TTA and foot components Flashcards
what does osteomyoplastic TTA allow?
WB on distal end
Name the 5 places that are pressure tolerant
Patella Tendon Gastroc/soleus muscle belly Pretibial muscles/DF muscle belly Popliteal Fossa Shaft of the Fibula
Name the 7 places that are pressure sensitive
Tibial Crest and Tubercle Fibular head and distal end Patella Hamstring tendons Peroneal n.
What would a total surface bearing socket look like
un-rectified socket w/o contours.
You always need to wear these with a liner cause obviously our legs aren’t shaped like this.
Pros of total surface bearing sockets
Decrease pistoning
Lower peak pressure in socket
Decrease need for other suspension
Increase ROM at the knee joint due to low walls
Cons of total surface bearing sockets
Complicated to don
Perspiration in the system
Anticipate volume changes at initial prosthetic limb and this does not accomidate for that, therefore not appropriate for initial prosthetic limb.
Bent knee prosthetic is designed for who
TTA with flexion contracture >50 degrees
Symes socket will have what unique feature
window so the malleoli can get in the socket and then the window can be closed for ease of donning
Explain where the anterior wall of the socket should be
bisect the patella, 1.5 inches from the PTB, should be bearing weight onto their patella.
Explain where the posterior wall of the socket should be?
In line or slightly higher than the PTB when viewed from the back
What happens when the posterior wall is too low?
not enough pressure on the patella bar, you’ll slip off or weight bear too much on the distal end
Medial aspect of the posterior wall is wider and lower due to what?
two hamstring tendons
You also have a popliteal push (this is a safe wt. bearing area) to direct body wt. onto PTB
Where do the medial lateral trim lines generally go for these sockets?
femoral condyles: resist rotations and give stability in this plane. They’re slightly higher than the anterior wall to do this.
Bench alignment starting point should be where?
is this before or after walking?
90 degrees with respect to the ground
BEFORE walking
What should the alignment of the prosthetic always be looked at with?
shoe on the prosthetic foot!
Ankle should be in what position in the sagittal plane on a prosthetic
neutral postition (make sure a shoe is on)
What degree of motion should the socket be in the sagittal plane
5-10 degrees of flexion (which would be putting the quad in a mechanically advantageous position on stretch; flexing the knee a little bit)
This also allows a larger surface area for wt. bearing
Wt. line should be ____ to the ankle attachment and GRF
anterior. This is how our body naturally works. makes it easier to push off but not too far forward.
Alignment of the socket in the frontal plane.
Foot should be ____ to the _____ from the ______. This creates a ______ force
foot should be MEDIAL to the MIDPOINT of the SOCKET.
This creates a varus force at the knee during gait.
Knee flexion contractures must be what in the socket?
accommodated!
According to Chris (so who knows) what is the most critical part of the prosthesis?
the suspension. Because poor suspension leads to pistoning.
Three evils of prosthetics
bacteria
peak pressure
shear forces
All are equally problematic
What is the goal of suspension?
to control shear forces within the socket
What are the three kinds of anatomical suspension?
shape of the socket, belt straps, thigh corset
thigh corset _____ and _____
unloads 30-40% and SUSPENDS
This is good for someone with a really short residual limb, unstable knee or fragile skin
What are the three major categories of suspensions?
anatomic, suction, vacuume suspension
4 major steps to don 3S?
fully deflect the liner
Distal end cups the distal limb (make sure there are no air pockets)
Roll the liner up the leg
Make sure the pin is straight to properly engage the shuttle mechanism
4 major steps to don suction liner
fully deflect liner
Distal end on distal end
Roll up the liner
instead of pin (like 3S pt will step down into the socket to force the air up and then roll u the outer sleeve to complete the seal
how do you discuss sock management
ply NOT the number of socks
If the top wall of the socket is on the distal end of the patella do you have too little or too few ply on?
too few. its slipping too high
Could also see pain in distal tibia when WB, abnormal thrusting or pistoning during swing
if the top wall of the socket is on the shin bone do you have too little or too much ply
too much ply
Could also see no distal end contact
What are other ways (other than where the anterior wall of the socket is) to tell if the ply is correct
iliac crests
patient report of where the most pressure is, the most should be at the patella tendon
What is the largest risk factor related to skin care
change in residual volume: shear or compressive forces
What is the biggest thing to not tell someone about sock managment
it has nothing to do with feet being cold
Gel liners
2 pros
1 con
decrease peak pressures, and friction reduction
Increased infections
Generally do you want the limb moist or dry
dryyyyyyy
daily care for liners
weekly?
mild soap and water, rinse and dry well
weekly alcohol
Warranty on liners?
25 month/pair
If you have two liners how to do wear them?
alternate every other day to increase the life of the liner
pylon connects what to what
socket to foot
what is the keel
central portion/main structure of prosthetic foot
Limited ambulators would use what kind of prosthetic foot?
SACH: solid ankle cushioned heel
These have no jt. movement, just the pin going into it. increase in energy to use
posterior bumper designed to take body weight and provide shock absorption but does this minimally
Single axis allows what motion? How much
PF 15 degrees (generally we need 20)
DF 5-7 (generally we need 10)
Posterior bumper in single axis controls what motion?
PF
Anterior bumper in single axis controls what motion/
DF
Why is single axis more commonly seen in TFA.
TTA have quads to be able to control knee during loading and create a bit of shock absorption.
Multiaxial allows what motion?
DF and PF
Inversion and Eversion
What is multiaxial good for that the ones prior to it are not?
uneven terrain: good for higher ambulator someone who wants to walk outside etc.
What is the function of the elastic Keel?
Who is it good for?
smooth rollover therefore it is easier to ambulate.
Good for elderly, light, non aggressive ambulators
There is limited push off. bc they can never get into DF
Function of dynamic response.
dynamic response are energy _____
active push off: as you load the foot it provides some push back
Dynamic response is ENERGY STORING
Who is the dynamic response good for?
a very active individual
Microprocessor feet do what to the terrain you’re walking on
actively adjust to it
But they’re heavy, need maintenance
What are hybrid limbs good for?
excellent performance on multip surfaces
But they’re heavy so not great for runners
Energy return of SACH?
39% the best are the dynamic responses and those only go up to 89%. Our human foot gives an energy return of 246%
How does the bionic foot function?
two motors and springs
Allows for smooth inclines and declines, user is able to change speeds quickly
Define “K”
medicare classification of patients POTENTIAL function
Define K0
no potential for transfers or ambulation
Define K1
potential household ambulator, including transfers
Define K2
potential limited community ambulator. Think of a grandparent
Define K3
Community ambulator that can VARY THEIR CADENCE.This is like every single one of us jogging or being active etc
Define K4
EXCEEDS normal ambulation skills, this is sport specific (flipper, olymp[ic runner etc, insurance s not covering this)
who pays for components?
CMS: centers for medicare and medicaid services
What did CMS fail to do?
implement standardized and objective process to determine potential functional level (K) but the defined the K levels
Name what kind of prosthetic would be used for which K
K0 K1 K2 K3 K4
K0 = none K1 = SACH K2: flexible keel (easy to anterior shift for low energy cost) and multi axis K3: energy storing feet K4: all feet/specialized level
what is the 3 point scoring for the Amp Pro and Amp NoPro?
Strong correlation with what?
0: inability to perform
1: minimal level of achievement or assistance
2: task completed independently
Strong correlation with 6MWT
AMPPRO scores are higher or lower than AMP noPRO scores for the same K levl?
Higher, they have an advantage bc they’re using prosthetic.
inverted pendulum model is important for what?
preservation of the intact limb
