Gait, Equipment and AD Flashcards
initial contact (heel strike)
the instant that the foot of the lead extremity strikes the ground
knee extensors (quads) are active at HS through early stance to control small amount of knee flexion for shock absorption
ankle DF decelerate the foot, slowing the PF from heel strike to foot flat
loading response (foot flat)
the first period of double supper immediately after initial contact until the contralateral leg leaves the ground
gastroc/soleus muscles are active from foot flat through mid stance to eccentrically control forward tibial advancement
midstance
the contralateral limb leaves the ground; BW is taken and advanced over and ahead of the supper limb
-period of single limb support
hip, knee and ankle extensors are active t/o stance to oppose antigravity forces and stabilize the limb
- hip extensors control forward motion of the trunk
- hip abductors stabilize the pelvis during unilateral stance
terminal stance (heel off)
the last period of single limb support that begins with heel rise and continues until the contralateral leg contacts the ground
peak activity of PF occurs just after heel off to push off and generates forward propulsion of the body
pre-swing (toe off)
the 2nd period of double support from IC of the contralateral limb to lift off of the support limb
hip and knee extensors may contribute to forward propulsion with a brief burst of activity
initial swing (acceleration)
the 1st portion of the swing phase from toe off of the reference limb until misdoing
forward acceleration of the limb during early swing is achieved through the brief action of quads
by misdoing the quads are silent and pendular motion is in effect
hip flexors aid in forward propulsion
midswing
the portion of the swing phase from max knee flexion of the reference extremity to a vertical tibial position
foot clearance is achieved by contraction of the hip, knee flexors and ankle DF
terminal swing (deceleration)
the portion of the swing phase from a vertical tibial position of the reference limb to just prior to IC
hamstrings act during late swing to decelerate the limb in preparation for IC
quads and ankle DF become active in late swing to prepare for IC
pelvic motion
the pelvis moves forward and back (transverse pelvic rotation)
forward rotation occurs on the side of the unsupported or swing extremity; mean rotation= 4deg
WB /stance limb rotates 4 degress (total of 8 deg)
the pelvis moves up and down on the swing side (lateral pelvic tilt): 5 deg; controlled by hip abductors
- high point at mid stance
- low point during double limb support
pelvics moves side to side 4cm, follows the stance limb
cadence
of steps/minute
mean cadence= 113 steps/min
step measures
length
time
width:
- normal 1-5 inches
velocity
walking speed
rate of motion in any direction
distance/time
average=82m/min (3mi/hour)
energy cost of walking
average oxygen rate for comfortable walking= 12 mL/kg x min
metabolic cost of walking: avg 5.5 kcal/min on level surfaces
trunk and hip deviations in stance
lateral trunk bending
-weak glut med - trendelenburg
backward trunk lean
- weak glut max
- difficulty ascending stairs
forward trunk lean
- result of weak quads (decreases flexor movement at the knee)
- hip and knee flexion contractures
excessive hip flexion
- weak hip extensors
- tight hip and/or knee flexors
limited hip extension
-tight/spastic hip flexors
limited hip flexion
- weak hip flexors
- tight extensors
abnormal synergistic activity (stroke)
- excessive hip adduction combined with hip and knee extension, PF
- scissoring or adducted gait pattern
antalgic gait (painful gait)
- stance time is abbreviated on the painful limb that results in an uneven gait pattern
- the uninvolved limb has a shortened step length since it must bear weight sooner than normal
knee impairments in stance
excessive flexion
- weak quads (buckles, wobbles)
- knee flexor contracture
- difficulty descending
- forward trunk bend to compensate
hyperextension:
- weak quads
- PF contracture
- extensor spasticity (quads and/or PF)
ankle/foot impairments in stance
toe first (at IC)
- weak DF
- spastic or tight PF
- shortened leg
- painful heel
- positive support reflex
foot slap
- weak DF or hypotonia
- compensated with stoppage gait
foot flat:
- weak DF
- limited DF ROM
- immature gait pattern (neonatal)
excessive DF with uncontrolled forward motion of the tibia (calcaneus gait):
-weak PF
excessive PF (equinus gait)
- spastic/contractured of PF
- poor eccentric contraction and advancement of tibia
supination
- spastic invertors
- weak evertors
- pes varus
- genu varum
pronation
- weak invertors
- spasticity
- pes valgus
- genu algum
toes claw
- spastic toe flexors
- hyperactive plantar grasp reflex
inadequate push off
-weak PF
-decreased PF ROM
pain in forefoot
trunk and hip impairments in swing
insufficient forward pelvic rotation (pelvic retraction): (stroke)
- weak abdominal muscles
- weak flexor muscles
insufficient hip and knee flexion
-weak hip and knee flexors
circumduction: (abd and ER)
- weak hip and knee flexors
hip hiking (QL action): -compensatory response for weak hip and knee flexors or extensor spasticity
excessive hip and knee flexion (steppage gait):
- compensatory response to shorten the leg
- result of weak DF
abnormal synergistic activity (stroke)
-excessive hip and knee flexion with abduction
knee impairments in swing
insufficient knee flexion:
- extensor spasticity
- pain
- decreased ROM
- weak hamstrings
excessive knee flexion:
- flexor spasticity
- flexor withdrawal reflex
ankle/foot impairments in swing
foot drop (equines) -weak or delayed contraction of DF or spastic PF
varus or inverted foot:
- spastic invertors (anterior tib)
- weak peroneals
- abnormal synergistic pattern
equinovarus
- spastic of post tib and/or gastro
- developmental abnormality
ambulatory aides
canes
crutches
walkers
wheelchairs
to use ambulatory aids, patients must be able to elevate the body using their UEs
-shoulder depressors (lower trap, pec major, lats)
CANES: indications measurement types gait
Indications:
- widen BOS to improve balance
- provide limited stability and unweighting (can unload forces on involved extremity by 30%)
- relieve pain, antalgic gait
Measurement:
- 20-30 deg of elbow flexion
- measure from greater trochanter to a point 6 inches to the side of the toes
Types:
- wood or aluminum (adjustable with push pin)
- standard, SPC
- quad cane: 4 contact points with ground provides increased stability but slows gait
- –SBQC- useful for stairs
- –LBQC- doesn’t fit on stairs
Gait:
-held in opposite hand as involved LE; advance together
Crutches
- indication
- measurement
- types
Indications:
- increase BOS
- prode mod degree of stability (lat)
- relieve WB on LEs
Measurement:
- 20-30 deg of elbow flexion
- standing pt: subtract 16 inches from height OR measure from a point 2 inches below axilla to a point 6 inches in front and 2 inches lateral to the foot
- if supine: measure axilla to a point 6-8 inches lateral to the foot
- forearm crutches: cuff should cover proximal third of the forearm- 1-1.5 in below elbow
Types:
1- axillary crutches: provide increased UE WB over forearm crutches
*prolonged leaning on axillary bar can result in vascular and/or nerve damage (axillary A/radial N)
2-forearm (Lofstrand) crutches:
-slightly less stability but increased ease of movement (frees hands)
3- forearm platform crutches: allow WB on forearm
crutch tips: provide suction, minimize slippage
3 point gait
both AD and involved leg are advanced together followed by uninvolved leg
2 point gait
1 AD and opposite leg move together followed by opposite AD and leg
allows for natural arm and leg motion during gait, and provides good support and stability from 2 opposing points of contact
4 point gait
slow gait pattern- 1 AD followed by opposite leg, then opposite AD and opposite leg
max stability with 3 points of support while 1 limb is moving
WALKERS
- indications
- types
- measurement
Indications:
- widen BOS
- provide increased lateral and ant stability
- can reduce WB on 1 or both LEs
Negative features:
- no reciprocal arm swing
- increased fwd posture
Types:
- folding
- rolling: 2 or 4
- stair climbing
- reciprocal walkers
- hemi walker
Measurements:
- 20-30 deg elbow flexion
- 6 inches to lateral foot
bariatric gait pattern with walker
may include increased hip abduction and rotation, decreased knee flexion, pronated feet and difficulty weight shifting
body weight support and motorized treadmill
initially support set at 40% BW and progressively lowered
> 55% contraindicated- interferes with gait cycle- unable to achieve flat foot during stepping
starts with speeds 0.6 and progress to normal (2.6 mph)
wheelchair seat
standard sling seat
- hips slide forward and thighs adduct/IR
- posterior pelvic tilt
insert or contour seat
- creates stable, firm sitting surface
- wood/plastic padded with foam
- improves pelvic position (neutral)
- reduces sacral sitting
seat cushion:
- distributes WB pressures
- prevents pressure ulcers
- prolongs sitting times
- pressure-relieving, contoured foam cushion: dense, layered foam
- pressure-relieved fluid/gel or combo (fluid/gel plus foam)
- pressure-relieved air
- adds measurements to determine back height
**pressure relieving push ups 15-20 min
wheelchair back
support to the mid scapular region is provided by most standard sling back
- lower heights to increase functional mobility
- high height necessary for patients with poor trunk stability or extensor spasms
insert or contour backs: improve trunk extension and upright alignment
lateral trunk supports: improave trunk alignment for patients with scoliosis, poor stability
wheelchair measurements
6 key measurements:
1- seat width
- hip width plus 2inches
- excessive width: can’t reach wheels, can’t fit through doorways,
- narrow width: pressure/discomfort on lateral pelvis/thighs
2- seat depth
- posterior butt to popliteal fossa minus 2-3inches
- too short: fails to support tight
- too long: compromise posterior knee circulation or promote kyphotic posture and posterior tilting/sacral sitting
3- leg length/seat to footplate length
- bottom of shoe to popliteal fossa minus seat cushion
- excessive length: sacral sitting
- too short: uneven weight distribution on thigh and excessive weight on ischial seat
4-seat height
-add 2 inches to leg length
5-arm rest heigh
- seat to just below elbow at 90deg plus 1 inch
- too high: shoulder elevation
- too low: fwd leaning
6- back height
- seat to lower angle of scapula, midscap, or top of shoulder (based on need) PLUS cushion
- added height increases difficulty traveling with chair
community mobility with w/c
ascending ramps: lean forward, use short strokes, move hands quickly
descending ramps: grip loosely, control descent
wheelies:
- move hands back on rims and pul forward abruptly and forcefully; head and trunk are moved fwd to keep from going back
- tips further back when pushed forward
- tips upright when wheels pushed back
orthosis function
- correct malalignment and prevent deformity
- restrict or assist motion
- transfer load to improve function
- reduce pain
major impairments requiring LE orthoses
congenital defects:
- CP
- spina bifida
- long bone malformations
- hemophilia
- osteogenesis imperfecta
- club foot
- charcot marie tooth
diseases:
- stroke
- muscular dystrophy
- arthritis
- MS
- legg calve perthes
- poliomyelitis
trauma:
- SCI
- fracture
- brain injuries
- muscle, cartilage or tendon rupture
foot orthoses
internal: insert closer to the foot and more effective at correcting alignment
external: modifications to the shoe don’t reduce shoe volume and can be worn as patient walks
Soft inserts: reduce areas of high loading, restrict forces and protect painful or sensitive areas of the feet
- metatarsal pad: posterior to MT heads, move pressure from MT heads to shafts; allows more push off in weak or inflexible feet
- heel insert: heel spurs, plantar fasciitis
Longitudinal arch supports: prevent depression of subtalar joint and correct pes planus
- scaphoid pad: supports longitudinal arch - pes planus
- Thomas heel/medial heel wedge: extended anteriorly along medial side to support arch
Rearfoot posting: alters STJ from IC to LR (dynamic control w/out eliminating motion)
- varus (medial) wedge: limits/controls eversion of calcaneus and IR of tibia after IC
- valgus (lateral wedge): controls calcaneus and STJ that are excessively inverted and supinated at IC (genu valgum)
Forefoot posting: alter MT alignment
- medial wedge: for forefoot varus
- lateral wedge: for forefoot valgus
Heel lifts (heel platform)
- accommodates LLD (up to 3/8 inch)
- accommodates DF limitation
Rocker/MT bar: located proximal to MT heads
- improves weight shift onto MTs
- metatarsalgia
Rocker bottom:
-builds up the sole over the MT heads and improves push off in weak or inflexible feet
AFO
consists of a shoe attachment, ankle control, uprights and proximal leg band
shoe attachment:
- foot plate
- stirrup (solid- fixed permanently to the shoe)
ankle controls
- free motion: med/lat stability, allows free motion in DF/PF
- solid ankle: no movement; indicated with severe pain or instability
- limited motion: allows motion to be restricted in 1 or both directions (anterior/DF stop or posterior/PF stop)
- DF assistance:
- —spring A
- —posterior leaf spring - prevents drop foot
- varus or valgus correction straps (T straps)
uprights and attachments (bands or shells)
- conventional AFOS- metal
- molded AFOs- light weight (contraindicated with changing leg volume)
- specialized AFOs (patellar tendon bearing brim; tone reducing orthosis- applies constant pressure to spastic or hypertonic muscles)
KAFO
KNEE CONTROLS:
1: hinge joint: provides med/lat and hyperextension control while allowing flexion/ext
- offset- hinge placed posterior to WB line to assist in extension, and stabilize knee in early stance; may flex inadvertently when ascending ramps
2: locks
- drop ring lock: locks knee in extension (a retention button may be added to hold the rink lock up)
- paw lock with bail release:
3: knee stability
- sagittal stability : achieved by bands/straps that provide a posteriorly directed force ; anterior bands can be pretrial or supra patellar for counterforce (may interfere with sitting)
- frontal plane controls: control genu varum/valgum
THIGH BANDS:
- provide structural stability to orthosis
- may have ischial WB or quadrilateral brim that reduces the WB though the limb
SPECIALIZED KAFOs
1: Craig-scott: paraplegia T9-12 lesions
- shoe attachment, reinforced foot plates, BiCAAL ankle joints set in slight DF, pretrial band, pawl knee locks with bail release and single thigh bands
2: Oregon orthotic system: a combo of plastic and metal components allows for triplanar control
specialized KO
articulated KO: controlls knee motion and provides added stability
- post-surgery KO- protects repaired ligaments
- functional KO- worn long term
- examples: lenox hill, proAM, canAm, don joy
Swedish knee cage: provides mild control for excessive hyperextension of the knee
patellar stabilizing braces
- improve patellar tracking, alignment
- lateral buttress (often felt) or strap positions patella medially
- a central patellar cutout may help positioning and minimizes compression
neoprene sleeves
- provide compression, protection and proprioceptive feedback
- provide little stabilization
- retains body heat, increases circulation
specialized HO
usually used for Legg-Calve-Perthes disease (avascular necrosis o the hip) in which hip is held in abduction and IR for proper centralization of the femoral head in the acetabulum (Toronto hip orthosis or Scottish Rite orthosis)
HKAFO
contains a hip joint and pelvic band added to KAFO
hip joint: typically metal hinge
- controls for abduction, adduction and rotation
- controls for hip flexion when locked, typically with a drop ring lock; a locked hip restricts gait pattern to either swing to or through
pelvic attachments: a leather covered, metal pelvic band
- attaches HKAFO to pelvis b/w greater trochanter and iliac crest
- adds to difficulty in donning/doffing
- adds weight and increases overall energy expenditure during gait
specialized THKAFOs and RGO
contains a trunk band added to a HKAFO
reciprocating gait orthosis (RGO): utilizes plastic molded solid ankle orthoses with locked knees, plastic thigh shells, a hip joint with pelvic and trunk bands
- the hips are connected by steel cables which allow for a reciprocal gait pattern (4 or 2 point)
- when the patient leans on the supporting hip, it forces it into extension, while the opposite leg is pushed into flexion
- allows limb advancement
corset
- provides abdominal compression
- increases intraabdominal pressure
- assists respiration in individuals with SCI
- relieves pain in LB disorders; SI support (pregnancy)
lumbosacral orthosis (LO)
control or limit lumbosacral motions
lumbosacral flexion, extension, lateral control orthosis (LS FEL) (knight spinal): includes pelvic and thoracic bands to anchor orthosis with 2 posterior uprights, 2 lateral uprights and an anterior corset
plastic lumbosacral jacket: provides max support by spreading forces over a larger area,
-more cosmetic but hotter
thoracolumbosacral orthosis (TLSO)
controls or limits thoracic and lumbosacral motions
thoracolumbosacral flexion, extension control orthosis (TLS FE) (Taylor brace): includes components of a LS FEL with the addition of axillary shoulder straps to limit upper trunk flexion
plastic thoracolumbosacral jacket: provides max support and control of all motions
- used for SCI
- allows for early mobilization out of bed and functional training
Jewett (TLSO): limits flexion, but encourages hyperextension (Lordosis)
-used for compression fractures of the spine
cervical orthosis (CO)
controls or limits cervical motion
soft collar: min levels of control (cervical pain, whiplash)
four-poster orthosis:
2 plates (occipital and thoracic) with 2 anterior and 2 posterior posts to stabilize the head
-used for mod levels of control in people with cervical fracture/SCI
halo orthosis:
- attaches to the skull with screws
- 4 uprights connect from the halo to a thoracic band or plastic jacket
- provides max control for patients with cervical fracture/SCI
- allows for early mobilization out of bed and functional training
minerva orthosis:
- a rigid plastic appliance that provides max control of cervical motion
- uses a forehead band without screws
scoliosis orthoses
used to prevent the lateral curve from increasing
Milwaukee orthosis:
- cervical, thoracic, lumbosacral orthosis (CTLSO)
- used to control scoliosis
- molded plastic pelvic jacket with 1 anterior and 2 posterior uprighs extended to a superior neck or chest ring
Boston orthosis (TLSO)
- low profile molded plastic orthosis for scoliosis
- can be worn under clothes
- used for mid thoracic or lower scoliosis curves
resting splint
“cock up splint”
anterior/palmar splint
wrist and hand in functional position
wrist in neutral or 12-20 deg extension
fingers supported and phalanges slightly flexed
thumb in partial opposition and abduction
patients with RA, carpal fractures, Colles’ fracture, CTS, stroke with paralysis
dorsal wrist splint
frees the palm for feeling and grasping by use of grips that curve around and over the 2nd and 5th MC heads, allowing for attachment of dorsal devices (rubber bands) to make it a dynamic device
airplane splint
positions arm in 90 deg ABD, and 90 deg elbow flexion
used to immobilize the shoulder following fracture or injury when strapping to the chest is undesirable (burns)
wrist driven tenodesis orthosis
“finger hinge orthosis”
assists the patient in using wrist extensors to approximate the thumb and forefingers (grip) in the absence of active finger flexion (facilitates tenodesis grasp in patient with quadriplegia (usually C6)
orthotic gait deviations: lateral trunk bending
patient leans towards orthotic side during stance
possible causes:
- KAFO medial upright is too high
- excessive abduction of hip joint of HKAFO
- insufficient shoe lift
anatomical causes:
- hip pain
- weak or tight abductors on orthotic side
- short leg
- poor balance
orthotic gait deviations: circumduction or vaulting
possible causes: -locked knee -excessive PF -weak hip flexors or DFs -
orthotic gait deviations: anterior trunk bending
leans forward during stance
possible causes:
- inadequate knee lock
- weak quads
- hip or knee flexion contracture
orthotic gait deviations: backward trunk lean
possible causes:
- inadequate hip lock
- weak glut max
- knee ankylosis
orthotic gait deviations: hyperextended knee
possible causes:
- inadequate PF stop
- inadequate knee lock
- poor for of calf band (too deep)
- weak wuads
- loose knee ligaments
- extensor spasticity
- pes equinus
orthotic gait deviations: knee instability
excessive knee flexion during stance
possible causes:
- inadequate DF stop
- inadequate knee lock
- knee and/or hip flexion contracture
- weak quads
- insufficient knee lock
- knee pain
orthotic gait deviations: foot slap
possible causes:
- inadequate DF assist
- inadequate PF stop
- weak DFs
orthotic gait deviations: toes first
possible causes:
- inadequate DF assist
- inadequate PF stop
- inadequate heel lift
- heel pain
- extensor spasticity
- pes equinus
- short leg
orthotic gait deviations: flat foot
possible causes:
- inadequate longitudinal arch support
- pes planus
orthotic gait deviations: pronation
possible causes:
- transverse plane malalignment
- weak invertors
- pes valgus
- spasticity
- genu valgum
orthotic gait deviations: supination
possible causes:
- transverse plane alalignment
- weak everters
- pes varus
- genu varum
orthotic gait deviations: excessive stance width
possible causes:
- KAFO height of medial upright is too high
- HKAFO hip joint aligned in excessive abduction
- knee is locked
- abduction contracture
- poor balance
- sound limb is too short
adhesive tape purposes
- limit ROM
- support injured body segment
- secure protective devices (felt, foam, gel or plastic padding)
- keep dressings and bandages in place
- preventative support for a joint at risk
- realign position and reduce pain (McConnell tape)
- may enhance proprioception
prosthesis=
replacement of a bod part with an artificial device
an artificial limb
levels of amputation
transmetatarsal
ankle disarticulation (Syme’s)
transtibial (below knee)
-20-50% of tibia spared
knee disarticulation
transfemoral (above knee)
35-60% of femur spared
hip disarticulation
hemipelvectomy
hemicorporectomy: amp of both LEs and pelvis below L4-5
transradial amp (below elbow)
elbow disarticulation
transhumeral amp (above elbow)
shoulder disarticulation
prosthetic sockets
- functions
- types
- socks
custom molded to the residual limb; total contact desired, with the load distributed to all tissues; assists in circulation and provides max sensory feedback
functions to:
- contain the residual limbs
- provide a means to suspend the prosthetic limb
- transfer forces from the prosthesis to the residual limb
Selective loading:
- pressure tolerant area are built up to increase loading (build ups for tendon bearing areas)
- while pressure-sensitive areas are relieved to decrease loading (relief for bony prominences, nerves, tendons)
Types
- most common: socket made of hard plastic with a soft polyethyliene foam liner
- flexible sockets- made up of soft, pliable thermoplastic material within a rigid frame
Socks:
- used in every suspension system except suction
- provide a soft interface between the residual limb and the socket
- minimize shear forces
- changing sock thickness can aid in accommodating changes in residual limb volume
partial foot prostheses
restores foot length
simulates the shape of the foot and assists in walking
protects the amputated residual limb
bottom may have a cover rocker bar to assist in push off
below knee prostheses
consists of a foot-ankle assembly, shank, socket and suspension
foot-ankle assembly:
functions to absorb shock at heel strike, PF in early stance
simulates MTP hyperextension in late stance
non-articulating feet
SACH foot (solid ankle cushion heel)
- most common, durable, easy to use,
- contains energy absorbing cushion heel and internal wooden keel that limits sagittal plane motion, primarily PF
- permits very small frontal and transverse motion
- assists in hyperextension of the knee (knee stability) in stance
SAFE foot (solid ankle flexible endoskeleton):
- flexible, similar to SACH
- allows more nonsagittal plane motions (prescribed for more active individuals)
Seattle foot
- slightly flexible plastic keep bands at heel contact; heavier than SACH
- stores energy and recoils in late stance releasing energy for springy termination to stance
Flex foot (spring-lite foot)
- leaf spring shank (not a foot)
- used with endoskeletal prosthesis
- long band of carbon fiber originates directly from the shank
- stores energy in early stance for later use during push off
- for more active individuals
articulating feet
single-axis foot
- most common articulating foot that permits PF and DF as well as toe break action
- does not allow med/lat motion
- maybe for people with bilateral transtibial amps
multi-axis foot:
- moves slightly in all planes to aid in walking on uneven terrain and slopes
- heavy and less durable
prosthetic shank
- provides leg length and shape
- transmits BW from socket to foot
exoskeletal shank: usually made of wood with plastic laminate finish that can be colored, very durable
endoskeletal shank: central aluminum or rigid plastic pylon covered with foam rubber and an external stocking
-offers improved cosmoses and ease in adjustments
patellar tendon bearing sockets
patellar tendon bearing (PTB)
- total contact socket that allows for moderate loading over patellar tendon
- assists in venous circulation
- provides tactile feedback
“reliefs” or pressure sensitive areas of transtibial residual limb include:
anterior tibia
anterior tibial crest
fibular head and neck
fibular nerve
“build ups” or pressure-tolerant areas of the typical transtibial residual limb include:
patellar tendon
medial tibial plateau
tibial and fibular shaft
distal end - rare
BK suspension
used to hold the socket onto the residual limb when NB is occurring (during swing)
Supracondylar cuff: leather strap that buckles over the femoral condyles and permits the user to adjust the snugness of the suspension easily
Supracondylar suspension:
- medial and lateral walls of the socket extend up and over the femoral condyles
- a removable medial wedge assists in donning/doffing
- more cosmetic
- provides increased med/lat stability
Supracondylar/suprapatellar socket suspension:
- similar to SC but with a high anterior wall
- assists in suspension of short residual limbs
Thigh corset suspension:
- hinged joint with metal uprights attached to a thigh corset
- provides larger surface for WB
- used for people with sensitive skin on the residual limb
- the knee joint allows for knee control (locks)
- pistoning may be a problem
transfemoral prosthesis
consists of a foot ankle assembly, shank, knee unit, socket and suspension device
knee unit
enables the wearer to bend the knee when sitting and during ambulation
Single axis: permits knee motions around a fixed axis
- knee flexion needed during late stance and swing, sitting and kneeling
- knee locks in extension for IC and LR
Polycentric system (multiple axis)
- changing axis of motion allows for adjustments to the center of knee rotation
- more stable than single axis joints
- complex, not widely used
Friction devices: control knee motions and provide resistance to pendular motion of the knee
Friction devices of the knee unit
constant friction:
-continuous resistance is provided by a clamp that acts on the knee mechanism
-friction device can be easily adjusted by screws
usually prescribed for older people who don’t vary gait speeds
Variable friction:
- resistance can be regulated to the demands of the gait cycle
- at early swing, high resistance is needed to prevent excessive heel rise
- during midswing when the leg swings forward, friction demands are minimal
- in late swing friction is increased to prevent terminal swing impact
Hydraulic knee units (fluid controlled) or pneumatic knee units (air controlled):
- adjusts resistance dynamically to the walking speed
- prescribed for younger, active people
- heavier, more complicated
- increased maintenance and cost
knee stabilization in extension is achieved by:
prosthetic alignment:
- the knee center is aligned posterior to the TKA line
- a knee aligned farther posterior will be very stable (won’t flex easily)
- may be prescribed for short residual limbs
- an unstable knee may occur if the knee falls anterior to the TKA line
Manual lock:
-for those who require a constantly locked knee (weakness of hip extensors, difficulty with clearing the leg during swing) can be controlled by shortening the total prosthetic limb length ~1cm
Friction brake:
-a device that increases friction at mid stance to prevent knee flexion, but permits smooth knee motion through the rest of gait
Extension aid:
-an external elastic strap or internal coiled spring that assists in terminal knee extension during late swing
AK socket
quadrilateral socket:
- most common AK socket, quadrilateral in shape
- contains a broad horizontal posterior shelf for seated of the ischial tuberosity and gluteals
- the medial wall is the same height as the posterior wall while the anterior and lateral walls are 2-3 inches higher
- a posterior directed force is provided by the ant and lat walls to ensure proper seating
- Scarpa’s bulge: built up area on anterior wall to distribute forces across the femoral triangle
Reliefs for AKA prosthesis
- adductor longus tendon
- hamstring tendons
- sciatic nerve
- glut max
- rectus femoris
Pressure sensitive ares of the typical transfemoral residual limb:
distolateral end of femur
pubic symphysis
perineal area
pressure tolerant areas of the typical transfemoral residual limb
ischial tuberosity
gluteals
lateral sides of residual limb
distal end-rare
AK suspension
suction suspension:
- max contact
- air is pumped out through a 1 way air release valve
strap suspension:
- adjustable, readily accommodates volume changes
- Silesian bandage: strap that anchors the TKA prosthesis by reaching around the pelvic ; controls rotatory motions
Hinge suspension:
- hinged hip joint attached to a metal/leather pelvic band, anchored around the pelvis
- adds control for med/lat stability of the hip
- reduces trendelenburg gait
- extra weight/bulky
prosthetic gait deviations with AKA: circumduction and vaulting
possible causes:
- long prothesis
- locked knee
- small or loose socket
- inadequate suspension
- foot PF
- abduction contracture
- poor knee control
prosthetic gait deviations with AKA: abducted gait
possible causes:
- crotch or medial wall discomfort
- longprosthesis
- low lateral wall or malalignment
- tight hip abductors
prosthetic gait deviations with AKA: lateral trunk bending during stance
possible causes:
- low lateral wall
- short prosthesis
- high medial wall
- weak abductors
- abductor contracture
- hip pain
- short amp limb
prosthetic gait deviations with AKA: forward flexion during stance
possible causes:
- unstable knee unit
- short ambulatory aids
- hip flexion contracture
prosthetic gait deviations with AKA: lumbar lordosis during stance
possible causes:
- insufficient support from anterior or posterior walls
- painful ischial seat WB
- hip flexion contracture
- weak hip extensors or abdominals
prosthetic gait deviations with AKA: high heel rise
during early swing the heel rises excessively
possible causes:
- inadequate knee friction
- too little tension in the extension aid
prosthetic gait deviations with AKA: terminal swing impact
possible causes:
- insufficient knee friction or too much tension in the extension aid
- patient fears the knee will buckle
- forcefull hip flexion
prosthetic gait deviations with AKA: swing phase whips
at toe off the heel moves either medially or laterally
possible causes:
- socket is rotated
- knee bolt is rotated
- foot is malaligned
prosthetic gait deviations with BKA: excessive knee flexion during stance
possible causes:
- socket may be aligned too far ahead or tilted anteriorly
- PF PF bumper is too hard and limits PT
- high heel shoes
- knee flexion contracture
- weak quads
prosthetic gait deviations with BKA: inadequate knee flexion during stance
possible causes:
- socket may be aligned too far back or tilted posteriorly
- PF bumper or heel cushion too soft
- low heel shoes
- anterodistal discomfort
- weak quads
prosthetic gait deviations with BKA: lateral or medial thrust at midstance
lateral thrust- foot is inset too much
medial thrust- foot is outset too much
prosthetic gait deviations with BKA: drop off or premature knee flexion in late stance
possible causes:
- socket is set too far forward or excessively flexed
- DF bumper is too soft resulting in excess DF of foot
- prosthetic foot keep too short
- knee flexion contracture
prosthetic gait deviations with BKA: delayed knee flexion during late stance
patient feels as if walking uphill
possible causes:
- socket is too far back or lacks sufficient flexion
- DF bumper is too stiff causing PF
- prosthetic foot keep too long
