Wheelchair Seated Posture Measurement in a Clinical Setting
ISO 16840 Part 1
Posture Measurement Standard
Summary and Proposed Changes
ISS 2014
Vancouver, Canada
Purpose of this session:
• Introduce ISO 16840-1/ background
• Describe ISO 16840-1 (2006)
• Review some proposed changes to ISO
16840-1
16840
1 (Voting to take place in 2014)
Barbara Crane PT, PhD, ATP/SMS
Associate Professor
University of Hartford
West Hartford, Connecticut, USA
bcrane@hartford.edu
We need different terms for
the body, the seating supports,
and the wheelchair
Why do we need a standard?
• Variation in terms and measures
– In clinical practice
– In research
– By manufacturers of equipment
• Body and support surface measures are usually
different – need to communicate clearly
– Example: Buttock/thigh depth vs
vs. Seat depth
• Communication barriers
– Inefficiency in service delivery
– Poor outcomes for patients
• Wheelchair frame and support surface
measures also frequently different
• Interferes with research
– Example: Seat depth vs. Wheelchair seat pan depth
– Note – Wheelchair frame dimensions are NOT in
16840-1
– Difficult to understand studies
– Difficult to compare results of studies
Example: Support Surface vs. Body Angles
ISO 16840-1
Wheelchair seating-part 1(2006):
Vocabulary, reference axis convention
and
d measures ffor body
b d segments,
t
posture and postural support surfaces
95°
98°
120°
105°
The result of a long process!
75°
95°
Takashi Handa, Barbara Crane, and Kelly G. Waugh
Wheelchair Seated Posture Measurement in a Clinical Setting
ISO 16840-1: 2006
ISO 16840-1 Evolution
ISO 16840-1
(2006)
Revision
Development of
Clinical Guide
(2013)
• Describes a global coordinate system
– Coordinate system conventions (rules)
– Multiple axis systems
• Defines measures of the seating support surfaces:
– Support surface angles (absolute and relative)
– Linear size measures
– Linear location measures
• Defines measures of the seated person:
– Body angles (absolute and relative)
– Linear size measures
Coordinate System Conventions
(Proposed)
• Right hand rule for axes
– Establishes positive direction for each axis
– New orientation for right hand (moves axes)
• Z
Y; Y
X; X
ISS 2014
Vancouver, Canada
Axes – Right Hand Rule
Current RHR
Proposed RHR
(first finger points to the right)
(thumb points to the right)
Z
• Three orthogonal planes
– Changes in which axes make up planes due
to changes to axes
• Right hand grip rule for direction of rotation
– Clockwise rotation negative
Current:
Axes and Planes
Coordinate System Components
(Proposed)
• Global coordinate system
– Origin external to body and support surfaces
• located on the floor
• Reference axis systems
Proposed:
Sagittal
(right side)
Frontal
Transverse
–
–
–
–
Wheelchair Axis System (may use as global)
Support Surface Axis System (and SSRP)
Seated Anatomical Axis System (and SRP)
Local Axis System
• For each body segment
• For each postural support
Takashi Handa, Barbara Crane, and Kelly G. Waugh
Wheelchair Seated Posture Measurement in a Clinical Setting
Wheelchair Axis System
Current:
ISS 2014
Vancouver, Canada
Support Surface Axis System
Current:
P
Proposed:
d
Proposed:
Seated Anatomical Axis System
Current:
Local Axis Systems
(Proposed)
Proposed:
Measuring Absolute Angles
Current:
“Compass Rose” system
(Left Hand Grip Rule)
clockwise positive
Proposed: Right Hand Grip Rule – clockwise negative
Takashi Handa, Barbara Crane, and Kelly G. Waugh
Current Absolute Angles
Uses Compass Rose (left hand grip rule), and
Body Segment Lines, vertical is zero,
Clockwise rotation is positive
Wheelchair Seated Posture Measurement in a Clinical Setting
Proposed Absolute Angles
Uses right hand grip rule and local axes
Clockwise is negative
Summary of Proposed Changes
• Changes in axes
• Changes in absolute angles
– Use of local axis system
• Reference positions are zero
• No more reference lines for support surfaces needed
• Changes
Ch
iin relative
l ti angles
l
– Thigh to lower leg
– Seat to lower leg support
Takashi Handa, Barbara Crane, and Kelly G. Waugh
ISS 2014
Vancouver, Canada
Relative Body Segment Angles
Current
Thigh to Lower Leg
Proposed
Thigh to Lower Leg
How does a standard help us?
• Development of new measuring methods
– Focus on sitting posture
– Better linear dimensions of person, postural
supports and wheelchair
• Development of new measuring tools
– Rysis
– Horizon
Standardized Seating Measurement: Introduction to a Clinical Guide
12/14/2012
Colorado, USA
A Clinical Application Guide to
the ISO 16840-1 Standard
Kelly Waugh, PT, MAPT, ATP
Senior Instructor/Clinic Coordinator
Assistive Technology Partners
University of Colorado Anschutz Medical Campus
Denver, Colorado, USA
Colorado is known for its
beautiful Rocky Mountains!!
Copyright © 2014, 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
A Clinical Application Guide to the ISO
16840-1 Standard
1. Background
2. Overview of the Clinical Application Guide
3. Angular Measures of the Body
 Background
 ISO 16840-1 published in 2006
 Costly to purchase
 Difficult to understand and apply clinically
 2011-2013: Paralyzed Veterans of America (PVA) Education
Foundation grant
 Funded development of two new free resources, based on the
ISO standard:
1. A clinical application guide to the ISO standard
2. A glossary of wheelchair terms and definitions

Both are available on our website
http://www.ucdenver.edu/academics/colleges/medicalschool/programs/atp/Resource
s/WheelchairSeating/Pages/WheelchairSeating.aspx
A Clinical Application Guide to Standardized
Wheelchair Seating Measures of the Body and
Seating Support Surfaces, Revised Edition
A Clinical Application Guide to the ISO
16840-1 Standard
1. Background
• Initially published in February 2013
2. Overview of the Clinical Application Guide
• Revised Edition posted July 2013
– Axis convention changed; Right hand grip rule reversed positive
and negative values for absolute angles
3. Angular Measures of the Body
• Updated November 2013
– Minor corrections made to cover page and page 43
• Japanese and Korean translations are under way!
Kelly Waugh, PT, MAPT
1
Standardized Seating Measurement: Introduction to a Clinical Guide
 What is the purpose of the Clinical Guide?
12/14/2012
 What is included in the Clinical Guide?
1. “Translate” the content of ISO 16840-1 standard into a resource
manual that is easy to understand and apply clinically
1. Explains foundational principles upon which the terms
and measures are based
2. Make the guide available on internet in PDF format, which is free
to download, so that everyone has access to it.
2. Defines terms for measures of the seated person
The main goal:
• Promote the adoption of standardized terms and measures in the
field of wheelchair seating
3. Defines terms for measures of seating support surfaces
 How is the content of the Clinical Guide different
from the ISO Standard?





Angular Body Measures
Linear Body Measures
Angular Support Surface Measures
Linear Support Surface Measures
Does not included Linear Location Measures
 Table of Contents of the Clinical Guide
CHAPTER 1: INTRODUCTION
•
•
The ISO standard includes only a definition of each measurement
term
Only talking about Angular Body
Measures in this presentation!
CHAPTER 2: ANGULAR BODY MEASURES
CHAPTER 3: ANGULAR SUPPORT SURFACE MEASURES
The Clinical Guide also includes:
– Simple description
– Sample measurement procedure
– Lots of diagrams
– Clinical relevance of measure
CHAPTER 4: LINEAR BODY MEASURES
CHAPTER 5: LINEAR SUPPORT SURFACE MEASURES
APPENDICES (4)
GLOSSARY
BIBLIOGRAPHY
A Clinical Application Guide to the ISO
16840-1 Standard
3
Angular Measures of the Body

Basic Concepts

Relative vs. Absolute Angles

Examples of Relative Angles

Examples of Absolute Angles
1. Background
2. Overview of the Clinical Application Guide
3. Angular Measures of the Body
Angular measures of the body
describe person’s seated posture
Kelly Waugh, PT, MAPT
2
Standardized Seating Measurement: Introduction to a Clinical Guide
12/14/2012
 Why measure wheelchair seated posture?
 Why measure wheelchair seated posture?
1. Helps with assessment and prescription
– Correlation of body angles to seating angles helps with clinical
problem solving
4. Justify need and cost of complex or custom seating system
5. Track postural change over time
2. Set measurable postural objectives
– Measure “current” posture (baseline)
– Document “desired” posture (goal) based on clinical assessment
3. Document outcomes
– Measure posture before and after seating intervention
Describing wheelchair seated posture using joint
motion terminology is not adequate for our field

Currently, therapists use joint motion terms to describe sitting
posture

“Mrs. Jones is sitting with hips extended, trunk laterally flexed to
the left, and legs abducted”

This is not adequate for wheelchair seating because
 Joint motion terms are frequently used inaccurately
 Joint motion terms do not help prescribe orientation of
seating supports
 Joint motion terms do not describe orientation in space of
body segments
 The Three Reference Planes
6. RESEARCH
– To investigate relationships between seated posture and
functional outcomes, we need to be able to measure seated
posture in a consistent and reliable manner
Next…..How do we describe, measure and document wheelchair seated posture?
The standard provides a different way to measure
seated posture using body segment angles
This method of seated posture measurement:

Views postural deviations in three planes

Divides body into segments

Identifies body landmarks on each segment

Connects landmarks with imaginary line

Measures orientation of the body segment line in two ways:

With respect to adjacent segment

With respect to gravity
 Postural deviations in sitting position can be described in
each of these same three reference planes
Body movement defined by:
1. The plane through which the
body limb moves
• Sagittal
• Frontal
• Transverse
2. For example, flexion/extension
occurs in sagittal plane
 The “Standing Anatomical
Position” is the zero reference
for joint range of motion values
Kelly Waugh, PT, MAPT
• Three perspectives:
• SIDE
SAGITTAL plane deviations
• FRONT
FRONTAL plane deviations
• TOP
TRANSVERSE plane deviations
3
Standardized Seating Measurement: Introduction to a Clinical Guide
 Body is divided into segments
Body
Landmarks
Dividing body into segments allows
us to:
• Describe seated posture by
measuring orientation of body
segments instead of joint
position
•
12/14/2012
Relate orientation of body
segments to the orientation of
their supporting surface
Body landmarks
were identified
on each
segment that
can be viewed
from side, front
and top
How can we measure the
orientation of the body segments?
Body
Segment
Lines
3
Lines connecting
the body landmarks
are called Body
Segment Lines.
The lines are used
to measure the
angular
orientation of the
segments in each
plane.
By measuring the angular
orientation of body
segments, you can define
the static posture of seated
person. The angles
formed are called body
segment angles.
 Relative vs. Absolute Angles
THERE ARE TWO DIFFERENT TYPES OF ANGULAR MEASURES:
• Relative angles define the angular relationship between two
adjacent body segments
• Reflects joint position
• Absolute angles define the orientation of a single body segment
with respect to an external, absolute reference such as the vertical or
horizontal
• Reflects orientation in space
Kelly Waugh, PT, MAPT
Angular Measures of the Body

Basic Concepts

Relative vs. Absolute Angles

Examples of Relative Angles

Examples of Absolute Angles
 Example of a relative angle
 The angle of the trunk relative to the
thigh is called the Thigh to Trunk Angle.
 Important because it reflects how much
hip flexion she is sitting in, which may
impact spinal posture, muscle tone or
comfort
Thigh to trunk angle = 105 degrees
Does the 105 degree thigh to trunk angle
give you information on the orientation in
space of her trunk or thigh?
4
Standardized Seating Measurement: Introduction to a Clinical Guide
 Absolute angles give information on orientation in space
12/14/2012
 Absolute angles give information on orientation in space
vertical
 The orientation in space of her trunk is
important because it affects her
balance and functional reach
 The slope of her thigh is important
because it may affect stability on seat
Sagittal trunk angle
= +5 degrees
 The sagittal thigh angle measures the
orientation in space of her thigh
relative to the horizontal, in the sagittal
plane
 The Sagittal Trunk Angle measures the
angle of the trunk with respect to the
vertical, in the sagittal plane
horizontal
Sagittal thigh angle = -15 degrees
 Absolute angles can change without a change in relative
angle
3
Angular Measures of the Body

Basic Concepts

Relative vs. Absolute Angles

Examples of Relative Angles

Examples of Absolute Angles
THI/TK=105°
THI/TK=105°
THI-sag = 0°
THI-sag = -15°
Thigh to trunk angle (THI/TK) is the same
Sagittal thigh angle (THI-sag) is different
Thigh to trunk angle
Relationship to hip flexion angle
Relative body segment angles
•
Relative body segment angles measure the angle between adjacent segments
The angle between the thigh
and the trunk, viewed from the
side
Kelly Waugh, PT, MAPT
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
The angle between the thigh and the
trunk, viewed from the side
More useful for
prescribing desired seat
to back support angle
…relationship to hip flexion
angle
5
Standardized Seating Measurement: Introduction to a Clinical Guide
3
Angular Measures of the Body

Examples of Absolute Body Segment Angles
Level I
Basic Concepts

Relative vs. Absolute Angles

Examples of Relative Angles

Examples of Absolute Angles
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 body segment angles measure the orientation of a single body segment in the
sagittal plane with respect to either the horizontal or vertical
SAGITTAL THIGH ANGLE
The angle of the trunk with
respect to the vertical, viewed
from the side
The angle of the pelvis with
respect to the horizontal,
viewed from the side
Kelly Waugh, PT, MAPT
‐ 15 degrees
•
How to define if thigh is rotated
upward or downward relative to
the horizontal?
•
Use positive and negative
numbers to indicate direction of
rotation away from reference axis
•
“Right hand grip rule” defines
positive and negative direction of
rotation away from zero reference
The angle of the thigh with
respect to the horizontal,
viewed from the side
Right Hand
Grip Rule
SAGITTAL THIGH ANGLE
Level II
Sagittal plane
Positive or negative value indicates direction of
rotation from zero reference position
Sagittal absolute body segment angles
•
12/14/2012
Frontal absolute body segment angles
•
•
Point thumb of your right hand along the
axis of rotation for plane in which the
angle lies
•
Axis of rotation is always perpendicular
to the plane
•
The direction that your fingers curl
around your thumb is the positive
direction.
‐ 15 •
degrees
Counterclockwise is positive when
viewing person from right side, front and
top
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
The angle of the pelvis with
respect to the horizontal,
viewed from the front
The angle of the whole trunk
with respect to the vertical,
viewed from the front
6
Standardized Seating Measurement: Introduction to a Clinical Guide
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 Z axis
The angle of the trunk with
respect to the wheelchair,
viewed from the top
The angle of the pelvis with
respect to the wheelchair,
viewed from the top

12/14/2012
Summary

By measuring the angular orientation of body segments in
each plane you can define the static posture of a seated
person. These are called body segment angles

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.

There is a free clinical guide to help you learn about these
measures.
The angle of the thigh with
respect to the wheelchair,
viewed from the top
 Practicum
LET’S PRACTICE SOME MEASURES!
Kelly Waugh, PT, MAPT
7
Practice: Thigh to Trunk Angle
THIGH TO TRUNK ANGLE
Type of Measurement: Relative body segment angle,
right and left
Description: The angle between the thigh and the trunk,
viewed from the side.
Landmarks used:
• Lateral hip center point (center of rotation)
• Lateral femoral condyle
• Lateral lower neck point
Body segment lines used to form angle:
• Sagittal trunk line
• Sagittal thigh line
Angle measured: The anterior side of the angle formed
between the sagittal trunk line and the sagittal thigh line.
SRP Value: 90 degrees
Typical Values: 90 – 120
Practice: Thigh to Lower Leg Angle
THIGH TO LOWER LEG ANGLE
Type of Measurement: Relative body segment angle,
right and left
Description: The angle between the thigh and the lower
leg, viewed from the side.
Landmarks used:
• Lateral femoral condyle (center of rotation)
• Lateral hip center point
• Lateral malleolus
Body segment lines used to form angle:
• Sagittal thigh line
• Sagittal lower leg line
Angle measured: The posterior side of the angle formed
between the sagittal thigh line and the sagittal lower leg
line.
SRP Value: 90 degrees
Typical Values: 80 – 120
Practice: Sagittal Trunk Angle
SAGITTAL TRUNK ANGLE
Type of Measurement: Absolute body segment
angle
Description: The angle of orientation of the
trunk with respect to the vertical, viewed from
the side.
Landmarks used:
• Lateral lower neck point
• Lateral hip center point
Lines used to form angle:
• Vertical (YWAS)
• Sagittal trunk line
Angle definition: Degree of rotation from the
vertical (YWAS) to the sagittal trunk line, viewed
from the side and projected to the sagittal plane
Practice: Sagittal Pelvic Angle
SAGITTAL PELVIC ANGLE
Type of Measurement: Absolute body segment
angle
Description: The angle of orientation of the
pelvis with respect to the horizontal, viewed
from the side.
Landmarks used:
• ASIS
• PSIS
Lines used to form angle:
• Horizontal (XWAS)
• Sagittal pelvic line
Angle definition: Degree of rotation from the
horizontal (XWAS) to the sagittal pelvic line,
viewed from the side and projected to the
sagittal plane.
Practice: Sagittal Thigh Angle
SAGITTAL THIGH ANGLE
Type of Measurement: Absolute body segment
angle, right and left
Description: The angle of orientation of the
thigh in the sagittal plane, with respect to the
horizontal.
Landmarks used:
• Lateral hip center point
• Lateral femoral condyle
Lines used to form angle:
• Horizontal (XWAS)
• Sagittal thigh line
Angle defined: Degree of rotation from the
horizontal (XWAS) to the sagittal thigh line,
viewed from the side and projected to the
sagittal plane.
Practice: Frontal Sternal Angle
FRONTAL STERNAL ANGLE
Type of Angle: Absolute body segment angle
Description: The angle of orientation of the
upper trunk with respect to the vertical, viewed
from the front.
Landmarks used:
• Upper sternal notch
• Lower sternal notch
Lines used to form angle:
• Vertical (YWAS)
• Frontal sternal line
Angle definition: Degree of rotation from the
vertical (YWAS) to the frontal sternum line,
viewed from the front and projected to the
frontal plane.
Practice: Frontal Pelvic Angle
FRONTAL PELVIC ANGLE
Type of Angle: Absolute body segment angle
Description: The angle of orientation of the
pelvis with respect to the horizontal, viewed
from the front.
Landmarks used:
• Right ASIS
• Left ASIS
Lines used to form angle:
• Horizontal (ZWAS)
• Frontal pelvic line
Angle definition: Degree of rotation from the
horizontal (ZWAS) to the frontal pelvic line,
viewed from the front and projected to the
frontal plane.
Practice: Transverse Pelvic Angle
TRANSVERSE PELVIC ANGLE
Type of Angle: Absolute body segment angle
Description: The angle of orientation of the
pelvis in the transverse plane with respect to the
wheelchair frame, viewed from the top.
Landmarks used:
• Right ASIS
• Left ASIS
Lines used to form angle:
• Wheelchair Z-axis (ZWAS)
• Transverse pelvic line
Angle defined: Degree of rotation from the
Wheelchair Z-axis (ZWAS) to the transverse
pelvic line, viewed from the top and projected to
the transverse plane.
Practice: Transverse Thigh Angle
TRANSVERSE THIGH ANGLE
Type of Measurement: Absolute body
segment angle, left and right
Description: The angle of orientation of the
thigh in the transverse plane with respect to
the wheelchair, viewed from the top.
Landmarks used:
• ASIS
• Superior knee point
Lines used to form angle:
• Wheelchair X-axis (X WAS)
• Transverse thigh line
Angle defined: The degree of rotation from
the wheelchair X-axis (X WAS) to the
transverse thigh line, viewed from the top and
projected to the transverse plane.