Question | Answer |
Prosthetics | -Replacement of all or part of an extremity |
Prosthetist | -Health professional who: designs, fabricates, fits, modifies a limb prostheses |
Types of prostheses | -Foot
-Syme's
-Transtibial
-Transfemoral
-Knee & hip disarticulation |
Partial foot prosthesis | -Plastic socket attached to rigid plate
-Cosmetic toe filler pictured |
Standard components | -Suspension
-Liners/socks
-Socket
-Shank/pylon
-Foot/ankle assembly |
Foot/ankle assembly | -Purpose to stimulate muscle and joint activity
-3 purposes of the foot and ankle: ? |
Foot/ankle assembly: 2 major categories | -Non-articulated vs articulated- related to motion
-Non- dynamic vs dynamic response-related to stored energy |
Foot/ankle assembly: Non-articulated | -No axis between foot and rest of prosthesis= no motion
-Lighter, more durable, more attractive
-High-heel versions |
Foot/ankle assembly: Articulated | -Separate foot and lower shank section joined by bolt or cable= motion
-Ankle and foot motion controlled by rubber bumpers
-May loosen/ make noise |
Foot/ankle assembly: Non-dynamic | -NO storing of energy
-NO give between parts |
Foot/ankle assembly: Dynamic | -Store & release energy giving some spring or recoil to a step:
-used for active people
-respond to more time spent on the forefoot
-allows for running and jumping |
Types of foot/ankle assembly | -Solid Ankle Cushion Heel (SACH)
-Stationary Attachment Flexible Endoskeleton (SAFE)
-FlexFoot & Springlite
-Single Axis
-Multi-axis
-Personal bionics |
SACH | -Wooden/metal center covered with rubber
-Soft heel simulates PF
-Non-articulated and non-dynamic |
SAFE | -Variation of SACH
-Good with uneven terrain:
Mobile rearfoot in med/lat directions
Limited DF/PF bumpers
More flexible foot
-Heavier/More expensive
-Non-articulated but dynamic |
Flex-foot and Spring-lite | -Long curved carbon fiber band
-Non-articulated but more dynamic |
Single axis | -Most common articulated foot
-Limited DF/PF: Bumpers, Toe action, No IV/EV
-Commonly used with trans-femoral/-tibial
-Non-dynamic |
Multi-axis | -Moves slightly in all planes with bumpers
-Heavier and less durable
-Dynamic and non-dynamic versions |
Personal bionics: Biom | -Mimics muscle function therefore dynamic
-Benefits:
-Normalize gait speed and energy use
-Alleviate comorbidities i.e. LBP/OA
-Improve ground adaptation
-Patient profile:
-190-250 lbs
-BKA or AKA
-Bluetooth capability settings |
Shank | -Substitute for human leg
-Transmits body weight from the socket to the foot
-Not present in Syme's prosthesis |
Shank: Exoskeletal | -Hollow wood/ plastic
-Non-changeable |
Shank: Endoskeletal | -Without cosmetic cover
-Central pylon
-Foam rubber cover |
Sockets | -Plastic receptacle for RL
-Vary with: Level of amputation/ Configuration of the limb
-Designed for:
-Weight-bearing
-Assisting circulation
-Providing feedback |
Movement within the socket may cause... | -Skin problems
-Abnormal gait
-Decreased limb security (i.e. falls) |
Pressure relief area | -Internal socket concavity |
Pressure tolerant area | -Internal socket convexity
-Not the bottom of the RL |
BKA | -Fibular head
-Anterior tibia: tibial crest/ tibial condyles
-Hamstring tendons |
AKA tendons | -Anteromedial: Adductor longus tendon
-Posteromedial: Hamstrings tendon/ Sciatic n
-Posterolateral: permit glute max m. function
-Anterolateral: rectus femoris tendon |
AKA: femoral triangle | -Anterior wall over femoral triangle: femoral n, femoral vv, lymphatic vv |
Common pressure tolerant areas | -BKA:
-Patellar tendon and tibial tubercle
-Proximal medial tibia and shaft (NOT condyle)
-Fibular shaft
-Gastrocnemius muscle bulk
-AKA:
-Ischial tuberosity
-Quads/hamstrings muscle bulk (not tendons) |
Greater surface area tends to be more... | -Pressure tolerant
-i.e. large/ flat bony landmarks and muscle bellies |
Smaller surface area tends to be more... | -Pressure relief
-i.e. small/ pointed bony landmarks and thin tendons |
Socket skin reactions | -Transient redness with pressure tolerant areas
-No reddness with pressure relief areas |
Syme's Socket | -Distal loading
-Cut out for bulbous RL
-No shank |
Transtibial Socket: PTB | -Patellar tendon bearing (PTB)
-Aligned on shank in slight flexion to:
-Increase patellar tendon loading
-Prevent genu recurvatum (hyperext)
-Prevent RL inferior sliding |
Transtibial socket: PTB cont... | -Also aligned in slight lateral tilt (genu valgus) to decrease fibular head load |
Knee Disarticulation Sockets | -Terminantes below ischial tuberosity |
Transfemoral sockets | -Quadrilateral-most common
-Ischial containment |
Transfemoral Sockets (Quadrilateral) | -Posterior shelf for ischial tuberosity and glutes plus medial dege at same level
-Higher anterior wall to push ischial tuberosity onto posterior shelf
-Lateral wall same height as anterior for stabilization |
Transfemoral socket (Ischial containment) | -Coverage for greater stabilization:
-Ischial tuberosity
-Pubic ramus
-Greater trochanter
-Mediolateral width narrower yo:
…↑ frontal plane stability
… minimize bulk between legs
-Anterior wall lower |
Transfemoral sockets: slight flexion to... | -Facilitate hip extensors
-Decrease lumbar lordosis
-Increase available hip extension ROM for equal step length |
Hip disarticulation/ hemipelvectomy sockets | -Molded plastic
-Weight-bearing on ischial tuberosities and gluteals instead of torso |
Liners | -Provides protection between skin and socket
-Liners: Gel or foam, rolled on/ off, lock or seal into socket |
Socks | -Cotton, wool, or synthetic fabric
-Add more as RL shrinks due to…
-Decreased swelling
-Atrophy |
Suspension methods | -Cuff/straps- grip above boney prominences
-Thigh Corset
-Brim (edge) Variants
-Sleeves
-Suction |
Transtibial Cuff | -Supracondylar cuff:
-Leather strap anchoring on femoral epicondyles
-May have waist belt attachment
-Good for short RL, heavy thighs, and active patients
-Easy adjustment except with visual or hand dysfunctions |
AKA straps | -Grip above iliac crest |
Thigh corset | -Lace up thigh w/ hinge to knee socket
-Advantage:
-Used on person w/ very sensitive skin
-Increases the weight bearing and contact area
-Disadvantage:
-Heavier and may foster pistoning & pressure atrophy of the thigh
-More difficult to don |
Transtibial Brim Variant | -Supracondylar suspension:
-Grips onto femoral epicondyles
-May be above patella also
-↑s medial/lateral stability
-Good for shorter RL |
Sleeves | -Grips soft tissue
-Made of rubber silicon
-Advantages:
-Used for AKA/BKA
-Grip is distributed over a greater area
-Disadvantages: patient needs two strong hands and firm thigh musculature |
Suction | -Works by pressure differences inside and outside of the socket
-Internal pressure < less than external pressure
-Atmospheric pressure causes the socket to remain on the thigh
-One way air release valve on bottom of the socket |
3 types of suction | -Total
-Partial
-No |
Total suction | -Very snug
-Max control without auxiliary suspension
-Most difficult donning/doffing |
Partial suction | -Mod snugness
-Sock needed
-Additional suspension device needed |
No suction | -Least snug
-Multiple socks needed
-Additional suspension device needed
-No valve but a hole
-Easy donning/doffing but control is sacrificed
-Decreases sitting comfort |
AKAs may also have... | -Knee unit and possibly...
-Hip unit components |
Knee unit: 4 possible components | -Axis system
-Friction mechanism
-Extension aid
-Stabilizers
-Personal bionics |
2 axis systems | -Single axis
-Multiple axes |
Friction mechanisms | -Changes speed of knee motion during various parts of swing phase according to walking speed
-Controls knee motions and provides resistance to pendular motion |
Friction mechanisms: 4 types | -Constant
-Variable
-Hydraulic/pneumatic
-Microprocessor control |
Constant friction | -Most popular
-Same friction throughout motion
-Easily adjusted
-Usually prescribed for older adults |
Variable friction | -Friction changes during swing phase
-Early swing: high friction used to slow heel rise
-Mid-swing: friction reduces to permit more natural swing
-Late swing: friction increases to prevent impactful extension |
Hydraulic or Pneumatic friction | -Oil/air medium
-Adjusts resistance dynamically per walking speed
-Prescribed for younger more active people
-Heavier, more complicated, more expensive and more maintenance is required |
Microprocessor control | -Can prevent stumbling
-Computerized control
-Beneficial when resistance is needed to change more frequently
-Blue tooth capability settings
-Computer Knee |
Extension aid | -Assists knee extension during the later part of swing phase
Keeps a constant rate of extension:
-External
-Simplest
-Elastic webbing in front of the knee axis provides recoil
-Internal: elastic strap or coiled spring inside the axis |
Stabilizer | -Uncommon: most use hip motion or posterior alignment for stabilization
-2 types: manual lock, friction brake |
Stabilizer: Manual lock | -Simplest
-Drop down loop over the hinge
-Pin lodges on receptacle |
Stabilizer: friction brake | -Brakes and slows knee flexion when weight bearing occurs with the knee in 0-20 degrees flexion |
Personal bionics | -Power knee |
Hip unit | -Provides flexion motions and extension aid to bias prosthesis toward neutral
-Set below normal hip:
-Relatively shorter thigh segment and longer leg segment
-Won’t protrude when seated
-Set anterior to normal hip to engage hip extensors |
General maintenance: Foot and ankle assemblies | -Bumpers shoulder be replaced as needed
-Keep dry
-Keep sand and debris out of articulation |
General maintenance: Socket & suspension | -Clean with damp cloth and mild soap, dry completely
-Keep suction valve clear
-Leather straps and corsets need saddle soap and conditioning |
General maintenance: Knee and hip units | -Oil and tighten as needed to maintain alignment
-Pneumatic and hydraulic units should be clear of debris, store upright with knee extended to remove air in the cylinder
-Keep sand out |
General maintenance: Exterior skeletons | -Clean, check for slitting
-Avoid direct heat like radiators, heat vents, etc |
Donning | -Show appropriate reference points and landmarks between the socket and RL
-The pt needs to learn the correct feel of the prosthesis
-The firmer the contact the more difficult it is to don (i.e. suction) |
Donning sequence: 1) Liner/Socks | -Should not be wrinkled or rotated
-Seam parallel to scar but not over it
-Used to control volume...never more than 15 ply (layers)
-Socks worn over a suction suspension or gel liner |
Donning sequence: 2) Insert RL into socket | -Roll liner up before donning
-Use powder or stockinet prn to pull RL into socket
-May have to pump a suction socket |
Donning sequence 3) | -Apply the suspension prn |
Doffing | -Usually just a reversal of the donning sequence as the suction interface is usually peeled off after the socket is removed from the pin |
Getting stuck | -Some patients may get stuck
Slide his hand between the liner and the skin
Break the suction and get out of the prosthesis |