Leg Prosthetics Flashcards
What is the difference between approaches for upper vs lower limb prosthetics?
Upper: ability to manipulate prosthetic to do different types of functions (ex. grasp)
Lower: provide a stable, sturdy limb that can bear weight and behave properly during locomotion
Cost ranges of leg prosthetics
JaipurKnee Project: $20
Below-knee: $6,000-$8,0000
Above-knee: $10.000-$15,000 (or up to 35k)
What is ReMotion knee?
The idea of the Jaipur knee was developed more by D-Rev and costs around $80 US.
Uses a poly-centric 4-bar design
What are the components of below knee prosthetic? (4)
Socket (suction suspension)
Shank (shin)
Pylon (support structure)
Foot
What are the components of above knee prosthetic?
Same as the below knee, but also a knee joint. It also is suspended with harness system instead of suction
What is the function of prosthetic leg?
Needs to be able to support the body during standing, normal walking, and locomoting in various environments
What are the metabolic effects of having a prosthetic leg?
Trans-tibial amputees expend 20% more energy when walking, trans-femoral is even higher
How do passive joints work?
Rely upon ground force effects and mechanical components like hydraulic valves and sliding joints.
What are the three Cs of prosthetic feet? What are the three types of feet?
Control, comfort, cosmetics
Conventional, Energy-Storing-and-Release (ESR), and Bionic.
Describe Conventional foot. What is the main type?
SACH foot (Solid Ankle Cushioned Heel)
Solid ankle, rigid keel, and cushioning at the heel; used for pediatric or geriatric amputees; single axis foot has bumpers to control ankle flexion
Describe ESR foot. Types?
Dynamic elastic response feet flex at heel strike and midstance and then spring back at late stance. Has energy return characteristics. Developed for individuals who wanted to participate in various sports. 100% flexible carbon fibre shank and foot to store and release energy
Carbon graphite foot, multiaxis foot, Flex-foot (8-A), Springlite foot (8-I)
What is the Seattle Foot?
Designed in 1985 by University of Washington; allowed for energy storage and expenditure; worn by over 120,000 users world-wide.
Used a patented spring called a monolithic keel, made of Delrin which stores energy.
Describe Bionic feet.
Can use pneumatics (that have muscle-like pneumatic actuators) or electric (uses spring ankles and series elastic actuators).
Examples of electric Bionic feet (3)
SPARKy (Spring Ankle with Regenerative Kinetics)
MIT Media Laboratory Powered Ankle
Proprio Foot
CESR Foot
Controller Energy Storing and Release.
Prosthetic foot which would recycle kinetic energy generated while walking; uses softer spring; University of Michigan. Generates more foot-ankle power than conventional.
Powered (BIOM) Foot
Found to reduce metabolic costs when walking up slopes. At 3 and 6 degree slopes, 5% less metabolic power.
How to classify knee joints? (3)
- No mechanical knee control
- Stance phase control only
- Stance and swing phase control
Types of stance phase control knees (5)
- Manual locking knees
- Knee units that are alignment controlled
- Friction brakes that lock knee on weight bearing
- Polycentric linkages
- Fluid resistive devices (hydraulic or pneumatic)
Swing phase control only: resistance levels (3)
- Constant resistance
- Variable resistance
- Cadence Responsive resistance
How does stance and swing phase control work?
Allows for both stance and swing to be controlled, has sensors for position and load.
Ex. C-Leg
Issues with inappropriate socket fit?
- Pressure sores
- Edema
- Development of compromised vascularity and lymphatic circulation
- Infections
How has socket technology evolved to get the right fit?
Used to use hand-rectified casting using plaster, now they use CAD-CAM technology to get an accurate cast
How can we account for dynamic loading in socket during walking?
Use finite element analysis to predict where excessive loading may be
What materials are used for socket liners?
- Silicone - most varied
- Urethane - best flow property
- Thermoplastic Elastomer (TPE) - accommodates a large range of limb sizes
