Prosthetic Sockets, Knees & Foot Types Flashcards
What determines the prosthetic Rx?
- Functional K Level
- Physical Concerns (level of amputation, disease pathology, BW, skin integ)
- Vocational and leisure activities
- Cognitive Skills
- Home environment
- Insurance
How many K Levels are there?
5 Levels
Level 0-4
Describe Level 0
no ability or potential for weight bearing or transfer
Describe Level 1
ability or potential to transfer and ambulate within household with an AD
Describe Level 2
Community ambulator with the ability or potential to traverse minor environmental barriers, fixed cadence
Describe Level 3
Community ambulator with the ability or potential to traverse all environmental barriers with a variable cadence
Describe Level 4
the ability or potential for prosthetic ambulation that exceeds basic skills, exhibiting high impact stress, or energy levels. Typical of the demands of a child, active adult or athlete.
What are physical concerns for amputation?
Amputation length Weight restrictions on components Vocational and Leisure activities Skin integrity Peripheral neuropathy/hand strength Disease Pathologies
What are some cognitive realities for amputees
- Ability to follow and remember instructions
- Pt compliance
- Ability to get on/off prosthesis independently
- Adjust prosthetic fit
- Is there reliable ‘help’ at home
What is insurance coverage like for amputees?
- Payers typically follow Medicare payment guidelines
- Detailed Rx and LOM needed
- Authorization required
- Replacement: physical changes, medical necessity, damage, change in K level
- Restrictions on ‘experimental’ technology commonplace
What costs more: transtibial or transfemoral?
Transfemoral $10-60,000 compared to transtibial ($7-14,000)
Our thought is more joints to replace with transfemoral
Fitting of a prosthesis
Start at a “bench alignment” to a “personal alignment”
Describe socket design, socket interface, and suspension
Socket Design: muscle cotouring and total contact
Socket interface: socks, gel liners
Suspension: sleeve, suction, pin locks, belts
What are the principles of socket design
- Contour, relief and support for functioning muscles
- Stabilize Skeletal Structure
- Position Muscles to optimize strength
- Minimize applied pressures to neurovascular structures
- Distribute forces within socket over the entire limb
Would you rather bear weight on bone or muscular structure
Muscular structure, tendon is what you want to bear weight on.
*Think when you sit, your ischial tubes are sore, so you don’t want to put a lot of pressure on a bone.
2 Types of Transtibial socket designs
- Patellar Tendon Bearing
2. Total Surface Bearing (newer)
Describe Patella Tendon Bearing socket (PTB)
- older style
- WB concentrated in specific areas (patellar tendon, medial tib flare, gastroc)
- relief modified into cast for boney anatomy
- Triangular shape to socket
- Excessive pressure in popliteal fossa or patella tendon
What are the specific WB areas concentrated in with Patellar Tendn Bearing
Patellar tendon
Medial tibial flare
Gastrocnemius
Describe Total Surface Bearing (TSB)
- Pressure distributed over ENTIRE limb surface
- Total contact with socket while every unit area is under compression
- Best incorporated with Suction Suspension or elevated vacuum
- Global volume reduction of residual limb
- Often used with gell liner interface
PTB vs. TSB vs. Hydrostatic
Really wish we could add pictures
PTB: pressure in only one section
TSB: full coverage
Hydrostatic: pressure from the inside going out
Describe Hydrostatic Design Sockets
- Also considered TSB but utilized compression chambers to achieve uniform fit
- Fluids in chambers utilized Pascal law
- Use silicon suction suspension sleeve
What is a Check Socket or Diagnostic Socket?
A transparent socket used to aid in assessing prosthetic fit.
What is a Definitive Prosthesis?
A prosthesis that is intended for long term usage, comfort, fit, cosmetic appeal and durability. Usually fit once the residual limb stabilizes.
What is Pistoning?
Refers to the residual limb moving up and down within the socket while walking.
What is a Preparatory Prosthesis?
Initial prosthesis that may or may not include definitive components. It is intended for temporary use to allow the patient to begin therapy for gait training. It is expected that it will need to be replaced within 3-9 months due to changes in the residual limb.
What is a Socket liner?
A soft interface used between the hard socket and residual limb. These can be made of various types of gel, socks or soft foams.
What is a Suspension Sleeve?
An elastic tube made of varying materials that is first pulled over the outside of the prosthesis and then rolled up onto the thigh once the prosthesis is put on.
What is a C-Leg?
The Otto Bock C-Leg features a swing & stance phase control system that senses weight bearing & positioning to provide the knee’s microprocessor info about the amputee’s gait, thus promoting smoother ambulation. The outer shell houses a hydraulic cylinder, microchip, & rechargeable battery.
What is an energy storing foot?
A prosthetic foot designed with a flexible heel, which stores energy when weight is
applied to it & releases this energy when weight is transferred to the other foot.
What is an Ischial containment socket?
In some amputation cases, usually those of the HP or HD, this socket is used to support the Ischium.
What is a multiaxis foot?
The multi-rotational axis allows for inversion and eversion of the foot, and it is effective for walking on uneven surfaces.
What is a pylon?
A rigid member, usually tubular, between the socket or knee unit and the foot that provides a weight bearing, shock-absorbing support shaft for the prosthesis.
What is a suction socket?
This socket is designed to provide suspension by means of negative pressure vacuuming. (achieved by forcing air out of the socket through a one-way valve when donning & using the prosthesis). In order for this type of socket to work properly, the soft tissues of the residual limb must precisely fit the contours of the socket. It is mainly used by AK amputees & work very well for those whose residual limbs maintain a constant shape & size.
What are the levels of LE amputation?
- Hemi-Pelvectomy
- Hip Disarticulation
- Trans-Femoral (AK)
- Knee Disarticulation
- Trans-Tibial (BK)
- Symes
- Partial Feet
What is the goal for an amputee?
RETURN TO FUNCTION
What are immediate post-op concerns?
- dog eared distal stump
- edema
- scar edges
- signs of infection
- discharge
What are the primary concerns for a new amputee?
- Protection of residual limb
- Reduce post surgical edema
- Maintenance of ROM
- Pain Management
- Maintain Strength & cardiac reserves
What are some options for a new amputee regarding protecting their residual limb?
- simple splint
- post-op cast
- removable post-op cast
- weight bearing post-op device
During your eval, what should you instruct/educate your transtibial amputee patient on not doing? (think of the cartoon)
- hang stump over EOB
- lie with knees flexed
- sit with stump flexed
- sit with knees crossed
- place pillow under hip or knee
- place pillow under back, curving spine
- place pillow between thighs
What are 3 ways to apply compression to reduce edema?
- Ace wrapping
- Shrinkers
- Post-op cast
What is the difference between a stump sock and a stump shrinker?
- -> sock - no elastic at the top and used to fill extra space in socket when residual limb decreases in size
- -> shrinker - Made of an elastic material that is always tapered to get edema out of the distal end of the stump.
What is tubular gauze?
Used as a double layer of material over the residual limb to provide uniform compression. IT is easy, but can get pulled down or wrinkled easily. (the tubing with a plastic piece in the middle)
What is a prosthetic shrinker?
A compression sock that is used to help control swelling in the residual limb and help shape the limb in preparation for prosthetic fitting
How are prosthetic socks measured? What is the RED FLAG for volume changes?
- Ply.
- 10 ply is a red flag.
Why does a patient need a prosthetic sock?
It allows a pt to manage small volume changes in limb size & add to the comfort of prosthesis
What should you assess every week on the residual limb? What should you educate the pt and family on?
- Girth & Wound healing.
- Positioning, skin inspection, assistance, etc.
After initial amputation, when is the incision fully healed and a cast for prosthesis applied? When does the pt get a temporary prosthesis and therapy? When does the pt get a permanent prosthesis?
- Incision fully healed and a cast for prosthesis applied = 4 - 8 wks
- pt gets a temporary prosthesis and therapy = 4 - 12 wks
- pt gets a permanent prosthesis = 6 mo - 1 yr
Characteristics of Dynamic Response/ “Energy Storing Feet”
- absorbs energy during mid and terminal stance
- releases this “energy” at toe off
- more energy efficient gait
- can incorporate pylon for increased reaction
- can incorporate inversion/eversion
- lightweight and durable
- body mass and activity sensitive
Characteristics of Multi-Axial Dynamic Response Feet
- provides multi axial compliance to uneven ground
- dynamic response at toe off for more dynamic walkers
- classified as “energy storing”
- split toe allows for inversion/eversion
Describe the specialty feet
- Microprocessor controlled ankle: adjusts PF and DF during gait
- Adjustable Heel Height: allows pt to modify alignment for varying heel heights
- Special Use: running and swimming
Describe Dynamic Pylons
- allow for energy to be stored as spring tension as they flex through midstance and terminal stance
- energy released in preswing to help with hip & knee flexion
- helps with toe clearance and limb advancement
- increases efficiency + less energy consumption
55-85% amputees experience some form of what kind of pain?
Phantom limb pain
What are the characteristics of an end-bearing Syme limb prosthesis?
- light enough to wear comfortably
- ability to supply equivalent of foot and ankle function
- lengthening of the limb to adjust for loss of the talus and calcaneous
- distribution of the high forces developed in the ankle area
- provision of rotary stability about the long axis
- provision of shock absorption
- suspension during swing phase
- readily donned without requiring multiple non-cosmetic, difficult fasteners
- adjustability to relieve pressure along a sensitive scar line
- cosmesis
85% of amputees lose limbs to what disease/condition?
Diabetes or related vascular disease
Different Types of Prosthetic Feet in Order of Progressive Complexity
- SACH or SAFE: most basic single axis ankle
- Multiple Axis Ankle and flexible keel
- Multiple Axis Ankle and energy storing keel
- Multiple Axis Ankle, Energy storing keel, and shock absorption
- Computer technology ankle/feet
History of Symes: weight and bulkiness
- pre-1940, prosthesis was a leather socket reinforced w/steel straps + an anterior tongue and lacer
- ankle was frequently a single-axis joint w/bumpers
- early use of polyester-fiberglass laminate w/an opening for entry of the residual limb materially reduced bulkiness
- commonly called “Canadian Syme Prosthesis”
History of Symes: Reproduction of Ankle Joint Motion
- limited space available between distal portion of residual limb and floor severely contrains designs of foot mechanisms
- articulated joints were plagued by chronic wear and tear and were abandoned; now a nonarticulated foot
- SACH foot only thing available for years
- wooden keel added significant stresses to prosthesis
- SAFE foot now used: flexible anterior keel allows easier rollover and reduces GRF
What type of gel liner has a “flow” characteristic?
Unlike silicone and copolymers, urethane has a “flow” characteristic. Urethane will flow and distribute pressure more evenly, so the patient doesn’t feel high-pressure points.
SAFE Foot
- Stationary Ankle Flexible Endoskeletal Foot
- same action as the SACH plus ability for sole to conform to slightly irregular surfaces (Mild Ever + Inver)
- easier for amputee to walk over uneven terrain
- AKA “Flexible keel” feet
Benefit of PTB SC (supracondylar)/SP (suprapatellar)
Suspends and stabilizes
Quantum Foot
- provides similar function as Litefoot
- uses fiberglass-reinforced spring keels/heels
- adapted for Syme prostheses
Ossur Low Profile Flex-Symes Foot
- carbon composite spring heel and keel to simulate ankle motion
- very active prosthetic wearer up to 285 lbs or low amputee weight up to 365 lbs
- fenestrated heel allows greater compression and less shock
Advantages of sleeve suspension (3):
Simple and effective means of suspension
Helps minimize socket pistoning
Does not create proximal constriction
Describe the mechanism of the Suction Suspensionw/elevated vacuum system
May be mechanical- activated by compression of pump created while walking or a powered pump
Define locking liners
Silicone liner in conjunction with Lanyard or strap
Cosmesis
- carbon fiber provide a thinner wall
- air cushion types that require no window and double walled types w/an inner elastic panel
- requires no straps, buckles, or other outside paraphernalia for closure
- thicker just above the ankle
The Seal-in-liner/Pull in liner or suction seal liner with one way value is used more in what type of amputee population?
Used more w/ AK amputees.
Describe the mechanism of the Suction Suspensionw/elevated vacuum system
May be mechanical- activated by compression of pump created while walking or a powered pump
Elevated Vacuum Suspension benefits (3):
Elevated vacuum systems try to reduce pistoning, perspiration, & provide better linkage between user & prosthesis.
What are the advantages and disadvantages vertical shock and torque absorbers?
Advantages:
- reduce impact at heel strike
- reduce rotational shear forces within socket
Disadvantages:
- increased weight
- increased maintenance and cost
- clearance an issue for long residual limbs
What are the characteristics of an end-bearing Syme limb prosthesis?
- light enough to wear comfortably
- ability to supply equivalent of foot and ankle function
- lengthening of the limb to adjust for loss of the talus and calcaneous
- distribution of the high forces developed in the ankle area
- provision of rotary stability about the long axis
- provision of shock absorption
- suspension during swing phase
- readily donned without requiring multiple non-cosmetic, difficult fasteners
- adjustability to relieve pressure along a sensitive scar line
- cosmesis
Provision for Donning
- necessary to allow the bulbous distal end to pass the narrow shank portion of prosthesis
- windows either medially, AP or posteromedially
- double wall prosthesis with flexible inner walls allows for expansion
- flexible inner socket material bridges the narrow portion of the stump above heel pad + maintains total contact
Different Types of Prosthetic Feet in Order of Progressive Complexity
- SACH or SAFE: most basic single axis ankle
- Multiple Axis Ankle and flexible keel
- Multiple Axis Ankle and energy storing keel
- Multiple Axis Ankle, Energy storing keel, and shock absorption
- Computer technology ankle/feet
History of Symes: weight and bulkiness
- pre-1940, prosthesis was a leather socket reinforced w/steel straps + an anterior tongue and lacer
- ankle was frequently a single-axis joint w/bumpers
- early use of polyester-fiberglass laminate w/an opening for entry of the residual limb materially reduced bulkiness
- commonly called “Canadian Syme Prosthesis”
History of Symes: Reproduction of Ankle Joint Motion
- limited space available between distal portion of residual limb and floor severely contrains designs of foot mechanisms
- articulated joints were plagued by chronic wear and tear and were abandoned; now a nonarticulated foot
- SACH foot only thing available for years
- wooden keel added significant stresses to prosthesis
SACH Foot
- single axis foot: provides PF moment at heel strike - improves stability
- Solid Ankle Cushion Heel foot
- BK w/weak quad strength can benefit
SAFE Foot
- Stationary Ankle Flexible Endoskeletal Foot
- same action as the SACH plus ability for sole to conform to slightly irregular surfaces (Mild Ever + Inver)
- easier for amputee to walk over uneven terrain
- AKA “Flexible keel” feet
Seattle Litefoot
- plastic spring keels that add a measure of dynamic response to the prosthesis
- cushion heel to simulate PF following heel strike
Quantum Foot
- provides similar function as Litefoot
- uses fiberglass-reinforced spring keels/heels
- adapted for Syme prostheses
Ossur Low Profile Flex-Symes Foot
- carbon composite spring heel and keel to simulate ankle motion
- very active prosthetic wearer up to 285 lbs or low amputee weight up to 365 lbs
- fenestrated heel allows greater compression and less shock
Distribution & Absorption of Stresses Developed During Stance Phase
- high forces in ankle area require sufficient material to absorb stress
- will be a bulky appearance to any prosthesis design
- constant problem in thickness requirements for strength and thinness required for appearance
Provision of Rotary Stability About the Long Axis
- patellar tendon bearing shape of proximal part of the brim will stabilize against the mediolateral flares of tibia
- flattening of post. portion of the brim adds to a triangulation effect
Provision of Pressure Relief Along a Sensitive Scar Line
direct end bearing can be reduced by proximal loading of the prosthesis along the tibial flares
Cosmesis
- carbon fiber provide a thinner wall
- air cushion types that require no window and double walled types w/an inner elastic panel
- requires no straps, buckles, or other outside paraphernalia for closure
- thicker just above the ankle
