Ch 6 - Prosthetics and Orthotics: Amputation and Upper Limb Prosthetics Flashcards
What are the main causes of amputation?
Dysvascular disease (DM and PAD)
Trauma
Cancer
Congenital
What is age is the greatest risk for limb loss?
> 65 yo
What is the mortality rate of individuals with amputation due to vascular disease?
1/2 die w/in 5 years of amputation
Describe the relationship of Diabetes and amputation.
Contributes to 2/3 of amputations
55% of Diabetic patients with LE amputation will have amputation of 2nd leg in 2-3 yrs
What is the leading cause of upper extremity amputations?
80% trauma
Majority digital amp
UE amp account for 2/3 of trauma related amp
What are the standard levels of upper-limb amputation?
- Transphalangeal (DIP, PIP, MCP)
- Transmetacarpal
- Transcarpal
- Wrist-disarticulation
- Transradial (below elbow)
- Elbow disarticulation
- Transhumeral (above-elbow) >6.5 cm proximal to the elbow joint
- Shoulder disarticulation
- Forequarter amputation
What is a Mangled hand?
Irreparable damage occurs to 4 of 6 basic parts
skin, vessels, skeleton, nerves, extensor, and flexor tendons
Describe a wrist disarticulation.
Spares the distal radial ulnar articulation and thus preserves full forearm supination and pronation
What is the most common upper-limb amputation level?
Transradial amputation
Describe the residual limb lengths in transradial amputation.
- Very short: Residual limb length <35%
- Short: Residual limb length of 35% to 55%
- Long: Residual limb length of 55% to 90%
Describe the preserved supination/pronation in transradial amputation.
Short: 60°
Long: 60° to 120°
What is the ideal transradial amputation level for body-powered prosthesis.
Long forearm residual limb of 60-70%
What are the pros of elbow disarticulation?
- Red surgery time and blood loss
- Improved prosthetic self-suspension
- Red rotation of the socket on the residual limb
- Greater lifting, pulling, and pushing power compared to above-elbow amputation
- No risk of HO formation
What are the cons of elbow disarticulation?
- Cosmetic d/t external elbow mech
* Limits use of externally powered mechanisms
Describe the residual limb lengths of transhumeral amputation.
- Humeral neck: <30%.
- Short transhumeral: 30%-50%.
- Standard transhumeral: 50%-90%.
What transhumeral ampuation length will give best control and function of prosthesis?
90% of humeral length
When are shoulder disarticulations or forequarter amputations typically seen?
Surgical removal of malignant lesion
What are characteristics of passive terminal devices?
– Lighter
– Have no functional mechanisms and provide no grasp
What are types of passive terminal devices (upper extremity)?
a. Passive hand: cosmetic use
b. Flexible passive terminal devices: can fit into a glove or mitt for sports and other activities
c. Specialty terminal devices with adapters for sports equipment, hand tools, or kitchen utensils
Describe the grip of a prosthetic hand.
3-jaw chuck pinch (grip w/ thumb, index, and middle fingers)
Describe the grip of a hook.
Lateral or tip pinch (lateral or key grip w/ pulp of the thumb w/ lateral aspect of finger)
What amount of force is added with each rubber band or spring on terminal devices?
Each rubber band provides about 1 pound of pinch force
What is the most common and practical body-powered terminal device?
Voluntary-opening
How are Externally powered terminal devices controlled?
Switches or myoelectric signals
What are prosthetic wrist units used for?
Attaching terminal devices to prostheses
Provide Pronation and supination
What does a wrist flexion unit allow terminal devices to do?
Be in flexed position, facilitating ability to perform activities close to the body
When are electric wrist rotators considered?
Bilateral UE amputee
Describe a friction wrist.
Permit pronation and supination of the terminal device and hold it in a selected position by means of friction
Describe a locking wrist.
Permit manual rotation
Lock terminal device in fixed position
Describe a split socket for transhumeral amputation.
Total-contact segment encasing the residual limb and connected by hinges to a separate forearm shell which wrist unit and the terminal device are
attached
When would a split socket for transhumeral amputation be used?
Patients who have very short residual limbs
Describe a Meunster socket.
Socket and forearm are set in flexion and the socket encloses the olecranon and epicondyle of the humerus
What is the most commonly used harness?
Figure-8 (O-ring) harness
Describe a Figure-8 (O-ring) harness.
–Axilla loop, on sound side, acts as a reaction point for the transmission of body force to the terminal device
–Anterior suspension strap on involved side gives support for pulling or
lifting, and attachment for the elbow loading strap
Describe a Figure-9 harness.
Used with self-suspended transradial socket that requires a harness only for controlling the terminal device or for long residual limbs with suction sockets
Describe a Chest-strap with shoulder saddle.
Used if the patient cannot tolerate the axilla loop or doing heavy lifting
What is a single-control cable system (Bowden cable system) used in?
Transradial single-control cable system
What is a single-control cable system (Bowden cable system) consist of?
One cable to transmit body power for a single purpose—to operate the terminal device
What are the muscle movements to operate the terminal device of a single-control cable system (Bowden cable system)?
Forward humeral flexion and biscapular abduction.
What is a dual-control cable system (split cable or fair lead cable system) used in?
Transhumeral control-cable system
Very short transradial split-socket prosthesis with locking hinge
What are the functions of a dual-control cable system (split cable or fair lead cable system)?
Flex the elbow unit when the elbow is unlocked
Operate the terminal device when the elbow is locked
What does an elbow disarticulation prosthesis provide?
Self-suspension
Allows for IR and ER of the humerus
When are External (outside) locking elbows used?
Elbow-disarticulations when residual limb extends more distally than 4 cm to the level of the epicondyles to maintain the elbow joint center equal to that in the nonamputated side
When are internal locking elbows used?
Transhumeral and shoulder prostheses
Amputation 4 cm or more proximal to the level of the epicondyles
Why are internal locking elbows preferred?
Greater mechanical durability
Cosmetically more appealing
Which harness design is most frequently used for transhumeral prostheses?
Modifications of the basic figure-8 and chest-strap patterns used with transradial prostheses
How is an elbow flexed from an unlocked and extended position in transhumeral prosthesis?
Flexing the shoulder (humeral flexion; assisted by biscapular abduction) transmits force to the forearm lever loop flexing the elbow to the desired level
How is an elbow locked/unlocked in transhumeral prosthesis?
Shoulder depression, extension, and abduction—“down, back, out”
How is the terminal device operated in transhumeral prosthesis?
Shoulder flexion and biscapular abduction
How is an elbow extended in transhumeral prosthesis?
Elbow is unlocked and the elbow extends by gravity
How are myoelectric terminal devices opened in below-elbow amputees?
Wrist extensors (extensor carpi radialis longus/brevis and extensor carpi ulnaris)
How are myoelectric terminal devices closed in below-elbow amputees?
Wrist flexors (flexor carpi radialis and flexor carpi ulnaris)
How are myoelectric terminal devices opened and elbows flexed in above-elbow amputees?
Biceps muscle
How are myoelectric terminal devices closed and elbows extended in above-elbow amputees?
Triceps muscle
How are myoelectric terminal devices and elbows controlled in transhumeral or shoulder amputees?
Shoulder girdle muscles
What are advantages of Body-powered devices?
Less expensive Lighter More durable Easier to repair Higher sensory feedback
What are disadvantages of Body-powered devices?
Mechanical appearance
Difficult to use for some people
Dependent on motor strength
What are advantages of Myoelectric devices?
Better cosmesis
Less harnessing
Stronger grasp force
What are disadvantages of Myoelectric devices?
More expensive
Heavier
Decreased durability due to electronic components and the need for daily recharging of batteries.
