Upper limb prosthesis

Rabia Mustafa shah
KING EDWARD MEDICALUNIVERSITY

Prior to antiseptic surgery and
antimicrobial drugs many amputations
of the limb were caused by fractures .
Although amputations of the upper limb
may be presumed to have occurred
from very early times the first record of
an artificial device used for an upper
limb amputation is thought to have
come from the second Punic war 218-
201 BC

6000 to 10,000 major amputations of
upper limb occur every year in united
states .
Upper limb amputations with hand loss
is extremely devastating , upper limb
traumatic amputations occur twice as
frequently as traumatic amputations of
lower limb

1- trauma
Trauma is undoubtedly the largest producer of upper limb
amputations and can include fractures , electrical ,
thermal burns , frostbite and machine injuries
2 - Tumor
Significant improvements in cancer detection and treatment
in recent decades are believe to have resulted in gradual
decline in upper limb amputations
3- Disease
Major limb amputations have been reported for vascular
complications secondary to infections produced by drugs
injected into back of hand or into wed spaces of digits.

Partial hand amputations may be
considered to be any number of
amputations involving any or all of
digits or the radial or ulnar border of
the hand.

The wrist disarticulation level
amputation is usually performed
when the partial hand residual limb
is without thumb or fingers and
when the motions afforded by the
wrist and palm of the hands has
virtually nothing to oppose it.

According to Taylor s’ a long trans
radial amputation is defined as 8 to
10 inches from the centre of lateral
Epicondyle to the end of the residual
limb

. Amputation at the level of elbow
disarticulation is performed for a
variety of reasons.

The long or standard trans
humeral amputation is defined as
one of 50 to 90% of the length of a
normal humeurs and is usually the
level of choice for amputation
above the elbow .

Shoulder disarticulation may be
defined as any amputation of the
arm from approximately 30% of the
humeurs through the shoulder joint

Shoulder disarticulation is usually
performed because of tumor . In the
forequarter the clavicle and scapula
are usually sacrificed as well as the
entire length of the humeurs and the
rest of the arm.

1. Body powered prosthesis
2. Electrically powered prosthesis
(Myoelectric prosthesis)
3. Hybrid prosthesis
4. Activity specific prosthesis

 Body-powered prostheses represent a
common type of prosthesis.
 These body-powered devices are durable
, often weigh less than their electrical
counterparts.
 Their mechanics depend on
proprioceptive feedback through the
harness system.
 Disadvantages of a body-powered
prosthesis revolve around the restrictive
nature of its design. The harness, which is
required for functionality and suspension,
limits the range of motion and functional
envelope of the individual.

 The functional envelope refers to the
range of motion around a person’s body
in which he or she can operate the
prosthesis without limiting or affecting
the function of the contralateral limb.
 When a patient uses a prosthesis outside
the functional envelope, it becomes
difficult to operate a terminal device
without having to use gross body
motion.
 Long-term use of a body-powered
prosthesis can accelerate shoulder
issues and anterior muscle imbalances
and lead to nerve entrapment within the
contralateral axilla.

The electrically powered
prosthesis provides more grip
force and enhanced functional
envelope, while reducing or
eliminating the overall harnessing
necessary with a body-powered
prosthesis.

Many different designs are
available. The term Myoelectric
commonly is associated with
electrical prostheses even though
other electrical control modalities.
These include Myoelectrodes,
switches, slider-type input devices
( linear, transducers, or
potentiometers) and force-sensing
resistors (or touch pads).

 Myoelectrodes collect and filter
surface electromyogram signals
generated through muscle
contractions and convert those
signals into a form that can influence
electrical motors.
 Muscle sites are based primarily on
the level of amputation and socket
design. It typically include the
anterior deltoid, biceps, wrist flexors,
posterior deltoid, infraspinatus, teres
major, triceps, and wrist extensors.

Any muscle that plays a reverse
action or postural role should be
evaluated carefully to avoid
unwanted muscle contraction.
A common example would be use
of the trapezius for a Myoelectric
control site. Another area of
concern is using a muscle for
Myoelectric control that is in close
proximity to cardiac muscle.

A variety of motions are possible
through different kinds of switching
devices.
 Many switches are activated by
pulling a cable or pressing a
button.
Switches are designed to perform
multiple functions and come in
many presentations. Harness-type
switches rely on some type of pull
to move the switch.

 Depressing the switch with a chin,
phocomelic finger, residual limb, or
contralateral hand moves another
type of switch, often referred to as a
push switch.
 A push switch may be placed distal
to the axilla on the inner side of the
person’s forearm on a transradial
level amputee and activated by
humeral abduction.
 More advanced switches are found
in multiposition types of applications

 Slider-type input devices convert distance,
speed, or force into proportional movement
of a prosthetic limb.
 As a result, feedback enhances
proprioception.
 Slider-type input devices come in two
varieties , the linear type of potentiometer is
a input device that translates linear motion
or into proportional function. Examples of
this input device is the Linear Potentiometer.
 The second variety is the force-sensing type
, such as Motion Control.

 Some electrical prostheses employ a force-
sensing Resistor . These types of input
devices consist of a force-sensing resistor
matrix.
 The amputee activates the force-sensing
resistor by moving the shoulder complex, a
phocomelic finger, residual humeral neck, or
other residual anatomy.
 It reduces the incidence of phantom limb pain
 Special care is require in force-sensing
resistors , Improper installation results in
premature failure and greater expense and can
produce uncomfortable perspiration,
moisture, and uneven shear force.

 The hybrid prosthesis combines the
benefits of body-powered and electrical
styles.
 This type of design allows simultaneous
control of the elbow and terminal device
and most commonly is simplified with the
use of a body-powered elbow , electrical
terminal device and wrist.
 In some cases, an amputee may choose a
fully conventional system with an
electronic wrist, but not usually as the first
option.

 The last prosthetic option is that of the activity-
specific prosthesis. This type of prosthesis is
designed for a specific activity where more
typical prosthetic options are not sufficient.
 Patients use this custom device successfully
for activities such as gardening, weightlifting,
and skydiving.
 These special prostheses allow patients to
resume meaningful activities and help life
‘‘return to normal’’ in a tangible way. These
devices also physically show to the amputee’s
family and friends that he or she is capable of
doing many diverse activities

Current advances in upper limb
technology can be divided into five
categories,
 Treatment protocol
 Prosthetic interface
Microprocessor technology
 Terminal devices

This process involves fitting the patient
within 2 to 3 days, then following the
patient consistently through
occupational therapy
 This close interaction allows clinicians
to evaluate better the interface,
component choice , use and
therapeutic issues.

 A major determining factor of whether a patient will
use a prosthesis comfortably is the design of
prosthetic interface.
 One type of interface method is beginning to be used
more frequently in upper limb prosthetics the roll-on
suction suspension liner.
 This design helps provide a positive type of
suspension, while eliminating suspension
harnessing, which allows the incorporation of more
functional control harnessing.
 Roll-on liners can be used with all type of
prostheses, including Myoelectric prostheses

A suction-type design is used to
stabilize the residual limb at the
contours of Epicondyle.
The transradial anatomic
contoured socket contours the
muscles of the residual limb and
maintains a suspension that
incorporates the benefits of the
mediolateral and anterior-posterior
contours of the residual limb.

Currently, microprocessor technology
influences terminal device control wrist
and elbow functions, and other options,
such as shoulder joint locking and
unlocking, remote on-and-off control,
and sensory feedback.
The microprocessor enhances input
characteristics to produce the desired
output optimizing prosthetic function
and increasing overall ease of use.

Two breakthroughs in terminal
device technology have had a
significant impact on the future of
electronic prostheses.
 The first is the introduction of
water/dust resistant components.
These new components function
better in the real world and have
fewer moisture-related problems.
 The second major development is
that of speed.

Upper limb prosthesis

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Upper limb prosthesis