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The seating clinic
Current Paediatrics (2001) 11, 68d72 ^ 2001 Harcourt Publishers Ltd doi:10.1054/cupe.2000.0145, available online at http://www.idealibrary.com on
The seating clinic S. M. Wallis Consultant Paediatrician, Dingley Child Development Centre, Royal Berkshire and Battle Hospital NHS Trust, Battle Hospital, Oxford Rd, Reading RG3 1AG, UK
Provision of an appropriate seat for a child with poor postural control or deformity not only improves function by ensuring he feels secure and comfortable, but also forms an important part of his programme of postural management. Children with severe physical disability often spend the majority of their day sitting or lying down and receive comparatively short periods of therapy. Long periods of immobility, particularly in an asymmetric posture, are a recognised cause of deformity.1 If special seating, together with devices to develop postural control in other positions such as lying and standing reflect and reinforce therapy aims, the child will be encouraged to develop and improve his postural control and the risks of deformity are reduced. A special seating clinic for children and teenagers was set up in Reading 9 years ago, as there were many young people with severe seating problems. At that time the wheelchair service was provided by the Artificial Limb and Appliance Centre and focused on mobility. The majority of patients seen were adults, frequently in the geriatric age group, and the needs of children were often poorly understood. Special seating depended on referral to the Regional Rehabilitation Service and this was usually not considered until deformity precluded use of a standard wheelchair. In 1991 the NHS took over the management of the Wheelchair Service. Their brief is now wider and includes consideration of their patients’ comfort, function, posture, pressure relief and changing needs as well as mobility. Seating advice for complex cases is available at supradistrict or regional level but dedicated children’s services are not available in all regions. This is disappointing as prescriptive seating has been developed for children with motor handicaps, combining bio-mechanical principles with therapy aims, so as to promote maturation of sitting posture and control deforming forces.
influenced by visual feedback. Control is achieved when one segment of the body is anchored, allowing counter balance of adjacent segments. There is an overlap between the infant’s ability to control his posture when lying on the floor and his stage of sitting ability. Mulcahy2 has defined these stages in normal infants (see Fig. 1) and found they are equally applicable to children with cerebral palsy. She found no child was able to maintain sitting balance (Level 3) until they were able to stabilise the trunk whilst lying on the floor and lift the head and limbs freely, enabling midline hand and foot play. In order to sit with an erect spine the child needed to be able to stabilise his pelvis and move forward over his sitting base (Level 4). A stable upper trunk and shoulder girdle is needed for head control and use of the hands. These stages have been used as the basis for the development of both a therapy programme and prescriptive seating for children with motor handicap.
DEVELOPMENT OF POSTURAL CONTROL
Biomechanical principles
Control of posture arises centrally from the brain and segmentally from the spinal cord and is particularly
THE UPRIGHT SITTING POSTURE The functional benefits of an upright posture have been well proven.3 Children with cerebral palsy, who are allowed to adopt a reclined posture, have increased extensor thrust of the head and trunk. This aggravates their sense of falling and directs their line of vision towards the ceiling and may be countered by a tendency to flex forwards. Extension of the neck also interferes with feeding, particularly swallowing which is a flexor activity. Increased spasm in the upper limbs adversely affects hand use. Studies of cognitive function have shown the ability to execute more complex tasks deteriorates when the child is reclined.
For normal upright sitting there should be a neutral pelvis with the trunk weight supported through the ischial tuberosities and the backs of the thighs (Fig. 2).
THE SEATING CLINIC
69
Figure 2 Normal upright sitting. Neutral pelvis allows spine to adopt its natural curvature. Body weight is supported through the ischial tuberosities and posterior thighs. Note on horizontal seat the femora slope downwards.
Figure 1 Levels of sitting ability with an individual placed on a flat box of the correct height, feet on floor. (Reproduced with kind permission of Chailey Heritage.) Figure 3 Poor postural control results in a slumped posture with a posteriorly rotated pelvis d sacral sitting.
Children with immature or abnormal postural control slump into sacral sitting in a moulded or horizontal seat (Fig. 3). They need an orthogonal seat base with ramped cushion (Fig. 4), sacral pad, curved but upright back rest, lap strap (Fig. 5) and, if necessary, knee block to maintain an upright sitting posture.3 The knee block can be used to control and correct windswept pelvic deformity resulting from asymmetric muscle tone which if untreated usually results in dislocation of the hip and spinal curvature (Fig. 6).4 Scoliosis pads to help control curvature of the spine must be aligned with the body contours so that the corrective forces are directed along the line of the ribs (Figs. 7 and 8). If support or correction of the scoliosis is the primary requirement a spinal brace should be provided before fitting the seat. Using these principles a prototype chair was developed known as the Chailey
Adapta Seat. Its success has resulted in a variety of similar chairs which permit adjustment for growth.
ORGANISATION OF THE SEATING CLINIC Referral The children likely to benefit from referral are those with delayed or abnormal postural control, due to neuromuscular disease, or deformity from musculoskeletal disorders (Table 1). Close liaison with medical colleagues and therapists is necessary to ensure early referral.
70
Figure 4 Provision of 153 ramped cushion supports femur in horizontal and achieves a neutral pelvis. But if lapstrap is used, depth of thorax is greater than pelvis so upper trunk flexes forward.
Figure 5 In order to lift the upper trunk the pelvis slides forwards under the lap strap and rotates posteriorly.
CURRENT PAEDIATRICS
Figure 6 Orthogonal base. Provision of a sacral pad allows for the difference in depth between the thorax and pelvis and together with the knee block counters the tendency for the pelvis to slide forwards and rotate posteriorly.
Figure 7 (A) Windswept pelvis and hips. Asymmetric muscle spasm results in right-sided retraction and adductor spasm of right femur. The right hip is liable to dislocate posteriorly. (B) Knee block used to correct pelvic rotation and counter the adductor spasm of right femur thus reducing the risk of dislocation of the hip.
The team approach A team approach is essential involving the child, his parents and carers, therapists, medical staff, including paediatrician, orthopaedic consultant and a rehabilitation engineer or orthotist and if appropriate teachers so that all views can be shared and considered. It is very easy for adults to take over and the child must be given opportunity and sufficient time to give his views, particularly regarding comfort, function and sense of security.
Establishing the requirements of the chair Questions should elicit why the chair is needed, whether this is due to growth or changing need, and how and where it will be used. Some chairs are required primarily for static activities such as feeding, play and
Figure 8 Posterior view of scoliosis. Note lateral pelvic pads hold the pelvis in the centre of the seat. Trunk support is provided through pads aligned with the body contours, so force is exerted along the line of the ribs to the spine.
THE SEATING CLINIC
Table 1 Some conditions likely to benefit from referral for seating advice Neuromuscular disorders: Cerebral palsy Severe/profound learning difficulties Myelomeningocele Muscular dystrophy Spinal muscular atrophy Arthrogryposis multiplex congenita Acute cerebral injury e.g. head injury cerebro-vascular accident tumours meningitis Musculoskeletal disorders Osteogenesis imperfecta Arthritis } severe Other Ventilator dependent children
71 Lastly, the child’s level of postural control needs to be established in lying, sitting and standing positions. The ability to balance and move within positions, and to get from one position to another can be scored to give a level of sitting ability (Fig. 1). Assessment of vision is necessary when the child is self-propelling and, if using a powered chair, assessment of the best means of accessing and operating a switch.
Seating prescription This is based on the following principles and adjusted according to the level of sitting ability, weight distribution and symmetry. E Aim for upright sitting posture for all children. Start with a stable mid-line pelvis and build trunk support segment by segment. Provide support for the feet.
Sitting Levels 1/3:
communication, either in the home or at school. In both settings there may be space constraints. If the chair is mainly used for mobility will it be self or attendant propelled or electrically powered, and will the child be attempting to get in and out of the chair himself? Has the house been adapted for the use of the wheelchair with ramps and sufficiently wide doorways and turning areas? The chair may need to be transported, if so it will need to be easy to fold, light to lift and sufficiently compact when folded to fit the boot of a car.
These children have very poor postural ability: ranging from total physical dependence even for observation of the environment to those at Level 3 who are learning to sit but are static tense observers, totally dependent on their hands for balance.
Level 1: The Level 1 child requires postural fixation with a stable pelvis and maximal trunk and head support. He will need an orthogonal seat with knee block to anchor the pelvis. A variety of harnesses are available to provide additional trunk support, a waistcoat with velcro fastenings is very useful. Stabilising the shoulder girdle by providing a tray at elbow height may assist head control.
The seating assessment This involves measuring the child’s current postural ability, likely areas of improvement and any existing or potential deformity. It is important to assess the child in his current chair. Abnormal movement patterns are sometimes used for function such as recovering head control. If the new chair attempts to correct and block these movement patterns, the child will be frustrated and the chair is likely to be rejected. The child should then be examined out of his chair, particularly noting ease of handling, and the presence of any fixed or correctable deformity of the spine, pelvis, hips and knees. Note any patches of reddened skin as possible pressure areas. Some children with cerebral palsy have strong or asymmetric extensor tone which increases with excitement and are very difficult to handle. So it is important to find the position in which these children are most relaxed in order to achieve optimal function.
Levels 2 and 3: Children with sitting ability Levels 2 and 3 need adjustable levels of trunk support to help them develop their own trunk control.
Level 4: The children at sitting Level 4 are improving their sitting balance. They require a stable symmetrical pelvis to encourage extension of spine and arm movement. This is provided by an orthogonal base, sometimes a pommel helps to widen the sitting base. Lateral support is proved by arm rests.
Level 5: From sitting Level 5 the child benefits if his feet are resting on the floor and he has a table of the appropriate
72 height to facilitate coming up to stand. An orthogonal base remains appropriate but a pommel may interfere with getting in and out of the seat independently. The child should be able to undo and fasten his lap strap. E
Avoid asymmetry where possible. Zones vulnerable to deviation should be supported and offloaded and tissue trauma prevented by distributing pressure over the largest possible area. In cerebral palsy mild rotational spasms can be controlled by seating systems using a knee block. A strong tendency to rotate will be extremely difficult to control by seating techniques alone and orthosis such as a spinal brace may prove impossible to wear from some athetoid patients as involuntary movement results in tissue trauma. In these circumstances a moulded seat may be the only solution but this will only accommodate the rotation so the child’s posture will appear very unsatisfactory but the best that can be achieved within the constraints of comfort and function. Children with fixed skeletal deformities may also need a specially moulded seat to accommodate their deformity. Several systems are available, the matrix or lynx system has the advantage of easy adjustment for growth and postural change.
E
The level of support should be adjustable so it can be reduced to enable practice of postural control and increased to facilitate head control and release of the hands for play or to provide security when the seat is used for transport. E Ensure the chair is tested for balance and stability if fixed to a wheelchair base.
Acceptance and use of the new chair The team approach together with careful explanation of use should ensure acceptance of the seat. Children who are not used to being upright may need a gradual introduction only spending short periods in their new chair initially. To prevent joint contracture and tissue damage no-one should sit for longer than 2 h. We have found the upright position is most easily accepted when introduced as a static chair to facilitate play, communication and feeding. Parents of children with feeding difficulties often prefer to feed them on their knee and worry about the difficulty of quickly
CURRENT PAEDIATRICS releasing a child from a chair should they choke. It is important to help them realise that choking is less likely if the child is well supported with the head prevented from retraction. For outdoor use parents often seek a chair that doesn’t look ‘handicapped’ and put forward strong arguments in favour of a standard buggy which is lightweight, easy to fold and compact. This argument is best countered by demonstrating a child’s improved independence and function with an upright posture.
Audit Careful scoring of the child’s level of sitting ability and recording of deformity at the initial assessment, forms a baseline against which the child’s progress and the performance of the chair can be measured. We have found polaroid photographs and video recordings helpful. Evidence that the chair is used regularly indicates it satisfies the needs identified by the team approach.
ACKNOWLEDGEMENT I am grateful to colleagues in the Reading Seating Clinic for sharing their knowledge with me.
REFERENCES 1. Brown J K, Fulford G E. Position as a cause of deformity in cerebral palsy. Dev Med Child Neuro 1976; 18: 305d314. 2. Mulcahy C M, Pountney T E, Nelham R L, Green E M, Billington G D. Adaptive seating for motor handicap: problems, a solution, assessment and prescription. Br J Occup Ther 1988; 51(10): 347d352. 3. Green E M, Nelham R L. Development of sitting ability, assessment of children with a motor handicap and prescription of appropriate seating systems. Prosthet Orthot Int 1991; 15: 203d221. 4. Scrutton D. Developmental deformity and the profoundly retarded child. In: Apley J ed. Care of the Handicapped Child. London: SIMP Heinemann, 1978.
FURTHER READING McCarthy G T, ed. Physical Disability in Childhood. Edinburgh: Churchill Livingstone, 1992. The Provision of Wheelchairs and Special Seating. London: Royal College of Physicians, 1995.
The seating clinic S. M. Wallis Consultant Paediatrician, Dingley Child Development Centre, Royal Berkshire and Battle Hospital NHS Trust, Battle Hospital, Oxford Rd, Reading RG3 1AG, UK
Provision of an appropriate seat for a child with poor postural control or deformity not only improves function by ensuring he feels secure and comfortable, but also forms an important part of his programme of postural management. Children with severe physical disability often spend the majority of their day sitting or lying down and receive comparatively short periods of therapy. Long periods of immobility, particularly in an asymmetric posture, are a recognised cause of deformity.1 If special seating, together with devices to develop postural control in other positions such as lying and standing reflect and reinforce therapy aims, the child will be encouraged to develop and improve his postural control and the risks of deformity are reduced. A special seating clinic for children and teenagers was set up in Reading 9 years ago, as there were many young people with severe seating problems. At that time the wheelchair service was provided by the Artificial Limb and Appliance Centre and focused on mobility. The majority of patients seen were adults, frequently in the geriatric age group, and the needs of children were often poorly understood. Special seating depended on referral to the Regional Rehabilitation Service and this was usually not considered until deformity precluded use of a standard wheelchair. In 1991 the NHS took over the management of the Wheelchair Service. Their brief is now wider and includes consideration of their patients’ comfort, function, posture, pressure relief and changing needs as well as mobility. Seating advice for complex cases is available at supradistrict or regional level but dedicated children’s services are not available in all regions. This is disappointing as prescriptive seating has been developed for children with motor handicaps, combining bio-mechanical principles with therapy aims, so as to promote maturation of sitting posture and control deforming forces.
influenced by visual feedback. Control is achieved when one segment of the body is anchored, allowing counter balance of adjacent segments. There is an overlap between the infant’s ability to control his posture when lying on the floor and his stage of sitting ability. Mulcahy2 has defined these stages in normal infants (see Fig. 1) and found they are equally applicable to children with cerebral palsy. She found no child was able to maintain sitting balance (Level 3) until they were able to stabilise the trunk whilst lying on the floor and lift the head and limbs freely, enabling midline hand and foot play. In order to sit with an erect spine the child needed to be able to stabilise his pelvis and move forward over his sitting base (Level 4). A stable upper trunk and shoulder girdle is needed for head control and use of the hands. These stages have been used as the basis for the development of both a therapy programme and prescriptive seating for children with motor handicap.
DEVELOPMENT OF POSTURAL CONTROL
Biomechanical principles
Control of posture arises centrally from the brain and segmentally from the spinal cord and is particularly
THE UPRIGHT SITTING POSTURE The functional benefits of an upright posture have been well proven.3 Children with cerebral palsy, who are allowed to adopt a reclined posture, have increased extensor thrust of the head and trunk. This aggravates their sense of falling and directs their line of vision towards the ceiling and may be countered by a tendency to flex forwards. Extension of the neck also interferes with feeding, particularly swallowing which is a flexor activity. Increased spasm in the upper limbs adversely affects hand use. Studies of cognitive function have shown the ability to execute more complex tasks deteriorates when the child is reclined.
For normal upright sitting there should be a neutral pelvis with the trunk weight supported through the ischial tuberosities and the backs of the thighs (Fig. 2).
THE SEATING CLINIC
69
Figure 2 Normal upright sitting. Neutral pelvis allows spine to adopt its natural curvature. Body weight is supported through the ischial tuberosities and posterior thighs. Note on horizontal seat the femora slope downwards.
Figure 1 Levels of sitting ability with an individual placed on a flat box of the correct height, feet on floor. (Reproduced with kind permission of Chailey Heritage.) Figure 3 Poor postural control results in a slumped posture with a posteriorly rotated pelvis d sacral sitting.
Children with immature or abnormal postural control slump into sacral sitting in a moulded or horizontal seat (Fig. 3). They need an orthogonal seat base with ramped cushion (Fig. 4), sacral pad, curved but upright back rest, lap strap (Fig. 5) and, if necessary, knee block to maintain an upright sitting posture.3 The knee block can be used to control and correct windswept pelvic deformity resulting from asymmetric muscle tone which if untreated usually results in dislocation of the hip and spinal curvature (Fig. 6).4 Scoliosis pads to help control curvature of the spine must be aligned with the body contours so that the corrective forces are directed along the line of the ribs (Figs. 7 and 8). If support or correction of the scoliosis is the primary requirement a spinal brace should be provided before fitting the seat. Using these principles a prototype chair was developed known as the Chailey
Adapta Seat. Its success has resulted in a variety of similar chairs which permit adjustment for growth.
ORGANISATION OF THE SEATING CLINIC Referral The children likely to benefit from referral are those with delayed or abnormal postural control, due to neuromuscular disease, or deformity from musculoskeletal disorders (Table 1). Close liaison with medical colleagues and therapists is necessary to ensure early referral.
70
Figure 4 Provision of 153 ramped cushion supports femur in horizontal and achieves a neutral pelvis. But if lapstrap is used, depth of thorax is greater than pelvis so upper trunk flexes forward.
Figure 5 In order to lift the upper trunk the pelvis slides forwards under the lap strap and rotates posteriorly.
CURRENT PAEDIATRICS
Figure 6 Orthogonal base. Provision of a sacral pad allows for the difference in depth between the thorax and pelvis and together with the knee block counters the tendency for the pelvis to slide forwards and rotate posteriorly.
Figure 7 (A) Windswept pelvis and hips. Asymmetric muscle spasm results in right-sided retraction and adductor spasm of right femur. The right hip is liable to dislocate posteriorly. (B) Knee block used to correct pelvic rotation and counter the adductor spasm of right femur thus reducing the risk of dislocation of the hip.
The team approach A team approach is essential involving the child, his parents and carers, therapists, medical staff, including paediatrician, orthopaedic consultant and a rehabilitation engineer or orthotist and if appropriate teachers so that all views can be shared and considered. It is very easy for adults to take over and the child must be given opportunity and sufficient time to give his views, particularly regarding comfort, function and sense of security.
Establishing the requirements of the chair Questions should elicit why the chair is needed, whether this is due to growth or changing need, and how and where it will be used. Some chairs are required primarily for static activities such as feeding, play and
Figure 8 Posterior view of scoliosis. Note lateral pelvic pads hold the pelvis in the centre of the seat. Trunk support is provided through pads aligned with the body contours, so force is exerted along the line of the ribs to the spine.
THE SEATING CLINIC
Table 1 Some conditions likely to benefit from referral for seating advice Neuromuscular disorders: Cerebral palsy Severe/profound learning difficulties Myelomeningocele Muscular dystrophy Spinal muscular atrophy Arthrogryposis multiplex congenita Acute cerebral injury e.g. head injury cerebro-vascular accident tumours meningitis Musculoskeletal disorders Osteogenesis imperfecta Arthritis } severe Other Ventilator dependent children
71 Lastly, the child’s level of postural control needs to be established in lying, sitting and standing positions. The ability to balance and move within positions, and to get from one position to another can be scored to give a level of sitting ability (Fig. 1). Assessment of vision is necessary when the child is self-propelling and, if using a powered chair, assessment of the best means of accessing and operating a switch.
Seating prescription This is based on the following principles and adjusted according to the level of sitting ability, weight distribution and symmetry. E Aim for upright sitting posture for all children. Start with a stable mid-line pelvis and build trunk support segment by segment. Provide support for the feet.
Sitting Levels 1/3:
communication, either in the home or at school. In both settings there may be space constraints. If the chair is mainly used for mobility will it be self or attendant propelled or electrically powered, and will the child be attempting to get in and out of the chair himself? Has the house been adapted for the use of the wheelchair with ramps and sufficiently wide doorways and turning areas? The chair may need to be transported, if so it will need to be easy to fold, light to lift and sufficiently compact when folded to fit the boot of a car.
These children have very poor postural ability: ranging from total physical dependence even for observation of the environment to those at Level 3 who are learning to sit but are static tense observers, totally dependent on their hands for balance.
Level 1: The Level 1 child requires postural fixation with a stable pelvis and maximal trunk and head support. He will need an orthogonal seat with knee block to anchor the pelvis. A variety of harnesses are available to provide additional trunk support, a waistcoat with velcro fastenings is very useful. Stabilising the shoulder girdle by providing a tray at elbow height may assist head control.
The seating assessment This involves measuring the child’s current postural ability, likely areas of improvement and any existing or potential deformity. It is important to assess the child in his current chair. Abnormal movement patterns are sometimes used for function such as recovering head control. If the new chair attempts to correct and block these movement patterns, the child will be frustrated and the chair is likely to be rejected. The child should then be examined out of his chair, particularly noting ease of handling, and the presence of any fixed or correctable deformity of the spine, pelvis, hips and knees. Note any patches of reddened skin as possible pressure areas. Some children with cerebral palsy have strong or asymmetric extensor tone which increases with excitement and are very difficult to handle. So it is important to find the position in which these children are most relaxed in order to achieve optimal function.
Levels 2 and 3: Children with sitting ability Levels 2 and 3 need adjustable levels of trunk support to help them develop their own trunk control.
Level 4: The children at sitting Level 4 are improving their sitting balance. They require a stable symmetrical pelvis to encourage extension of spine and arm movement. This is provided by an orthogonal base, sometimes a pommel helps to widen the sitting base. Lateral support is proved by arm rests.
Level 5: From sitting Level 5 the child benefits if his feet are resting on the floor and he has a table of the appropriate
72 height to facilitate coming up to stand. An orthogonal base remains appropriate but a pommel may interfere with getting in and out of the seat independently. The child should be able to undo and fasten his lap strap. E
Avoid asymmetry where possible. Zones vulnerable to deviation should be supported and offloaded and tissue trauma prevented by distributing pressure over the largest possible area. In cerebral palsy mild rotational spasms can be controlled by seating systems using a knee block. A strong tendency to rotate will be extremely difficult to control by seating techniques alone and orthosis such as a spinal brace may prove impossible to wear from some athetoid patients as involuntary movement results in tissue trauma. In these circumstances a moulded seat may be the only solution but this will only accommodate the rotation so the child’s posture will appear very unsatisfactory but the best that can be achieved within the constraints of comfort and function. Children with fixed skeletal deformities may also need a specially moulded seat to accommodate their deformity. Several systems are available, the matrix or lynx system has the advantage of easy adjustment for growth and postural change.
E
The level of support should be adjustable so it can be reduced to enable practice of postural control and increased to facilitate head control and release of the hands for play or to provide security when the seat is used for transport. E Ensure the chair is tested for balance and stability if fixed to a wheelchair base.
Acceptance and use of the new chair The team approach together with careful explanation of use should ensure acceptance of the seat. Children who are not used to being upright may need a gradual introduction only spending short periods in their new chair initially. To prevent joint contracture and tissue damage no-one should sit for longer than 2 h. We have found the upright position is most easily accepted when introduced as a static chair to facilitate play, communication and feeding. Parents of children with feeding difficulties often prefer to feed them on their knee and worry about the difficulty of quickly
CURRENT PAEDIATRICS releasing a child from a chair should they choke. It is important to help them realise that choking is less likely if the child is well supported with the head prevented from retraction. For outdoor use parents often seek a chair that doesn’t look ‘handicapped’ and put forward strong arguments in favour of a standard buggy which is lightweight, easy to fold and compact. This argument is best countered by demonstrating a child’s improved independence and function with an upright posture.
Audit Careful scoring of the child’s level of sitting ability and recording of deformity at the initial assessment, forms a baseline against which the child’s progress and the performance of the chair can be measured. We have found polaroid photographs and video recordings helpful. Evidence that the chair is used regularly indicates it satisfies the needs identified by the team approach.
ACKNOWLEDGEMENT I am grateful to colleagues in the Reading Seating Clinic for sharing their knowledge with me.
REFERENCES 1. Brown J K, Fulford G E. Position as a cause of deformity in cerebral palsy. Dev Med Child Neuro 1976; 18: 305d314. 2. Mulcahy C M, Pountney T E, Nelham R L, Green E M, Billington G D. Adaptive seating for motor handicap: problems, a solution, assessment and prescription. Br J Occup Ther 1988; 51(10): 347d352. 3. Green E M, Nelham R L. Development of sitting ability, assessment of children with a motor handicap and prescription of appropriate seating systems. Prosthet Orthot Int 1991; 15: 203d221. 4. Scrutton D. Developmental deformity and the profoundly retarded child. In: Apley J ed. Care of the Handicapped Child. London: SIMP Heinemann, 1978.
FURTHER READING McCarthy G T, ed. Physical Disability in Childhood. Edinburgh: Churchill Livingstone, 1992. The Provision of Wheelchairs and Special Seating. London: Royal College of Physicians, 1995.