Describe the components of a prosthesis, also mention the interfaces and end effector
Stump –> Inner socket (has stump interface) –> socket (has socket/hand interface) –> wrist –> end effector –> (optional) glove
Explain the following terms in the context of a prosthesis: Action, efferent, afferent, sensation
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.
What is a cosmetic prosthesis?
A prosthesis designed to look similar to a real body part, is often used for cosmetic purposes.
Name 6 benefits with cosmetic prosthesis
- 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
Name a con with cosmetic prosthesis
No functionality
What are activity-specific prostheses?
Prosthesis designed to facilitate a specific need
Name 3 pros with activity-specific prosthesis
- 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)
What are body-powered prostheses?
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
Name one con with activity-specific prosthesis
- They are less suited for children
Name 7 pros with body-powered prostheses
- Low weight
- Technical reliability
- Durability
- Low cost
- Good visual feedback
- Ability to grasp small objects
- Proprioceptive feedback
Name 4 cons with body-powered prosthesis
- Poor appearance
- Irritation of the shoulder and
the axilla - Compensatory movements
- Large activation force
What are externally powered prostheses, how does it work?
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.
Name 5 cons with externally powered prosthesis
*Heavy (in comparison to body-powered)
*Battery dependent
* High initial cost
* High repair cost
* Limited grasping capabilities
* No feedback
Name 2 pros with myoelectric hooks in comparison to hands
More durable
Can generate higher force
Name 4 pros with externally powered prostheses
- No harness
- Antropomorphic*
- Proportional control
- Good grip force
What are Multiarticulating/polyarticular myoelectric hands
Multi-DoF Myoelectric Hands
What are different to Multiarticulating/polyarticular myoelectric hands in comparison to “regular” myoelectric hands
They have more than one motor and can produce more than one grip pattern
Name 3 pros with Multiarticulating/polyarticular myoelectric hands
- Esthetics
- Versatility
- Dexterity
Name 5 cons with Multiarticulating/polyarticular myoelectric hands
- Robustness
- Battery dependent
- High initial cost
- High repair cost
- No feedback
How are multi-DOF myoelectric prostheses usually operated? What does that imply?
As finite-state machines
Different devices (or joints) can be controlled sequentially
What is the difference between passive and active prostheses?
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.
What’s a common form of hybrid prosthesis (upper limb), and how do they work?
Transhumeral and shoulder disarticulation prostheses most commonly include a body-powered elbow and a myoelectric terminal device (hook or hand).
Name 3 pros with hybrid prostheses
- Better functionality
- Dexterity (more
movable components) - Simultaneous control of
multiple joints
Name 3 cons with hybrid prosthesis
- Battery dependent
- High initial cost
- High repair cost
