Unit 4 Prosthesis
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Transcript of Unit 4 Prosthesis
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UNIT 4
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Syllabus
PROSTHETIC AND ORTHOTIC DEVICES
Hand and arm replacement different types
of models, externally powered limb
prosthesis, feedback in orthotic system,
functional electrical stimulation, sensory assist
devices.
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Amputation
Amputation is theintentional surgicalremoval of a limb orbody part or thetraumatic loss of a limb.
As a surgical measure,it is used to control painor a disease process inthe affected limb, suchas malignancy organgrene.
In some cases, it iscarried out onindividuals as apreventative surgery forsuch problems.
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Types of amputation
leg
amputation of digits
partial foot amputation
ankle disarticulation
below-knee amputation(transtibial)
knee-bearing amputation(knee disarticulation)
above knee amputation(transfemoral)
Van-ness rotation
hip disarticulation
arm
amputation of digits
metacarpal amputation
wrist disarticulation
forearm amputation(transradial)
elbow disarticulation
above-elbow amputation(transhumeral)
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Reasons for amputation
Amputation isperformed for thefollowing reasons:
to remove tissue thatno longer has anadequate blood supply
to remove malignant
tumors because of severe
trauma to the body part
The goal of allamputations is twofold:
To remove diseased
tissue so that thewound will heal cleanly.
To construct a stumpthat will allow the
attachment of aprosthesis or artificialreplacement part.
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Although over 90% of
limb loss is "acquired",
up to 4% is congenital
(present at birth).
Of all the amputations
performed:
up to 90% are due to
vascular disease(circulation problems),
especially in people
with diabetes, but also
in non-diabetic
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While over 90% of
amputations due to
vascular disease involve
the lower limb, nearly70% of amputations
due to trauma involve
the upper limb.
The remaining ~10% are
needed, either after
limb trauma or as part
of the treatment forbenign or malignant
limb tumours.
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Complications of amputation
Joint deformity
Haematoma formation
Necrosis Wound opening from poor healing
Phantom limb syndrome
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A large proportion ofamputees (50-80%)experience thephenomenon ofphantom limbs.
They feel body partsthat are no longerthere.
These limbs can itch,ache, and feel as if theyare moving.
Some scientists believeit has to do with a kindof neural map that thebrain has of the body,which sends
information to the restof the brain about limbsregardless of theirexistence.
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Phantom sensations
and phantom pain may
also occur after the
removal of body partsother than the limbs.
e.g. after amputation of
the breast, extraction of
a tooth (phantom tooth
pain) or removal of aneye (phantom eye
syndrome).
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What is a prosthesis?
A prosthesis is an
artificial part of the
body that is custom
made and used in placeof the part that has
been lost.
An orthopedic
prosthesis is an internal
or external device that
replaces lost parts orfunction of the
neuroskeletomotor
system.
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Factors to consider when choosing prosthetic
components
Amputation level andresidual limb strength
Contour of the residuallimb
Health status
Physical status (ie, balance,strength) and fitness level
Effects of peripheral
vascular disease anddiabetic nephropathy,which may cause unstableresidual limb volume
other neurologic deficits(ie, stroke)
Sensorimotor deficitscaused by peripheral nervedysfunction
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Expected function and needs of the
prosthesis
Patient's vocation (for example, desk job vs
manual labor)
Patient's avocational interests (ie, hobbies)
The cosmetic importance of the prosthesis
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Acute postsurgical phase
The major issues in this phase are adequate
wound healing, pain management, the
administration of soft and rigid dressings for
limb shaping and exercises and to improvestrength and mobility.
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A skin desensitization program consists
of the following
Gentle tapping andmassage (with awashcloth) on the distalportion of the residual
limb Scar mobilization and
massage to preventexcessive scar formation
from causing the softtissues and skin to adhereto underlying bone
Edema control
The application ofpressure to the distalaspect of the residual
limb to prepare the limbfor weight acceptance
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A rigid, removable dressing may be used over
the residual limb during this phase
The rigid dressing servesthe following functions:
Aids in edema control andleads to rapid residual limb
shrinkage Promotes healing by
providing protection andpreventing edema
Desensitizes the limb
Prevents residual limbtrauma
Reduces wound pain
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Lower Limb Prosthesis
Loss of lower limb
causes :
Loss of Structural
support for the upperbody in standing
Along with complex
joint articulations and
muscular motor system
involved in walking
Apart from this ,
multimode sensory
feedback is lost ,
pressure sensors on thesole of the foot
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Length and force sensors in the muscles
And position sensors in the joints which closed
the control loop around the skeletomotor
system.
The body also has lost a significant percentage
of its weight and unbalanced.
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Lower Extremity Prosthesis
Components
The major components of a lower extremity
prosthesis are the socket (with or without a
socket liner)
a suspension system
interposed joint components (as needed)
a shank (pylon)
and a prosthetic foot.
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The socket
The socket serves as the
interface between the
residual limb and the
prosthesis.
It must not only protect
the residual limb but
must also appropriately
transmit the forcesassociated with
standing.
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The preparatory socket
can be created by using
a plaster mold of the
residual limb as atemplate
The preparatory
(temporary) socket will
likely need to be
adjusted several timesas the volume of the
residual limb stabilizes.
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Some prosthetic
manufacturing facilities
use computer-assisted
technology to map theresidual limb,
manufacturing a socket
directly from that data.
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patellar tendon-bearing (PTB) socket
The most common
socket used in a
transtibial amputation
is a patellar tendon-bearing (PTB) socket
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TSB
An alternative socket
design for transtibial
amputees is the TSB
socket that is used withan elastomeric liner
system.
When used with gel
liners, the TSB socket is
believed to distribute
pressures moreuniformly within the
socket
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The suspension mechanism
Need:
Every prosthesis
requires some type of
suspension system tokeep it from falling off
the residual limb.
Self-suspension of the
socket
Suction suspension
Suspension device orharness equipment
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The suspension mechanism
Suspension can be
achieved by a variety of
methods:
Suspension device orharness equipment :
includes belts, cuffs,
wedges, straps, and
sleeves.
Self-suspension of the
socket - This makes use
of the anatomic shape
of the residual limb(Syme or knee
disarticulation).
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Suction suspension :
Methods of creating
suction suspension
include the use of anappropriate suction
socket design, of a gel
suspension liner.
A bi ti f th t h i l
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A combination of these techniques also
can be used.
Standard suction is a
common suspension
choice for transfemoral
prostheses.
It employs a total-
contact, form-fitting,
rigid or semi rigid
socket with a 1-way airvalve in the distal end
that allows air to be
expelled after the
socket is donned.
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When air is driven outof the end of the
socket, a small negative
pressurestrong
enough to suspend thesocket on the residual
limbdevelops inside
the socket.
The socket's intimate fit
creates a seal between
the skin of the residual
limb and the socket.
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This form of suspension
allows excellent
proprioceptive feedback
and is lightweight.
One disadvantage of
the suction socket is its
inability to tolerate
much weight or volumefluctuation.
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A total elastic
suspension (TES) belt, a
single-axis knee with
extension assist,endoskeletal
components, and an
energy-storing foot
(anterior view).
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Lateral view with flexed
knee.
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Auxiliary suspension options for the patient with a
transfemoral amputation.
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Silesian belt The Silesian belt fastens
to the socket laterally,above the greatertrochanter, and wrapsaround the opposite
iliac crest. Because it does not
control rotation verywell, people using thistype of suspension belt
often have difficultywith internalrotation, especially ifthe residual limb isfleshy.
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TES(TOTAL ELASTIC SUSPENSION)
The TES belt is morecommonly used todaythan the Silesian beltand aids in rotational
control. It slips over the outside
of the prosthetic socketand surrounds the waistabove the iliac crest to
provide suspension.
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TES
The TES belt is made from the neoprene
material .
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SUCTION SUSPENSION SYSTEM
Patients with a
transfemoral or
transtibial amputation
may utilize the gelliner suction system,
which uses a gel
elastomeric liner.
The liner rolls onto the
residual limb and is
then inserted and
locked into the socket.
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SUCTION SUSPENSION SYSTEM
This suspension system
can reduce shear
between the residual
limb and the socket,and minimizes pistoning
of the residual limb in
the socket.
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SUCTION SUSPENSION SYSTEM
Heat buildup, skin problems, and decreased
proprioception can be drawbacks to this
suspension system
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Pelvic belt and band
A single-axis hip joint is
integrated into the
lateral socket wall and
pelvic band to controlrotation and is used for
weak hip adductors or
short residual limbs
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TRASFEMEORAL
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Auxiliary suspension options for patient with
a transtibial amputation.
Knee joint
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j
The prosthetic knee must fill the following 3functions:
Provide support during the stance phase ofambulation
Produce smooth control during the swing phase
Maintain unrestricted motion for sitting and
kneeling The prosthetic knee can have a single axis with
a simple hinge and a single pivot point, or it mayhave a polycentric axis with multiple centers ofrotation.
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TYPES OF KNEE
The manual-locking knee
The hydraulic knee
Polycentric knee
The hydraulic-based Otto Bock C-Leg
The weight-activated, or safety knee
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The manual-locking knee provides the most
stability, but the gait is awkward and energy
consuming.
Polycentric knees are heavy, costly, and
require high maintenance.
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The hydraulic knee
The hydraulic knee (pneumatic or oil) allowsfor cadence (tempo) variance.
This design uses a piston in a fluid-filledcylinder that accommodates the swing phaseof the patient's gait.
The knee is heavy, costly, and requires highmaintenance.
Th h d li b d Ott B k C
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The hydraulic-based Otto Bock C-
Leg The hydraulic-based
Otto Bock C-Leg (Otto
Bock Health Care,
Minneapolis, Minn)provides several
benefits over purely
mechanical knee
systems.
These microprocessor-
controlled knees
improve upon the
timing of the hydraulicand pneumatic knees
Th h d li b d Ott B k C
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The hydraulic-based Otto Bock C-
Leg The patient can
ambulate at greater
speeds with optimal,
biomechanically correctsymmetry while
expending less energy.
Most importantly, the
user can safely walk
step over step up and
down stairs.
Th h d li b d Ott B k C
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The hydraulic-based Otto Bock C-
Leg The built-in battery lasts
anywhere from 25-40hours, which meansthat it can support a full
day of activity.
The recharge can be
performed overnight
or while traveling in a
car (via a cigarettelighter adapter).
Th i h i d f k
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The weight-activated, or safety knee
The safety knee canaccommodate up to 20of kneeflexion, produces
friction, and preventsbuckling.
It allows ambulation on
uneven surfaces.
The safety knee is a
common initial
prosthetic knee for
geriatricpatients, persons with
extreme weakness, and
patients with poor hip
control
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The pylon and ankle
The pylon is a simpletube or shell thatattaches the socket tothe terminal device.
Pylons have progressedfrom simple, staticshells to dynamicdevices that allow axialrotation and that
absorb, store, andrelease energy
The pylon can be an
exoskeleton (soft foam
contoured to match the
other limb andcovered with a hard,
laminated shell) or an
endoskeleton (an
internal, metal framewith cosmetic soft
covering).
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The pylon and ankle
The ankle functionusually is incorporatedinto the terminaldevice.
A separate ankle jointcan be beneficial inheavy-duty industrialwork or in sports suchas mountain climbing,
swimming, and rowing.
However, theadditional weight of aseparate joint requiresmore energy
expenditure and greaterlimb strength to controlthe additional motion.
Th l d kl
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The pylon and ankle
P th ti f t
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Prosthetic feet
The 5 basic functions of the prosthetic footare as follows:
Provide a stable, weight-bearing surface
Absorb shock Replace lost muscle function
Replicate the anatomic joint
Restore cosmetic appearance
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Nonenergy-storing feet
Non
energy-storing
feet include the solid-
ankle/cushioned-heel
(SACH) foot and the
single-axis foot.
The single-axis foot
adds passive plantar
flexion and dorsiflexion,
which increase stability
during stance phase
and smooth gait
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Energy-storing feet
The energy-storing feet
are the multiaxis foot
and the dynamic-
response foot.
The multiaxis foot adds
inversion, eversion, and
rotation to plantar
flexion and dorsiflexion
It handles uneven
terrain well and is a
good choice for the
individual with a
minimal-to-moderate
activity level
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The dynamic-response foot is the top-of-the-
line foot and is commonly used by young
active individuals and athletic individuals with
amputations
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Lower limb prosthetics
SACH (single axis
composite heel) foot,
Seattle light foot
(energy storing footwith Delrin keel),
Carbon Copy II (energy
storing foot with carbon
keel).
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Lower limb prosthetics.
Seattle Light Foot
(energy storing foot
with Delrin keel).
The space between 1st
and 2nd toe, which
allows patient to wear
toe strap sandals