The Lateral Abductor Device
Claude Valiquette, CP(c)
Guy Robert, OT
Jean Audet, Eng jr.
Introduction
Of the general guidelines established in the
seating field, a position of symmetrical hip
abduction is one of the most-mentioned, important conditions for proper posture. Abduction allows equal weightbearing through
both ischial turberosities and thighs, thus
permitting better pressure distribution (1). It
provides a wider, more stable support base
for the upper body while limiting contratures and deformities that could interfere
with function (1-3).
Several methods and technical aids have
been used to promote hip abduction, but the
most widely used is the abduction block or
pommel (2-5). The pommel is a very simple,
effective device that can be used in many
situations. Some have advocated its use as a
way to prevent forward sliding (6). Others,
including the authors, believe abduction
pommels were not designed for that purpose
and should not be used thus (3). In fact, the
pommel should be clear of the groin area to
avoid irritation.
The conventional pommel with a central
anchoring point has drawbacks, especially
when used with individuals exhibiting abduction and flexion of the hips due to severe
spasticity and strong muscle tone or stiffness
of the lower limbs. Patients showing this synergic pattern of abduction and flexion will
usually sit in an overlapping or crosslegged
position of the knees (see Figure 1
). It renders hygiene difficult and may lead to hip
rigidity, contracture, circulatory problems
and even pressure sores.
In these conditions, a conventional pommel can often be inadequate, partly from the
difficulty in forcing the pommel in place
while simultaneously maintaining both
thighs in abduction. This action requires
considerable strength, and the struggle,
combined with the anxiety of the patient,
often increases spasticity.
A pommel's bulkiness increases difficulty
of installation. For example, an optimal abduction range on a 16-inch seat can require a
block up to eight inches in width, if not
more. Also, the pommel's height will have to
be greater than normal to keep the leg from
crossing over. These pommels are very difficult to grasp and position, even with a tilting
mechanism (see Figure 2
).
Finally, to restrain flexion movement,
straps or transverse supports are usually installed with the pommel. Apart from being
unaesthetic, straps increase the risk of skin
problems due to friction and installation difficulty.
For these reasons attending personnel
may often refuse to position patients in adaptive seats. Plus, with a central anchoring
pommel, teaching patient attendants appropriate inhibiting manipulation techniques to
facilitate proper positioning would not be
realistic.
Consequently, an abductor device was designed that combines functionally and physiologically sound features. It promotes the
use of proper manipulation techniques for
patients with strong abduction and flexion
spasticity or rigidity.
The Apparatus
The device is composed of three or four components and can be used on Everest and Jennings Premier series chairs or Otto Bock
Moss II chairs. Components include:
- vertical plunger (on E&J chairs)
- swivel
- flexion restraint and
- abductor components (see Figure 3
).
Prototypes were made out of chrome-plated
steel-and-PVC tubing (see Figure 4
).
The swivel's main body can be positioned
in depth by horizontal sliding attachments.
The swivel axis rotates 90 degrees around the
vertical axis and supports the square-sectioned "L" post (see Figure 5
). This "L" post
is permitted to slide along the vertical axis
for height adjustment and is positioned with
a set screw.
The flexion restraint component is a cushioned rod located transversely above the anterior distal thigh area. The end of the flexion restraint component is fitted with a 90degree elbow connection that supports the
abductor component. This elbow rotates
freely around its axis. The abductor component, a cushioned rod, follows an arc-shaped
course from the medial metaphysis of the
femur, around and below the internal condyle and extending over the medial tibial
flare. The latter is considered a pressure-tolerant area (see Figure 6
) (7).
The device has a standard "one size"
design and adjusts to accommodate most
adult anthropometry. Sliding attachments
equipped with set screws permit the positioning of the restraint components, relative
to the user, in height and depth.
The abductor and flexion restraint components, made of PVC tubing, are precut to
size and handshaped with a heat gun. If need
be, the component can be custom-padded to
the individual needs of the user. The width
between the "L" post and the abductor component is adjusted to the patient by cutting
the flexion restraint component at the desired length.
The device is anchored to each side of the
wheelchair and supports the thighs independently (see Figure 7
). It can be swung away
for easy access to the front of the wheelchair
or removed to accommodate transfers.
Advantages
Since there is one device per limb, each can
be manipulated and positioned independently. The orderly can perform this task alone
with minimal effort. The patient is not as
anxious and thus presents less spasticity.
When installing the device, the orderly
will abduct the leg by slowly pushing against
the knee with one hand (see Figure 8
). The
flexion restraint component can then be rotated 90 degrees over the thigh, and the abduction restraint component can be lowered
next to the medial side of the knee with the
other hand (see Figure 9
, and Figure 10
).
With a pommel, untrained personnel
would, more often than not, try to force it in
place between the legs of the patient without
abducting the legs beforehand. The abductor device is designed to maintain both flexion and abduction. Unlike the pommel, no
straps are needed, and it can be adjusted to
any range of abduction without increasing
bulkiness. It is also less noticeable than an
oversize pommel.
Evaluation
The abductor device was furnished as part of
a whole seating unit. For the first weeks of
use, the patients were checked by the prosthetist who had assembled the seats. Devices
were evaluated by nurses, occupational therapists and orderlies using questionnaires.
Unfortunately, only one patient was able to
comment on the device.
Seven patients were evaluated. All were
female. Most were diagnosed as having senile dementia. Two patients had multiple
sclerosis and one had Alzheimer's disease.
Mean age was 78 (+/- 17) years (see Table 1
).
The devices were used an average of 5 (+/- 2)
hours per day. Re-evaluation of the device
was done after more than six months of use.
Many users increased their sitting time after being fitted with the seating unit. In fact,
previously, some patients were almost bedridden. Although the abductor device plays
a role in maintaining proper posture, the
improvement is due to the whole seating
unit.
It was difficult to evaluate to what extent
the device had an effect on spasticity since
most patients received medication to control
this condition. It was noted, however, that
after being seated spastic patients would relax whereas rigid patients would continue
straining against the device. This can be of
importance when the patient is at risk of
developing pressure sores.
After initial evaluation, one patient developed skin problems. Consequently, the padding over the bearing area was thickened.
Afterward the devices at this center were
used cautiously for two hours per day intermittently.
In most cases, the device did not seem to
interfere with daily activities. It fits under
wheelchair trays and does not restrict access
to tables. Two comments were made concerning inconvenience-in one case when
using a patient lift, in another case for patient transfer. However, the device can be
removed in these cases.
In two cases where a pommel had been
used, the lateral abductor device was preferred because personnel found the device
easier to use, and it maintained better posture. In every case, personnel said they were
satisfied with the device. All mentioned that
the device properly maintained abduction of
the hips and prevented leg crossing (see Figure 11
, Table 2
).
Criticism of the device focused on difficulties in learning how to use it and assembling
it properly when it had been removed from
the chair. These points are important since
the device is to be used mainly by attending
personnel. Orderlies will not necessarily be
very familiar with the device and will not
have time to tinker with it. These problems
inherent to the design can be fairly easily
addressed through modifications in later designs.
One therapist commented that when seating the patient and adjusting the device, orderlies had to strain against the patient's leg.
It has to be remembered that manipulation
of hypertonic patients, especially spastic patients, is better done slowly, thereby permitting the patients to relax. Although this device can promote better manipulation techniques, it is no substitute for proper training
of personnel.
Re-evaluation was performed on six of the
seven devices since one patient's condition
had deteriorated, and she could no longer be
seated.
Overall response remained much the same
as for the first evaluation. Skin redness was
apparent in pressure-bearing areas in three
cases (see Table 3
).
Conclusion
The lateral abductor device was developed
for users presenting hypertonicity of the lower limbs. The device is designed to maintain
proper abduction and flexion of the hips.
The advantages over a conventional pommel
include better posture maintenance, promotion of proper manipulation techniques since
each leg can be handled independently and a
reduction in bulkiness. The device is adjustable to any morphology.
Preliminary testing has verified these advantages. Further developments will alleviate skin pressure and simplify assembly of
the device. This approach to promoting hip
abduction and independent limb restraint
opens up new design possibilities that could
be applicable to other clientele with different
needs, such as pediatric or para/quad clients.
Claude Valiquette, CP(c), is a graduate prosthetist specializing in seating at the Institut de Réadaptation de Montréal, 6300 ave Darlington,
Montreal (Quebec), Canada H3S 2J4; tel: (514)
340-2079; fax: (514) 340-2149.
Guy Robert, OT, specializes in seating at the
Institut de Réadaptation de Montréal.
Jean Audet, Eng Jr., is the technical aids department's development coordinator at the Institut de
Réadaptation de Montréal.
References:
- Pope PM. Proposals for the improvement of
the unstable postural condition and some cautionary notes. Physiotherapy March 1985 ;71 :3:129131.
- Falk Bergen A, Colangelo C. Positioning the
Client with Central Nervous System Deficits: The
Wheelchair and other Adapted Equipment, 2d ed.,
Valhala Rehab. Pub. 1985:105.
- Silverman M. Commercial options for positioning the client with muscular dystrophy. Clinical Prosthetics and Orthotics 1986;10:4: 159-170.
- Mulcahy CM, Pountney TE, Nelham RL,
Green EM, Billington GD. Adaptive seating for
the motor-handicapped: problems-a solution,
assessment and prescription. Physiotherapy October 1988;74:l0:531-536.
- Ward D. Positioning the Handicapped Child
for Function, 2d ed. Phoenix Press, 1984:78.
- Motloch WM. Seating and positioning for
the physically impaired. Orthotics and Prosthetics
June 1977;31:2:11-21.
- Radcliffe CW, Foort J. The Patellar-Tendon-Bearing Below-Knee Prosthesis, revised ed.
The Regents of the University of California,
1961 :24.
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