Handouts PC03 - International Seating Symposium

Instructions for ISS 2013 Pre-Conference Course PC3

Measuring Wheelchair Seated Posture and Seating Supports: A Practicum

Kelly Waugh, PT, MAPT, ATP Dr. Barbara Crane, PT, PhD, ATP/SMS

Handouts posted on ISS website include:

1. Course Agenda 2. PDF of Power Point lecture 3. Link to the Clinical Application Guide: http://at-partners.org/WheelchairSeating

The manual titled Clinical Application Guide to Standardized Wheelchair Seating Measures of the Body and Seating Supports, upon which this course is based, is a very large resource (over 300 pages); therefore you do not need to print it out as a “handout”. As an alternative, the following is recommended:

1. Download the PDF from the Assistive Technology Partners website, and bring the electronic PDF file with you on a laptop or tablet if at all possible.

• We will be dividing the class up into 10 groups; we are hoping that there will be at least one participant with a laptop in each group.

• We will project the relevant pages and measures onto the screen during the practicum; however, your learning experience will be enhanced if you are able to bring a laptop with you to the course. This will allow you to practice navigating through this large manual, and it will be easier to see and follow the written methodologies during the hands-on portions.

2. As an alternative to #1, you can print out the relevant pages of the guide, which are listed on the Course Agenda.

3. Please also bring the following if you have them:

• ½” metal tape measure • 180 degree goniometer without a large dial in the middle • Inclinometer (non-digital)

If you have any questions, please contact me by email:

[email protected]

Regards,

Kelly Waugh 2/19/13

Kelly Waugh, PT, MAPT, ATP AGENDA_Seating Measurement_ISS 2013.docx Page 1 of 2

Measuring Wheelchair Seated Posture and Seating Supports: A Practicum

Kelly Waugh, PT, MAPT, ATP & Barbara Crane, PT, PhD, ATP/SMS

ISS 2013 Pre-Conference Course PC3, 3/5/2013

Time Topic Handout/Measures 8:00am – 9:45am

Introduction to the Clinical Application Guide and Foundational Concepts

PDF of power point

9:45am – 10:00am

Relative Body Segment Angles, Demo

10:00 – 10:15am

Break

10:15am – 11:00am

Relative Body Segment Angles Practicum

Clinical Guide Ch. 2, pp. 44-54 Thigh to trunk angle Thigh to lower leg angle Lower leg to foot angle Thigh to pelvis angle

11:00am - 12:00pm

Relative Support Surface Angles

Clinical Guide Ch.3, pp.116-117, 122-127 Seat to back support angle Seat to lower leg support angle Lower leg support/foot support angle

12:00pm – 1:00pm

LUNCH

1:00pm – 2:00pm

Absolute Body Segment Angles

Clinical Guide Ch. 2, pp.80-85, 58-63, 100-102 Frontal Pelvic angle Frontal sternal angle Frontal trunk angle Sagittal pelvic angle Sagittal trunk angle Sagittal thigh angle Transverse thigh angle

2:00pm – 3:00pm

Absolute Support Surface Angles

Clinical Guide Ch. 3, pp. 130-132, 154-156, 164-165, 192-193 Seat sagittal angle Back support sagittal angle Head support frontal angle Lateral knee support transverse angle

3:00pm – 3:15pm

Break

3:15pm – 4:00pm

Linear Body Measures

Clinical Guide Ch. 4, pp.214-215, 223-225 Buttock/thigh depth Effective buttock/thigh depth Shoulder height Max sitting height

Kelly Waugh, PT, MAPT, ATP AGENDA_Seating Measurement_ISS 2013.docx page 2

4:00pm – 5:00pm

Linear Support Surface Measures

Clinical Guide Ch. 5, pp.279-290, 292, 316-319 Seat depth Effective seat depth Seat thickness Inferior thigh support thickness Medial thigh support height Pelvic contour height Back support length Back support height Seat surface to foot support Seat surface to floor height

5:00pm – 5:30pm

Summary / Q & A

Link to: A Clinical Application Guide to Standardized Wheelchair Seating Measures of the Body and Seating Support Surfaces http://at-partners.org/WheelchairSeating Bring to course if possible:

1. Laptop or tablet with the PDF version of above guide loaded 2. ½” metal tape measure 3. 180 degree goniometer, with small center dial 4. Inclinometer (non-digital)

Measuring Wheelchair Seated Posture and Seating Supports ISS 2013

1 Kelly Waugh, PT, MAPT

Measuring Wheelchair Seated Posture

and Seating Supports

Kelly Waugh, PT, MAPT, ATP Senior Instructor/Clinic Coordinator

Assistive Technology Partners

University of Colorado Anschutz Medical Campus

Denver, Colorado, USA

Copyright © 2013, The Regents of the University of Colorado, a body corporate. All rights reserved.

Created by Kelly Waugh, Assistive Technology Partners; supported by Grant #668 from the PVA Education Foundation

Barbara Crane, PT, PhD, ATP/SMS Associate Professor

Department of Rehabilitation Sciences

University of Hartford



1. Background

2. Overview of the Clinical Guide

3. Foundational Concepts

4. Angular Measures

5. Linear Measures

6. Tools for Measurement

7. Future

Need Identified for Term Standardization

• There is much variation in use of terms to describe and quantify both seated posture and the linear and angular dimensions of person’s seating support surfaces

• This creates barriers to communication between all people involved in wheelchair service delivery process = poor outcomes and inefficiency

• Research on wheelchair seated posture requires standardized measures



Development of ISO 16840-1:2006

• 1998: U.S. submitted proposal to ISO (International Standards

Organization) to develop an international standard for wheelchair

seating terms and definitions

• 1998 -2006: After 8 years of international collaboration, this standard

was published by ISO:

• ISO 16840-1 (2006): Wheelchair Seating – Vocabulary, reference

axis convention and measures for body posture and postural

support surfaces.

Purpose of ISO 16840-1:2006

1. Objectively describe and measure posture of the wheelchair seated person

2. Quantify angular orientation of seating support surfaces, and be able to relate these to the posture of the person

3. Standardize terms and definitions for linear dimensions of seated person’s body

4. Standardize terms and definitions for linear dimensions of seating support surfaces

Scope of ISO 16840-1: 2006

• Defines a global coordinate system for quantifying measures of a wheelchair-seated person and their seating support surfaces

• Defines measures of the seated person:

– Body Angles

– Linear Measures

• Defines measures of the seating support surfaces:

– Support surface angles

– Linear size measures

– Linear location measures



Positive Outcomes of ISO16840-1

• It established some foundational principles from which to develop standardized terms and definitions for seating measures

• It has facilitated the development of measurement and recording tools

• Horizon tool and Rysis software, developed in Japan

• It is facilitating research in reliability of the new measures

• Locating body landmarks

• Reliability of measures using the new measurement tools

The negative…….

• There has been minimal adoption and use of the terms and measures defined in ISO 16840-1 by clinicians, wheelchair suppliers, manufacturers and researchers. Why?

The ISO standard is complex and difficult to understand

The ISO standard is expensive and must be purchased

PVA Education Foundation Grant 2011-2012

• In 2011, Waugh awarded grant from Paralyzed Veteran’s of America

(PVA) Education Foundation to fund development of the clinical guide

to the ISO standard.

• Members of the project team:

• Kelly Waugh, PT (Project Director); Dr. Barbara Crane, PT, PhD;

Susan Johnson Taylor, OT; Kim Davis, PT and Susan Cwertnia, PT

• The name of this guide is:

• A Clinical Application Guide To Standardized Wheelchair Seating

Measures Of The Body And Seating Support Surfaces

http://at-partners.org/WheelchairSeating








1. Background



4. Angular Measures

5. Linear Measures


7. Future

Purpose of the Clinical Guide

• “Translate” the content of ISO standard into a resource manual which is easier to understand and apply clinically

• Make the guide available on internet in PDF format, which is free to download, so that everyone has access to it.

Our main goal is to:

• Promote the adoption of standardized terms and measures in the field of wheelchair seating

Table of Contents of the Guide

CHAPTER 1: INTRODUCTION

CHAPTER 2: ANGULAR BODY MEASURES

CHAPTER 3: ANGULAR SUPPORT SURFACE MEASURES

CHAPTER 4: LINEAR BODY MEASURES

CHAPTER 5: LINEAR SUPPORT SURFACE MEASURES

APPENDICES (5)

GLOSSARY

BIBLIOGRAPHY



The Guide is very comprehensive…..

• 130 terms

• For each measurement term: Description, accurate

definition, clinical relevance, sample measurement

procedure, and 1-3 figures illustrating the measure

• Because most people using wheelchairs have simple

postural support requirements, only a small subset of

these measures would be used in most clinical seating

applications.

The list of measures is not prescriptive…

• Measures are categorized as either a Level 1 or Level 2

measure, to suggest a selection of measures to take

based on complexity of person’s postural deviations and

support needs

• However, the choice of measurements used in any

clinical situation will depend on the complexity of the

person’s postural deviations, as well as the goals of the

measurement process.

Clinical Guide vs. ISO16840-1:2006

• The ISO 16840-1:2006 standard needs to be revised

• The Clinical Guide is based on the anticipated

revisions to the ISO 16840-1 standard

• ISO standard includes only a definition of the

measurement term

• The guide includes sample methodology, lots of

diagrams and clinical relevance





1. Background



4. Angular Measures

5. Linear Measures


7. Future

3 Foundational Concepts

Body segment and seating support terminology

Joint motion terminology & body planes

Describing wheelchair seated posture

Body segment lines

Support surface reference planes and lines

Relative vs. Absolute angles

Reference system

Body segment terminology

Dividing the body into segments

• Can describe seated posture

by measuring orientation of

segments

• Can relate orientation of body

segments to the orientation of

their supporting surface

• Helps define and label

seating supports



Seating support terminology

• Labeling convention for seating supports:

– Supports are named by the body segment intended to contact,

and the side of the segment where typically placed

• Inferior/superior, anterior/posterior, medial/lateral

– Supports should NOT be labeled by their purpose. The purpose

of the support is client specific, and is dependent on how it is

applied.

• Examples of correct terms:

– Lateral thigh support, not “hip adductor”

– Medial knee support, not “hip abductor”

– Lateral trunk support, not “scoliosis pad”

– Posterior upper arm support, not “elbow block”

Seating support terminology - Exceptions

• If support is segment’s primary weight bearing surface, don’t use the

directional term. For example:

– Head support, not “posterior head support”

– Foot support, not “inferior foot support”

– Seat (not inferior buttock/thigh support)

– Back support (not posterior trunk support)

– Arm support (not inferior forearm support)

Differentiating terms for the body vs. seating

supports vs. wheelchair

• It is critically important to differentiate between measures of the

seated person’s body from measures of the seating support

surfaces, because they are not necessarily the same

• Also important to differentiate terms and measures of the wheelchair

frame from the seating supports

• For example: Seat depth







Body segment lines



Reference system

Joint Motion Terminology & Body Planes

Body movement defined by:

1. The plane through which the body limb moves

• Sagittal

• Frontal

• Transverse

The “Standing Anatomical Position” is the zero reference for joint range of motion values

The Three Body Planes

Postural deviations in the sitting position can also be

described as occurring in these same three planes

• Clinicians often describe postural deviations in sitting by

viewing the client from three perspectives:

• From the side – to observe sagittal plane deviations

• From the front - to observe frontal plane deviations

• From the top – to observe transverse plane deviations







Body segment lines



Reference system


Using terms for joint motion

Most clinicians use terms for joint motion

to describe postural deviations in the

sitting position.

“Mrs. Jones sits in her wheelchair with a posterior

pelvic tilt, left pelvic obliquity, right pelvic rotation,

trunk leaning to left. Her hips are extended,

abducted and externally rotated.”

Why is this not adequate for our field?

Terms are frequently used inaccurately

Doesn’t provide a measure of orientation in

space

Does not help with prescription of seating

support surface angles


Using body segment angles

The standard provides a new set of terminology to define and

quantify seated posture which is based on the orientation of

body segments, called body segment angles

By measuring the angular orientation of body segments you

can define the static posture of a seated person.

The corresponding angular measures of the seating support

system are called support surface angles.

The same conventions are used to measure body segment

angles and support surface angles - helps with prescription.

The new terms for Body Segment Angles do not REPLACE standard terms

for joint range of motion, but rather AUGMENT them.







Body segment lines



Reference system

Thigh

Head

Foot

Lower Leg

Pelvis

Neck

Upper Trunk

Trunk

How would you measure the orientation of her body

segments in this plane?

You need to identify a line on each segment in

order to measure its angular orientation

AND, you need to be able to measure its

orientation in each of the three planes

Body

Landmarks

Body

landmarks

were identified

that can be

viewed from

side, front and

top



Body

Segment

Lines

Lines connecting

the body landmarks

are called Body

Segment Lines.

These are used to

measure the

angular orientation

of the segments

Sagittal head line

Sagittal thigh line

Sagittal lower leg line

Sagittal pelvic line

Sagittal upper trunk line

Sagittal neck line

Sagittal foot line

Body Segment Lines

– Sagittal View

Each body segment

line is labeled based

on the name of the

body segment and

the view

Sample

Body

Segment

Lines –

Frontal view

Frontal right lower leg line

Frontal pelvic line

Frontal head line

Frontal sternal line



Transverse foot line

Transverse pelvic line

Transverse forearm line

Transverse thigh line

Transverse trunk line

Sample

Body

Segment

Lines –

Transverse

view

Body Segment Lines and Landmarks

• To measure the orientation of a body segment, need to locate a line on the segment, to represent the orientation in each plane

• Body segment lines defined by connecting landmarks

– Sagittal plane (side view)

– Frontal plane (front view)

– Transverse plane (top view)

– Body landmarks must be accessible when seated in wheelchair

• Body Segment Lines joining body landmarks define the body segments and allow measurement of their orientation in each plane

To summarize….





Body segment lines



Reference system



Support Surface Reference Planes and Lines

• To measure the orientation of individual support surfaces, need to

locate a reference line on the contact surface

• Three concepts needed:

• Support surface reference plane

• Support surface geometric center

• Local X, Y, Z axes

• The reference line that is used to measure the orientation of a

seating support is one of the local axes

Z

Y X





Body segment lines



Reference system

Relative vs. Absolute Angles

• It is clinically important to be able to define the orientation of a body

segment or support surface in two ways:

1. With respect to an adjacent segment or surface (because this

reflects joint position and common seating angles), and

2. With respect to an external, absolute reference (because this

reflects orientation in space and influence of gravity)

• Therefore, two types of angles are defined




• Relative angles define the angular relationship between

two adjacent body segments, or between two adjacent

seating support surfaces

• Absolute angles define the spatial orientation of a single

body segment or support surface with respect to an

external, absolute reference such as the vertical or

horizontal

Sagittal thigh line

Sagittal trunk line

Thigh to trunk angle = 105 degrees

Example of Relative Angle:

The angle of the trunk relative to the thigh

is called the “Thigh to Trunk Angle”.

This is a relative angle - formed by the

intersection of the sagittal trunk line and

the sagittal thigh line

Absolute Angles:

What if you wanted to measure the

orientation in space of the trunk?

Or the orientation of the thigh?

How would you measure it?

You need a ZERO REFERENCE







Body segment lines



Reference system

Reference system

Coordinate Axis System Convention

The 3 Reference Planes

Wheelchair Axis System

Seated Reference Position

Support Surface Reference Position

Coordinate axis system convention

• Left hand rule convention

• Labeling of axes X, Y, Z

This shows the

axis system

superimposed

on a wheelchair

seating system

and on a seated

person.



Three reference planes

The three reference planes – Sagittal, Frontal and Transverse - are defined by the coordinate axes

Wheelchair Axis System (WAS)

• The absolute, global reference system to which angular

orientations of the body or support surfaces are

compared for measurement of absolute angles

The Seated Reference Position (SRP)

• SRP = A specified hypothetical zero reference position for seated posture, used to define absolute angular measures of the body, where the body segments are at 90 degrees to one another, and in line with the vertical or horizontal

• In the SRP, body segment lines are parallel to one of the WAS axes



The Support Surface Reference Position (SSRP)

• SSRP = A specified hypothetical zero reference position for the body support system, used to define absolute angular measures of the support surfaces, where the supports are orthogonal, in line with vertical or horizontal

• In SSRP, the support surface reference axes will always be parallel to one of the WAS axes



1. Background



4. Angular Measures

5. Linear Measures


7. Future

4 Angular Measures


Relative Angles

Absolute Angles



Relative vs. Absolute Angles - Body

Relative vs. Absolute Angles –

Seating Support Surfaces

4 Angular Measures


Relative Angles

Absolute Angles



Primary 3 Relative Support Surface Angles

Seat to Back Support Angle

Seat to Lower Leg Support Angle

Lower Leg Support/Foot Support Angle

95°

105°

120°

These angles DO NOT describe the posture of the seated person !

Primary 3 Relative Body Segment Angles

Thigh to Trunk Angle

Thigh to Lower Leg Angle

Lower Leg to Foot Angle

98°

75°

95°

Relationship between Body Segment Angles and Support

Surface Angles

If seated person’s body

segment lines are parallel

to the corresponding

support surface reference

lines, then the body

segment angles will be

the same as the support

surface angles (both

absolute and relative)



Relative Angles - Determining angular value

• Relative angles measure the angle between adjacent body segments or support

surfaces

• An angle can be measured on either of two sides….which side do you measure?

An angle can be measured on

either of two sides….

…the values add up to 360

degrees

Supplementary angles add up

to 180 degrees

Level I

Level II

Sagittal plane Thigh to trunk angle

Thigh to lower leg angle

Lower leg to foot angle

Thigh to pelvis angle

Relative body segment angles • Relative body segment angles measure the angle between adjacent segments

(currently defined in the sagittal plane only)

The angle between the thigh

and the trunk, viewed from the

side

The angle between the thigh

and the lower leg, viewed from

the side

The angle between the lower

leg and the foot, viewed from

the side



Thigh to trunk angle

Relationship to hip flexion angle

The angle between the thigh and the

trunk, viewed from the side

…relationship to hip flexion

angle

…relationship to knee flexion angle The angle between the thigh and

the lower leg, viewed from the

side

Thigh to lower leg angle

Relationship to knee flexion angle

The angle between the lower leg and

the foot, viewed from the side …relationship to dorsiflexion angle

Lower leg to foot angle

Relationship to ankle dorsiflexion angle



Level I

Level II

Sagittal plane Seat to back support angle

Seat to lower leg support angle

Lower leg support to foot support angle

Seat to upper back support angle

Seat to lower back support angle

Relative support surface angles • Relative support surface angles measure the angle between adjacent supports

(currently defined in the sagittal plane only)

The angle between the seat

and the back support, viewed

from the side

The angle between the seat

and the lower leg support,

viewed from the side

The angle between the lower

leg support and the foot

support, viewed from the side

SEAT TO LOWER LEG SUPPORT

ANGLE

LOWER LEG SUPPORT TO FOOT

SUPPORT ANGLE


With and without a posterior lower leg support in place

Seat to lower leg support angle - Definition: The posterior side of the angle formed between the

seat reference plane and the lower leg support reference plane, as viewed from the side

SEAT TO LOWER LEG SUPPORT

ANGLE, no calf pad SEAT TO LOWER LEG SUPPORT

ANGLE, with calf pad

Seat to lower leg support angle - Description: The angle between the seat and the lower

leg support, as viewed from the side




vs. “wheelchair lower leg support assembly angle”

Seat to lower leg support angle - Definition: The posterior side of the angle formed between the

seat reference plane and the lower leg support reference plane, as viewed from the side

Wheelchair manufacturers label the angle of the “front end” of the wheelchair, which usually

includes the leg support/foot support structure, as either a 60, 70, 80 or 90 degree angle. This

represents the angle between the extension of the seat rail, down to the vertical hanger tube

4 Angular Measures


Relative Angles

Absolute Angles

Level I

Level II

Sagittal plane Sagittal Pelvic Angle

Sagittal Trunk Angle

Sagittal Thigh Angle

Sagittal Head Angle

Sagittal Upper Trunk Angle

Sagittal Sternal Angle

Sagittal Abdominal Angle

Sagittal Lower Leg Angle

Sagittal Foot Angle

Frontal plane Frontal Pelvic Angle

Frontal Sternal Angle

Frontal Trunk Angle

Frontal Head Angle

Frontal Lower Leg Angle

Frontal Foot Angle

Transverse plane Transverse Pelvic Angle

Transverse Trunk Angle

Transverse Head Angle

Transverse Thigh Angle

Transverse Foot Angle



Examples of Absolute Support Surface Angles

Support name Level 1 Measures Level 2 Measures

Seat Seat sagittal angle Seat frontal angle

Seat transverse angle

Foot support

Foot support sagittal angle Foot support frontal angle

Foot support transverse angle

Arm support

Arm support sagittal angle

Arm support frontal angle

Arm support transverse angle

Back support

Back support sagittal angle Back support frontal angle

Back support transverse angle

Head support Head support sagittal angle Head support frontal angle

Head support transverse angle

Lower leg support

Lower leg support sagittal angle Lower leg support frontal angle

Determining the value of an absolute angle

• The absolute angle of an individual body segment or support surface

is the degree to which it has rotated, or deviated away from the zero

reference orientation

• This is measured by comparing the orientation of the body segment

line or support surface reference line to the specified axis of the

Wheelchair Axis System

• Sagittal and Frontal Angles reference the horizontal or vertical

• Transverse Angles reference the wheelchair X axis

Sagittal angles reference

the horizontal or vertical

Frontal angles reference

the horizontal or vertical

Transverse angles reference

the wheelchair X or Y axis



Example: Sagittal thigh angle

SAGITTAL THIGH ANGLE

• Sagittal thigh angle = the

degree of rotation of the sagittal

thigh line away from the

horizontal

Horizontal

Sagittal Thigh line

Sagittal thigh angle – Direction of rotation

SAGITTAL THIGH ANGLE

• How to define if thigh is rotated

upward or downward relative to

the zero reference axis?

• Use positive and negative

numbers to indicate direction of

rotation away from reference line

• “Left hand grip rule” defines

positive and negative direction of

rotation away from zero reference

• Clockwise rotations are positive,

counterclockwise rotations are

negative

+ 15 degrees

The Clockwise Rule: Clockwise rotations are positive*

*viewed from

right side

*viewed from front

*viewed from top



Level I

Level II

Sagittal plane Sagittal Pelvic Angle

Sagittal Trunk Angle

Sagittal Thigh Angle

Sagittal Head Angle

Sagittal Upper Trunk Angle

Sagittal Sternal Angle

Sagittal Abdominal Angle

Sagittal Lower Leg Angle

Sagittal Foot Angle

Frontal plane Frontal Pelvic Angle

Frontal Sternal Angle

Frontal Trunk Angle

Frontal Head Angle

Frontal Lower Leg Angle

Frontal Foot Angle

Transverse plane Transverse Pelvic Angle

Transverse Trunk Angle

Transverse Head Angle

Transverse Thigh Angle

Transverse Foot Angle

Sagittal absolute body segment angles • Sagittal body segment angles measure the orientation of the body segment in the

sagittal plane with respect to either the horizontal or vertical

The angle of the trunk with

respect to the vertical, viewed

from the side

The angle of the pelvis with

respect to the horizontal,


The angle of the thigh with



Frontal absolute body segment angles

• Frontal body segment angles measure the orientation of the body segment in the

frontal plane with respect to either the horizontal or vertical

The angle of the sternum with

respect to the vertical, viewed

from the front



viewed from the front

FRONTAL TRUNK ANGLE

The angle of the whole trunk

with respect to the vertical,




Transverse absolute body segment angles

• Transverse body segment angles measure the orientation of the body segment in the

transverse plane with respect to either the wheelchair X or Y axis

The angle of the trunk with

respect to the wheelchair,



respect to the wheelchair,

viewed from the side The angle of the thigh with respect to

the wheelchair, viewed from the top

TRANSVERSE THIGH ANGLE

Examples of Absolute Support Surface Angles

Support name Level 1 Measures Level 2 Measures

Seat Seat sagittal angle Seat frontal angle

Seat transverse angle

Foot support

Foot support sagittal angle Foot support frontal angle

Foot support transverse angle

Arm support

Arm support sagittal angle

Arm support frontal angle

Arm support transverse angle

Back support

Back support sagittal angle Back support frontal angle

Back support transverse angle

Head support Head support sagittal angle Head support frontal angle

Head support transverse angle

Lower leg support

Lower leg support sagittal angle Lower leg support frontal angle

Lower leg support transverse angle

Lateral trunk support Lateral trunk support frontal angle

Lateral trunk support sagittal angle

Lateral trunk support transverse angle

Lateral knee support Lateral knee support transverse angle

Lateral knee support sagittal angle

Lateral knee support frontal angle

Sagittal absolute support surface angles

• Sagittal support surface angles measure the orientation of a support surface in the

sagittal plane with respect to either the horizontal or vertical

The angle of the back support



The angle of the seat with



The angle of the arm support

with respect to the horizontal,




Frontal absolute support surface angles

• Frontal support surface angles measure the orientation of a support surface in the

frontal plane with respect to either the horizontal or vertical




The angle of the head support

with respect to the horizontal,


The angle of the lateral trunk

support with respect to the

vertical, viewed from the front

Transverse absolute support surface angles

• Transverse support surface angles measure the orientation of a support surface in the

transverse plane with respect to either the wheelchair X or Y axis


with respect to the wheelchair

Y axis, viewed from the top

The angle of lateral knee

support with respect to the

wheelchair X axis, viewed

from the top

The angle of the lower leg

support assembly with respect

to the wheelchair Y axis, viewed

from the top



1. Background



4. Angular Measures

5. Linear Measures


7. Future



5 Linear Measures

General comments

Terminology convention

Examples of linear body measures

• Actual vs. effective

Examples of linear support surface measures

• Height vs. length

• General guidelines

• Actual vs. effective

General Comments on Linear Measures

• Guide includes linear dimensions of the body and seating supports. Wheelchair frame dimensions are not defined or included.

• Linear measures of body taken with person in desired seated position and posture. Why?

• Linear measures of the body are used to specify support surface linear dimensions and placement

• It is important to differentiate body and support surface linear measures

• For example, Buttock/thigh depth does not equal seat depth

• Consistent rule for using terms length, width, depth, thickness and height

Terminology Convention for Linear Measures

• Length (A) = linear dimension in direction of Z axis

• Depth (B) = linear dimension in direction of X axis

• Width(C) = linear dimension in direction of Y axis

• Thickness (D) = linear dimension taken perpendicular to the support surface reference plane

• Height = linear dimension in direction of Z axis measured from an external reference point to a point on the body or support



Examples of linear body measures

Actual vs. Effective Linear Body Dimensions

The term for the linear measure represents the actual dimension of that single

body segment. If it is more clinically relevant to stay ‘orthogonal’ to a reference

axis while taking the measurement, then add the word “effective” to clarify.

Examples of support surface linear measures

Depth measures Width measures Length measures

Depth, width, length and thickness are “size” dimensions



Examples of support surface linear measures

Height vs. length

Height or Placement measures Length measures

General Guidelines for Linear Support Surface Measures

• Measures are taken on the contact surface side of the support

• Measures are taken parallel to the support surface reference plane at centerline

• Measures are taken in an unloaded state

• Dimensions are straight linear measures, not curved.

Actual vs. Effective Linear Support Surface Dimensions

• Terms for size dimensions as defined represent the actual dimension of the contact

surface side of the support component.

• The word “effective” can be added to any length, depth or width measure to indicate

that the useable contact surface has been either increased or reduced by the location

of a separate, adjacent or attached component.



STOP! WHY ARE WE DOING THIS?

• When and why would you take these

measures you just learned about?

Clinical application of these measures

When Purpose Measures

Initial clinical assessment To document current set up of

equipment

Support surface relative angles

Support surface linear dimensions

To document current posture as a

baseline

Body segment relative angles

Body segment absolute angles

To set postural goals Body segment relative angles


For prescription Body linear dimensions



At delivery To ensure accurate set up of seating

supports



To document outcomes relative to

postural goals



At follow - up To document intentional or

unintentional change in seating set up



To document positive or negative

postural change



To document change in body size

Body linear dimensions

• Comparing body segment angles to support surface angles helps to

highlight mismatch, which prompts problem solving

• Comparing mat exam findings to current relative angles and linear

dimensions of the seating system helps to determine the source of

postural problems, informs intervention strategy.

Clinical application of these measures

Helps with problem solving during assessment



Measure person: Body Segment Relative Angles

Measure equipment: Support Surface Relative Angles



1. Background



4. Angular Measures

5. Linear Measures


7. Future

6 Tools for measurement

Tools used to measure relative angles

Goniometer

Tools used to measure absolute angles

Inclinometer or “Angle Finder”

Goniometer with a bubble level

Horizon tool

Tools used to measure linear dimensions

Metal tape measure

Calipers or ‘M-L’ sticks





1. Background



4. Angular Measures

5. Linear Measures


7. Future

7 Future

• Guide is posted on Assistive Technology Partners website:

– http://at-partners.org/WheelchairSeating

• Printed, bound version will be available for purchase soon

• Waugh awarded PVA GRANT YEAR TWO 2012-13

– Education and training on the Guide

– Develop a Glossary of Wheelchair Terms and Definitions (like a

dictionary, with up to 450 terms)

• Revision of ISO 16840-1

7 Future

• Continued tool development

Simple inexpensive tools for use in clinical setting

More sophisticated tools for research

• Research

Improved anatomical landmarks

Reliability/validity of measures

Measure outcomes relative to postural change

Measure relationship between body angles and support surface

angles






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Handouts PC03 - International Seating Symposium

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