LE PROSTHETICS Flashcards
Alignment
looking at whole relationship between all componentry, socket, patient anatomy to get most optimal gait possible
Pylon
Pylon is a rigid, usually tubular structure between the socket (or knee unit) and the foot that provides a weight bearing shock-absorbing support shaft for the prosthesis.
K-level
Determines what insurance will pay for an individual that needs a prosthesis –> where we think they will get with proper rehabilitation
score assigned when evaluating a patient
“functional level”
socket
“inferface”
what residual limb fits into
What is the most common reason for LE amputation?
dysvascular 65% followed by trauma 26%
The most common levels of LE amputation
75% transtibial
19% transfemoral
3%/3% either partial foot or other various levels
-more energy expenditure is required the higher up the amputation is
-200% increase in energy expenditure during gait with bilateral transfemoral amputee
K level 0
The patient does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance their quality of life or mobility.
K level 1
The patient has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence. This is typical of a household ambulator or a person who only walks about in their own home.
K level 2
The patient has the ability or potential for ambulation with the ability to traverse low-level environmental barriers such as curbs, stairs or uneven surfaces. This is typical of the limited community ambulator.
K level 3
The patient has the ability or potential for ambulation with variable cadence. A person at level 3 is typically a community ambulator who also has the ability to traverse most environmental barriers and may have vocational, therapeutic or exercise activity that demands prosthetic use beyond simple locomotion.
K level 4
The patient has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress or energy levels. This is typical of the prosthetic demands of the child, active adult or athlete.
-child, active adult, athlete
Post-operative care following amputation
IMMEDIATE
-healing
-compression/limb shaping
-contracture prevention
-prevent scar adhesion
-preserve or regain strength and stamina
-rigid removable dressing for contracture prevention and fall protection
SHRINKER (as long as the incision looks good)
-control edema
-phantom pain/sensation management
-compression and limb shaping
Immediate post-op prosthesis
-“rrd” - removable rigid dressing
-to be worn immediately after surgery
-allow for swelling to go down
-learn to bear weight early on
Amputation level LE prostheses
hip disarticulation
transfemoral
transtibial
transmetatarsal/partial foot
Types of partial foot prostheses
-transmetatarsal (may lose digit)
-partial foot amputation
Types of suspensions for LE prosthesis
pin lock liner or lanyard
suspension sleeve
suction
elevated vacuum
Pin lock liner suspension facts
-gel liner rolled on the residual limb
-connecting pin at distal end of liner–> connects to socket
-locking mech. incorporated into socket
PROS
-simple, easy to use
-suspension seen, felt, heard (good for visual impairment)
-ease of don and doff
-liner protects skin from shear and pressure
CONS
-pistoning can occur (person’s residual limb moving up and down within socket)
-distal pulling
LEVEL
-most common at transtibial level
Lanyard type suspension facts
l-gel liner rolled on the residual limb
-lanyard connected at distal end of the liner
-lanyard exit port and velcro anchor in socket
PROS
-simple, easy to maintain
-suspension seen, felt, heard (good for visual impairment)
-ease of don and doff
-pt can forcefully pull limb into socket
-liner protects skin from shear and pressure
-helps reduce rotation of residual limb in socket
CONS
-pistoning can occur
-distal pulling
LEVEL
-most common transfemoral level
Sleeve suspension facts
-gel liner rolled on the residual limb
-knee sleeve extends from socket to thigh section
PROS
-simple, easy to maintain
-ease of don and doff
-liner protects skin from shear and pressure
-helps reduce rotation of residual limb in socket
CONS
-multiple layers of material restricts the knee
-pistoning can occur
LEVEL
-only used at TT level
Suction (sealing liner) suspension facts
-gel liner rolled onto the residual limb
-sealing gaskets on the external surface of the liner create an air-tight seal against the interior socket wall
-one expulsion valve in the socket wall
PROS
-liner protects skin
-reduce rotation
-*reduced pistoning
CONS
-diff to don and doff (due to seal)
-diff to manage volume fluctuations
LEVEL
-used at TF and TT level
Suction (skin fit) suspension facts
-pt uses a donning sleeve or pull sock to put the residual limb soft tissue into socket
-exclusive to above-the-knee amputees
PROS
-reduced rotation
-reduced pistoning
CONS
-diff to don and doff
-diff to manage volume fluctuations
-difficult fitting process
LEVEL
-only TF
Elevated vacuum suspension facts
-liner rolled onto the residuum
-pump mechanism evacuates air from socket–> vacuum environment
-knee sleeve extends from socket to thigh creating airtight seal
PROS:
-most solid and secure
-solidification of soft tissues
-lack of rotation and pistoning
-encourages circulation in the limb
-reduces or eliminates volume fluctuations
CONS:
-VERY difficult to don and doff
-restriction of knee flexion due to multiple material layers (back of knee)
-more maintenance required
LEVEL:
-TT and TF
Types of knee units LE prostheses
manual locking
stance brake
polycentric
hydraulic (microprocessor)
Manual lock knee facts
-typical for K1
-locking mechanism engages manually or automatically upon full extension
-user must manually disengage the lock to sit (only time it will be disengaged)
PROS
-lightweight
-low cost
-certainty and security of lock mechanism
CONS
-no transition from the stance phase to the swing phase
-have to compensate with gait deviations for ambulation
SWING PHASE CONTROL:
-none
-extension assist
-constant friction
Stance brake knees facts
** weight activated brake
-typical for K1-K2
-braking mechanism engages under load and disengages when unloaded
PROS
-light to moderate weight
-security of stance brake
-can adjust braking mechanism
-less effort needed for the patient to control their knee in stance (esp with limited quad strength)
CONS
-slight gait deviations needed to ambulate
SWING PHASE CONTROL
-extension assist
-constant friction–>prevent quick extension during swing
-hydraulics
Polycentric knees facts
-K2-K4
-constructed of a series of linkages
-design brings the center of rotation of the knee proximal and posterior–> more stability
PROS
-inherent stability
-a smooth transition from stance to swing
-imitates normal knee –> better swing clearance
-stance flexion is possible
CONS
-must control knee in stance - glute activation
SWING PHASE CONTROL
-constant friction
-hydraulic
Hydraulic knees facts
-K3-K4
-single axis or polycentric
-provides resistance in the stance phase and/or swing phase
-built to match other knee with timing of critical events of gait
-want to try to get knee centers to match on amputated vs non-amputated leg
PROS:
-good stance phase stability
-can vary resistance in stance and swing
-smooth gait
-stance flexion possible
CONS
-heavy
-increased maintenance-leaking
SWING PHASE CONTROL
-hydraulic or none
Microprocessor hydraulic knee facts
-K3-K4 patients
-hydraulic unit valves are controlled by an onboard programmable processor
-microprocessor senses direction, monitors gait force at each phase of gait
-microprocessor calculates data to adjust fluid within knee
PROS
-less energy and concentration required by patient
-less buckling because this knee knows where it is in space
CONS
-increased maintenance
-leaking possible
-has to be charged
-risk of water damage
-heavy
SWING PHASE CONTROL
-hydraulic or none
Knee unit considerations
-Before beginning gait training understand how the knee is controlled in swing and stance
-patients with long residual limbs may have uneven knee centers
-more features–> more weight, more complicated gait training, more maintenance
Types of feet prostheses
SACH- solid ankle cushion heel
Flexible Keel
Dynamic Response
Vertical Shock
SACH facts
-“solid ankle cushion heel”
-K1-2
-rigid wood or plastic core
-foam or rubber exterior
-durometer materials in heel stimulate eccentric PF
PROS
-light weight
-low maintenance
-low cost
CONS
-unresponsive
-poor compliance
Flexible Keel facts
-K2-3
-composite or carbon fiber keel
-compressible heel
-simulated foot articulation, PF and DF
-flexibility level corresponds to patient weight and activity
PROS
-light weight
-low maintenance
-low cost
-smoother gait
-some are multi-axial
CONS
-minimal energy return
Dynamic response foot facts
-K3-K4 patients
-series of composite or carbon fiber keels/blades/struts
-simulated foot articulation, PF and DF
-flexibility level corresponds to patient weight and activity
PROS
-very smooth gait
-multi-axial - allows 15-20 deg rotation
-energy stored and returned
-minor torque and shock absorption
CONS
-increased weight
-high cost
Vertical shock foot facts
-K3-K4+ patients
-series of composite or carbon fiber keels/blades/struts
**keels designed to flex under high impact
-simulated foot articulation, PF and DF
-flexibility level corresponds to patient weight and activity
-ex: running and sprinting
PROS
-max energy return
-max torque and shock absorption
-max compliance
CONS
-max cost
Bionic prostheses
-K3-K4+ patients
-electronic motors power the knee and/or ankle
-some systems can synchronize knee and ankle motion
-few patients can obtain this technology
-can to fit knees and feet that operate and communicate together
**very difficult to justify to insurance **
PROS
-replaces lost muscle function
CONS
-max cost
-bulky
-max weight
-have to charge
How to manage volume fluctuations
-socks are used to manage volume changes throughout the day
-the socket must be built to accommodate this range of volume
-if don’t address volume changes, can lead to:
-skin breakdown
-pressure on bony prominences
-height discrepancy
-instability
-socket rotation
-loss of suspension
*want to avoid extra pressure on the condyles, fib head, tibia, patella
What is a common prosthetic or patient cause of uneven step length or uneven step timing?
pain caused by socket
pain caused by OA
What is often the single greatest limitation to normalized gait in patients with above-the-knee prostheses?
fear or anxiety of falling
