Page 284 - Handbook of Electronic Assistive Technology

Chapter 9 • Powered Mobility 273

• Recline alone may be helpful in opening the hips to relieve internal abdominal
pressure or to help manage a painful hip, but without a change in tilt is likely to
lead to the person sliding down in the seat; this is classically where ‘bed sores’ are
acquired and is best avoided in most circumstances.
• Used in conjunction with tilt, however, recline can be very effective at providing a
rest position, which may improve sitting tolerance and allow the person to remain
in their wheelchair for longer. This may enable them to travel and to take longer
trips away from home, and may reduce the amount of care that would otherwise
be required, for example, in assisting the person back to bed for a rest.
• Where a wheelchair seat is comfortable and allows for a resting position, there can
be an increase in social interaction and quality of life.
• Pressure distribution: In a recumbent position the spine has greater contact with
the back support because the orientation of the body segments relative to the effect
of gravity is altered. In upright sitting, gravity can lead to increased kyphosis which
results in the trunk pulling away from the back support, whereas when the trunk
is angled backward, gravity applies a force anteriorly to the chest, thus pushing
the trunk into the support, and starts to offload the pelvic bones; however, the
effectiveness of tilt and recline in reducing point loading is less easily understood –
there are complex and confounding factors which come into play. RESNA (2015) states
that pressure relief can become effective when tilt is used in combination with recline.
Points to consider are:
• Past history of pressure ulceration.
• Length of time spent in wheelchair.
• Length of time spent in one position in wheelchair.
• Amount of tilt available – it is sometimes suggested that an angle of at least
65 degrees is required to achieve offloading of the pelvic bones. Not many chairs
can offer this much tilt and it is a dysfunctional position which can only really be
used as a resting position (RESNA, 2015).
• Functional requirements demanding use of an upright position may limit the
amount of time which can be spent tilted and reclined.
• Orientation of the pelvis (obliquity, rotation and tilt), shape of the spine
and limitations in movement of the hips will all impact upon how the body is
loaded.
• Postural control: The ability to alter the positions of the body segments relative
to gravity not only helps with offloading pressure, but also assists with stabilising
the person’s posture, particularly the trunk, shoulders and head, enabling them to
maintain a comfortable and optimal position throughout the day (Lacoste et al.,
2003):
• Less effort/energy is required to sit in a tilted position (Pope, 2007), i.e., it is more
restful and akin to the difference between sitting at a dining table and sitting on a
sofa – each has its functional purpose but it is usually the latter on which one may
occasionally fall asleep.