Prosthetics Flashcards
Define prosthesis
An artificial device used to replace a missing body segment
Define prosthetic
(adj) relating to a prosthesis
Define prosthetics
the process of developing prostheses
Define prosthetist
A professional who evaluates, designs, fabricates and fits artificial limbs
What are the most common causes of LE amputation?
neuropathy/vascular disease (80%) > trauma > congenital amputations > tumor
What kinds of disease contribute to LE amputation?
DM, arterial sclerosis, neuropathy, infection
What kinds of infections increase the risk of amputation as we try to control spread?
osteomyelitis, gas/wet gangrene
What kinds of tumor classifications can lead to need for amputation?
Ewings sarcoma (in long bones) Osteosarcoma (usually at distal femur)
What is PFFD?
Proximal Femoral Focal Deficiency
Affected femur is 1/3 the length of the C/L femur
What is the order of amputations in terms of most to least common?
TT > TF > Knee Disarticulation > Ankle Disarticulation > Hip Disarticulation
What are the 2 primary surgical stabilization procedures during amputation?
- Myodesis - attach muscle to periosteum of the bone
2. Myoplasty - attach agonist muscle to antagonist muscle over end of limb
What are advantages of myodesis v. myoplasty?
Myodesis - may have better proprioception
Myoplasty - may heal faster bc of higher vascularization
What are the normal pressure points of the foot?
GT - 2pts
Rays 2-5 - 1pt each
Calcaneus - 6 points
Each foot as 12 points with 8.5%BW in each point)
What are ‘prosthetics” tools to manage a ray amputation?
toe filler to prevent bunion
skin breakdown at great toe
skin breakdown at 5th MTP
What gait changes might we expect following ray amputation?
some loss of propulsion force
What kind of prosthetic is used for trans metatarsal amputation? Why?
spring steel footplate - extends toe lever, helps with propulsion, helps even out step length B/L
What is a Lisfranc amputation?
Disarticulation between metatarsals & cuboid/cuneiforms
What mechanism is maintained with a Lisfranc amputation? What mechanism is reduced?
Maintained - DF mechanism
Lost - toe lever
What is a Chopart’s amputation?
disarticulation @ talonavicular/calcaneocuboid
What are disadvantages of a Chopart’s amputation?
Disrupts attachment of anterior tibias - causes PF contracture
Achilles pulls calcaneus into downward rotation - causes leg lengthening on affected side
What kind of amputation occurs with disarticulation at the talocrural joint?
Ankle disarticulation
What are 4 general considerations wrt TT prosthesis?
- length of the residual limb
- degree of intact proprioception
- inherent control of the limb
- pt activity level
What is our primary concern wrt to mobility with decreased femoral length?
Loss of adductor muscle causes:
- decreased stability
- ABD contracture & Trendelenberg gait
What are advantages of a knee disarticulation amputation & who is most likely to have it?
Advantage - maintains long lever arm, preserves ADDs
Population - pediatrics due to preservation of distal femoral epiphysis
What are elements of the objective exam for prosthetic Rx?
ROM, joint integrity, skin integrity, limb volume/length, sensation, circulation, mobility/transfers, condition of remaining extremity, UE function, vision, cognition
What are general considerations to keep in mind when managing the pt with an amputation?
- increased risk of - edema, pressure injuries, osteoporosis
- increased fatigue due to increased E expenditure
- altered heat regulation - heat accumulation in socket with decreased SA to dissipate means increased perspiration to regulate core temp
- complications - decreased wound healing (if vascular condition), loss of ROM
What are 3 primary goals of acute management sp amputation?
- promote wound healing
- residual limb shaping
- promote bed mobility, transfers
How do we promote early residual limb care?
- wound inspection
- teach difference between pressure & pain
- use shrinker to manage limb volume
- manage scar tissue via cross friction massage
- Use ACE wrap in X pattern
What are the pros and cons of using an ACE wrap to manage limb volume?
Pro - can modify pressure and direct pressure forces
Con - pt can apply incorrectly and cause tourniquet effect, risk of skin damage with use of butterfly clips
What are common contractures aw TT amputation?
knee flexion
hip flexion
What are common contractures aw TF amputation?
hip flexion
hip ABD
What are common gait deviations aw hip flexion contracture?
increased lumbar lordosis
increased knee flexion
decreased step length on trailing limb
What are the “principles of prosthetic prescription”? (SPSPS)
Situational
Patient Specific
Problem Solving
What is Medicare’s definition of “Functional Level?”
Functional Level = a measurement of the capacity or potential of a pt to accomplish post-rehab daily function
Define each functional level according to Medicare
K0 - pt has no ability/potential to ambulate or transfer independently and is not a candidate for fitting
K1 - pt has ability/potential to transfer/ambulate on level surfaces at a fixed speed
K2 - pt has ability/potential to ambulate and traverse low level barriers
K3 - pt has ability/potential to ambulate with variable cadence
K4 - pt has ability/potential to ambulate beyond basic skills
Who is most likely to be a K4?
Children, active adults, athletes
What are the 2 general prosthetic design options?
- exoskeletal
2. endoskeletal
What are pros & cons of exoskeleton design?
pro - durable, cheaper, quick to make
con - heavier, fixed alignment
What are pros & cons of endoskeleton design?
pro - lighter, adjustable
con - at-home alignment
What are the 2 primary structural goals of a prosthesis?
- replace structural support to remaining skeletal structures
- Transfer & dissipate forces into remaining skeletal structures/soft tissues
Where do we try to direct pressure?
Towards pressure tolerant areas
What are pressure tolerant areas wrt TT prosthesis?
patella tendon, femoral condyles, medial/lateral aspect of anterior tibia
What are pressure sensitive areas wrt TT prosthesis?
anterior tibia, hamstring tendons, fibular head
What role does suspension play wrt TT prosthesis?
Suspension - mechanism by which prosthesis stays on the body
What are types of suspension available with TT prosthesis? What are pt requirements for each?
- Pin lock - pt must have dexterity to roll on
- Seal-in liner - pt must have stable limb volume
- Elevated vacuum
What are advantages of an elevated vacuum suspension system?
- helps maintain uniform limb size/shape
2. reduces moisture buildup in socket
What is a “check socket”?
clear prototype of socket for skin inspection & modifications before final prosthesis is made
What is a predatory prosthesis? What are pros and cons?
Prepatory prosthesis - limb which is fit as soon as sutures are healed
Pro - helps reduce edema
Con - may need to be replaced if limb changes volume dramatically
What is a definitive prosthesis? How long does it last?
Prosthesis which is fit once the residual limb size/shap has stabilized.
Lasts 3-5 years.
SACH Foot:
What is it?
Who gets it?
- Solid Ankle Cushion Heel - provides no ankle movement but heel compression mimics PF and acts as 2nd rocker for roll-over
- For lower K levels (1,2)
Single Axis Foot:
What is it?
Who gets it?
- Foot mechanism which allows movement in sagittal plane (DF/PF)
- For lower K levels (2,3)
Multi Axis Foot:
What is it?
Who gets it?
- Foot mechanism which allows movement in frontal, sagittal and transverse planes (PF/DF/Inversion/Eversion/IR/ER)
- For ambulation on uneven terrain to absorb torque and reduce shear on residual limb (Level K2 +)
Energy Storing Foot:
What is it?
Foot mechanism that allows dynamic response due to E absorption during stance and E release during swing
What are 2 optional foot enhancements? What does each do?
- Rotational torque absorber - provides rotational stability for standing twisting movements
- Heel heigh adjustable foot - allows variable heel heights without changing distance from heel to knee center
What is the standard heel height?
3/8” to 3/4”
What are 2 primary causes of foot failure?
- inappropriate alignment
2. wrong shoes
What is the optimal foot progression angle? Why?
7-10˚
Want this range in order to avoid rotational moment (tibial ER) at knee
Describe the best fit of a TF prosthesis to prevent ADD roll
Socket fit over the ischial tuberosity
What are 4 options for suspension of TF prosthesis?
- Silesian belt
- Hip joint, pelvic band & waist belt
- Full suction
- Partial suction
Silesian Belt: Pros? Cons? Indications? Contraindications? Type of prosthesis?
Pro - easy don, adjustable
Con - bulky, poor frontal plane control
Indications - pt who can’t use suction this is used as auxiliary suspension for added rotational control
Contraindications - pt who needs higher frontal plane control
Type - TF prosthesis
Hip joint, pelvic band & waist belt: Pros? Cons? Indications? Contraindications?
Pro - easy don, control during swing, control in frontal plane
Con - heavy, bulky
Indications - pt who needs frontal plane control, needs control during being phase
Contraindications - if we have any better option
Full Suction suspension: Pros? Cons? Indications? Contraindications? Type of prosthesis?
Pro - no postponing, better proprioception due to skin-to-device contact
Con - harder to don
Indications - pt with long limbs, good skin condition, good balance for donning, good UE mobility
Contraindications - pt without stable residual limb volume, with severe scarring, with decreased UE function
Type - TF prosthesis
Partial Suction suspension:
Con?
con - pt must have secondary suspension component (i.e. belt)
What is the TKA line? Where does the knee fall relative to this line? Why is it set up that way?
Trochanter - Knee - Ankle Line
Knee falls 1/4” posterior to weight line to create stable extension moment at the knee during stance
What are pros and cons of a single axis knee?
pro - cheaper, allows control of lower leg through swing phase
con - less stability at heel strike
What are pros and cons of a polycentric knee?
pro - easy to initiate swing phase and provides stability at heel strike
con - requires more maintenance
What are pros and cons of a manual lock knee? Who uses this type of knee?
Pro - prevents knee collapse
Con - pt has to manually unlock it to sit
Who - lower levels K1,2
What is the most popular knee in the US? Who can use this knee?
Stance controlled knee - locks during stance phase
Used for K1,2,3
Which type of knee might be best for higher K levels (2, 3, 4)? Why?
- Fluid Controlled Knee (K2,3,4)
It allows for variable cadence and simulates knee ROM from 110˚-175˚ - Microprocessor Knee (K3,4)
Allows for customized programming of gait pattern for different activities.
Why do knees fail?
- improper use - wrong heel height, walk with no shoes
2. Improper adjustment
What are the 6 CPG recommendations for post LE amputation care?
- Perioperative education regarding procedure (residual limb care, phantom sensation, rehab process, prognosis…)
- Perioperative education regarding individual (pain, emotional state, individuals needs…)
- Provision of peer mentoring
- RRDs should be used to reduce healing time and time to prosthetic fitting
- RRDs should be used to reduce post edema
- RRds are better that soft dressings immediately posted
