Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Prosthetic Study > Myoelectric Prostheses > Flashcards

Myoelectric Prostheses Flashcards

1
Q

Myoelectric Prostheses

A

EXTERNALLY POWERED artificial limbs

Using BATTERIES AND ELECTRONIC SYSTEM to control movement of a TERMINAL DEVICE

Sensors used with prosthesis to detect minute MUSCLE, NERVE, and EMG (Electromyography) SIGNALS, primarily from FLEXORS and EXTENSORS

Translates MUSCLE ACTIVITIES into information that controls ARTIFICIAL LIMB MOVEMENTS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Myo Advantages

A

DOES NOT REQUIRE STRAPS OR HARNESSES to function, usually fit as supracondylar or suction suspension

USER CONTROLLED STRENGTH AND SPEED of limb’s movements and grip by varying muscle intensity

GOOD DEXTERITY allow manipulations of small items through function of the fingers

MINIMAL COSMETIC APPEARANCE SACRIFICE

Offer GREATER ROM during functional movement. Ex. performs both opening and closing of terminal device voluntarily (not exclusively one or the other)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Myo Disadvantages

A

WEIGHT, batteries, electronic components, terminal device, do not use harnesses to counter balance weight across the body

COST, since more electronic components are added to provide more functionality ex.. wrist rotator offers pronation/supination

LACK OF SENSORY FEEDBACK

SUSCEPTIBILITY TO WATER DAMAGE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Patient Considerations for Myoelectric Prostheses

A

AMPUTATION LEVEL

CONTOUR of residual limb

COGNITIVE FUNCTION of the patient

ACTIVITIES of patient

COSMETIC IMPORTANCE of the prosthesis

FINANCIAL RESOURCES of the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Patient Indications for Myoelectric Prosthesis

A

Muscles in the residual limb must be CAPABLE OF EMITTING SUFFICIENT EMG signals to operate myoelectric prosthesis

COMMITMENT TO THERAPY, to “learn” how to use prosthesis

COMPLIANT WITH LIMITATIONS of myoelectric use, battery charging, service required

FUNDING AVAILABLE $$

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Patient Contraindications for Myoelectric Prosthesis

A

Muscles of residual limb UNABLE TO PRODUCE SUFFICIENT EMG signal

EXCESSIVE SCAR TISSUE on residual limb

COGNITIVE IMPAIRMENT

LIFESTYLE/JOB would damage myoelectric components (Ex. Extreme Sports, Manual Labour, Exposure to Water)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Components of Transradial Myoelectric Prosthesis

A

Internal socket

Forearm Outer shell

Electrodes

Controller

Batteries

Wrist

Terminal Device

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Internal Socket

A

SELF SUSPENDING SOCKETS

Need to have CLOSE FIT TO MAINTAIN CONTACT with ELECTRODES

Get HAND POSITION in casting

  • Northwestern (Supracondylar)
  • 3/4’’
  • Muenster (Narrow A-P)
  • Basic socket type

Silicone and thermoplastics (Seaflex 200) commonly used in myoprostheses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Forearm Outer Shell

A

Can be exoskeletal laminated forearm or endoskeletal forearm

Section is where all electronic components are housed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Electrodes

A

ELECTRONIC SENSORS

SMALL METALLIC CONTACTS that rest against skin on the electrode sites

Find ideal locations in order to detect the best myoelectric circuit

Signal sent to myoelectric circuit, designed to LOCATE< AMPLIFY, FILTER and RECTIFY the EMG signal from a normal muscle

DIALS ON THE SENSORS can be adjusted for the AMPLIFICATION of the EMG signals to further control SENSITIVITY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Controllers

A

LOGIC SENSORS

Once EMG is RECEIVED, CONTROLLER OPERATES THE TERMINAL DEVICE

Numerous control options such as

  • DMC (Dynamic Mode Control), which CONTROLS the HAND PROPORTIONATELY based on MUSCLE SIGNAL SPEED and STRENGTH
  • DIGITAL, that can be used with 1 or 2 electrodes or switches

CHANGES can be made using COMPUTER SOFTWARE such as MyoSelect, MotionContol, Liberating Control or changing coloured “coding plugs” directly within the device

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Myoelectric Batteries

A

Patient ACTIVITY LEVEL, along with COMPONENTRY to be used should be considered

Factors when choosing battery

  • CAPACITY (milliamp/hour) (mAh)
  • VOLTAGE (V), CORRECT FOR TERMINAL DEVICE selected (pediatric or adult)
  • CHARGING TIME (in hours)
  • SIZE AND WEIGHT

ENERGY DENSITY is of interest - more energy dense, more mAH per volume (mAH/volume)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Types of Batteries

A

Nickel Cad (NiCd)

  • old tech
  • cheap
  • memory effects

Nickel Metal Hydride (NiMH)

  • newer
  • less memory effect
  • mid range in expense

Lithium Ion

  • newest
  • more energy dense
  • small battery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Wrist units

A

QUICK DISCONNECT - allows patient to use MORE THAN ONE TERMINAL DEVICE such as hand or greifer, mounted inside forearm using a lamination ring, 4 metal bands on the coaxial plug send power and control info to the hand via the coaxial bushing

FLEXION/EXTENSION

Units are available in different sizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Terminal Devices

A

Depending on NEEDS and LEVEL OF FUNCTION of the patient, many options available

MODIFIED VERSIONS available for WRIST DISARTIC and TRANSCARPAL

Commonly used “ELECTRIC HANDS”

  • SENSORHAND SPEED, fast, sensors on thumb automatically adjust to grip
  • DIGITAL TWIN, combines both classical digital control (open and close) and double channel control in a single hand, constant speed and grip force to open close the hand
  • DMC
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Myoelectric Site Selection and Signal Training Criteria

A

Selecting muscles used for control, must be

  • SUPERFICIAL AND ACCESSIBLE with prosthetic design/space considerations
  • NOT INTERFERE with or inhibit normal activity
  • APPROXIMATE normal movement
  • GENERATE SIGNALS of sufficient STRENGTH
  • be completely UNDER VOLUNTARY CONTROL
17
Q

One site (Single site)

A

PEDIATRIC site selection usually starts with ONE SITE

SINGLE SITE

VOLUNTARY OPEN system using EXTENSOR muscles

USUALLY FITTED BETWEEEN 10-12 months to 3 yrs of age

VOLUNTARY OPEN / AUTOMATIC CLOSE

“COOKIE CRUSHER”

3 STATE (rate or level sensitive)

USUALLY HAS PARENTAL/THERAPIST TRAINING SWITCH, allows therapist or parent to place objects in hand for grasp and release training or playing

ELECTRODE SENSITIVITY is usually set to high for EASY ACTIVATION to catch attention of the child

LEVEL REDUCED GRADUALLY, until OPTIMAL LOWEST LEVEL is achieved and the child can open hand fully at will

18
Q

Two Site

A

Occurs when PRESCHOOL AGE is reached between 3-4 yrs of age

Child has improved COMMUNICATION/COGNITIVE skills, TRANSFERRED from 1 site –> 2 site

FLEXOR MUSCLE SITE MUST BE ACCESSIBLE with prosthetic design and space available

Site must not interfere with normal daily activities

MUSCLE MUST GENERATE SUFFICIENT STRENGTH and be completely UNDER VOLUNTARY CONTROL

19
Q

Ottobock components

A

Electrodes

Electrode cables

Coaxial plug

Battery cable

Battery Box

Lamination Collar

20
Q

How to Activate Terminal Device

A

SWITCHES
-Rocker, pull push, multi positional, harness mount

FORCE SENSITIVE RESISTOR

CAPACITIVE TOUCH CONTROL

LINEAR TRANSDUCER- device that USES BODY MOVEMENT TO TRANSLATE TO ELECTRONIC SIGNAL

MYOELECTRIC SIGNAL

21
Q

Electrodes Detect

A

EMG

Wave of depolarization

22
Q

Put It All Together

A

Connection cables

Battery to everything

Amplifiers to control board

Control board to motor if necessary

23
Q

Trouble Shooting - Hand does not function at all

A

Both electrodes not working (not likely)

Battery

Coaxial plug

Hand

24
Q

Trouble Shooting - Hand operates in one direction

A

Electrodes or cables

Coaxial plug

Hand malfunction

25
Q

Thresholds

A
  • used to ELIMINATE UNWANTED INPUT from the electrode, caused by either external or internal signals
  • SET AS LOW AS POSSIBLE to allow client GREATEST ACCESS to signal generation
26
Q

Rate vs. Level Sensitive

A

Rate - SPEED of contraction

Level- STRENGTH of contraction

27
Q

Internal Power Source

A

Pros

  • cosmetic
  • lighter
  • can’t lose battery

Cons

  • can’t swap out when power is drained
  • need to install a switch for “off”
28
Q

External Power source

A

Pros
- INTERCHANGEABLE for charged, when on the go

Cons

  • Cosmesis
  • Charger can be bulkier
29
Q

Pattern Recognition

A
  • uses algorithms to identify the muscle pattern generated when user performs a certain movement
  • classifier then links the pattern to the specific movement of the component
  • uses array of electrodes instead of 1 or 2 as in direct control to gather more data from the muscles
  • aims to provide intuitive and simultaneous control of myoelectric components
30
Q

TMR

A

Targeted Muscle Reinnervation

  • surgical procedure that aims to provide easier and more intuitive prosthetic control for UE amputees
  • typically performed for higher amputation levels, fore quarter, shoulder disartic, transhumeral
  • residual nerves in amputated limb transferred to target muscles (pectoral muscles)
  • additional signal sites allow users to operate 2 components independently without having to switch modes

Prosthetic Study (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions