Overview of Assistive Technologies for Mobility and Positioning

Increasing the Conformance of Academia towards Rehabilitation Engineering
i-CARE
586403-EPP-1-2017-1-PS-EPPKA2-CBHE-JP
web | icare.alazhar.edu.ps
eMail | icare@alazhar.edu.ps
This project has been co-funded with support from the European Commission. The European Commission support for the production of this publication does not constitute endorsement of the contents which reflects the
views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein
PROJECT
PARTNERS
Assistive Technology for Physiotherapy (AMSP 43**)
Orthotics
Dr. Suad Ghaben
Lecturer @ Physiotherapy Department, Faculty of AMS
Al Azhar University – Gaza, Palestine

Contents ..
 Overview of the foundation theories for sensory-motor rehabilitation.
 Overview of the Human Activity Assistive Technology Model “HAAT”, and the Rehabilitation model.
 Physical Therapy Management in Assistive technologies: ,,,,,
 Overview of Assistive technologies designed for mobility: principles of design, criteria of prescription,
and The Best Practice Guideline from PT perspective.
⚫ Walking aids: cane, crutches and walker
⚫ Wheelchair: types, design, measurements, seating principles Fitting, and custom training
⚫ Rehabilitation Robotics
⚫ Overview of different types of Assistive technologies designed for positioning (Seating technologies, and
orthotics)
 Overview of Assistive technologies designed for environmental interaction.
 Overview of Assistive technologies designed for augmentation and alternative communication.
 Overview of Assistive technologies designed for education.
 The socioeconomic aspects of AT .
 Standardization within AT field, and service delivery of AT,
 How to Establish new track related to “rehab tech” in physiotherapy practice
 Professionalism and ethical standards in Assistive Technologies
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Module Developed as Part of (i-CARE) project Curricula Development Activities (WP3) || Co-funded by EU – Erasmus+ Program
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Overview of ATs designed for mobility
and positioning ,,,
❑ Walking aids: cane, crutches and walker
❑ Wheelchair: types, design,
measurements, seating principles Fitting,
and custom training
❑ Overview of different types of Assistive
technologies designed for positioning
(Seating technologies, and orthotics)
❑ Rehabilitation Robotics

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Orthotic devices,,
❑ It is an external device design to apply, distribute or remove
forces to or from the body in a controlled manner to
perform one or both the basic function of control body motion
❑ Orthosis is an external appliance worn to:
❑ Correct mal-alignement and prevent deformity, thus maintain
anatomical and functional position
❑ restrict or assist motion or
❑ transfer load from one area of the body to another, so to improve
function
❑ Reduce pain
❑ The older term, brace, is a synonym.
❑ A splint connotes an orthosis intended for temporary use.

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Splint,,
❑ An orthopedic device use to immobilize and
support the body part.
❑ A temporary device that may serve the same
function of orthosis.
❑ Material generally not as durable; able to
withstand prolonged use.
❑ Brace,,
❑ Brace is a device fitted to the body part
which is weak and injured to give support. Eg:
Knee brace for OA.

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Classification of orthosis ,,
Orthosis
Articular Non-
Articular
Location
Direction
Purpose
Type

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Types of orthosis according to body regionlocation,,
❑ LOWER-LIMB ORTHOSES
❑ Shoes
❑ Foot Orthoses
❑ Ankle–Foot Orthoses
❑ Knee–Ankle–Foot Orthoses
❑ Hip–Knee–Ankle–Foot Orthoses
❑ Trunk–Hip–Knee–Ankle–Foot Orthoses
❑ Alternative Lower-Limb Orthoses
❑ TRUNK ORTHOSES
❑ Corsets
❑ Lumbosacral andThoracolumbosacral Orthoses
❑ CERVICAL ORTHOSES
❑ SCOLIOSIS ORTHOSES

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Types of orthosis according to body region ,,
❑ UPPER-LIMB ORTHOSES
❑ Shoulder & Arm orthosis
❑ Elbow Orthosis
❑ Wrist Orthosis
❑ Hand Orthosis

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Orthotic Considerations ,,
1. Cost
2. Energy efficiency
3. Cosmesis
4. Temporary versus
permanent
5. Dynamic versus static
6. Encourage normal
Movement

General Principles of Orthosis,,
1- General Structure:
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General Principles of Orthosis,,
2- Use of forces
Orthosis utilizes forces to limit or assist movements for example.
⚫ a. Rigid material spanning a joint prevents motion, e.g posterior tube
splint
⚫ b. A spring in a joint is stressed by one motion and then recoils to
assist, the opposite desired motion. E.g. leaf spring orthosis
 Other components,,
⚫ hinge,, provide free movement
⚫ pin: limit movement
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The spring-hinged ventral shell Ankle-
Foot Orthosis, including possible
adjustments using the hinge.
• The hinge allows:
• A, the stiffness to be varied towards
dorsal flexion and plantar flexion;
• B, adjustment of the alignment of the
ventral shell with respect to the foot;
• C, the range of motion to be varied,
although this is also dependent of the
spring inserted (stiffer springs allow
less range of motion).
• Figs adapted from Fior & Gentz.

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General Principles,,
3- Limitation of movement: Limiting motion may reduce pain.
4- Correcting a mobile deformity: a flexible deformity may be
corrected by an orthosis. Corrective forces must be balanced
according to principle of jordan.
5- Fixed deformity: if the fixed deformity is accommodated by an
orthosis, it will prevent the progression of deformity.
6- Adjustability: orthotic adjustability is indicated for children to
accommodate their growth and for patients with progressive or
resolving disorders.
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7- Maintenance and cleaning: the orthosis should be simple to
maintain and clean.
8- Application: the design should be simple for easy donning and
doffing.
9- Sensation: An orthotic device does not provide sensation, in fact it
often covers skin areas and decreases sensory feedback.
10- Gravity: Gravity plays an important role in upper limb orthosis,
especially in those joints where the heaviest movement masses are
present.
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11- Comfort: The Orthosis should be comfortable. Pressure should
be distributed over the largest area possible.
12- Utility: the Orthosis must be useful and serve a real purpose, a
well functioning opposite extremity is a major deterrent to the use of
an upper extremity orthosis as most activities can be performed with
the good hand.
13- Duration: Use only as indicated and for as long as necessary.
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14- If the orthosis does not add significance to their function, the
patients typically discontinue its use.
15- Cosmesis: Cosmesis is important especially in hand orthosis. A
functional but unsightly orthosis is often rejected if the patient values
appearance over function.
16- Appropriateness: it should allow joint movement whenever
appropriate
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Biomechanical Principles of orthosis,,
1. Three point pressure: (JORDAN’S Principle)
2. Four point pressure system
3. Mechanical Advantage
4. Direction of stress
5. Torque: the rotational moment across the joint?
6. Control of Line of action of ground reaction force
7. Control Normal force across the joint
8. Control axial Forces across a joint
9. Degree, Duration & Repetition of Stress

Three point pressure: (JORDAN’S Principle)
 PRINCIPLE OF JORDAN:
⚫ Most splint follow this principle to affect a joint motion
⚫ It is the basic mechanical principle of orthotic correction.
⚫ This system applies corrective or assistive force at the area
of deformity, the forces are implemented at the surface of
the orthosis through the skin and are transmitted to the
underlying soft tissues and bones.
⚫ To remain stable, the body has to have one point of
pressure (at the area of deformity or angulation) opposed
by two equal points of counter pressure in such a way
that F1 = F2 + F3
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Three point Pressure,,
 "The sum of the forces and the bending moments created is
equal to zero.“
 A single force is placed at the area of deformity; two additional
counter forces act in the opposing direction.
 During "quiet" standing, line of gravity (wt line) passes through:
⚫ posterior to hip joint
⚫ anterior to knee joint and
⚫ anterior to ankle joint
 Total contact:
⚫ “Pressure is equal to the total force per unit area.
• “P = force Area of application
⚫ The greater the area of a pad of an orthosis, the less force will be
placed on the skin.
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Three Point Pressure System

Four-point force systems,,
 Four-point force systems are applied in
orthotic design to achieve translational
control that prevents displacement of one
segment in relation to another.
 These are commonly seen in a knee brace
use to control tibial displacement in
relation to the femur for an anterior
cruciate ligament deficient knee.
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Four Point Pressure System

Mechanical Advantage ,,
 Splint incorporate lever system,
which incorporate forces, resistance,
axes of motion, and movement arm.
 Example:
⚫ Volar based wrist cock up splint here
for mechanical advantage forearm
length is made longer so splint has
better pressure distribution support
and comfortability.
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Direction of stress,,
 There are three direction of force to act:
1. Tension
2. Compression
3. Shear
 Tension occur when forces both are
acting on opposite direction.
 Compression occur when force acting in
same direction
 Shear force occurs when parallel forces
are applied in equal and opposite
direction.
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Torque,,
 It is biomechanical principle defined as rotational effect of mechanism.
 Torque is the production of the applied force multiplied by
perpendicular distance from the axis of rotation to the line of
application. Most important for dynamic splint.
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Torque,,
 If a Force does not act directly on the COM of an object it will rotate the object.
If a force does not act through the middle of a joint with another segment it will
change the angle of the joint.
 The force produces a Torque that is the size of the force times the length of
the lever arm (distance from the line of action of the force to the joint center).
 In normal human movement the moment created by an externally applied
GRF is balanced (for the most part) by an internally generated muscle force
which provides an opposing moment
 The orthosis control the rotational moment across a joint as it
surrounds the joint being influenced
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In this example the dorsiflexion moment created by the
anterior GRF is balanced by the planter flexors through
tension in the Achilles Tendon. This muscle has a fixed
lever arm

Ground Reaction Force,,
 (GRF) occurs when contact occurs with a support surface, it is equalling and
opposing the force due to body mass passing through the foot to the ground
surface.
 It should be noted that the ‘force due to body mass’ includes the momentum
and accelerations of body mass as well as just the effect of gravity on it. Hence
it is different and yet similar to the weight line.
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A: knee extension moment
created by GRF is balanced by
posterior joint capsule tension
B: knee flexion moment
created by GRF is balanced
by quadriceps contraction
C: greater knee flexion moment
created by GRF is balanced by
stronger quadriceps contraction

Moments created by GRF & balanced by Opposing Forces,,
 A: If the GRF is anterior to the knee then the GRF tends to extend the knee while the
posterior joint capsule tension normally resists, holding the knee in a neutral position.
 B: If the GRF happens to be just behind the knee, the GRF with the lever arm d2 flexes
the knee. In this situation the quadriceps must be active to prevent knee flexion.
 C: If the GRF is a larger distance behind the knee joint then there is a longer lever arm
(d3) from the line of action of the GRF to the joint center. This increases the magnitude
of the torque/moment (force times lever arm) tending to flex the knee. This increases
the requirement for the quadriceps, a stronger contraction of the quadriceps is needed.
 One aim of orthotic therapy for children with CP is to normalize the position and
timing of GRF movement as this will lead to normalized muscle activation patterns in
children. When the knee is in significant flexion this increases the energy consumed by
increasing the magnitude of required muscle contractions.
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Floor reaction ankle-
foot orthoses to control
knee flexion moment

Orthosis & GRF,,
 Orthotists can change the point of application of the GRF
through the design of an orthosis. By moving the foot into relative
plantarflexion the GRF is moved anteriorly, increasing the knee extension
moment.
 In practice, the biomechanical design principles of an AFO change the
body position and movement.
 Use of the biomechanical principles for orthoses should eliminate unsafe
pressure thus increasing comfort while applying forces to the human body
that improve the clinical circumstances for the user. An understanding of
biomechanics is important for orthotists and people referring to an
Orthotist as biomechanical principles are central to how an orthosis
works.
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Control of line of action of Ground Reaction Force,,
 This principle is only applicable to LE orthosis.
 As foot is placed on ground it experience GRF.
 As stance phase is from heel strike to toe off the force
and pressure applied is moving from heel to metarsal
head that is toe off.
 In normal “quite standing” joint line of gravity “LOG”
passes from posterior of Hip, anterior of knee, front of
ankle.
 “LOG” moves throughout gait cycle, and the GRF line
of action change too..
 Now due to some asymmetric movement this pattern
of GRF is altered so orthosis is needed for alignment
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Control of GRF line of action
 So, in this case orthosis management
would be moving the line of gravity to
center that is close to joint line. Which
can be achieved by modifying the limb
movement during gait.
 This is done in two way:
1. By altering angular relationship with
plantar surface of foot and floor
2. By altering the angular relationship with
most distal joint.
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Control line
of action of
LOG, GRF

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Orthosis to Control of GRF line of action,,,

Control Normal force across the joint,,
 Now two free body load carrying are shown in figure when are subjected
to ground reaction force are free to rotate the are maintained in extension
this is normal joint is maintained by capsule and ligaments. But in abnormal
joint we require orthosis to correct it.
 So, the role is to correct excessive translation movement. But this rotatory
creates anticlockwise moment now to balance this also is role of orthosis
 Thus a force system from R1 to R4 with rigid framework helps to maintain
translation and balance anticlockwise moment this is four point pressure
system.
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Control axial Forces across a joint,,
 In normal healthy individual load is carried through bony structures and
layers of articular cartilage which have immense strength to bear this
weight. Now due to some degenerative change the integrity of this
structure is lost which will cause excessive compression on joint.
 So, here come role of orthosis to offload the joint. This process of
offloading depends on two thing:
1. How the orthosis is fitted
2. Orthosis and body segment
interface
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Control axial force,,
1. The orthosis here is incorporated as rigid orthosis framework and
strapping it at the end of two limb segment which would divide the
force into half.
2. The second criteria is the transfer of load across skin and orthosis
solely depend on friction of orthosis and underlying skin.
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Stress; Degree, Duration & Repeatition,,
 Generally low stress can be tolerated for longer period of time,
whereas high stress over long period of time cause damage.
⚫ Therapist must remember the least stress is tolerated is skin. Skin
become ischemic if load increases.
⚫ Distribution of stress is most important for long term wearing of
orthosis(decrease pressure over the area)
 If repetitive stress is applied in moderate amount may lead to
breakdown and damage to skin, to avoid that traction must be
release to avoid unnecessary tension and well distributed pressure.
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Factors affecting response to orthosis,,
 Extrinsic factors:
⚫ Pressure.
⚫ Shear
⚫ Interface with the microenvironment
 Intrinsic factors: does not allow movement.
⚫ Tissue mechanics: the compressibility of the soft tissues influences
their susceptibility to the breakdown process; the more compressible
the tissues the more likely it is that blood vessels will be occluded.
⚫ Load transmission across the interface between the orthosis and the
⚫ tissues.
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The patient Orthosis interface,,
 The patient-orthosis interface may be defined as the junction between
the body tissues and orthosis. This is the support surface through
which forces are transmitted.
 When force is applied through an interface there will be some
deformation of both surfaces, depending on:
⚫ their relative thickness,
⚫ the relative shapes of the underlying rigid structures and
⚫ the level of the applied force.
 This leads to a progressive breakdown of that tissue and, in the case of
paraplegia with loss of sensation and the shift reflex; this is the basis for
the formation of a pressure sore.
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Functional Classification of orthosis,,
1. Supportive:
2. Functional
3. Corrective
4. Protective
5. Preventive
6. Strengthen
7. Relieve Pain
8. Weight relieving

Functional Classification of Orthosis,,
 Supportive: It stabilizes the joints
and supports the body in its
anatomical position,
⚫ e.g. Calipers (FO, AFO, KAFO,
HKAFO)
 Functional: It stabilizes the joint
and also makes up for lost function,
E.g. Foot drop splint in common
peroneal nerve palsy
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KAFO
AFO-Drop
foot splint
AFO-Drop

 Protective: To protect a part of the body during its healing. E.g. rigid
four post collar for fracture cervical vertebrae.
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 Prevent substitution of function: In a full length caliper,
substitution of hip flexors by Abductors or adductors of hip and
other similar trick movements are prevented.
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 Orthosis which strengthen certain group
of muscle E.g. Tenodesis Splint
⚫ Dynamic splint,,
⚫ Depends on the biomechanical principle of
the hand, tendinosis effect:
⚫ Tenodesis Splint is a device used to grasp
objects by C6-C7 quadriplegics who lack
finger movement but retain the ability to
extend their wrist.
⚫ The splint straps onto the user’s forearm,
hand, and fingers.
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Dynamic Tenodesis,,
 Dynamic Tenodesis is defined as the concept of
movement at one joint transmitting power to
an adjacent joint( usually distal)
⚫ As the wrist flexes , the extensor tendons tighten and the
flexor tendons relax, both actions serving to produce
extension of the MP joints.
⚫ The intrinsic tendons tighten with MP extension,
augmenting PIP extension The lateral bands & the ORL
are lax with PIP flexion and tighten with PIP extension.
The Tenodesis effect of the ORL can be demonstrated by
checking passive flexion of the DIP joint with the PIP joint
in flexion and extension
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 Relief of pain: e.g. Lumbosacral corset supports lower back,
preventing painful movement.
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 Prevent weight bearing: A weight relieving orthosis,
prescribed for conditions like fracture calcaneum will
take weight away from injured site into proximal site
like the patellar tendon bearing area.
⚫ The farther the point of force from the joint, the greater the moment arm
and the smaller the magnitude of force required to produce a given
torque at the joint.”
⚫ The greater the length of the supporting orthotic structure, the greater
the moment or torque that can be placed on the joint or unstable
segment.
 Ischial Weight Bearing (unweighting) KAFO-
⚫ Ischial containment or Quadrilateral style brims with high trimlines.
⚫ Generally used with paralytic limbs.
⚫ Not as effective with larger or obese individuals
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 Corrective: To correct deformities E.g. knee valgusvarus
deformity or Club foot boot in CTEV
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Types of orthosis,,
 Temporarily orthosis: Used for certain time after injury
or operation.
 Permanent orthosis: Used for ever when there is muscle
weakness, paralysis or deformity cannot be corrected.
 Static orthosis: does not allow movement.
 Dynamic orthosis: allows movement.
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MATERIALS,,
 An orthosis can be constructed from metal, plastic, leather, synthetic
fabrics, or any combination.
 Plastic materials are the materials most commonly used in the
orthotic industry.
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Indications and clinical implications,,
 To relief pain.
 To limit motion (immobilization after surgery, after traumatic injury, Compression #
management & Kinesthetic reminder to avoid certain movements).
 To correct deformity e.g. Scoliosis management
 To relieve symptoms of a disease by supporting or assisting the MSk & neural systems.
 To reduce axial loading, mechanical unloading
 To improve function in a certain segment of the body.
 Assist and improve movement and function
 Reduce muscle tone.
 Protect against injury.
 Provide proprioceptive feedback.
 Provide rest
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Contraindications,,
 Skin infections
 When the muscle power is very much affected by the weight of the
orthosis.
 In case of severe deformity which cannot be accommodated in the
orthosis.
 If it limits the movement at other normal joints
 Where the orthosis interferes grossly with clothing or limits other
functions
 Lack of motivation or other psychological problems
 Very young or old patients
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Disadvantages,,
 Loss of skin integrity due to compressive forces
 Weakening of axial muscles
 Increased movements at ends of immobilized segments
 Physical and psychological dependence.
 Osteopenia
 Lack of cosmesis
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Orthotic intervention ,,
1. Ensure continued proper fit
2. Donning/doffing orthosis
3. Implement progressive wearing schedule
4. Patient/caregiver teaching:
5. Skin Inspection
6. Care of orthosis
7. Mobility training with orthosis
8. Correct alignment permits effective function
1. minimizes movement between limb and orthoses (pistoning)
2. minimizes compression on pressure sensitive tissues

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❑ PhysicalTherapy Management &
Orthotics
❑ Pre-orthotic Examination
❑ Orthotic Prescription
❑ Orthotic Examination and Evaluation
❑ Facilitating Orthotic Acceptance
❑ Orthotic Instruction andTraining
❑ Final Examination and Follow-up Care

Pre-orthotic Examination,,
 Joint Mobility
 Limb length
 Muscle function
 Sensation
 Functionality if relatedother body region
 Psychological Status
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Orthotic Prescription,,
 Particular diagnosis
 Prognosis
 Lifestyle
 Cosmetics
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Orthotic Examination and Evaluation,,
 The therapist should examine the orthosis through analysis of
(1) effects and benefits in terms of improved function,
(2) practicality and ease of use and maintenance,
(3) fit and alignment, and
(4) safety during use of the device.
 It is imperative to determine whether the orthosis functions properly
before attempting to instruct the patient to use it
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Facilitating Orthotic Acceptance,,
 Clinic team management is valuable in fostering acceptance of the
orthosis by the patient.
 The team enables clinicians to join efforts to help the individual
achieve the maximum benefit from rehabilitation.
 Bringing the new wearer of an orthosis in contact with other users in
the physical therapy department can help the new patient recognize
that orthotic use is not a strange occurrence.
⚫ Peer support groups helpful for sharing concerns and anxieties,
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Orthotic Instruction and Training,,
 Orthoses are designed to provide the individual with a maximum of function with a
minimum of discomfort and effort.
 The therapist should examine the orthosis through analysis of
(1) effects and benefit in terms of improved function,
(2) movement while the patient wears the device,
(3) practicality and ease of use,
(4) fit and alignment, and
(5) safety during use of the device.
 No single instruction & training suits every orthosis, the Therapist should
instruct every patient for
⚫ Correct manner of donning the orthosis,
⚫ Developing standing balance,
⚫ Walking safely, and performing other ambulatory activities.
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Module Developed as Part of (i-CARE) project Curricula Development Activities (WP3) || Co-funded by EU – Erasmus+ Pr ogram
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Final Examination and Follow-up Care,,
 Prior to discharge, the patient and orthosis should be examined to
make certain that fit, function, appearance, and use is acceptable.
 Frequent follow up visits:
⚫ Monitor the individual’s function,
⚫ Reinforce skills taught in the intensive instruction and training program
⚫ Address any new problems the patient may present.
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Overview of Assistive Technologies for Mobility and Positioning

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