Transtibial Prosthesis Flashcards
4 Key Components to Transtibial Prosthesis
Prothetic Foot
Shank
Socket
Suspension
Transtibial Shank - EXOskeleton
- prior to vietnam war
- lamniate that formed outside dimensions
- stong enough to support body weight
- heave and inflexible
- very little adaptability
- very durable
Transtibial Shank - ENDOskeleton
- internally supported by an internal pylon/pipe
- interchangability
- post fabrication adjustable
- strength - very durable
- light weight
- covering options
Transtibial Shank - Pylons
- narrow vertical support connecting the socket to the ankle/foot assembly (shank)
- shock and torque absorption pylons can be added for additional responsiveness, stress, shear and torque reduction
Socket Design: PTB WB force Distribution
- developed 1950s
- most commonly prescribed
- WB areas
- through PT and post popliteal tisues
- fibular shaft
- tibial shaft
- tibial flares
- fem condyles
- Protect:
- fibular head
- peroneal nerve
- anterior distal tibia
- HS tendons
- tibial crest,
- ant tibial tubercle
- distal fibula
- patella
- adductor tub
PTB Socket Advantages and Disadvantages
- Exert forces in all directions equally
- advantages
- evenly distrib. forces across RL - max WB
- liner offeres good shear and friction reduction
- enhancement comfort
- Disadvantages
- skin irritations
- some hypersensitive areas cannot tolerate the even pressure
Socket Interface b/t Residual Limb and Socket Design
Hard Socket = Thin Sock
Soft Socket = Foam “pelite” liner
Hard Socket Interfaces
- Rigid plastic interface
- direct contact b/t socket and residual limb
- shearing/friction are minimized
- enhanced cosmesis
- easy to cleen
- durable = easy to replace thin sock
- requires increased skill of prosthesis
- difficult to adjust/modify
- may not be appropriate for fragile skin
- MATURE LIMBS ONLY
- minimize bulk
- reportedly cooler
- 3 goals
- help cushion - good fit
- accomodate volume change
- wick moisture
Soft Liner Interface
Foam Pelite Liner
Advantage:
- adds cushion
- easily modifiable
- suspension can be incorporated
Disadvantage:
- adds bulk
- increases friction
- insulative properties
- skill required for donning/doffing
Soft Interface
Custom Liners
- indicated for uniquely shaped and/or scarred limbs
- were the first silicone liners available
- advantages
- reduced friction and shear
- suspension mechanisms may be included
- disadvantages
- expensive and hot at first
- potential for skin problems - humidity and friction
- add bulk
Soft Interface
Off the Shelf Liners
- most manufacturers now have their own line
- advantages:
- reduce friction and shear
- suspension may be included
- different thickness and styles
- silicone, mineral oil gels, even with aloe
- customizable
- disadvantage
- may be hot
- add bulk
- potential for skin problems
Suspension - Cuff Strap
advantages:
- simple and effective means of suspension
- suspends over the condyles
- attachment points approximate knee center
- leather or leather and elastic
disadvantages
- does not provide AP or ML stability
- may impede circulation and knee flexion >90
- not very cosmetic
Suspension
Waist Belt and Fork Strap Suspension
Advantages
- removes all suspension burden from the limb
- elastic anterior strap - accomodate extra length in knee flexion during end stage of stance and assists with knee extension during swing
- usually added as an auxillary suspension
- often used for high lvel athletes
Disadvantages
- hot
- allows for piston action
- bulky
Suspension - PTB Supracondylar
Advantages:
- often dont need another suspension
- added ML stability
- some recurvatum control
- increased socket surface lowers pressure overall
- one piece design
Disadvantages:
- higher trim lines
- requires dexeterity to don/doff
Suspension
Locking Pin
-pin is incorporated into the distal end of the gel liner and must be guided into the shuttle at the distal end of the socket
Advantage:
- pistoning reduced
- secure suspension
Disadvantage:
- suspension forces concentrated distally
- mechanical complications
- flexion limitations
- some feel milking action at and of residual limb