Week 9 Lower Extremity Prosthetics Flashcards
What is a socket?
where the residual limb inserts
What is a Pylon?
area below the socket
What is the most common cause for LE amputation?
Dysvacular (PVD, DM2)
True/False of persons with diabetes who have lower extremity amputation up to 55% will require amputation of the second leg within 2-3 years.
true
True/false nearly 50% of the individuals who have an amputation due to vascular disease will die within 5 years
true
Should prosthesis be viewed as a tool/ assistive device
yes
What is a K level and how many are there?
individual with an amputation functional level
4 levels to describe function
does not have the ability or potential to ambulate or transfer with or without assistance and the prosthesis does not enhance their quality of life or mobility
Level 0
Has the ability or potential to use prosthesis for transfers or ambulation on level surfaces at fixed cadence. Typical of the limited and unlimited household ambulator
Level 1
Has the ability or potential for ambulation with the ability to traverse low level environmental barriers such as curbs, stairs or uneven surfaces. Typical of the limited community ambulator
Level 2
Has the ability or potential for ambulation with variable cadence. typical of the community ambulator who has the ability to transverse most environmental barriers and may have vocational, therapeutic or exercise activity that demands prosthetic utilization beyond simple locomotion
level 3
Has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, energy levels. Typical of the prosthetic demands of the child active adult or athlete
level 4
What are some immediate post op concerns?
healing
compression/limb shaping
contraction prevention
prevent scar adhesion
preserve or regain strength and stamina
What doe a rigid removable dressing do?
contracture prevention
fall prevention
what does a shrinker do? and when do you fit a patient with one
6 weeks post op
control edema
phantom pain/sensation management
compression/limb shaping
What are the 4 LE prostheses levels
hip disarticulation
transfemoral
transtibial
trans metatarsal
Gel liner rolled onto residuum
connecting pin at distal end of liner
locking mechanism incorporated into socket
Pin locking liner
What level is most common for a pin locking liner
Transtibial
Advantages
Disadvantages to a pin locking liner
advantage: simple easy to maintain
suspension is seen, felt and heard by patient
ease of donning and doffing
liner protects skin from shear and pressure
Disadvantage: pistoning can occur
distal pulling
gel liner rolled onto residuum
lanyard connected at distal end of liner
lanyard exit port and velcro anchor incorporated into socket
lanyard
what is the common level for a lanyard
transfemoral
What are advantages/disadvantaged to a lanyard
advantages: easy to maintain
suspension is seen and felt by the patient
ease of don doff
patient can forcefully pull limb into the socket
liner protects skin from shear and pressure
helps reduce rotation
disadvantage: pistoling can occur
distal pulling
gel liner rolled onto residuum
knee sleeve extends from socket to thigh section
sleeve suspension
what level is the sleeve suspension used at
only transtibial
what are some advantages/disadvantages of sleeve suspension
advantages: simple, easy to maintain
ease of donning and doffing
liner protects skin from shear and pressure
reduce rotation
disadvantage: multiple layers of material restricts the knee
pistoning can occur
gel liner rolled onto residuum
sealing gaskets on external surface of liner create an airtight seal agains the interior socket wall
one way expulsion valve in socket wall
sealing liner
What level is the sealing liner used?
both transtibial and transfemoral
what are the advantages/disadvantages to the sealing liner
advantages: liner protects skin from shear and pressure
reduce rotation
reduce pistoning
disadvantage: difficult to don doff
difficult to manage volume fluctuations
patients uses a donning sleeve or pull sock to pull the residual limb soft tissue into the socket
one way expulsion valve in socket wall
skin fit suction
what are the advantages/disadvantages to the skin fit suction
advantages: reduced rotation
reduced pistoning
disadvantages: difficult to don and doff
difficult to manage
volume fluctuations
difficult fitting process
What level are suction fit used at
transfemoral only
liner is rolled onto the residuum
pump mechanism actively evacuates air from the socket
maintaining a vacuum environment within the socket
knee sleeve extends from socket to thigh creating an airtight seal
elevated vacuum
what are the advantages/disadvantages to elevated vacuum
advantages: most solid and secure option
solidification of soft tissues
eliminates rotation and pistoning
encourages circulation in limb
reduces or eliminates volume fluctuations
disadvantages: very difficult to don and doff
multiple layers of material restricts knee flexion
more maintenance is required
what level is a elevated suction used for
transfemoral and transtibial
Typical for a K1 who is very limited or only transfering
locking mechanism engages manually or automatically upon full extension
user must manually disengage lock to sit
manual lock knees
advantages/disadvantages to a manual lock knee
advantages: lightweight
low cost
certainty and security of locking mechanism
disadvantage: no transition from stance phase to swing phase
necessitates gait deviations to ambulate
Typical for k1-k2 patients
braking mechanism engages automatically under load
brake disengages automatically when unloaded
stance brake knees
Advantages/ disadvantages to stance brake knees
A: light to moderate weight
certainty and security of stance brake
braking mechanism is typically adjustable
less effort needed for patient to control knee in stance
disadvantage: necessitates slight gait deviation to ambulate
available for k2-k4 patients
constructed of a series of linkages
design brings the center of rotation proximal and posterior= stability
polycentric knees
Advantages/disadvantages to polycentric knees
advantages: inherent stability
smooth transition from stance to swing
imitates normal knee- better clearance in swing
stance flexion is possible
disadvantages: patient must control knee in stance- glute activation
available for k3 - k4 patients
can be single axis or polycentric
hydraulic unit provides resistance in stance phase/swing phase
Hydraulic knees
advantages/disadvantages hydraulic knees
A: good stance phase stability
variation of resistance in stance and swing possible
very smooth gait
stance flexion is possible
D: heavy
increased maintenance
available for k3-k4 patients
haydraulic unit provides resistance in stance and swing
hydraulic unit valves are controlled by an onboard programmable processor
microprocessor hydraulic knees
advantages/disadvantages for microprocessor hydraulic knees
a: same as hydraulic knees
less energy and concentration required by patient
d: same as hydraulic knees
increased maintenance
has to be changed
risk of water damage
typically for k1-k2 patients
rigid wood or plastic core. foam or rubber exterior
various durometer materials in heel simulate eccentric plantar flexion
solid cushion ankle
advantage/disadvantage to solid ankle cushion heel
A: light weight low maintenance
low cost
D: unresponsive poor compliance
Typical for k2-k3 patients
composite or carbon fiber keel
compressible heel
simulated foot articulation, plantarflexion and dorsi
various flexibility categories corresponding to patient weight and activity
flexible keel
advantages/disadvantages to flexible keel
a: light weight
low maintenance
low cost
smoother gait
some are multiaxial
disadvantages: minimal energy return
typical for k3- k4 patients
series of composite or carbon fiber keels/blades/struts
simulated foot articulation, plantarflexion and dorsiflexion
various flexibility categories corresponding to patients weight and activity
dynamic response
advantages/disadvantages to dynamic response
advantages: very smooth gait
mulitaxial
energy stored and returned
minor torque and shock absorption
disadvantage: increased weight high cost
typically for k3- k4+ patients
series of composite or carbon fiber keels/blades/struts
keels designed to flex under high impact
simulated foot articulation, PF, DF
various flexiability categories corresponding to patient weight and activity
vertical shock
advantages/disadvantages to vertical shock
advantages: max energy return
max torque and shock absorption
max compliance
d: max cost
true/false every human is in constant sate of volume fluctuations
true
true/false socks are used to manage fluid fluctuations during the day
true
failure to address volume changes can lead to what
skin breakdown
pressure on bony prominences
height discrepancy
instability
socket rotation
loss of suspension
gait deviation: excessive flexion moment at the knee
prosthetic cause: heel to firm
foot too dorsiflexed
patient: knee flexion contracture
weak knee extensors
gait deviation: excessive extension moment at the knee
prosthetic cause: heel to soft
foot too plantarflexed
gait deviation: uneven step length uneven timing
pain (socket)
pain (OA)
poor balance
fear
gait deviation: lateral trunk bend
prosthetic cause:
lack of lateral femoral support
prosthesis too short
Patient:
weak abductors
gait deviation: abducted gait
prosthetic cause:
prosthesis too long
pressure on socket
Patient: abduction contracture
fear, habit
gait deviation: circumduction or vaulting
prosthesis:
too long
knee flexion resistance too high
patient:
abduction contracture
fear of toe clearance
habit
Gait deviation: knee instability
prosthesis: knee too far anterior
heel too firm
Patient cause:
weak hip extensors
Gait deviation: lumbar lordosis
prostheis:
insufficient socket flexion
patient cause:
hip flexion contracture
weak hip extensors
gait deviation: uneven timing
prosthesis: pain
knee flexion resistance too low
patient cause: muscle weakness
poor balance fear
