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Seating and positioning

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5
Seating and positioning
Craig A. Kirkwood and Geoff I. Bardsley
Introduction
Spasticitycauses seatingchallengesfor awidevariety
of people with disabilities: from children with cere-
bral palsy, young adults with head injuries, middle-
aged people with multiple sclerosis (MS) and older
persons who have suffered cerebrovascular acci-
dents (CVAs) and use wheelchairs.
The nature of spasticity is complex and controver-
sial, as discussed elsewhere in this volume. Clinical
characteristics described as constituting spasticity
and that influence seating include increased muscle
tone, hyperactive stretch reflexes, changes in muscle
structure and function and abnormal activity caused
by posture (e.g. tonic neck and labyrinthine reflexes)
(Ford, 1986; Shepherd, 1995).
Spasticity, in itself, is not necessarily a problem
and may assist in maintaining a seated posture. This
is in contrast to hypotonia, where providing seated
support in a functional position is often very difficult.
However, there are three key problems that spasticity
can cause to the person in a seated position:
1. Postural instability
2. Reduced upper limb function
3. Joint contractures
Correct positioning of the person can assist in reduc-
ing these problems (Zollars, 1993). Addressing one
of the areas has a largely beneficial effect on the oth-
ers, so there is little trade-off in strategies to tackle


these problems. Barnes (1993) states: ‘positioning
of the individual is the most important element in
the management of spasticity’(see also Vaughan &
Bhakta, 1995).
Appropriate seating should be seen as adjunct
to the other approaches discussed in this book
which may have greater precedence with increasing
severity of spasticity (e.g. pharmacological, surgical)
(Richardson&Thompson, 1999). This is important to
note,asthereareoftenexpectationsthatcorrectseat-
ing will tackle all problems an individual has result-
ing from spasticity when other methods have been
unsuccessful.
As Barnes (1993) notes, the management of spas-
ticity requires a team approach with the involve-
ment of ‘nurses, physiotherapists, physicians,
occupational therapists, orthotists and wheelchair
specialists’ in addition to the patient and their carers.
This multidisciplinary approach should be regarded
as ‘best practice’ as often the various health profes-
sionals seek to tackle spasticity with little knowledge
of what the others are doing.
Although this chapter is mainly concerned with
the seated aspect of positioning, particularly for
those who spend long periods in a wheelchair, it is
important to rememberthat people also spend many
hourslying down, and correctpositioningduring this
period is equally important (Scrutton, 1971, 1978;
Todd, 1974; Bell & Watson, 1985; Nelham et al., 1992).
Whilethesameprinciples in terms of positioning and

design considerations apply,it is also important that,
over a 24-hour period, a variety of positions be used
to move joints through their range of motion (ROM)
99
100 Craig A. Kirkwood and Geoff I. Bardsley
and prevent soft tissues from becoming contracted
in a ‘seated’ position.
Clinical assessment
Detailed assessment is essential so that a full pic-
ture of the patient’s problems relating to spasticity
is drawn up in order that clear, specific and realis-
tic objectives can be agreed on by all those present
and a detailed prescription produced to achieve the
objectives.
Assessing the patient with spasticity for seating
may involve four procedures to assist in determin-
ing the effect of the spasticity:
1. History taking. Soliciting information of the par-
ticular problems that occur with increased tone
and factors which exacerbate tone and produce
associated reactions. This background informa-
tion is particularly important, as the clinical sit-
uation itself can have a significant effect on the
patient’s presentation (Harburn & Potter, 1993),
and he or she may also have recently had medica-
tion to control spasticity – particularly if traveling
a distance to an appointment. It may be useful
for video to be used to unobtrusively monitor the
patient in particular situations where there is a
problem – as in feeding.

2. Examination on plinth in supine.While determin-
ing range of joint motion, account can be taken of
resistance to motion and variation according to
speed of movement.
3. Support in seated posture. While the patient is
well supported in a seated posture (by one or
more staff), account can be taken of tone in body
(by those supporting) and changes to apparent
range of motion in lower limbs, as it is often found
that in patients with very high tone, hip flexion
in supine is extremely difficult; but when seated
with support, there is a reduction in tone, allow-
ing true level of contractures to be assessed. As
sitting balance is affected by the level of spastic-
ity (Yang et al., 1996) it may be useful to grade
this – as by using the Chailey scale (Green &
Nelham, 1991).
4. While supported in a seating simulator. Account
can be taken for functional ability (e.g. to lift cup
and drink) and the simulator can be adjusted to
check for variations in function.
Principles of seating and positioning
The basic philosophy of seating is the same for
all patients: ‘that the body should be maintained
in a balanced, symmetrical and stable posture
that is both comfortable and maximizes function’
(Barnes, 1993). It is the nature of spasticity to pro-
duce postures that are unbalanced, nonsymmetri-
cal and unstable with the result that the patient is
uncomfortable and thereisimpairmentoffunctional

ability.
The following are ten principles which should be
consideredinseekingtoachievean‘optimum’seated
position for those with spasticity. They explore the
diverse range of factors which relate positioning and
spasticity and which may affect postural stability,
function and the development of contractures.
Sustained muscle stretch
The key principle in reducing spastic contraction is
thesame as that applied inphysiotherapy – sustained
muscle stretch, that is, working against the spastic
muscle (Bobath, 1977). Stretching reduces spasticity
directly in the muscle being stretched by depressing
the muscle spindle (Kaplan, 1962). It also reduces the
possibility of contractures (Harburn & Potter, 1993;
Bakheit, 1996). It has also been demonstrated that
such a reduction of spasticity may also permit greater
use of the upper limbs (Nwaobi, 1987a).
As such, correct positioning in seating is consis-
tent with a physiotherapy program that emphasizes
the importance of daily ROM exercises and static
muscle stretch to prevent contracture and reduce
spasticity (Little & Massagli, 1993). Odeen (1981)
reported increased ROM and decreased activation
of the antagonist in voluntary abduction by using
a mechanical leg abductor for 30-minute treatment
sessions.
Seating and positioning 101
Figure 5.1. Effect of hamstring stretch on seated posture.
As well as reducing spasticity, sustained muscle

stretchhelps to prevent contractures which is impor-
tant because of pain they can produce and the dif-
ficulty of treating (Botte et al., 1988). The muscle
contracture itself may potentiate the stretch reflex
(O’Dwyer et al., 1996) causing further problems with
spasticity.
When applying a muscle stretch using seating sup-
port elements, the same principle as serial cast-
ing (Brunner et al., 1996) can be utilized, whereby
gains in comfortable ROM at a joint can be con-
solidated and increased by providing progressively
greater stretch. This implies that the seating must be
monitored and frequently reviewed to build on gains
and address failures.
One possible exception to this principle, when
applied to the seated posture, is stretching of the
hamstrings. This is because they extend over two
joints; therefore, in the common case where there
is knee flexion produced by spasticity, extending the
knee also acts to posteriorly rotate the pelvis (Zol-
lars, 1996) and has tendency to pull the person out of
the wheelchair and produce a kyphtoic spinal pos-
ture (see Fig. 5.1). In order for a hamstring stretch to
be effective, the pelvis must be firmly secured both
anteriorly and posteriorly to prevent movement, and
in practice this is difficult to achieve.
The link between hip flexion and hand function
is controversial. No relationship was reported by
Seegeret al. (1984), but Nwaobi et al.(1986) reported
that 90 degrees gave better function compared to 50,

70 and 110 degrees.
Using standing (e.g. tilt table) for load bearing
(Odeen & Knutsson, 1981; Tremblay et al., 1990) has
been successful in producing a muscle stretch that
reduced spasticity. This position has other benefits,
such as bladder drainage and increasing bone den-
sity for those who spend long periods sitting.
Maintenance of hip integrity
A common problem encountered in seating children
with cerebral palsy is hip subluxation and disloca-
tion. Kalen and Bleck (1985) identify the primary
aetiology and therefore the primary focus of treat-
ment to be adductor and iliopsoas spasticity and
contracture.
It has been noted from X-rays that the acetabulum
of the adducted hip does not develop normally, with
increasing subluxation and eventual dislocation of
the hip (Fulford & Brown, 1976). Howard et al. (1985)
found from examining the X-rays of hips of patients
with cerebral palsy that 79% of bilateral hemiplegics
had abnormal hips; the majority of these were
102 Craig A. Kirkwood and Geoff I. Bardsley
nonwalkers and the others required a frame or rolla-
tor. Young et al. (1998) found that of patients deter-
mined to have spastic quadriplegia, 25% had hip dis-
location and 63% subluxation. This reinforces the
need to address hip status, particularly among chil-
dren with more involved cerebral palsy.
In addition to the pain that can be caused to the
patient by compromised hips (Bagg et al., 1993),

there is then an asymmetry in the interface between
the patients’ pelvis and hips and the seated sur-
face, thus producing an asymmetric pelvis and con-
sequent postural scoliosis, which may become less
flexible with time. There is also an increased risk of
pressure sore problems on the more heavily loaded
side of the pelvis.
Helping to maintain hip joint integrity is therefore
an important part of seating in wheelchairs. Prob-
lems are particularly likely in patients with adductor
spasticity. When the distal end of the femur is pulled
to the midline, this tends to pull the femoral head
away from the socket, therefore compounding the
lack of normal weight bearing in promoting acetab-
ular development. Scrutton (1991) emphasizes the
need for correct positioning and the experience of
standing for those under 4 years of age, as this is
when such problems begin to develop.
A common, related problem is ‘windsweeping’,
where there is an abduction contracture of one hip
and an adduction contracture of the contralateral
hip, with subluxation or dislocation (Lonstein &
Beck, 1986). This is often related to pelvic obliquity
and scoliosis, thus presenting a significant seating
problem (Young et al., 1998). As Young et al. state:
‘those with asymmetry of tone and severe spastic-
ity seem to be at the greatest risk for dislocation,
with a windswept hip deformity toward the opposite
side’.
Tight, and eventually contracted adductors with

consequent dislocated hips cause serious toileting
problems (Cornell, 1995) and represent a common
indication for surgery, together with the impossibil-
ity of relocating the hip joint by soft tissue opera-
tions alone (Samilson et al., 1967). As Spencer (1999)
emphasizes, the complexity of surgery, the problem
of postoperative pain for the child and great difficulty
in treating a painful dislocation in young adults are
strong indicators for the close monitoring and con-
servative management of hips in children with cere-
bral palsy.
This problem needs to be addressed primarily
by abducting the hips. In seating, it is important
that sufficient abduction is used to produce the
required muscle stretch and maintain the integrity of
the femoral head/acetabulum interface. Many pom-
mels that are commonly used in cushions are rel-
atively narrow in width and therefore serve mainly
to prevent contact between the thighs, thus limiting
adduction without producing abduction. This may
be general practise because a pommel wide enough
to produce an abducted hip position would have
poor cosmesis and may be impractical when skirts
are worn.
An alternative option is the use of a hip abduction
orthosis (Bower, 1990) to maintain the relationship
between the femurs and pelvis combined with use of
a seating system. Another is to use a seating orthosis
combing spinal jacket and abduction orthosis (Carl-
son & Winter, 1978), which gives better control of hip

position.
An approach commonly used in seating that
addresses the problem of windsweeping is the appli-
cation of a knee block (Scrutton, 1978; Green & Nel-
ham, 1991). Figure 5.2 illustrates the application of
forces to produce a corrected position. The knee
block works by applying a derotational force along
the femur of the abducted hip and an abducting force
to the adducting hip together with stabilization of
the pelvis. It is critical that a knee block be adjusted
and used correctly if it is to be effective and that hip
integrity is established on the side that the derota-
tional force is applied.
Proper positioning following hip surgery is also
crucial in order to maximize its benefits (Scrutton,
1989). It is vital, therefore, particularly when casts
are removed, that the hips be positioned correctly
when the patient is seated in the wheelchair in order
to consolidate gains made by surgery.
Trunk orientation
Appropriate orientation of the trunk in space is an
important consideration in any seating system. As a
Seating and positioning 103
Corrected
Uncorrected
Figure 5.2. Application of forces to correct windswept deformity and establish hip integrity.
number of patients present with anterior trunk pos-
tural stability problems, it is often tempting to use
a seated orientation that is tilted back to increase
use of the back rest and utilize the effects of gravity

to locate the patient against the back rest, therefore
reducing the need for activation of postural support
muscles.
Research with able-bodied people has shown that
sitting against a more reclined back rest reduced
activation of the back extensor (Andersson et al.,
1974, 1975). This finding, however, cannot be trans-
ferred to those with spasticity, where factors such as
labyrinthine responses and a feeling of disorienta-
tion and falling (Green et al., 1992) can have a signif-
icant effect.
It has been shown that muscle activity and move-
ment time of upper limbs increased in children with
cerebral palsy when a back rest reclined from the
upright was used (Nwaobi & Trefler, 1985; Nwaobi,
1987a).
Nwaobi (1986) looked at twelve children with
cerebral palsy (spastic diplegia, mild to moderate)
who were tested in an upright and 30 degrees tilted
back position. There was a marked and statistically
significant (p ≤ 0.05) increase in activity of back
extensors when tilted back (the hip adductors and
ankle plantar flexors showed small increasesin mean
value, but this was not statistically significant).
The variability of such studies was shown when
Nwaobi et al. (1983) looked at eleven children with
cerebral palsy in seven combinations of seat and
back rest inclination. This study showed that the
mean EMG increased with a rearward inclined back
rest, but not significantly (p = 0.05) so; there was

a marked and significant change with the back rest
inclined forward by 15 degrees.
Tilting someone back also reduces their ability to
interact with their environment and decreases social
stimulation and visual awareness. While a compro-
mise may be considered in a device with variable tilt,
it is important that the way such a device is used
be discussed with the patient’s caregivers, so that it
is tilted back only when appropriate (e.g. if the user
falls asleep).
Restraint of arm movement
It may be appropriate in certain situations that
unwanted arm movement is restrained to help
reduce tone and associated reactions and produce
functional gains.

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