Prosthetics Flashcards
Content: Basic Prosthetic Goals (3)
- Reestablish functional ambulation and ADLs
- Comfort
- Comestics
Content: Prosthetics Componenets (5)
- Socket Suspension
- Socket Interface
- Knee
- Pylon
- Foot
Q: What is the number one cuase of hip disarticulation?
Cancer
Q: What is a knee disarticulation preferred over a transtibial amputation?
With KD the natural end of the femur provides a WB surface AND the adductors are still naturally connected
T/F: Following a partial foot amputation, it is common to have higher level amputations within a few years.
True
Q: Why would a toe filler be added to a shoe following a toe, ray, or transmetatarsal amputation?
To improve push off
Term: Disarticulation of the tarsal and metatarsal bones
Lisfranc (partial foot) amputation
Term: Foot disarticulated between the talonavicular and calcaneocuboid joints
Chopart (partial foot) amputation
Q: What are the negative functional outcomes associated with Lisfranc and Chopart amputation? (2)
- Increased PF contracture over time
- Negative impact on skin integrity over distal end
Q: How does prosthetic foot height affect gait?
The higher the prosthetic foot height, (or the more room left for a prosthetic foot) the more energy return from the prosthesis which can improve gait effeciency
Q: What is done with pediatric patients to address prosthetic foot height?
Commonly bone growth is stopped surgically to allow for a WB distal end and provide increased potential for foot height and prosthetic options in the future
T/F: The longer the lever arm, the higher the pressure at the terminating point and the more force required to move the prosthesis.
False, shorter the lever arm
Q: Foot prosthesis requires replacement of the _____ __________ for support. Needs to come up to the _______ to reestablish _______ _____.
toe, rocker, leg, push, off
Content: Ankle Disarticulation (3)
- Affects talocrural joint - shave malleoli and reposition fat pad of heel
- WB is possible
- Often results in leg length discrepancy
Q: Which prothesis is typically used to address ankle disarticulation?
(Mid-)Patellar Weight Bearing - to replace levers from fot must extend device up the tibial shaft
Q: What is the most common lower extremity amputation level?
Transtibial
Content: As residual tibial length decreases… (3)
- Ipsilateral knee extensors work harder
- SA for WB decreases
- Discomfort & irritation within prosthesis may increase
Q: What is the ideal transtibial length and why?
6-8 inches from mid patellar tendon
- Long enough lever to control prosthesis
- enough soft tissue for WB
- enough room for prosthesis components (increased functionality)
Q: What issues arise with a transtibial amputation that is 13-14 inches in length from the mid patellar tendon (3)
- WB on the thinnest part of the tibia
- Don’t have much soft tissue to pull over residual limb
- Less room for prosthetic components
T/F: The shorterthe residual limb, the less additional bracing required.
False: more bracing further up the chain for support
Content: Four factors that vary the design of transtibial prostheses?
- Length of residual limb
- Sense of proprioception
- Inherent control
- Activity level
Content: Knee Disarticulation (3)
- Long lever arm
- Adductors intact
- WB end possible
Content: Advantages of Knee Disarticulation Prosthesis (3)
- Lower proximal trim lines
- Good WB
- Long intact femur
Content: Problems with Knee Disarticulation Prosthesis (4)
- Unequal knee center/tibial plateaus
- Sitting/squating can be difficult
- Sitting with limited knee space
- Altered swing phase
Q: What is the main goal of fitting a knee disarticulation prosthesis?
Want mechanical knee center as close to anatomical knee center as possible
Content: With transfemoral amputations as the residual femoral length decreases…. (3)
- SA for WB decreases
- Stability decreases due to loss of adductor muscles
- Discomfort and irritation within a prosthesis may increase
Q: What is the ideal length of a transfemoral amputation?
3 inches proximal to anatomical knee joint
T/F: The shorter the residual limb, the more support that needs to be built into the prosthesis.
True
Content: Design considerations for Transfemoral Prostheses (4)
- Pts. needs and potental improvement in funciton
- Suspension
- Knee/foot selection
- Containment of the ischium
Content: Hip Disarticulation & Hemipelvectomy (4)
- Most challenging levels of amputation
- Not very common
- Higher complication rates
- Typically slower walking speed (compared to lower level amputations)
Q: With hip disarticulation patients need a __________ ______ and _________ ________.
strong, core, flexible, trunk
T/F: Suspension if difficult with hip disarticulation.
True
T/F: Symmetric gait is typical with hip disarticulation.
False: non-symmetric - trunk movement create momentum for swing
Content: Pre-surgery Information (3)
- Pt./Caregiver education
- Peer support
- Strengthening upper limbs and core
Content: Postoperative care (3)
- Rigid dressing and compression therapy within 24 hrs
- Pre-prosthetic training
- Temporary devices (2-4 wks)
Content: Preparatory Prosthesis (3)
- “Training Wheels”
- Allows for evaluation of potential
- 4-8 weeks
Content: Definitive Prosthesis (2)
- 6-12 mo
- Ongoing care
Q: What are the stages of rehab for prostheses?
Pre-op > Post-op > Temporary Device > Preparatory > Definitive prosthesis
Q: How many prosthetics does an amputee typically have in the first year s/p?
2
T/F: As a patients gait improves a new prosthesis is required.
False: just needs adjusted - continual prosthetic adjustments are to be expected
Q: What is the one rule of prosthetics (particularly shortly after surgery)
No falling - a fall can delay the process
T/f: You want to load the end of the bone.
False: soft tissue, not the cut bone end
- exceptions = Semes and knee disarticulation
T/F: Skin and bone with no soft tissue is not an easy way to walk on a prosthesis.
True
Q: What are the typical complaints of gel liners?
They’re hot and trap perspriation.
Content: Challenges and Priorities for New Amputees (4)
- Regaining balance
- Rebuilding proprioception
- Establishing security and confidence
- Establishing good walking habits
Q: What is a crucial step in the recommendation of the prosthesis?
Physical evaluation of the pt. and residual limb
Content: Four variables specific to the residual limb
- Condition (sensation/pain, shape, bony anatomy, skin integrity/quality
- Stability of remaining joints (M/L, A/P)
- Muscle strength
- Range of motion
Content: Types of sockets (2)
- Soft protective cover with inner pylon
- Hard exterior with inner rigid foam
Content: Four types of transtibial socket designs
- Patellar Tendon Bearing
- Total surface bearing
- Supracondylar-Suprapatellar
- Joint and Corset
Content: Osteoarthritis bracing (3)
- Similar to ACL brace
- Good for unicompartmental OA
- Applies force to open up joint space on compressed side to disperse froce to nonOA compartment
T/F: Where you set the prostheis under the knee can create a varus or valgus moment.
True
Q: What are the typical types of prosthetics and which is more commonly used now?
Endo and Exoskeleton
Used to see more exo, now primarily endo
Q: When would an exoskeleton be prefered over an endoskeleton?
When the pts. work environment is rough and you want to protect the integrity of the prosthesis. ex. farmer
When the pts. is used to it ex. has been using that type for 20+ years
Q: In a PTB socket, what are the areas of pressure tolerance? (4)
- Patella tendon
- Lateral/medial pre tibial shaft
- Lateral shaft of fibula
- Gastrocnemius (Calf)
Q: In a PTB socket, what are the areas of pressure intolerance? (5)
- Distal patella
- Tibial crest (including anterior distal tibia/cut end of bone)
- Fibular head
- Distal end of fibula
- Hamstring tendons
Q: If a patient suddenly has pressure areas in their socket what is the problem and how can you fix it?
Problem: Residual limb reduction
Fix: Add a prosthetic sock
Q: What is the hardest thing to teach a pt. regarding their prosthetic?
Sock application management
Q: How does the residual limb change throughout the day?
Biggest in the morning, shrinks throughout day
Q: What should their patient do if their prosthetic hurts?
Add a one ply sock
Better - add one more one ply, keep adding till feels resolved
Worse - take some off
No change - try 5 ply
Q: How does you manage sock application when you have no sensation?
Look at the patellar location
Goal - right on trim line
Too low = add socks
Too high = remove socks
Q: Describe the flow characteristic of gel liners
Allows for equal distribution of pressure to improve comfort, decrease skin abrasions, and increase suction
Gel moves away from areas of high pressure
T/F: When gel liners are worn daily their loose their flow characteristic more quickly.
True: alternate gel liners to allow them time to return to its normal form
T/F: When creating a prosthetic should use build in areas of relief over bony prominences.
True
Content: Two types of transfemoral socket design
- Ischial containment
- Sub-ischial
Content: Supracondylar suprapatellar advantages (3)
- Cup medial femoral condyle to keep prosthesis on
- Proves ML stability (lengthens lever arms)
- Above patella = extension stop
Content: Transfemoral sockets (3)
- tight fit/cup ischium, don’t want any ML movement
- Not tight, femoral ABD, can’t keep pelvis level
- If can’t tolearte cupping - ischial containment
Q: What can be an issue with morbid obesity and transfemoral amputations?
sub ischial socket - can’t get to ischium and sitting is uncomfortable due to too much belly
Content: Vacuum suspension (3)
- Can hang upside down by prosthesis and not fall out
- For running and cycling
- Can lower trim lines
Content: Prosthetic Interfaces (3)
- Soft foam interface
- Gel liner
- Socks
Content: Suspension Systems (5)
- Roll on liner
- Suspension sleeves (external sleeve)
- Anatomical suspension (supracondylar or supramalleolar) (w/w/o strap
- Cuff suspension or belts (soft or rigid)
- Skin fit suction
Content: Roll on liner Pin (5) vs. Suction (4)
Pin
- In swing, socket drops
- Gel liner elongates
- “Milks” residual limb
- Skin break down
- Good for kneeling - keeps prosthesis on
Suction:
- Gold standard for transfemoral
- Maximizes proprioception
- Can’t be fit till volume stabilizes
- If volume is changing can create air pockets and funny noises
Content: Optimal Prosthetic Gait: Symmetry in Stance (4)
- Equal stride length (then lengthen stride length)
- Foot flat on floor
- Knee flexion in stance
- M/L stability at midstance
Content: Optimal Prosthetic Gait: Symmetry in Swing (3)
- Equal heel rise, hip rotation, and arm swing
- Toe clearance
- Controlled deceleration
T/F: You what equal WB on both limbs with prosthetic walking.
True
T/F: The sound limb ages at a normal rate.
False: accelerated, esp. when not walking with equal WB and stride length
Content: Limited Community Ambulator (4)
- Activity
- Control
- Speed
- Terrain
- Low activity
- Low voluntary control
- Single speed ambulation
- Indoors on level, even ground
Content: Limited Community Ambulator Prosthetic Requirements (5)
- Stability
- Comfort in socket
- Reliable suspension
- Swing toe clearance
- Confidence thatthe knee/foot will support them at all times
Content: Community Ambulator (3)
- Activity
- Control
- Terrain
- Moderate activity
- Moderate voluntary control
- Level, uneven ground and ramps
Content: Community Ambulator Posthetic Requirements (5)
- Balane between stability/performance
- Allow for change in walking speed
- Adaptable for change in surface/slope
- Comfort/control in socket
- Reliable suspension
Content: Unlimited Community Ambulator (4)
- Activity
- Control
- Speed
- Need
- Higher activity
- Full control of prosthetic
- Has ability to change speed quickly
- Higher demands/goals, needs a device that can keep up
Content: Unlimited Community Ambulator Prosthetic requirements (6)
- Balance
- Variable speed
- Higher impact
- Multifunction knee
- Energy return foot
- Biofeedback and responsive socket design
Q: Prosthetic design is always a balance between what two things?
Security (physical, psychosocial, specific needs)
Performance (activities, vocations, future needs)
Content: Four categories of prosthetic feet
- SACH
- Single Axis
- Mutli-Axis
- Dynamic Response - hybrid designs
Content: Knee Technology
- Single Axis Frame: weighted activated stance locking, friction swing control
- Plycentric Frame: position activated stance locking, pneumatic swing control
- Single Axis Frame: hydraulic stance and swing control, electronic sensor activation
Content: Heel Rocker (Loading Response) (4)
- Controlled PF
- Absorb loading forces
- Reudces knee flexion moment
- Maintain forward progression
Content: Ankle Rocker (Midstance) (3)
- Stable tripod foot-flat posture
- Heel, 1st and 5th MT
- Maintain forward progression
Content: Forefoot Rocker (Terminal Stance) (3)
- Forefoot locks and becomes rigid
- Heel rise against a rigid forefoot lever
- Energy storage in the PF
Content: Function of the Foot and Ankle (3)
- Force attenuation
- Ground accommodation
- Rigid lever arm
Content: K Level (3)
- 0-4
- A method of rating functional abilities and potential to ambulate
- Can change over time
Content: K Level 0 (2)
- No ability or potential to ambulate or transfer
- Prosthesis does not enhance quuality of life
Content: K Level 1 (2)
- Ability or potential to transfer or ambulate on level surfaces at fixed cadence
- Prosthesis achieves limited or unlimited household ambulation
Content: K Level 2 (2)
- Ability or potential for ambulation with ability to traverse low level barriers
- Prosthesis achieves limited community ambulator
Content: K Level 3 (3)
- Ability or potential to ambulate with variable cadence
- Likely achieve community ambulation with ability to traverse most environmental barriers
- Activity that demands prosthetic use beyond simple locomotion
Content: K Level 4 (2)
- Ability or potential to ambulte which exceed basic ambulation skills
- Most commonly children, active adults, athletes
Content: K Level 0 Component Selection (2)
- Bed or Chair Restricted
- Prosthesis not medically necessary
Content: K Level 1 Component Selection (2)
- Transfers & Household Ambulation
- SACH or Single Axis
Content: K Level 2 Component Selection (2)
- Limited, single speed community ambulating (low level barriers)
- Flexible keel or multiaxial ankle/foot
Content: K Level 3 Component Selection (2)
- Variable speed, community ambulating
- Energy storing, multiaxial/dynamic response, flex foot, flexwalk
Content: K Level 4 Component Selection (1)
No limitations
T/F: There is a single best prosthetic foot.
False: no single best
- best foot defined by functional abilities/needs
- best foot may change through the course of rehab
Q: When should a foot for a K1 amputee enable safety?
EARLY STANCE
Q: When should a foot for a K2 amputee enable safety?
MIDSTANCE
Q: When should a foot for a K3/4 amputee enable safety?
LATE STANCE/PRESWING
Content: Implications of a rigid ankle/stiff heel (3)
- Flexion moment at the knee
- Potentially unstable
- Especially with weak knee extensors
Content: Implications of a rigid ankle/stiff heel on resistances in the socket (2)
- Residual tibia extends into the socket
- Creates localized pressure
Q: What does SACH stand for?
Solid Ankle Cushion Heel
Content: Effects Stiff heel vs. Compressive heel on Gait
- Stiff heel - create potentially dangerous knee flexion moment
- Compressive heel reduces flexion moment, shifts GRF atnerior
Content: Characteristics of SACH (3)
- Simple
- Inexpensive
- Durable
Content: Single Axis Foot (4)
- Mechanical axis with bumpers
- Resistance to DF and PF
- Reduces flexion moment
- Shifts GRF anteriorly quicker
Content: Characteristics of a single axis foot (3)
- Rapid flat foot
- Increased weight
- Increased maintenance
Content: Posterior Bumper (2)
- Eccentric DF
- Too stiff = force knee flexion/instability
Content: Anterior Bumper (2)
- Eccentric PF
- Too soft = knee will buckle
Content: Multi-axial foot (3)
- Provides multiaxial foot movement (PF/DF, Inv/Ev, IR/ER)
- Preferred for uneven terrain
- Absorbs gait torque to reduce shearing forces on the residual limb
T/F: The more flex in the foot the less energy return.
False: more energy return
Q: What is a shank foot good for?
For those carrying heavy loads ex. construction workers
Content: Foot: Energy Storage and Return (3)
- Initial contact opens to allow PF
- Internal keel structure absorbs energy during midstance and terminal stance
- Releases energy to preswing to provide a smoother gait
Q: When are the benefits of energy storage and return more apparent?
At higher speeds
- smoother dynamics during gait
- reduced impact on the sound side heel strike
Content: Endoskeletal construction allows for the following (2)
- Facilitates multiple alignment options/changes
- Allows feet to be interchangeable
Q: What allows for angular alignment changes (length of the toe/heel) in an endoskeletal construction?
four set screws acting against an inverted pyramid
Content: Transtibial Heel Height Considerations (2)
- Aligned to a single heel height
- A change in shoes can dramatically affect overall alignment
Content: Transfemoral Heel Heigh Consideration
Considerable attention is givein to the relative postiion of the prosthetic knee over the prosthetic foot
Q: What is a footshell?
A covering for the prosthetic foot that comes in various colors, split toe options
Content: Foot: Rotational Torque Adapter (3)
- Reduces shearing forces
- Built into the foot or attache das a separate component
- Provides rotation mobility for standing and twisting movements
Content: Foot: Vertical Shock Absorbers (4)
- Built into foot or separate component
- Reduce impact forces during stance phase
- Reduce sheer forces within the socket
- Improves prosthetic rotational forces at heel strike
Content: Foot: Running Feet (3)
- Efficient J-shaped springs
- Absorb energy during loading
- Release energy at toe off
T/F: Running feet are conducive for walking.
False: they are too stiff and have no heel
Content: Heel Height Adjustable Foot (2)
- Pt. can change height to accommodate various shoes
- Does not change overall prosthetic alignment
Content: Patient Requirements (Knee Prosthetics) (3)
- Weight (max now at 600lb)
- Height (effects lever arm)
- Functional age
Q: What type of knee would you choose if the pt. need variable cadence?
Pneumatic or hydraulic
Content: Things that can cause knee prosthetics to fail (6)
- Alignment (TKA line)
- Inappropriate use
- Selected knee
- Prosthetic Care/Managment
- Shoe selection
- Adjustment
Diagram: Knee Selection
Content: Pros and Cons of Single Axis Knee (2/2)
Pro:
- Less moving parts and simple design
- Lower fabrication costs
Con:
- Less stable at heel strike
- One axis to absrob gait stress
Content: Pros and Cons of Polycentric Knee (2/3)
Pro
- Inherent stability at heel strike (at full extension)
- Easy to initiate swing phase
Con:
- Tend to be heavier
- Increased maintenance
- Catch toe = will fall
Content: Pros and Cons of Manual Lock Knee (1/2)
Pro:
- Simple design, provides a non-flexing knee while standing/ambulating
Con:
- Patient must unlock knee manually to sit
- If patient falls, the knee will not collapse under them
Content: Pros and Cons of a Friction Knee (1/2)
Pro
- Simple design, functionally acts like a simple door hinge.
Cons
- Friction setting allows for only one walking speed
- Friction plates wear and will require regular maintenance and replacement
Q: What types of knees are for K1-2? (3)
- Manual Lock
- Friction
- Stance Control
Content: Pros and Cons of Hydraulic Knee (2/2)
Pro
- Hydraulic mechanism provides resistance to flexion/extension during swing phase
- Provides variable cadence; ability to change walking speeds without hesitation
Con
- Tend to be heavier due to hydraulic fluids in cylinder
- Require regular maintenance
Q: what types of knees are for K3-4? (3)
- Stance Control
- Hydraulic
- Microprocessor
Content: Microprocess knees provide (5)
- Comfort
- Security
- Stability
- Function
- Freedom
Q: How many times per second does a microprocessor receive information?
50 times, allows for instantaneous adjustment for every step/movement
Q: How should prosthetic users be taught to descend stairs (if their prosthesis is capable)?
Step over step, prosthesis half off the step to allow unloading and bending of the knee
Q: Microprocessor knees allow for _________ flexion up to ____ degrees and ______ __________.
stance, 10, shock, abosorption
