Upper Limb Prosthetics - intro and body powered Flashcards
What is biomechatronics?
The science of using mechanical devices with human muscle, skeleton, and nervous system to assist or enhance motor control lost by trauma, disease or defect.
What is a prothesis?
An artificial device extension that replaced part of all of a missing body part.
What are the design considerations for artificial limbs?
- Function versus Form
- Weight
- Usability/Comfort
- Durability/Repair
- Power Sources
- Control Systems
- Cost
What is the most common reason for amputations in those ages 0-15 years?
Congenital deformity or tumor.
What is the most common reason for amputations in those ages 15-45 years?
Trauma, with tumors being a distant second.
What is the most common reason for amputations in those ages 60+ years?
Upper extremity amputations tend to be rare in patients who are older than 60 years, but they may be required secondary to tumor or medical disease.
What are the different names for levels of upper limb amputations?
What is a Transpalangeal amputation?
Resection of the thumb or fingers at distal interphalangeal (DIP), proximal interphalangeal (PIP), or metacarpophalangeal (MCP) levels or at any level in between
What is a Transmetacarpal amputation
Resection through the metacarpals
What is a transcarpal amputation?
Resection through the carpal bones
Why are Transmetacarpal and transcarpal amputations less advised?
They, except for select circumstances, provide for decreased functional outcomes.
What is a Wrist disarticulation?
Transection between the carpals and radius/ulna
What is a Transradial amputation
Below-elbow amputation (May be classified as long, medium, or
short.)
What is Elbow disarticulation?
Transection through the elbow joint
What is transhumeral amputation?
Above-elbow (Standard length is 50-90% of humeral length.)
What is shoulder disarticulation?
Transection through the shoulder joint
What is interscapulothoracic disarticulation (forequater)
Amputation removing the entire
shoulder girdle (scapula and all or part of the clavicle) (Some surgeons choose to leave part of the medial clavicle.)
What is a residual limb
Remaining portion of the amputated limb
What is relief?
A concavity within the socket that is designed for areas that are sensitive to high pressure (bony prominences)
What is buildup?
A convexity that is designed for areas that are tolerant to high pressure (such as a bulge)
What is a terminal device?
The most distal part of a prosthesis that substitutes for the hand; it may be a prosthetic hand, a hook, or another device.
What is Myodesis?
Direct suturing of residual muscle or tendon to bone/periosteum.
What is Myoplasty?
Suturing of agonist-antagonist muscles pairs to each other.
What is prehensile?
Grasp
What are the pros of a body powered prosthesis?
- moderate cost
- moderately lightweight
- most durable
- highest sensory feedback
- variety of prehensors available for various activities
What are the cons of a body powered prosthesis?
- most body movement needed to operate
- most harnessing
- least satisfactory appearance
- increased energy expenditure
What are the pros of a battery powered prosthesis?
- moderate or no harnessing
- least body movement needed to operate
- moderate cosmesis
-more function-proximal areas - stronger grasp in some cases
What are the cons of a battery powered prosthesis?
- heaviest
- most expensive
-most maintenance - limited sensory feedback
- extended therapy time for training
What is a battery powered prothesis?
Myoelectric and/or switch controlled
What is a socket?
typically has a dual-wall design fabricated from lightweight plastic or
graphite composite materials. A rigid inner socket is fabricated to fit the
patient’s residual limb and the second, outer wall is added, designed to be the same length and contour as the opposite, sound limb. Comfort and function are directly tied to the fit of the inner socket.
What is suspension?
The suspension system must hold the prosthesis securely to the
residual limb, as well as accommodate and distribute the forces associated with the weight of the prosthesis and any superimposed lifting loads.
What are the different types of suspension
- Harnessed based systems: most used
- Self-suspending sockets: largely limited to wrist or elbow disarticulations and to transradial amputations.
- Suction sockets: attaches by creating a vacuum between the stump and the prosthesis. As the patient dons the prosthesis, air is expelled from the socket through a one-way valve. The negative pressure around the stump holds the prosthesis in place until the user releases it by opening the valve
What are the types of strap systems based on location of amputation?
What are the indications, advantages and disadvantages of a Figure-8 Harness?
Indications
- transradial
- transhumeral
- light to normal activities
Advantages
- simple, durable, adjustable
Disadvantages
- axillary pressure produced discomfort
What are the indications, advantages and disadvantages of a shoulder Saddle and Chest Strap Harness?
Indications
- transradial
- transhumeral
- heavy lifting
Advantages
- greater lifting ability
- more comfortable than figure-8 harness
Disadvantages
- reduced control compared to the figure-8
- for women it is difficult to adjust as straps cross breast
What are the indications, advantages and disadvantages of a shoulder self-suspending?
Indications
- wrist disarticulation
- elbow disarticulation
-short transradial
- myoelectric transradial
Advantages
- ease of use
Disadvantages
- limited lifting capacity compared with harness systems
- compromised cosmesis
- reduced elbow flexion
What are the indications, advantages and disadvantages of a suction socket with air valve?
Indications
- transhumeral with soft tissue cover
Advantages
- secure suspension
- elimination of suspension straps
Disadvantages
- requires stable residual volume
- harder to put on than other suspension systems
What are the indications, advantages and disadvantages of a suction gel sleeve with locking pin?
Indications
- transhumeral
- transradial
- compromised limbs with scarring or impaired skin integrity
Advantages
- accommodate limb volume change with socks
- reduced skin shear
Disadvantages
- greater cleaning and hygiene needs
- can be uncomfortable in hot climates
What is a control cable system?
Body-powered prosthetic limbs use cables to link movements of one part of the body to the prosthesis in order to control a prosthetic function.
What is a Bowden Cables?
A bowden cable is a flexible cable used to transmit mechanical force or energy by the movement of an inner cable (most commonly of steel or stainless steel) relative to a hollow outer cable housing. The housing is generally of composite construction, consisting of a helical steel wire, often lined with plastic, and with a plastic outer sheath. The linear movement of the inner cable is used for transmitting a pulling action.
What are the movements used to control cables?
- Glenohumeral forward flexion
- Biscapular abduction (chest expansion, mutual protraction
- Glenohumeral depression/elevation, extension, abduction
- nudge control
What is glenohumeral forward flexion?
A natural movement that provides excellent power and reach and that can activate the terminal device or flex an elbow joint; it is good for activities away from midline.
What is Biscapular abduction (chest expansion, mutual protraction?
A movement that can activate the
terminal device; however, the device must stay relatively stationary and the force generated is weak. This movement is easy for the amputee to do. It is good for fine motor activities that are performed near the midline or close to the trunk of the body. Shoulder protraction can occur on just the ipsilateral side for terminal-device control without biscapular abduction (mutual protraction) for
prosthetic control. Chest expansion results in biscapular abduction without actual protraction.
What is Glenohumeral depression/elevation, extension, abduction?
Other body movements that the amputee can utilize to control prosthetic components/function; these movements are most frequently used simultaneously, in a maneuver to lock or unlock an elbow for a patient with a transhumeral amputation, via a separate, anterior cable in a dual-cable system. This maneuver can be difficult to master. The use of a waist belt or groin loop allows the amputee to employ scapular elevation as an alternative motion, one that operates a prosthetic function by utilizing a cable that has been run through a pulley.
What is nudge control?
Less cosmetic appearing action; however, nudge-control devices and similar types of systems are sometimes invaluable, Offering cable-control options for more complex cases where many control functions are needed.
What is the terminal Device?
A major function of the hand that a prosthesis tries to replicate is grip (prehension). May be Active or Passive
What is a voluntary opening mechanism?
The terminal device is closed at rest
What is a voluntary closing mechanism?
The terminal device is open at rest
