Transtibial Prosthetics Flashcards
What is the preferred length of the residual limb? Explain why…
6-7 inches
There is sufficient calf musculature but it is not too long as in to limit the use of good prosthetic feet
What are the 3 goals post-op transtibial amputation?
- facilitate healing
- reduce edema
- prevent contractures
What are the 2 most common contractures in transtibial amputees?
hip and knee
What are the 4 types of “dressings” that can be used to reduce edema?
- immediate post-op prosthesis
- removable rigid dressing
- ACE wrap
- BK shrinker
What is a disadvantage to using a IPOP?
They are typically not user friendly
What are 3 common mistakes when using an ACE wrap?
- just wrapping the distal end
- not wrapping at an angle
- do not cover everything that is within the prosthesis
What is 1 advantage and 1 disadvantage to using a shrinker sock?
Patients can usually don/doff this independently
It may be tender to the patient
When should the patient be fitted for their preparatory prosthesis?
Around the 6-8 week mark to allow for wound healing
What are the 3 purposes of the preparatory prosthesis?
- early ambulation
- shape of the residual limb
- cost effective
How long is the preparatory prosthesis typically worn for?
6-8 months
What are the 6 components of the preparatory prosthesis?
- prosthetic socks
- socket suspension
- socket insert/end pad
- socket
- pylon
- foot
What are 2 of the materials a socket can be made out of?
- laminated
- polypropylene
Why is the socket insert/end pad essential in transtibial amputations?
Cushions the numerous bony prominences
What type of prosthetic foot is typically used on the preparatory prosthesis?
SACH foot
What is the advantage on the SACH foot having a cushion heel?
It allows for foot flat without the ankle moving
What indicates the thickness of the prosthetic socks?
1, 2, 3, 4, ply
When donning the prosthetic sock it is essential to avoid what?
wrinkles
What is the main purpose of the prosthetic sock?
It positions the residual limb in the socket
*not used for suspension, comfort, etc.
When is a patient considered “ready” to be fitted for their definitive prosthetic?
When the residual limb has a constant volume
What are the 2 construction design of the definitive prosthetic?
- exoskeletal (not common)
- endoskeletal
What are the 3 advantages to using an exoskeletal prosthetic?
- durable
- lightweight
- cost effective
What are the 3 disadvantages to using an exoskeletal prosthetic?
- cosmesis
- alignment cannot be adjusted
- there is a limited component selection
What are the 3 advantages to using an endoskeletal prosthetic?
- cosmesis
- alignment can be adjusted
- wide variety of component selection
What are the 3 disadvantages to using an endoskeletal prosthetic?
- expensive
- durability
- weight
Although endoskeletal prosthetics are becoming lighter in weight, what is one way in which they are perceived as lighter?
When the weight is placed proximally rather than distally
What are the 4 types of socket designs? What 2 are used the most?
- patella tendon bearing*
- total surface bearing*
- open end
- knee joints and thigh lacers
True or False
Socket length is identical to the residual limb length
True
What is the idea behind the total surface bearing socket?
the more area that is loaded, the less pressure that is felt on any one area/prominence
In what type of patient are knee joints and thigh lacers used in?
Those with poor knee stability and short residual limbs
How do thigh lacers enhance knee stability?
They lengthen the lever arm
What are the 7 types of suspension techniques?
- waist belt
- supracondylar cuff
- supracondylar sleeve
- supracondylar wedge
- suction suspension
- pin suspension
- sub-atmospheric suspension (vacuum)
How does the supracondylar wedge create suspension?
The medial femoral condyle produces a “shelf” for the wedge to sit on
What does the supracondylar wedge suspension system result in?
Atrophy proximal to the knee
What are 2 ways in which the prosthetic socket achieves suction via suction suspension?
- expulsion valve
- suspension sleeve
What is the #1 method of socket suspension?
sleeve suspension with an expulsion valve
When donning a suspension sleeve what is one thing to ensure the patient does?
Ensure the sleeve is pulled up over the socks and is in contact with the skin
What is an advantage to the pin suspension method?
It is quick and easy (say they have to get in and out of bed frequently throughout the night)
What is a disdvantage to the pin suspension method?
The suspension is not very good which creates pistoning and rotation of the residual limb
What type of patients cannot use vacuum suspension methods?
Those who’s body volume changes often (new amputees, diabetics, etc.)
What are the 2 advantages to using vacuum suspension?
- creates a large constant suspension
- eliminates pistoning
What are the 4 types of socket liners and which are the most common?
- gel*
- pelite*
- multidurometer
- hard socket
What are the 5 basic categories of prosthetic feet?
- SACH
- single axis
- multiaxis
- flexible keel
- energy storing
What does SACH stand for?
Solid Ankle Cushion Ankle
Are single axis feet endo- or exoskeletal?
They can be either
A SAFE foot is a commonly used flexible keel foot, what does it stand for?
Stationary Attachment Flexible Keel
What is the brand name of an energy storing foot that looks real in appearance?
Seattle foot
What material are energy storing feet typically made of?
carbon
What are 4 brand names of energy storing feet?
- Flex Walk Foot
- VSP
- Reflex Rotate
- Flex
What is the significance of the split toe on energy storing feet?
It allows for ground manipulation such as rocks
What are 3 disadvantages to the Symes amputation?
- very limited on foot selection
- typically too tender for weightbearing
- cosmetically unppealing
What type of prosthetic is required in a Symes amputee?
One with a posterior opening (window) that allows the bulbous end to fit down into the prosthetic
What is the most common place for a sore to develop on the transtibial amputee?
anterior-distal tibia
What are 7 possible causes of anterior-distal tibia soreness?
- not enough socks
- patient wearing shoes with too high of a heel
- foot placed too posterior
- too much flexion in the socket
- heel is too stiff
- posterior shelf too low
- not enough relief in the socket
What are the 5 stages of prosthesis design?
1) patient evaluation
2) impression technique
3) positive model modification
4) socket fabrication
5) alignment process
What are the 3 purposes of the preparatory prosthesis?
- early ambulation
- shaping of the residual limb
- cost effective
What are the weightbearing surfaces of the PTB socket?
- patellar bar
- medial flare of the tibia
What is the purpose of the posterior shelf in the PTB socket?
Gives room to the hamstrings
Where must the posterior shelf be aligned with and why?
The patella tnedon in order to provide counterforce
What are the 3 biomechanical objectives of the PTB socket?
- maximize the weight bearing surface
- maintain ML stability
- encourage knee flexion throughout stance phase
What are the 6 surfaces of the residual limb that are pressure tolerant?
- patella tendon
- medial tibial flare
- medial tibia
- pre-tibial muscles
- shaft of the fibula
- gastrocnemius
What are the 7 surfaces of the residual limb that are pressure sensitive?
- tibial tubercle
- tibial crest
- anterior-distal tibia
- fibular head
- peroneal nerve
- distal fibula
- hamstrings tendons
What are the 3 alignment stages?
1) bench alignment
2) static alignment
3) dynamic alignment
In transtibial prosthetics the goal is to maintain a _____ moment during stance phase
flexion
How can the knee flexion moment be increased?
By flexing the socket which will cause increased foot dorsiflexion and therefore promote knee flexion
*ski boot example
If the socket is not flexed enough what will occur?
the foot will plantarflex and knee hyperextension will occur
Where is the pressure distributed if there is a flexion moment?
anterior distal and posterior proximal
The more _____ the socket is the more flexion moment there is
posterior
A flexed socket also _____ the surface area of the load
increases
During what phase of gait is there an extension moment?
heel off
Typically how big are prosthetic feet in regards to shoe size?
1/2 size smaller
What things should you look for in regards to the pylon during bench alignment?
it should be vertical
What landmark is used to base the prosthetic measurement?
patellar tendon
In the coronal plane the socket should be vertical and aligned in - degrees of adduction
5-7
Describe what will happen if the foot is inset too far
The socket moves laterally and produces lateral distal and medial proximal pressures
Describe what will happen if the foot is outset too far
The socket moves medially and produces medial distal and lateral proximal pressures
If the patient demonstrates genu valgum the solution is to ____ the foot.
If the patient demonstrates genu varum the solution is to ____ the foot.
inset
outset
The prosthetic should be rotated so that there is how many degrees of toe-out?
5-7 degrees
As toe out increases the lever arm ____.
decreases
