lower extremity prosthetics Flashcards
1
Q
lower extremity amputation by cause - percentages
A
- 66% dysvascular (PVD, DM2)
- 26% trauma
- 5% tumor
- 3% congenital
2
Q
LE levels of amputation - percentages
A
- 75% transtibial
- 19% transfemoral
- 3% partial foot
- 3% other various levels
3
Q
increased energy expenditure with amputation - percentages
A
- transtibial amputees from 9% to 20%
- transfemoral amputees from 45% to 70%
- bilateral transtibial 41%
- bilateral transfemoral amputees up to 200%
4
Q
considerations for amputees
A
- 55% of those with diabetes who have a LE amputation will require amputation of the second leg within 2-3 years
- 50% of individuals with amputation due to vascular disease will die within 5 years
- most successful when prosthesis is viewed as a tool or assistive device
- functional difficulty directly proportional to amputation level
5
Q
K-levels
A
- 0: does not have ability or potential to ambulate or transfer with or without assistance, prosthesis does not enhance QoL
- 1: ability or potential to use prosthesis for transfers/ambulation, typical of limited and unlimited household ambulator
- 2: ability or potential for ambulation with ability to traverse low level environmental barriers (curbs, stairs, uneven surfaces), typical of limited community ambulator
- 3: ability or potential for ambulation with variable cadence, typical of community ambulator who can traverse most enrivonmental barriers, may have demands for prosthetic utilization beyond simple locomotion
- 4: ability or potential for prosthetic ambulation that exceeds basic ambulation; typical of prosthetic demands of child, active adult, or athlete
6
Q
post-operative care
A
- immediate post operative concerns: healing, compression/limb shaping, contracture prevention, prevent scar adhesion, preserve or regain strength and stamina
- rigid removable dressing: contracture prevention, fall protection
- shrinker: control edema, phantom pain/sensation management, compression/limb shaping
7
Q
lower extremity prostheses by amputation level
A
- hip disarticulation
- transfemoral
- transtibial
- trans-metatarsal, partial foot
8
Q
LE prostheses by suspensions
A
- pin-lock liner, lanyward
- suspension sleeve
- suction
- elevated vacuum
9
Q
pin-locking liner
A
- makes noise - good for blind patients
- gel liner rolled onto residuum, connecting pin at distal end of liner
- locking mechanism incorporated into socket
- advantages
- simple, easy to maintain
- suspension is seen, felt, and heard by patient
- ease of donning and doffing
- liner protects skin from shear and pressure
- disadvantages
- pistoning can occur
- distal pulling
most common at TT level
10
Q
lanyard
A
- gel liner rolled onto residuum
- lanyard connected at distal end of liner
- lanyard exit port and velcro anchor incorporated into socket
- advantages
- simple, easy to maintain
- suspension seen and felt by patient
- ease of donning and doffing
- patient can forcefully pull limb into socket
- liner protects skin from shear and pressure
- helps reduce rotation
- disadvantages
- pistoning can occur
- distal pulling
most common at TF level
11
Q
LE sleeve suspension
A
- gel liner rolled onto residuum
- knee sleeve extends from socket to thick section
- advantages
- simple, easy to maintain
- ease of donning and doffing
- liner protects skin from shear and pressure
- reduce rotation
- disadvantages
- multiple layers of material restricts knee
- pistoning can occur
- can be difficult to put on with hands
only used at TT level
12
Q
LE suction (sealing liner)
A
- gel liner rolled onto residuum
- sealing gaskets on external surface of liner create an air-tight seal against the interior socket wall
- one-way expulsion valve in socket wall
- advantages
- liner protects skin from shear and pressure
- reduce rotation
- reduce pistoning
- disadvantages
- difficult to don and doff
- difficult to manage volume fluctuations
used at TT and TF level
13
Q
LE suction (skin fit)
A
- patient uses a donning sleeve or “pull sock” to pull residual limb soft tissue into the socket
- one-way expulsion valve in socket wall
- advantages
- reduced rotation
- reduced pistoning
- disadvantages
- difficult to don and doff
- difficult to manage volume fluctuations
- difficult fitting process
only at TF level
14
Q
LE elevated vacuum
A
- liner is rolled onto residuum
- pump mechanism actively evacuates air from socket
- maintaining a vacuum environment within the socket
- knee sleeve extends from socket to thigh creating an airtight seal
- advantages
- most solid and secure option
- solidifcation 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 required
TT and TF levels
15
Q
LE prostheses by knee units
A
- manual locking
- stance brake
- polycentric
- hydraulic (microprocessor)
focusing on stance phase control
16
Q
manual lock knees
A
- typical for K1 who is limited or only transferring
- locking mechanism engages manually or automatically upon full extension
- user must manually disengage lock to sit
- advantages
- light weight
- low cost
- certainty and security of lock mechanism
- disadvantages
- no transition from stance phase to swing phase
- necessitates gait deviations to ambulate
- swing phase control
- none
- extension assist
- constant friction
17
Q
stance brake knees (weight activated brake)
A
- typical for K1-K2 patients
- braking mechanism engages automatically under load
- brake disengages automatically when unloaded
- advantages
- 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
- disadvantages
- necessitates slight gait deviations to ambulate
- swing phase control
- extension assist
- constant friction
- hydraulic
18
Q
polycentric knees
A
- available for K2-K4 patients
- constructed of a series of linkages
- design brings the center of rotation proximal and posterior = stability
- 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
- swing phase control
- constant friction
- hydraulic
19
Q
hydraulic knees
A
- available for K3-K4 patients
- can be single axis or polycentric
- hydraulic unit provides resistance in stance phase and/or swing phase
- advantages
- good stance phase stability
- variation of resistance in stance and swing are possible
- very smooth gait
- stance flexion is possible (slope and stair decent)
- disadvantages
- heavy
- increased maintenance - leaking
- swing phase control
- hydraulic
- none
20
Q
microprocessor hydraulic knees
A
- available for K3-K4 patients
- hydraulic unit provides resistance in stance phase and/or swing phase
- hydraulic unit valves are controlled by an onboard programmable processor
- advantages
- same as hydraulic knees
- less energy and concentration required by patient
- disadvantages
- same as hydraulic knees
- increased maintenance
- has to be charged
- risk of water damaged
- swing phase control
- hydraulic
21
Q
knee unit considerations
A
- many combinations of features are possible
- 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
22
Q
LE prostheses by feet
A
- SACH
- flexible keel
- dynamic response
- vertical shock
23
Q
SACH
solid ankle cushion heel
A
- typical for K1-K2 patients
- rigid or wood plastic core, foam or rubber exterior
- various durometer materials in heel simulate eccentric plantar flexion
- advantages
- light weight
- low maintenance
- low cost
- disadvantages
- unresponsive
- poor compliance
24
Q
flexible keel
A
- typical for K2-K3 patients
- composite or carbon fiber keel
- compressible heel
- stimulated foot articulation, plantar flexion, and dorsi flexion
- various flexibility categories corresponding to patient weight and activity
- advantages
- light weight
- low maintenance
- low cost
- smoother gait
- some are multi-axial
- disadvantages
- minimal energy return
25
dynamic response foot
* typical for K3-K4 patients
* series of composite or carbon fiber keels/blades/struts
* simulated foot articulation, plantar flexion, and dorsi flexion
* various flexibility categories corresponding to patient weight and activity
* **advantages**
* very smooth gait
* multi-axial
* energy stored and returned
* minor torque and shock absorption
* **disadvantages**
* increased weight
* high cost
26
vertical shock foot
* typical for K3-K4+ patients
* series of composite or carbon fiber keels/blades/struts
* keels designed to flex under high impact
* simulated foot articulation, plantar flexion, and dorsi flexion
* various flexibility categories corresponding to patient weight and activity
* **advantages**
* max energy return
* max torque and shock absorption
* max compliance
* **disadvantages**
* max cost
27
LE prostheses - types of electronics
bionic
biomechatronic
motorized
28
LE bionics
* K3-K4+ patients
* electronic motor powers the knee and/or ankle
* some systems can synchronize knee and ankle motion
* few patients can obtain this technology
* **advantages**
* replace lost muscle function
* **disadvantages**
* max cost
* bulky
* max weight
* charge batteries
29
LE prostheses and all the classifications
30
managing volume fluctuations
* every human is in a constant state of volume fluctuation
* in this patient population: high incidence of DM, PVD, kidney disease - complications can cause residual limb to have significant changes in volume
* ambulation compresses limb causing fluid evacuation
* volume can change drastically in just minutes
* socks are used to manage changes throughout the day
* socket must be built to accommodate range of volume
* failure to address volume changes can lead to many problems: skin breakdown, pressure on bony prominences, height discrepancy, instability, socket rotation, loss of suspension
31
transtibial gait deviations
32
transfemoral gait deviations
* fear or anxiety of falling is often teh single greatest limiting factor at the transfemoral level
