Prosthetics Flashcards
Lower-Limb prosthetic devices: Partial plastic foot
Restores foot length, protects amputated stump
Function may be improved by adding rocker bottom of plastic calf shell
Lower-Limb prosthetic devices: BKP foot-ankle assembly
Absorbs shock at heel strike
PF at early stance
Permits MTP hyperextension in late stance
Cosmetic foot replacement
Lower-Limb prosthetic devices: SACH foot
(Solid ankle cusion heel)
Most common
Non-articulated, contains energy-absorbing heel
Internal wooden keel permits sagittal plane motion - esp PF
Permits very small amount of mediolateral and transverse motion
Assists knee hyperextension (stability) during stance
Lower-Limb prosthetic devices: SAFE foot
(stationary attachment flexible endoskeleton)
Flexible, non-articulated
Permits more non-sagittal plane motions
Prescribed for more active individuals
Lower-Limb prosthetic devices: Flex-foot
Leaf-spring shank (not a foot)
Used with endoskeleton prosthesis
Long band of carbon fiber originates directly from shank, stores energy during push-off
For more active people
Lower-Limb prosthetic devices: Single-axis foot
Articulated foot with lower shank
Motion controlled by anterior and posterior rubber bumbers that limit DF and PF
More stable (permits only sagittal plane motion)
For people with bilateral AK amputations
Lower-Limb prosthetic devices: Shank
Exoskeletal: Usually made from wood with plastic laminated finish. Colored for cosmesis. Durable.
Endoskeletal: Contains a central metal shanke
Covered by soft foam and external stocking
Offers improved cosmesis, modular components allows for increased ease of prosthetic adjustment
Lower-Limb prosthetic devices: PTB socket
Patellar tendon bearing
Total contact socket that allows for loading over area of PT
Pressure sensitve areas of TT stump:
Anterior tibia and tibial crest, fibular head and neck, peroneal n.
Pressure tolerant areas:
PT, medial tibial plateau, tibial and fibular shafts
Lower-Limb prosthetic devices: BK Suspension
Supracondylar leather cuff: Buckles over femoral condyles, widely used, easily adjusted.
Supracondylar socket suspension: Medial and lateral walls of socket extend up and over femoral condyles. Removeable medial wedge assists don/doff. More cosmetic, no buckles, increase med/lat stability/
Supracondylar/suprapatellar: Similar to SC but with high anterior wall. Assists suspension of short stump/
Thigh corset: Hinged joint with metal uprights attached to thigh corset. Larger surface area for WB. For people with sensitive skin on stump. Knee joint allows for knee control (locks). Pistoning may be a problem.
Rubber sleeve: For prostheses with no mechanical joints or straps. Decreases pistoning.
Fork strap: Strap around waist attached to SC cuff. For active people who need additional suspension or will spend extended time with prosthetic unsupported by the ground (e.g. standing on ladder)
Lower-Limb prosthetic devices: AKP knee unit - Axis
Single axis: Permits knee motions to accor around a fixed axis
Knee flexion needed during late stance and swing and during sitting and kneeling.
Polycentric axis: Changing axis allows adjustments in center of knee rotation. More stable. Complex, not widely used.
Lower-Limb prosthetic devices: AKP knee unit - Friction devices
Control knee motions. Provides resistance to pendular motion.
Constant: Continuous resistance provided by clamp acting on the knee. Easily adjusted by screws. Usually for older individuals who do not vary gait speen greatly.
Variable: Resistance regulated to demands of gait cycle. High resistance at early swing to prevent excessive heel rise and late swing to stop terminal swing impact. Minimal resistance at mid swing. (e.g. sliding friction with two solid structures resisting motion by sliding against one-another. Rarely used).
Hydraulic/pneumatic: Adjusts resistance dynamically to walking speed. For younger, active people. More complicated, increase maintenence and cost.
Lower-Limb prosthetic devices: AKP knee unit - Stabilization in extension
Alignment: Knee center posterior to TKA line. Further posterior for short stumps - will not flex easily.
Manual lock: For people who need constantly locked knee (weak hip extensors). Difficulty with clearing limb can be controlled by shortening prosthesis by ~1cm.
Friction brake: Increases friction at midstance to prevent knee flexion, permits smooth knee motion through rest of gait.
Extension aid: External elastic strap or internal coiled spring which assists terminal knee extension at late swing.
Lower-Limb prosthetic devices: AKP quadrilateral socket
Most common
Contains broad horizontal posterior shelf for seating gluts and ischial tuberosity.
Medial wall is same height as posterior wall, anterior/lateral walls are 2.5-3” higher.
Posterior force provided by anterior and lateral walls to ensure proper seating.
Scarpa’s bulge: Area built up in anterior wall to distribute forces across femoral triangle.
Reliefs provided for adductor longus/hamstrings tendons, sciatic nerve, glut max and rec fem.
Lower-Limb prosthetic devices: AKP ischial containment socket
Higher trim line with ischial tuberosity contained within socket
Narrower mediolaterally
Better hip-pelvic stability and more normal alignment
May be better for shorter stumps
Lower-Limb prosthetic devices: Pressure sensitive/tolerant areas for AK
Sensitive:
Distolateral end of femur, pubic symphysis, perineal area
Tolerant:
Ischial tuberosity, gluts, lateral sides of stump
