Prosthesis Technology

Question 1

Describe the components of a prosthesis, also mention the interfaces and end effector

Answer 1

Stump –> Inner socket (has stump interface) –> socket (has socket/hand interface) –> wrist –> end effector –> (optional) glove

Question 2

Explain the following terms in the context of a prosthesis: Action, efferent, afferent, sensation

Answer 2

Action: Movement or operation of the prosthesis.
Efferent: Signals that travel from the central nervous system (the brain and spinal cord) to the muscles and organs to control the prosthesis.
Afferent: These signals travel in the opposite direction, from the muscles and sensors in the prosthesis back to the central nervous system. They provide feedback
Sensation: This is the feeling or perception resulting from afferent signals.

Question 3

What is a cosmetic prosthesis?

Answer 3

A prosthesis designed to look similar to a real body part, is often used for cosmetic purposes.

Question 4

Name 6 benefits with cosmetic prosthesis

Answer 4

• Are easy to control (often used by young children and recent amputees)
• Offer high comfort
• Offer high quality appearance
• Enhance the self-image and self confidence
• Enhances the rehabilitation of the user (they help to forget the disability)
• Can be used to support, stabilize, push, pull, hold objects

Question 5

Name a con with cosmetic prosthesis

Answer 5

No functionality

Question 6

What are activity-specific prostheses?

Answer 6

Prosthesis designed to facilitate a specific need

Question 7

Name 3 pros with activity-specific prosthesis

Answer 7

• Good durability
• Are a great way to learn a new skill
• Are used with a quick-release wrist to allow easy exchange of the tool among tasks (adaptable)

Question 8

What are body-powered prostheses?

Answer 8

Body-powered devices are operated using cable and harness systems that
require the patient to use body movements to pull the cable and make the terminal device

Question 9

Name one con with activity-specific prosthesis

Answer 9

• They are less suited for children

Question 10

Name 7 pros with body-powered prostheses

Answer 10

• Low weight
• Technical reliability
• Durability
• Low cost
• Good visual feedback
• Ability to grasp small objects
• Proprioceptive feedback

Question 11

Name 4 cons with body-powered prosthesis

Answer 11

• Poor appearance
• Irritation of the shoulder and
  the axilla
• Compensatory movements
• Large activation force

Question 12

What are externally powered prostheses, how does it work?

Answer 12

An electrically powered prosthesis include motors, batteries, sensors (depending on needs)
* Sensors are used to detect muscles activation in the residual limb. These sensors send a signal to the prosthesis, to activate the desired movements.

Question 13

Name 5 cons with externally powered prosthesis

Answer 13

*Heavy (in comparison to body-powered)
*Battery dependent
* High initial cost
* High repair cost
* Limited grasping capabilities
* No feedback

Question 14

Name 2 pros with myoelectric hooks in comparison to hands

Answer 14

More durable
Can generate higher force

Question 15

Name 4 pros with externally powered prostheses

Answer 15

• No harness
• Antropomorphic*
• Proportional control
• Good grip force

Question 16

What are Multiarticulating/polyarticular myoelectric hands

Answer 16

Multi-DoF Myoelectric Hands

Question 17

What are different to Multiarticulating/polyarticular myoelectric hands in comparison to “regular” myoelectric hands

Answer 17

They have more than one motor and can produce more than one grip pattern

Question 18

Name 3 pros with Multiarticulating/polyarticular myoelectric hands

Answer 18

• Esthetics
• Versatility
• Dexterity

Question 19

Name 5 cons with Multiarticulating/polyarticular myoelectric hands

Answer 19

• Robustness
• Battery dependent
• High initial cost
• High repair cost
• No feedback

Question 20

How are multi-DOF myoelectric prostheses usually operated? What does that imply?

Answer 20

As finite-state machines
Different devices (or joints) can be controlled sequentially

Question 21

What is the difference between passive and active prostheses?

Answer 21

Passive: (usually) an intact limb is used to control the mechanism (force is applied externally)
Active: the force to adjust the grasping
the mechanism is applied internally, for example, by an electric actuator or a body-powered cable.

Question 22

What’s a common form of hybrid prosthesis (upper limb), and how do they work?

Answer 22

Transhumeral and shoulder disarticulation prostheses most commonly include a body-powered elbow and a myoelectric terminal device (hook or hand).

Question 23

Name 3 pros with hybrid prostheses

Answer 23

• Better functionality
• Dexterity (more
  movable components)
• Simultaneous control of
  multiple joints

Question 24

Name 3 cons with hybrid prosthesis

Answer 24

• Battery dependent
• High initial cost
• High repair cost

Question 25

What are the three keys to developing prosthesis?

Answer 25

• Physical interfaces between the individual neuromuscular system and the machine
• Physiologically appropriate control systems
• Physiologically appropriate sensory feedback schemes