FUNDAMENTAL

SEATING

PRINCIPLESPower Point PDF

Bengt EngströmPhysiotherapist

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Starting with a few questions!

How do you want your clients to sit?

What kind of problems do you see?

How are your clients sitting?

How long time are your clients sitting?

What can you change to improve sitting?

What kind of wheelchairs do you work with?

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A healthy upright

position is a goal.Why are so many

clients collapsing?”Standard” can be quite dangerous !

What influences what?ERGONOMICS

ERGONOMICS

An office workplace...

WHEELCHAIR-

ERGONOMICS

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LONGTERM SITTING

What may become a problem?

l PRESSURE - TOO HIGH or NOT ENOUGH

l SHEAR - TOO STRONG SOFT TISSUE DEFORMATION

l MUSCLES - HIGH TENSION, FATIGUE or INACTIVITY

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RESULTING IN

l PHYSICAL INJURY and DECREASE OF FUNCTION!

l POOR TISSUE FLEXIBILITY (CONTRACTURES)

Not sitting

properly…?

WHY?

What is the

reason?

Hmm…why?

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SOLUTION

WHATdo we see?

WHYis it so?

HOWcan we make a

change?

CAUSEProblem?

Potential?!

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SEATING

HOW is a physical

change achieved?

Product

DESIGN!

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Pressure

Shear

Gravity

Softness…

Contours...

Angles…

Materials...

Measures...

Influence

The Body

System

+ TIME!

Changing the forces by moderating

NORMAL BEHAVIOUR IN SITTING(compensations)

MOVING FORWARD ON THE SEAT

ASYMMETRY OF THE TRUNK

LEG and FOOT POSITIONS CHANGE

ARM POSITIONS CHANGE

COMBINATIONS - MANY!!

HEAD POSITION CHANGES

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LEGS AND ARMS IN SITTING

MOVING THE FEET...

LEGS CROSSED...

KNEES APART or TOGETHER...

ARMS AGAINST THE CHEST...

ARMS LIFTED UP and BACK...

EXTENDING or BENDING LEGS...

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LOGICAL COMBINATIONS!

IMPORTANT FACTORS IN SITTING

STABILITY - find a ”stop”

FREEDOM - for motion

CONTROL - static-dynamic muscle activity

TIME!

COMFORT

COMFORTABLE?

l muscle tension, joint position...

l pressure, shear, temp., humidity...

l communication - head & hands

EQUILIBRIUM!!

Time Tolerance Level !

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…is a feeling! (like or not like)

…your senses inform you!

THE SPINAL COLUMN IN SITTING

SYMMETRY OF THE SPINAL COLUMN

The core for freedom to move the trunk.

ASYMMETRY OF THE SPINAL COLUMN

When the trunk moves and for trunk stability

SPINAL COLUMN MOVEMENTS

Forward Bending, Rotation, Side Bending

(Scoliotic...), Extension and - Combinations!

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DESIGNING IT or RE-DESIGNING IT!

Never forget!

If this is your work, YOU are a designer!

We dictate how the user’s body is influenced when

changing Softness, Contours, Angles and Measures.

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BALANCING THE “TOWER” FOR THE HEAD

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The Center of Mass of the Head

Active

and

passive

stabilize

Upright and well

balanced position

Tendency in a

balance position

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THE BASE POSTURE

Task A Reach for a glas on the table.

Task B Scratch your left lower leg.

Task C Take an apple on a plate just behind you.

Task D Bend forwards and ush the wheelchair with your arms.

Move to

Return

SEATING ADAPTATION GOAL

STABILITY

FREEDOM

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CONTOUR

FOLLOW BODY CONTOUR

PRESSURE DISTRIBUTION

AND LATERAL STABILITY

CONTOUR

PREVENTION OF

FORWARD SLIDING AND

POSTERIOR ROTATION

PELVIS and HIP AREA

IMPORTANT SEAT CUSHION FEATURES

PELVIC STABILITY

Pressure

from seat

surface

Pressure

from

back

support

CONTOUR

Pressure Distribution

Pelvic Stability

CONTOUR

Functional Leg Support -

for Trunk Stability

Slide Prevention

CONTOUR

Comfortable Leg

Support - stabilizing

Pelvis and Trunk

PELVIS & HIPS LEGS / THIGHS

Basic Shape of a Seat Cushion / Surface

Slide Prevention

PELVIS & LEGS

s

Slide Prevention

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SEAT-ON-BACK INFLUENCE

Functional thigh contact against the front area of

the seat stabilizes (presses) the trunk/chest

against the middle to upper area of the backrest.

A functionally stabilized pelvis

stabilizes the thorax (downwards).

Comfortable and safe pressure in the buttock area is a must to

prevent sliding and shifting of the pelvis (due to discomfort or pain).

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GOAL: Pelvic stability and trunk freedom.The seat lower under the pelvis combined with

forward angle, frees the trunk in direction forward

and makes it also easier to extend the trunk.

GOAL: Pressure distrubution and trunk stability.Lower under the pelvis (knees higher than hips) increases

the collapse of the trunk. A sacral support stabilizes!

COMBINATION SEAT CONTOUR and SEAT ANGLE

GOAL: Creating more trunk stability.Knees still higher than the hips means a stronger

trunk collapse and sacral support is highly

necessary to stabilize the (weak) trunk!

NEUTRAL

1-2 POSITION OF THE PELVIS / THE SACRUM

By allowing room behind the pelvis for placing it and the Sacrum in space, the base for L5 is decided for an optimal alignment of the rest of the vertebras of the Spinal Column.

With a stable pelvis it is easier to maintain the trunk in an upright position - the vertical collapse of the spine is more or less blocked.

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This is the first and second KEY-ADAPTATION!

3 EXTENSION OF THE THORACIC SPINE

Make room for a personal extension of the trunk and support comfortably against the Thorax, behind and sides.

This balances the weight of the upper trunk and, when assisted by gravity, its contact against the back support is maintained. It stabilizes the pelvis and prevent a negative, posterior rotation.

Placing the chest places the neck, head and shoulders in space.

This is the third KEY-ADAPTATION!

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4 CONTOURING FOR THE LOW BACK

The size of the Lumbar Lordosis is dictated by the position of the sacrum in space AND the extension of the thoracic spine (the position of the chest in the sagital plane).

Follow the Curve of the Lumbar Lordosis.

Observe, not too much pressure!

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The fourth KEY-ADAPTATION!

Supporting in the midline and

from the sides against

the Pelvis and Thorax

stabilizes the chest and spinal

column, making it easier to

keep the trunk symmetrically

upright.

SYMMETRIC STABILITY OF THE TRUNK

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= Key support areas

Contact Contact

Supporting in the midline, just

below* the scapulas,

the”Scapula Triangle”, stabilizes

the trunk while allowing the upper

trunk and the shoulders more

funtional freedom**.

This adaptation also improves the

head’s overall freedom for easier

movement and control. Even better

when the head is well balanced!

* For users who need a high back support.

** The top of the back should be arched, higher in

the middle and lower on the sides.

TRUNK STABILITY / SHOULDER & HEAD FREEDOM

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!!

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CONCLUSION OF THE PRINCIPLES

BACK SUPPORT

SEAT

Copyright 2001

Pressure Distribution

for Pelvis Positioning

and Stability

Comfortable Leg

Support for

Pelvis Positioning and

Trunk Extension

Pelvic Stability

Preventing

Forward Sliding

on the Seat

Stabilizing Pelvis and Sacrum

Placing Pelvis and Sacrum

Extension of the Spine and

Thorax-Support

Contouring for the Low Back

SEATSEAT

BACKRESTBACKREST

Wheelchair Education since 1990 www.engstromconcept.com

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