prosthetic descriptions and types

1. SUBMITTED TO : DR. SHABNAM
SUBMITTED BY : MANOJ PUROHIT
170171720001

2. PROSTHESIS
• A prosthesis is a device that is designed to
replace, as much as possible, the function or
appearance of a missing limb or body part.
• It is a device that is designed to support,
supplement, or augment the function of an
existing limb or body part.

3. Functional prosthesis generally can be divided into
the following two categories
1. Body-powered prosthesis - Cable controlled
2. Externally powered prosthesis – Electrically
powered
•Myo-electric prosthesis
•Switch-controlled prosthesis

4. Body-powered prosthesis (cables) usually are of
moderate cost and weight.
They are the most durable prostheses and have
higher sensory feedback.
A body-powered prosthesis is more often less
cosmetically pleasing than a myoelectrically
controlled type is, and it requires more gross limb
movement.
Body Powered Prosthesis

5. Externally Powered Prosthesis
Prosthesis powered by electric motors may provide
more proximal function and greater grip strength,
along with improved cosmesis, but they can be heavy
and expensive.
Patient-controlled batteries and motors are used to
operate these prosthesis. Currently available designs
generally have less sensory feedback and require
more maintenance than body-powered prosthesis.
Externally powered prosthesis require a control
system. The two types of commonly available control
systems are myoelectric and switch control

6. A typical example of a transradial (below-elbow) prosthesis
includes a voluntary opening split hook, a friction wrist, a
double-walled, plastic-laminate socket, a flexible elbow
hinge, a single–control-cable system, a triceps cuff, and a
figure-8 harness.
TYPICAL COMPONENTS BODY-POWERED
PROSTHESIS
• Socket
• Suspension
• Control-cable system
• Terminal device
• Components for any interposing joints as needed according
to the level of amputation

7. The socket of an upper extremity prosthesis typically has a
dual-wall design fabricated from lightweight plastic or
graphite composite materials.
In this design, a rigid inner socket is fabricated to fit the
patient's residual limb and the second, outer wall is added,
designed to be the same length and contour as the opposite,
sound limb.
Comfort and function are directly tied to the fit of the inner
socket. An alternative approach parallels the rigid frame,
flexible liner approach sometimes used in lower extremity
socket fabrication.
The inner socket is fabricated from flexible plastic materials
to provide appropriate contact and fit. Surrounding the
flexible liner, a rigid frame is utilized for structural support
and for attaching the necessary cables and joints as needed.
The windows in the outer socket allow movement, permit
relief over bony prominences, and enhance comfort.
Socket

8. The suspension system must hold the prosthesis
securely to the residual limb, as well as
accommodate and distribute the forces associated
with the weight of the prosthesis and any
superimposed lifting loads.
Suspension systems can be classified as follows:
• Harnessed-based systems.
• Self-suspending sockets.
• Suction sockets.
Suspension

9. The major function of the hand that a prosthesis
tries to replicate is grip (prehension).
The 5 different types of grips are as follows
Precision grip
Tripod grip
Lateral grip
Hook power grip
Spherical grip
TERMINAL DEVICE

11. MYOELECTRIC PROSTHESIS
A myoelectric prosthesis uses signals or potentials from
muscles through electromyography, within a persons stump.
The signals are picked up by electrodes on the surface of the
skin which activates a battery-driven motor that operates a
prosthetic component, like the finger.
Control of the motor regulates the extent or speed of the
prosthesis, such as elbow flexion or extension, or opening
and closing of the fingers of the terminal device

12. ADVANTAGES
• Use of natural muscle stimuli.
• More accurate control with less energy expenditure.
• Eliminates the shoulder harness.
• Decreased body movement to control prosthesis.
• The myoelectric prosthesis provides more mobility,
pinch force, and cosmetic appearance than body powered
prostheses.

13. DISADVANTAGES
• They are very expensive
• In the event of a breakdown, it needs very skilled technical
backup to repair. Also they need servicing on a regular basis
• Component operation is noisy and slow.
• The energy source is from a battery, which would have to be
recharged regularly.
• Lack of proprioceptive feedback as from the harness in body
powered systems.
• It is heavy, It cannot control fine rhythmic and fast
movements.
• There is poor control of co-contracting muscles and poor
motor control.
• Myoelectric components get dysfunctional in water or
around magnetic or electronic fields.
• The cosmetic/protective gloves get dirty very easily

15. BIOMECHTRONIC HAND
 The objectives of the work of an bio mechtronic is to
develop an artificial hand which can be used for
functional substitution of the natural hand and for
humanoid robotics application.
 The artificial hand is designed for replicating sensory
motor capabilities of human hand.
 Commercially available prosthetic devices, such as
Otto bock sensor hand, as well as multifunctional
hand designs are far from providing the grasping
capabilities of human hand.

16.  In prosthetic hands active bending is restricted to two or
three joints which are actuated by single motor drive
acting simultaneously on the metacarpo-phalangeal
joints of the thumb, of the index and of the middle
finger while other joints can bend only passively.
 This limitation in dexterity is mainly due to the very
basic requirement of limited size and weight necessary
for prosthetic applications.
 On the other hand robotics have achieved high level
performance in grasping and manipulation, but they
make use of large controllers which are not applicable in
prosthetics or humanoid robotics where it is necessary
to provide the user with wearable artificial hand.

17. BIO MECHATRONIC DESIGN
 The main requirements to be considered since the
very beginning of artificial hand design are the
following : natural appearance, controllability,
noiselessness, lightness and low energy consumption.
 These requirements can be fulfilled by implementing
an integrated design approach aimed at embedding
different functions within a housing closely
replicating the shape, size and appearance of human
hand.
 This approach can be synthesized by the term
biomechatronic design.

18. ARCHITETECTURE OF THE BIOMECHATRONIC HAND
 The biomechatronic hand will be equipped with three
finger to provide a tripod grasp : two identical finger.
 The finger actuator system is based on two micro –
actuators, which drive the MP and the PIP joints
respectively ; for cosmetic reason ,both actuator are
fully integrated in the hand structure: the first in the
palm and the second within the proximal phalange.
 The grasping task performed by the biomechatronic
hand is divided in the subsequent phases:
1. Reaching and shape-adapting phases;
2. Grasping phase with thumb opposition