The Gluteal Challenge: Sitting Up Again! The Development of the
Contour Foam Base
Charisse Turmbull1 and David Huynh2
1NSW
State Spinal Cord Injury Service, Sydney
2Assistive
Technology and Seating Centre, Prince of Wales Hospital, Sydney
1. Abstract
Background: Seating acquired pressure ulcers cause suffering and poor quality of life for
people with spinal cord injury (SCI). Currently there are limited seating solutions for
individuals who have significant tissue atrophy in the lower limbs who are already utilising
high-end pressure care cushions such as the ROHO® air flotation cushion. Aims: To
present the development and outcome of the custom seat base for the ROHO ® air flotation
cushion to improve the quality of pressure management for individuals with SCI and
significant lower limb tissue atrophy. Methods: (a) Clinical reasoning behind the design of
the Contour Foam Base (CFB), (b) prototype development, fabrication and fitting
techniques, (c) Testing and evaluation of the CFB with ROHO® cushion on 13 SCI clients
over 24 months using data from interface pressure mapping system and a Patient Outcome
survey. Results: The interface pressure mapping indicates an increase of 16.15% in mean
contact surfaces area, a reduction of 9.60% in mean average pressure and a reduction of
22.18% in mean in peak pressure. The client outcome survey indicated a positive effect on
client’s postural stability and function. Conclusion: The CFB as a seat base under their
ROHO® air flotation improved client’s pressure management in seated position.
Key words
spinal cord injury, seating, custom fabrication, air cushion, pressure ulcer management and
pressure mapping
2.
Introduction
The Seating Service at Prince of Wales Hospital (POWH) regularly receives referrals to
assess and to provide seating interventions for clients with spinal cord injury, who have
acquired pressure ulcers. Many of these clients have significant muscle atrophy at the
pelvis and lower legs and have less contact on seat support surface to distribute weight.
Majority of these clients are already utilising a high-end commercial pressure care cushion
such as the ROHO® air flotation cushion and their options are limited.
This paper will outline the design, development and evaluation of the Contour Foam Base
(CFB) fabricated by POWH seating service since 2005. CFB offers a better seating solution
in pressure management for these clients.
3.
Background to the design concept of the Contour Foam Base (CFB)
The CFB is a “shaped” seat base that is placed in between the ROHO® cushion and the flat
wheelchair seat base.
Figure 1: Top View of CFB on manual wheelchair
The CFB was developed using these three key concepts for pressure management:3.1 Pressure (P) is defined as the force (F) per unit area (A) exerted perpendicular to the
plane of interest.
P = F/A.
By increasing the magnitude of support surface area (A) to distribute weight, we reduce
the magnitude of pressure (P), as experience by body tissue on seat support surface. A
strategy to increase support surface area is through immersion which is defined as
depth of penetration (sinking) into a support surface (National Pressure Ulcers Advisory
Panel, 2007). For example, a ROHO® High Profile (HP) cushion has 4 inches (or 101.6
millimetres) air cells height and offers a maximum of 3.5 inch (or 88.9 millimetres) of
immersion to increase support surface for pressure distribution. Whereas, a Low Profile
ROHO® cushion has 2.5 inches (or 63.5 millimetres) cell height and offers a maximum
of 2 inches (or 50.8 millimetres) of immersion.
100 mm
Figure 2: Skeleton immerse (sink) in
Figure 3: Sagittal view of pelvis immerse
ROHO® HP cushion
in ROHO® HP cushion
3.2 A symmetrical posture promotes even body weight distribution on the seat support
surface.
3.3 A stable posture may reduce undesirable movement of the skeleton on the seat support
surface, and thus minimises shear.
4 The Design
The CFB has anterior and lateral wedges to promote pelvic stability and to enhance the
property of immersion around the pelvis and the thigh. The idea of the CFB is to bring the
seat surface surrounding the pelvis and the thigh upward to the person to provide contact
with minimum changes to seat to floor height.
4.1 Anterior Wedge
Anterior Wedge
Figure 4: Sagittal view of pelvis on High Profile ROHO® cushion on anterior wedge (left)
and CFB (right)
A formal biomechanical assessment or MAT evaluation is conducted to consider the degree
of pelvis tilt and the location of the ischial tuberosity along the seat depth. The anterior
wedge starts about 25 mm in front of the ischial tuberosities. The height of the wedge is 50
mm (See figure 4). If it is too high when compared to the acetabulum position, it may result
in the femur being push upward by the anterior wedge.
For those clients who have minimum weight or tissue bulk on their lower legs, some
downward force may be applied on the thigh to assist with immersion into the ROHO ®
cushion during air inflation adjustment. The foam wedges can be customised to meet the
client’s individual postural and pressure care requirements.
4.2 Lateral Wedges
Greater
Trochanters
Ischial
Tuberosities
Lateral
wedges
Figure 5: posterior view of pelvis on
Figure 6: posterior view of pelvis on
ROHO® cushion on flat surface
ROHO® cushion with lateral wedges
The other structural components of the CFB are the two lateral wedges. They increase the
ROHO® contact surface around the pelvis when compared to the standard or flat seat
board. To construct the contour foam base according to the shape to the client’s pelvis, we
take note of the location of the Ischial tuberosities, which are usually around are about 120
millimetres apart. The wedges are placed about 25 mm laterally to the ischial tuberosities.
The heights of the wedges are usually 50 mm. The wedges assist in positioning of the
pelvis to midline, so to promote symmetrical posture and skeletal alignment.
If the slope of foam wedge is too great, the CBF may affect the performance of the ROHO ®
cells, as they become too horizontal. Additional 50 millimetres height extension blocks can
be added to the side of the CFB to add width if the client has excess tissue bulk.
5 Prototype
Back
Front
Figure 7: Frontal view CFB upholster in neoprene
The anterior and lateral wedges are made from closed cell foam called polyethylene (PE)
foam. The wedges are built on top of 5 mm close cell foam Ethylene Vinyl Acetate (EVA)
base. The foam wedges are 50 mm high. The combination of foam wedges gives the
contour shape base.
After client’s successful trial, the CFB is upholstered in 3 mm neoprene (a flexible and
durable close cell rubber). The neoprene provides a non-slip surface against the ROHO®
cushion base. The CFB is secured on the seat board or seat upholstery using Velcro.
6 The Complete Seat Base with ROHO® cushion
The seat base consists of ROHO® HP cushion as top layer and CFB as bottom layer.
Figure 8: Frontal view ROHO® HP Cushion on Contour Foam Base (CFB)
It is important to re-adjust the air inflation in the ROHO® cushion when using the CFB.
Otherwise the ROHO® cushion will be over inflated with this contour shape under it. As the
air inflation of ROHO® cushion is purposely set up for use with CFB, it would not be
practical if the client alternates the usage ROHO® cushion onto another seating base. The
training of equipment usage and provision of instructions are part of the intervention
program.
7 Evaluation
The evaluation was conducted on 13 clients who trialled the CFB over a 2 years period.
Using the Xsensor, an interface pressure mapping system, clients were mapped in their
current cushion, and then with ROHO® cushion on the CFB. A client satisfaction survey was
also conducted to evaluate it’s effectiveness in addressing perceived seating issues.
7.1 Quantitative analysis of the interface Pressure Mapping
7.1.1 Case Example
Below is a case example of interface pressure mapping of a C4 SCI male client, 6
foot tall, and weights 44 kg, sitting on a ROHO® Quadtro Select (QS) High Profile
(HP) with correct air inflation at the initial assessment. This pressure mapping of this
cushion set up is presenting with high pressure on ischial tuberosities and sacrum.
Ischial tuberosities
Sacrum
Figure 9: Pressure mapping of client on ROHO® QS HP cushion (Knees were
orientated at the top)
Pressure mapping was conducted on the client on the same ROHO® QS HP
cushion with CFB after air adjustment (see Figure 10 below).
When compared to the initial mapping, the new set up has improved pressure
management on the support surface by:
-•
increasing 38% in contact surface area
•
reducing 26% in average pressure, and
•
reducing 57% in peak pressure.
Figure 10: Pressure mapping of client on ROHO® QS HP cushion on CFB
7.1.2 Results of Quantitative Analysis using Pressure Mapping
Data collected from pressure mapping of the 13 clients were analysed to calculate
the mean contact surface area, mean average pressure and mean peak pressure:
• Contact Surface Area - the result shows an increase of 16.15% in mean contact
surface area for body weight distribution on the cushion support surfaces.
• Average Pressure - the result shows a reduction of 9.6% in mean cushion
average pressure. This means less pressure on tissue contact with seating
surface.
• Peak Pressure - the result shows a reduction of 22.18% in mean peak pressure
at bony prominence areas, such as the Ischial tuberosity.
Measured factors
Changes (%)
Contact Surface area
+ 16.15%
Average pressure
+ 9.60%
Peak Pressure
+ 22.18%
Quantitative Result (n = 13 clients)
7.2 Qualitative Analysis Using Client Survey
In addition to interface pressure mapping analysis, 13 clients who are using the CFB were
interviewed to evaluate their perceived impact of the CFB. There were 12 male and 1
female subjects.
7.2.1 Demographic information
Reasons for referral to Seating Clinic
The survey shows 85% of these clients referred to seating clinic have existing
pressure ulcer. Other referral reasons included: •
Management of post- flap surgery
•
Prescription of replacement wheelchair
•
Postural issues
•
Pain
Ischial
Tuberosity
Sacrum
Greater
Trochanters
15%
23%
15%
23%
Total: 13 clients
Figure 10: Location of pressure areas
80
%
70
%
69%
Gluteal fold
Groin
60
%
50
%
40
%
30
%
20
%
10
%
0
%
Location of Pressure Areas
The survey result shows 69% of clients have pressure areas on their ischial
tuberosity and 23% of clients with pressure on gluteal region. Some clients have
reported more than 1 pressure ulcers at the time of assessment. Other clients’
location of pressure areas is shown in Figure 10 above.
Level of Injury
Tabulation of survey result shows 62% of clients had C3 to C5 level of injury.
Other clients’ level of injury is shown in Table 1 below.
Location
Percentage
C3-5
62%
C6-8
15%
T1-5
15%
T6-12
8%
Table 1: level of injury
Number of years since spinal cord injury
Tabulation of survey result shows 54% of clients with SCI for 20 years and more.
Other clients’ years since injury are shown in Table 2 below.
Year since injury
Percentage
20+
54%
16 to 20
8%
11 to 15
0%
6 to10
23%
5 to 0
15%
Table 2: years since injury
Type of Cushions used (pre-intervention)
The result indicates 76% of clients were using ROHO® cushion at the initial
appointment. One client did not have a cushion, as he had been bed resting to
manage his pressure areas for 5 years. Types of cushions used at pre-intervention
are shown in figure 11 below.
Figure 11: Types of cushions used at initial appointment
Type of Cushions used with CFB (Post Intervention)
At post intervention, there were 84% of clients using ROHO® Quadtro Select high
profile cushion with CFB. It was found that the CFB when used in combination with
ROHO® High Profile Quadtro Select cushion provided optimal postural control and
immersion, as air inflation and air movement can be regulated in the 4 chambers.
The single valve ROHO® cushion did not perform as well on the CFB, as we cannot
regular the air flow for immersion around the thighs for those who have minimum
weight or tissue bulk on their lower legs.
Types of cushions used with CFB are shown in Figure 12 below.
\
Figure 12: Post intervention - cushions types used with CFB
7.2.2 Survey questions
Clients were asked the following questions in the outcome survey:
“ Has the CFB: - prevented further development of pressure ulcer in your seating system?
- increase sitting hours per day?
- reduce frequency of bed rest to manage pressure areas?
- reduced the incidence of sliding down in your wheelchair?
- improved your posture and positioning?
- enhanced your functional abilities?
- cause NO negative impact in your environmental requirement? “
“Are you satisfied with the overall seating outcome?”
7.2.3
Survey results:
The survey result is represented in bar graph below. (Figure 13)
Figure 13: Clients’ satisfaction and perceived impact of the CFB
The result of the client outcome survey indicates: o
Majority of the 13 clients had a positive outcome from the use of CFB with their
pressure management, postural stability and positioning. Most clients were able
to increase sitting hours per day and reduced bed rest periods of pressure
management.
o
It is important to consider the client’s posture and positioning, to promote an
even weight distribution on the support surface.
o
Reducing the incidence of sliding minimises undesirable movement of the
skeleton on the support surface, and lessen the damages from shear
o
All clients were satisfied with the overall seating intervention.
4.
Conclusion
Prince of Wales Seating Services found that using the Contour Foam Base (CFB) under
ROHO® cushion has enhanced client’s pressure management by increasing the seat
support surface for weight distribution. The CFB has benefited clients with high-level spinal
cord injury and complex seating needs. The client survey responses also indicated a
positive effect on their postural stability and positioning.
5.
Acknowledgments
We would like to thank our clients who participated in the survey, staff at POWH Seating
Service, and the NSW State Spinal Cord Injury Service.
Illustrations used with permission from Seating Dynamics Ltd and Michael Babinec.
6.
Correspondence
Charisse Turnbull, BAppSc (OT), Cert 4 (Training and Assessment)
Project manager,
Spinal Seating Professional Development Program,
NSW State Spinal Cord Injury Service,
600, Victoria Road,
Ryde, NSW 2112.
Ph: +61 2 9808 9666
Mob: +61409558909
Fax: +61 2 9808 9658
Email: cturnbull@nsccahs.health.nsw.gov.au
David Huynh, B.E (Elect), Dip. Eng Practice,
Rehabilitation Engineer
Assistive Technology and Seating Centre,
Prince of Wales Hospital,
Level B1, Clinical Science Builiding,
Randwick, Sydney
Ph: +61 2 9382 5202
Email: david.huynh@sesiahs.health.nsw.gov.au
7.
References
National Pressure Ulcers Advisory Panel (NPUAP) (2007), Support Surface Standards and
Initiative Terms and Definitions
www.npuap.org/NPUAP_S3I_TD.pdf
8.
Summary
“Gluteal Challenge: sitting up again!” describes the development of the custom seat base
under the ROHO® air flotation cushion. It demonstrates positive pressure management
outcomes for individuals with spinal cord injury who has significant lower limb tissue atrophy
through quantitative and qualitative analysis.