Pressure Ulcer Prevention and Treatment Following Spinal Cord Injury - 60

PRESSURE ULCER PREVENTION AND TREATMENT FOLLOWING SPINAL CORD INJURY

the sitting surface, to forward lean, or to side-toside lean (Sprigle, et al., 2010).
The purposes of mechanical pressure
redistribution systems are-

to allow for altering sitting pressures and for
change in body pressure distribution to assist
in the prevention of pressure ulcers;

to allow for the change of postural alignment
while sitting; and

to allow the person to function for a longer
period of time while sitting, given the ability
to change positions for comfort and function.

Some wheelchairs have a fixed seat-to-back
angle, which can be tilted in space to redistribute
pressure by shifting weight off of the ischium
onto the back. Typical tilting wheelchairs can
obtain tilt angles from 45 degrees to as much as
60 degrees from a horizontal plane. Sprigle et al.
(2010) in a small sample study of spinal injured
subjects who used tilting wheelchairs found a
46% decrease in seat load when at full tilt.
Hobson's (1992) research has shown that a
minimum of 45 degrees of tilt/rotation is required
for adequate pressure distribution. Henderson, et
al. (1994) report 65 degrees of tilt has significant
reduction in maximum point pressure at ischial
tuberosities, whereas 35 degrees of tilt did not
demonstrate significant reduction of ischial
tuberosity pressure. These systems are frequently
selected if a significant problem with spasticity
exists. When the body is in the tilted position,
pressure is reduced without change in hip and
knee flexion. With these systems pressure
redistribution can be achieved without requiring
passive movement of the hip and knee joint,
thereby avoiding a stimulus to spasticity.
Goossens et al. (1997) discusses how local shear
stress is affected by changes in body posture,
including head and arm movements while sitting.
Tilt-in-space systems will also minimize frictional
shear (Goossens et al., 1997; Hobson 1992).
Bladder drainage while in the tilted position
must be assessed so as to avoid medical
complications that can occur with urine backflow.
Tilt systems facilitate consistent positioning and
access to secondary switches mounted onto the
wheelchair throughout the arc of movement
(Sprigle et al., 2010).
Other pressure redistribution systems work
by reclining the wheelchair to elevate the legs to
approximately horizontal position, helping to
redistribute weight-bearing pressure over a larger
body surface. Power reclining systems must be
evaluated for the possible effect of increasing and
eliciting extensor spasticity in the body due to this

tendency when moving from a static to dynamic
position (Sprigle et al., 1997). The reduced shear
reclining-back style-one that allows the back to
slide during the reclining movement-is preferred
due to reduced risk of shearing to the skin of the
back when the seat and back angle are changed.
Backrest recline decreased mean maximal
pressure of the ischial tuberosities but caused the
greatest ischial tuberosity shift, up to 6 cm
(Henderson, et al., 1994).
Upon opening the hip-to-back angle during
the recline phase, the stretch of muscles
surrounding the pelvis can be placed on a quick
stretch. This movement may result in the loss of
pelvic and spinal support, which may lead to
increased pressure and shearing over the bony
areas of the pelvis. In cases where pressure
redistribution is not as effective with the use of
a tilt system as compared to a recline system,
a combination tilt and recline system may be
considered. The individual is recommended to
initially move to a fully tilted position to stabilize
the pelvis, and then follow with activation the
recline system so as to minimize loss of postural
stability (Kreutz, 1997). The subsequent
activation order is then reversed to return to
upright sitting to minimize loss of stability.
When using power recline or combination
tilt/recline systems for pressure redistribution,
clinicians often instruct wheelchair users to lean
forward away from the wheelchair back before
returning to upright sitting position. This helps to
reduce potential skin shearing that can occur
along the chair's back (Gilsdorf et al,1990;
Sprigle et al. 1997).
There is no consensus as to whether a tilt-inspace or a reclining wheelchair is more effective
in preventing pressure ulcers. However, it seems
that a tilt and recline combination provides the
most pressure redistribution when used on a
consistent basis. Aissaoui et al. (2001) conducted
a study of pressure distribution and sliding on 10
able-bodied subjects by assuming 12 postures on
a simulator chair. Posterior tilt angle ranged from
0 degrees to 45 degrees and the recline angle
varied from 90 degrees to 120 degrees. Back and
seat force sensing array mats were used to
measure the interface pressure at the seat and
back with subjects seated on a flat foam cushion.
Mean pressure, peak pressure, and peak pressure
gradient were calculated for all positions tested.
The study found that when subjects sat at 45
degrees of tilt and recline of 120 degrees, a 40%
maximum reduction in peak pressure under the
ischial tuberosities was found. These findings
concluded that the highest reduction of pressure

Pressure Ulcer Prevention and Treatment Following Spinal Cord Injury

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