prosthetic componentry

K0

does not have ability to transfer safely with or without assist and prosthesis does not enhance QOL or mobility, prosthesis will not help function

K1

ability or potential to use prosthesis for transfers or amb on level surface at fixed cadence, limited or unlimited household amb, w/c level outside home

K2

ability or potential for amb with ability to traverse low level environmental barriers, limited community, can’t cary cadence

K3

ability or potential for amb with variable cadence, community amb who can traverse obstacles, demands prosthetic utilization beyond simple locomotion

K4

ability or potential for amb that exceeds basic skills, high impact or energy levels
child, active adult, or athlete

check sockets

clear socket as part of prototype to evaluate fit in advance of finish fabrication

rotator

used for sitting cross legged, moving leg out of way for driving or sitting in tight areas

endoskeletal

support internally through pylons and modular parts
lighter, easier to change, can switch components, cover for cosmesis

exoskeletal

support structure externally through laminated socket, rarely used, heavy, difficult to change or adjust

interface

liners, socks, sheath
against the skin, protective layer between limb and socket

socket

rigid structural component that connects limb to WB componentry

suspension

method of securing prosthetic limb to remaining portion of actual limb
sleeves, straps, belts, pins and pinlocks, lanyards/KISS, suction, elevated vacuum, joints and corsets, BOA system

interface options

socks, woven fabrics and textiles
thermoformable polyethylenes
gel infused stockings, gel interfaces

prosthetic socks

for skin protection and volume management, nylon can wick sweat away so better for skin integrity

prosthetic foams

closed cell polyethylene foam, thermoformable, barrier between hard laminated socket and skin that is moldable

gel infused stockings

gel sheaths, liner-liners, allows normal skin migration with WB

gel liners: silicone

easy to clean, good rebound/return

gel liners: urethane

easy to clean, slower return than silicone, can put different thickness in areas of high pressure

gel liners: TPE

slowest return and greatest flow, conforms to irregular limb shapes

gel liners: custom

for accommodation of atypical and irregular limb shapes and contours, built from impression of limb, allows variable thicknesses of gel, limb protection and pain relief when prefab isn’t adequate

transtibial socket design

anatomically based shapes that contain residual limb and facilitate securement while maximizing WB surface
patellar tendon bearing, total surface bearing, supracondylar or supracondylar suprapatellar

patellar tendon bearing

press in tolerant areas and release in intolerant areas

total surface bearing

more comfortable, forces dispersed

supracondylar and supracondylar suprapatellar

short residual limbs and ligamentous instability, SC ML instability only, SCSP ML and flex instability

transfemoral socket design

quadrilateral brim, comfort flex socket, ischial containment, sub ischial socket, MAS socket, socketless and strut style

quadrilateral brim

square, narrow AP, ischial tuberosity sits on
older prosthesis

comfort flex socket

flexible brim that deforms under pressure but returns to shape

ischial containment

ischium contained in post wall of socket, less comfortable

sub ischial socket

doesn’t cover pelvis, lose forces so need hip strength, need long enough residual limb for suspension, > 50% of femur left

MAS socket

grabs ischial tuberosity and pubic ramus for control, more ML control

socketless and strut style socket

most pts don’t like, fewer contact points so higher forces and need to tighten significantly
adjustable and reduces heat but often movement between limb and socket, pistoning, rotation, inability for prosthetist to adjust

sleeve suspensions

transtibial prostheses, located on outside of socket using circumferential contact with limb, need some contact with skin for optimal suspension, requires hand strength to pull up

below knee suction suspension

sleeve over outside of prosthesis, reduced pistoning and improved comfort but more wear and tear on sleeve, less secure if not functioning appropriately
lots of kneeling can break seal

transtibial suspension straps

supracondylar: don’t use if poor circulation
hip belt with y-strap: common with IPOP, not very effective
velcro strap at proximal knee: children and small circumference thighs, can tighten once on for increased contact

transfemoral suspension belts

pts don’t typically like as primary, can be secondary suspension for sports and work, don under underwear
TES: neoprene stretchy belt over contra iliac crest
silesian belt: cloth and velcro with d-rings over contra iliac crest, can have secondary strap to maintain contact
pelvic belt with hip joint: circumferential pressure in pelvic fossa, cumbersome, lat hip stability for trendelenburg with short residual limb

pins and pin locks

common transtibial, pins incorporated into liners and locks laminated into socket
with transfemoral can have rotation issues

below knee locking suspension

most common BKA suspension used today
ease of donning, secure, audible click but can get pistoning, rotation, problems with alignment of pin

above knee locking suspension

pistoning, rotation, difficulty donning, knee/lock location conflict, harder with longer residual limb

lanyard suspension/KISS

primarily AKA, easiest system to don but may get pistoning and rotation, allows for shrinkage
lanyard: velcro straps attached to liners, d-rings on socket that feed lanyard through slot in socket to d-ring
KISS: 2 straps attached to liner and feed through windows in sockets and connect 2 straps

suction

silicon rings on liner to create seal against socket distal to ring, suction valve allows air to be expressed out of socket, if push on valve button air can move in and out
direct skin suction only with transfemoral but not many people can tolerate

vacuum pin

combo of pin lock and negative pressure to minimize pistoning and ensure prosthesis stays attached, reduces friction and helps manage fluctuations in residual limb volume
gel liner interface with sleeve over top, WB in stance reseals each time

elevated vacuum system

air removed by mechanical or electrical pump, ideal suspension strategy
enhances microvascular circulation, cellular hydration contributes to consistent limb volume creating secure fit and eliminating pistoning
could get negative pressure blisters from air in liner

joints and corsets

transtibial prostheses for short residual limbs or severe ligamentous instability, prolonged use leads to quad atrophy

BOA system

more adjustable and comfortable fit, twist dial to tighten, if want to relieve pressure open the dial

connectors

components to connect primary parts of prosthesis to each other to facilitate alignment changes and are weight specific

feet and K levels

K1: SACH, single axis
K2: flexible keel, multiaxial, single axis, SACH
K3: carbon feet, microprocessor feet
K4: all K3, running feet

prosthetic foot heel

shock absorption achieved with knee flexion during loading response, incorporates heel cushion or bumper or level to achieve heel rocker

prosthetic foot keel

semi-rigid lever arm to control advancement of the limb over the foot to replicate ankle rocker, excessive rigidity or flexibility can cause deviations
compresses during loading and springs into place during terminal stance, energy storing forefoot rocker

SACH foot

rigid combination of rubber and wood, soft section under heel that compresses under weight simulating PF at heel strike, toes flex during 3rd rocker to simulate DF
stable at midstance, better for transtibial than transfemoral (rigidity affects function of prosthetic knee joint)

single axis feet

ankle joint with DF and PF controlled by interchangeable bumpers
PF heel strike through post bumper, quick to foot flat
primarily AKA, simulates heel rocker with weight acceptance facilitating knee control

flexible keel feet

simulates ankle movement through entire length of foot by flexible inner keel within rubber footshell
better ground compliance, usually contains multiaxial component, lighter than single or multiaxial feet

mutiaxial feet

similar to single axis but incorporates inversion/eversion or torsion for ground compliance

carbon feet

energy storing or dynamic response feet, contain carbon structure that flexes and stores energy during gait cycle providing energy return during 3rd rocker, good ground compliance, may incorporate multiaxial and vertical shock component

running feet

specific to activity, not for everyday walking, lightweight and highly flexible
usually set plantarflexed to created LLD, attaches to bottom of socket

microprocessor controlled feet

change PF/DF resist with different activities

specialized prosthetic feet

symes feet, adjustable heel height feet

stubbies or foreshortened prostheses

for bilat transfemoral

single axis knee design

transverse hinge allows shank to swing flex/ext, stability achieved by alignment, can add ext assist

multiaxial knee design

2 or more bars connect socket to lower shank, bar pivots at both ends creating moving center of rotation
inherent stability in stance, appropriate if weak hip ext or short limb, puts knee axis of prosthesis and knee axis of sound limb more symmetrical so better if longer limb

mechanical prosthetic knee

single or multiaxial, can be locked in full ext for safety, may have friction brake or stance flexion capability, may have hydraulic or pneumatic swing/stance control

K1/2 knees

nonhydraulic, locked, single axis (with or without ext assist for safety), multiaxial

K3/4 knees

hydraulic or pneumatic, single axis or multiaxial, swing only resist or swing and stance resist, microprocessor

locked knee K1-K2

max stance stability, knee does not flex so gait deviations occur, can shorten prosthesis 1/4”, unlock in sitting

nonhydraulic knees K1-K2

lightweight, stability is primary attribute, optional locking mechanism, optional stance flexion, extension assist

hydraulic knees K3-K4

resistance to motion
swing hydraulics give resist in swing as shank moves forward, adjusts speed from terminal stance flex to terminal swing ext simulating HS eccentrics
stance hydraulics resist flex in closed chain (stance), simulates eccentric quads
mimics natural gait, high adaptable and adjustable

microprocessor controlled prosthetic knees

functionality across ADLs, incorporate hydraulics for smooth gait and rapid response to changing surfaces, battery powered
good for higher level pts but heavier and more expensive

powered knee systems

primarily military, concentric quads power for stand

osseointegration

implant pin into distal bone, risk of infection but offers more control
specified protocol you must follow