputee must use approximately 80% more energy to walk
than a person with two whole legs.
• Transradial Prostheses replaces an arm missing below the elbow. Two
main types of prosthetics are available. Cable operated limbs work by
attaching a harness and cable around the opposite shoulder of the
damaged arm. Alternative is myoelectric arms – muscle sensing.
• Transhumeral Prosthesis replaces an arm missing above the elbow.
Such amputees experience some of the same problems as transfemoral
amputees, due to the similar complexities associated with the movement
of the elbow. Mimicking the correct motion with an artificial limb is very
difficult.

9. Recent Developments
• New plastics and other materials, such as carbon
fibre, have allowed artificial limbs to be stronger
and lighter, limiting the amount of extra energy
necessary to operate the limb. This is especially
important for transfemoral amputees.
• Other synthetic materials have allowed artificial
limbs to look much more realistic, which is
important to transradial and transhumeral
amputees because they are more likely to have
the artificial limb exposed.

10. Artificial Legs
• Is only one leg missing?
• How much of the leg is
missing?
• Clearly these issues are
vital to the type of
artificial leg needed
• The more to be replaced,
so the more difficult the
problem is.

11. C-Leg
• The best known present day
artificial leg is the C-Leg produced
by Otto Block.
• The user can choose between two
modes: one for walking and one for
bicycling (or any other
preprogrammed activity). The
"problem" is switching between
modes, as the wearer has to swing
the leg forward in a jerky fashion.
• The C-LEG supports up to 10
programmable modes, switchable
through a small remote control
device about the size of a car alarm
remote. Reprogramming a mode
with another special activity
requires a technician.

12. C-Leg
• An inbuilt microprocessor
interprets the user’s
movements and
anticipates their actions,
allowing motion changes
in real time.
• The system is actuated
through the leg’s hydraulic
movement.
• It gives users greater
flexibility to change speed
or direction without
sacrificing stability.

13. C-Leg
• The 10 switchable modes enable various sports
activities, including cycling, running, natural
driving and other programmable activities that
require different leg actions to normal walking
and stair climbing.
• Current challenges are to stretch the unit’s
battery life to 50 hours on one charge and to
make the leg salt-water resistant. These are
both requirements to support military use.

14. Heather Mills
• In August 1993 Heather was hit by a police
motorcycle by Kensington Palace, London.
• Her injuries included crushed ribs and a
punctured lung. She needed a metal plate
put into her pelvis and also the amputation
of her left leg below the knee.
• Mills has a prosthetic leg, taking it off and
showing it to USA talk show host Larry
King during his interview with her in
October 2002.

16. Feet
• With artificial legs usually the knee joint is
critical
• Feet tend to be either non-existent, e.g.
Aimee Mullins, or are more for cosmetic
purposes – they are not functional
• Stability is important but not dexterity
• Tend to be purpose directed – what is the
leg for?

17. Artificial arms and hands
• Stability and power carrying are not big
issues here
• Elbow joints clearly are important
• But most critical are hand movements –
what will the hand have to do? – how is it
to be controlled? – what will it look like?
• Functionality is important – but cosmetics
are also very important

18. Artificial Arms and Hands
• Important if one or both have been lost
• It is possible to do many activities with one hand
or using a residual limb(s).
• Many arm amputees do not use any prostheses
or special tools. It is easy and possible to get
dressed/write/type with one hand.
• Some continue their work with a special
attachment only e.g. carpentry, car driving.
• Nevertheless, having a prosthesis can be a big
help, especially for manual labour.

19. Prosthesis
• Learning to use a prosthesis takes hard work
and practice. It is only worth the effort if it
improves a person’s ability to hold and use
things.
• An arm-hand prosthesis has three basic parts:
the socket, which fits over the residual limb; the
arm section, which may or may not include an
elbow joint; and the hand/tool, which can be like
a hand, a hook, or some other shape to allow
the person to hold and use things.
• Often a hook is preferred as it is extremely
functional

20. Body-powered prostheses
• Some prosthetics clinics make available body-
powered arm prostheses.
• These have straps or cables that attach to other
parts of the body, so that by moving a shoulder,
the person can make the hand close or bend the
elbow of the prosthesis.
• Body-powered prostheses often have metal
hooks instead of fingers. The hooks are better
than artificial fingers for hard work and can pick
up smaller things.

21. Electric-powered prostheses
• Electrical prostheses are available in some
countries, but they are relatively expensive.
• Perhaps not available where they are needed -
most (countries at war/strife).
• Muscles in the arm operate electric motors,
which close and open the hand.
• Electrical prostheses look more like real arms,
but they are not as strong and they break more
easily.

23. Cosmetic prostheses
• Cosmetic arms look like real arms but the hands
either do not move at all or can be pulled (by
another hand) into a fixed position.
• They can help a little (for example, the cosmetic
arm can hold down a paper while the other hand
writes on it), but the real purpose of a cosmetic
arm is to look natural.
• Very useful for someone in the public eye.
• Useful if only one hand has been lost.

24. Krukenberg surgery
• Some people missing both hands choose to have
surgery, called the Krukenberg surgery.
• This separates the two bones of the forearm to
make a new kind of “hand.”
• The bones can be used like two fingers, and
because the skin and bones are real, the person
can feel what they are doing.
• This greatly benefits amputees who are blind.
• It is still possible to wear a prosthesis over the
residual limb even after the surgery.

25. The i-LIMB Hand
• From Touch Bionics
• http://www.touchbionics.com/

26. The i-LIMB Hand
• The i-LIMB Hand is controlled by a system that uses a
two-input myoelectric (muscle signal) to open and close
the hand’s fingers.. This signal is picked up by electrodes
that sit on the surface of the skin. Existing users of basic
myoelectric prosthetic hands are able to adapt to the
system and can master the device’s functionality within
minutes.

27. Bionic Arm
• In 2001 Jesse Sullivan lost both his
arms when he was electrocuted.
• He has received an artificial
arm/hand controlled from his
nervous system.
• The nerves that used to go to the
arm were moved onto chest
muscles. The nerves grew into the
chest muscles, so when Jesse
thinks "close hand," a portion of
his chest muscle contracts and
electrodes that detect this muscle
activity tell the computerized arm
to close the hand. Thus, Jesse
thinks "close hand" and his
artificial hand closes.
• Work of Todd Kuiken.

28. Claudia Mitchell
• Lost her left arm in
a motorcycle
accident.
• In 2007 became
the 4th person to
have this type of
procedure – Rehab
Institute of
Chicago

29. Next Lecture
• Deep Brain Stimulation