Transtibial Prosthetics Flashcards
What are the 4 main components of transtibial prosthetics
- Socket and interface (socks, liners)
- Suspension mechanism
- Shank or pylon
- Foot
What does the socket do
Contacts and dispenses pressure around the patient’s residual limb, supports residual limb during weight bearing, transmits forces from the limb to control placement of foot
What are the 3 socket types for transtibial amputations
- Patellar tendon bearing
- Total surface bearing used with soft liner
- Flexible socket/rigid frame
Where are the weight bearing surfaces of the PTB socket
Patella tendon and counter force from popliteal fossa
What is the most effective residual limb shape
Conical
What is a conical shaped limb
Circumference of distal aspect of limb is smaller than proximal limb
What is a cylindrical shaped limb
Circumference of the limb is the same at all points
What is a bulbous shaped limb
Circumference of distal aspect of limb is larger than proximal aspect
True or False:
With a longer residual limb you can make a smaller socket and prosthesis
True`
What are the pressure tolerant areas around the knee with a transtibial amputation (6)
- Medial tibial flare
- Fibular shaft
- Patellar tendon
- Posterior compartment
- Femoral condyles
- Anterior compartment
What are the pressure intolerant areas around the knee with a transtibial amputation (4)
- Fibular head
- Tibial crest
- Hamstring tendons
- Distal tibia
How long does a patient with an amputation need to be in compression
23 hours of the day
True or False:
Total surface bearing sockets distribute weight more evenly throughout the limb with assistance of the liner
True
True or False:
Total surface bearing sockets are primarily used with pin/shuttle suspension
True
What happens if you have someone with a large fibular head or tibial crest
You can cut out a hole for those areas and put in a soft liner to help provide contact
What are the 2 goals of prosthetic socks
- Cushion forces applied to residual limb
2. Accommodate for the change in volume of residual limb
Socks are made of what typically
Wool or cotton
What are the types of ply layers you can have with a sock
1, 3, or 5
Where does the heaviest ply go
Closest to the skin
What is the baseline ply for all amputation patients
3 ply
What happens when you get 10-15 plys
You need a new socket
When would you use a half sock
When you need to increase the ply of the distal limb if an extra ply is needed but can’t wear prosthesis with a full 1 ply sock so get rid of proximal half of sock
What is worn directly against the skin
Sheaths
What do sheathes do
Wick moisture, decrease shear, and improve hygiene
Why do you need to change the socket when you get to 10-15 ply worth of socks
Due to increased temperature and shearing of prosthetic
True or False:
With a hard socket there is no additional liner (soft insert) worn
True
When is a hard socket interface indicated (3)
- Limbs with intact sensation
- Good soft tissue coverage
- No sharp bony prominences
What is the advantage to a hard socket (3)
- Less bulky
- Easy to clean
- Durable
What are the disadvantages to a hard socket (3)
- Prosthetic labor
- More difficult to fit and modify
- Less comfortable
What are soft liners indicated for
Patients with fragile skin, bony prominences, or high level of activity
What do soft liners do
Provide additional protection, padding, and they are easily adjustable
What are soft liners commonly made of (6)
- Pelite
- Nickelplast
- PPT
- Silicone gel
- Plastazote
- Leather
What is the order of putting things on with a prosthetic (4)
- Sheath
- Socks
- Liner
- Prosthetic
What do suspension mechanisms do (3)
- Hold prosthesis firmly to the limb during gait
- Allow patient to sit comfortably
- Minimize movement pistoning/torque between socket and limb
What is choice of suspension mechanism influenced by (5)
- Patient present and predicted activities
- Goals
- Physical abilities
- Climate
- Distance to prosthetist
What are the 7 types of suspension systems
- Supracondylar cuff
- Supracondylar system (PTB SC)
- Supracondylar/suprapatellar system (PTBSC/SP)
- Thigh corset
- Waist belt
- Sleeve
- Pin/shuttle
How does the supracondylar system (PTB SC) work
Wedge suspension captures femoral condyles as they taper into shaft of femur
When is a supracondylar system (PTB SC) indicated (2)
- Short residual limb
2. Provide M-L stability to knee
How does the supracondylar suprapatellar (PTBSC-SP) suspension system work
Encapsulates the patella and quadriceps and leaves knee in slight flexion and an anterior wall is added
When is a supracondylar suprapatellar (PTBSC-SP) suspension system indicated (3)
- Short residual limb
- Instability A-P and M-L
- Ligamentous difficulty
True or False: Supracondylar suprapatellar (PTBSC-SP) suspension systems make it difficult to kneel
True
True or False:
Thigh corset and knee joint cause serious atrophy of the thigh
True
What is a sleeve suspension made of
Neoprene, urethane, or latex
How is the sleeve suspension positioned
Around the shank and rolled over thigh
What is the advantage of sleeve suspension (4)
- Cosmetic
- Airtight
- Showering
- Unrestricted knee motion
What is the disadvantage of sleeve suspension (3)
- Not durable
- Hygiene
- Need good hand function to don/doff
What is a shuttle/pin design often used with
Total surface bearing (TSB) socket
What is the advantage of shuttle/pin design (2)
- Unrestricted knee flexion
2. Minimal pistoning
When is a shuttle/pin design suspension system indicated
Scarred or sensitive limb
What is the disadvantage of shuttle/ pin design suspension system (3)
- Expensive
- Not durable
- Need good hand function
When is a suspension design indicated (2)
- Cannot tolerate thigh lacer
2. Present with extremely short residual limb
How much of a difference can be present for a suspension design to be used
Less than 2 inches from knee center to distal residual limb
What is the shank/pylon of an endoskeletal design
Modular and central tube transmits weight from socket to foot
What is the shank/pylon of an exoskeletal design
Outer wall transmits weight from socket to foot and like a crustacean
What are the 3 types of prosthetic alignment
- Bench
- Static
- Dynamic
What is bench prosthetic alignment
Done at office how things are lined up nice and vertical
What is static prosthetic alignment
Put prosthetic on patient and stand them up in parallel bars and visually inspect for verticality
What is dynamic prosthetic alignment
Patient walks with prosthesis and you fine tune the prosthesis
True or False:
Slight knee flexion of the prosthesis provides nice distribution of pressure
True
True or False:
You can angulate the socket to keep the foot flat on the floor
True
Why is the foot set in
So we land on our heel and roll lateral to medial and have quality push off
What happens if the prosthesis rotates medially
You will have contact with the fibular head
What does DF of the prosthetic foot cause
Knee flexion
What does PF of the prosthetic foot cause
Hyperextension
What happens at the knee if the heel is too firm
You get into knee flexion
What happens at the knee if the heel is too soft
You get hyperextension at the knee
True or False:
When the prosthesis gets taken off the patient it is good to see pinkness on the skin but not good to see redness on the skin
True
What is the lipstick test
Put lipstick on a sore spot and the lipstick will rub off on prosthesis and you will be able to put pads around the area to relieve pressure
What is the powder test ball and clay test
Take play doh and drop a dime sized ball in prosthesis and have patient walk and if play doh is still a ball then some sock layers need to come off, if too flat add socks, if nicely flattened keep sock layers
