Any wheelchair user needs a well-fi tting wheelchair with an effective cushion if the dangers of prolonged pressure and poor posture are to be minimized. Even the most sophisticated cushion cannot work optimally if it is not adequately supported by the wheelchair. It is therefore essential when assessing a wheelchair user that the wheel-chair and cushion are considered as one unit. On completion of the assessment and prescription, the seating must be fitted properly to the individual as otherwise it may itself become the cause of tissue trauma (Batavia & Batavia 1999).
The purpose of the seating is to offer the user a stable and com-fortable base from which he can function at his full potential with maximum effi ciency and minimum effort. It should also promote a symmetrical posture and provide adequate skin protection. If the position of the patient is not stable on the seat, the patient will tend to slide on the seat, causing friction, which is more damaging to the
Figure 6.1 Prone position of patient on a pack bed.
Ch06-F10180.indd 77
Ch06-F10180.indd 77 5/9/2006 6:49:00 PM5/9/2006 6:49:00 PM
skin than pure pressure. Regular friction may be indicated by the reduction in hair growth in patches over the ischii. The seating system should be supportive but not restrictive. Normal posture is dynamic – the patient recently out of bed should be encouraged to change his posture frequently in the chair but also know how to return to a symmetrical upright posture.
Posture
Most patients with a recent spinal cord injury will need some encour-agement and support to adopt the correct position in the wheelchair.
Due to the lack of, or altered, sensation below the level of the lesion, the patient will not receive the normal sensory input to tell him when he is adopting a normal posture in the chair. He needs time to learn to recognize when he is positioned correctly by using the sensory input from the unaffected parts of the body. To achieve this, it is crucial that this sensory stimulus is that of normal postural align-ment from the first day out of bed, and this should be carried on throughout the 24 hour period, not just when the patient is up in the wheelchair. Attention to detail and a consistent approach to position-ing in the early days of rehabilitation will soon show the benefit. The therapist needs to take a very active role in guiding and supporting not only the patient but also all other professionals involved with positioning the patient, whether in the wheelchair or in bed. This is particularly the case with patients who have high tone, asymmetrical neurological defi cit or incomplete lesions. The patient’s position in bed needs to address the postural problems observed in sitting without compromising the skin integrity of the patient. A commonly used and very effective position in bed for patients with a scoliosis or increased kyphosis is the hipfl icked position as described earlier.
This position is very effective in breaking up high tone patterns, stretching the side flexors of the trunk, and it encourages trunk extension if positioned well.
After the prolonged period of bedrest, the postural muscles unaf-fected by the spinal cord injury will inevitably be weak. It is benefi cial if static neck and back extension exercises can be initiated during the last 2 weeks prior to getting up and carried on during the initial rehabilitation phase.
When the patient is positioned in the wheelchair he should sit with the bottom right to the back of the seat, the trunk and head sym-metrical, all four limbs resting in normal alignment, the weight dis-tributed evenly over as wide an area as possible and the anatomical curves of the spine maintained.
In order to achieve this it is essential that the wheelchair used when mobilizing the patient is a good fit.
Seat width – it should be possible to just slide a hand between the widest point of the hips and side of the chair. Recent weight gain or weight loss must be considered.
79
PRESSURE – EFFECTS AND PREVENTION
If the seat is:
1. Too narrow – there is danger of excessive pressure on the hips (trochanters). If the trunk cannot be accommodated comfortably within the back uprights the user will tend to rotate with one side comfortably within the backrest and the other on top of the backrest upright.
2. Too wide – this is likely to lead to asymmetrical pelvic posture as the patient tends to place the hips to one side or the other for stability. This in turn will lead to pelvic obliquity and scoliosis with increased risk of developing a pressure area on the lower ischium and possibly also on the side of thorax resting against the side support of the backrest.
Seat depth – the whole length of the thighs should be supported to within 5 cm (2 inches) (maximum) of the popliteal fossa.
If the seat is:
1. Too long – the patient will not be able to get to the back of the seat and will slump and gradually slide forwards. This will create excessive pressure and friction on the sacrum.
2. Too short – the area over which the weight can be distributed will be decreased, thereby increasing overall pressure on the remaining contact area.
Footplates – must be adjustable to allow the thighs to be in contact with the full length of the cushion.
If the footplates are:
1. Too high – the area over which the weight is distributed is reduced and the pressure will be increased over the remaining contact area.
2. Too low – increased pressure on the distal part of the thigh will reduce venous return and increase the risk of oedema to the lower legs and feet. The downward drag of the feet will make it harder for the patient to lift fully back onto the seat.
Backrest height should be high enough to give adequate support without interfering with the shoulder girdle and upper limb function when propelling the wheelchair. For patients with levels above T6 the backrest should be no higher than the inferior angle of the scapulae.
For paraplegic patients with levels below T6 the backrest should be no lower than the level of sensation.
If the backrest is:
1. Too high – the patient will feel as if he is being pushed forward and will frequently ask to have his hips pulled forwards to compensate, resulting in a slumped position. This will encourage the body to gradually slide further forwards on the seat with ever increasing trauma to the sacrum. Furthermore the loss of lumbar lordosis will lead to gradually increasing thoracic kyphosis and increased cervical lordosis often associated with neck pain.
Ch06-F10180.indd 79
Ch06-F10180.indd 79 5/9/2006 6:49:00 PM5/9/2006 6:49:00 PM
2. Too low – if the backrest does not offer suffi cient support the newly injured patient will typically tend to arch over the backrest with an anteriorly tilted pelvis. In order to compensate and gain increased trunk support they will lower themselves in the chair by bringing their hips forward. This results in posterior tilt of the pelvis and increased thoracic kyphosis. A temporary back extension may help until the patient’s balance and postural control have improved.
Backrest angle should be as close to vertical as the patient can tolerate. If the patient needs to be tilted back it is important to main-tain a minimum of 90° hip flexion to prevent sliding forward and losing the lumbar curve. This may be achieved either through inde-pendent adjustment of back/seat angle or by reclining the backrest with simultaneous ramping of the cushion at the front by inserting a wedge under the first third of the cushion. If the wedge goes further under the cushion, the patient tends to be raised overall in the seat and the effect is lost.
Maintaining the normal curves of the spine can be very difficult to achieve in a standard slingback style backrest. A tension adjustable backrest (see Fig. 11.3) provides the most effective and comfortable way of sculpting the backrest to the contours of the individual. Most newly injured patients tend to be very stiff in the lumbar spine when fi rst mobilizing out of bed. The tension adjustable backrest can be altered regularly as the spine becomes more flexible.
Armrests will assist newly injured patients to maintain their balance in the chair. Being able to rest on armrests occasionally will help to alleviate fatigue of the postural muscles of the trunk. As they make it easier for patients to alter their position in the chair, armrests also encourage a more dynamic posture. Armrests should ideally be height adjustable for optimum support.
If the armrests are
1. Too high – the shoulders will be elevated and may lead to shoulder/neck pain.
2. Too low – the patient will have to stoop to rest on them, which will encourage kyphotic trunk posture. There may also be drag on the shoulder joint leading to shoulder pain.
For more detailed description of wheelchair options and adjustments, see Chapter 11.