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Posture, postural ability and mobility in cerebral palsy

Rodby Bousquet, Elisabet

2012

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Citation for published version (APA):Rodby Bousquet, E. (2012). Posture, postural ability and mobility in cerebral palsy Department of Orthopaedics,Lund University

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Posture, postural ability and

mobility in cerebral palsy

Elisabet Rodby Bousquet

Copyright © Elisabet Rodby Bousquet

Faculty of Medicine, Department of Orthopaedics

ISBN 978-91-87189-64-7

ISSN 1652-8220

Printed in Sweden by Media-Tryck, Lund University

Lund 2012

Contents

Abstract 5

Abbreviations 6

Definitions 7

Original papers 9

Thesis at a glance 10

Introduction 11

Cerebral palsy 11

Definitions 11

Prevalence 12

Classifications 12

Musculoskeletal problems 15

CPUP - Cerebral Palsy follow up program 16

Sitting and standing 17

Mobility 18

Systems theory and motor control 18

Posture and postural ability 19

Assessment tools for posture 20

The Posture and Postural Ability Scale 21

The Functional Mobility Scale 23

Aims 24

Methods 25

Design 25

Participants 25

Data collection 27

Statistical analysis 28

Ethical considerations 29

Results 30

Sitting and standing (study I) 30

Wheeled mobility (study II) 31

Walking performance (study III) 32

Postural asymmetries (study IV) 33

Evaluation of the Posture and Postural Ability Scale (study V) 35

Discussion 37

Sitting and standing 37

Wheeled mobility 39

Walking performance 41

Postural asymmetries 43

Evaluation of the Posture and Postural Ability Scale 45

Conclusions 47

Further research 48

Sammanfattning, Summary in Swedish 49

Acknowledgements 51

References 53

5

Abstract

Cerebral palsy (CP) is the most common cause of motor disability in children and

adolescents with a prevalence of 2-3/1000. CP is characterized by disorders of

posture and movement with impairments ranging from mild to severe. The ability

to control posture is an important prerequisite for all voluntary movements. A

sustained asymmetric posture predisposes to progressive deformities in people

with CP, such as scoliosis, hip dislocations and contractures.

The aim of this thesis was to enhance knowledge of posture, postural ability and

mobility in people with CP, their use of assistive devices and also to evaluate a

clinical tool for assessment of posture and postural ability.

Study I-III were cross-sectional studies of 562 children with CP, aged 3-18 years,

describing sitting, standing, sit-to-stand and the use of assistive devices, wheeled

mobility, and walking performance according to the Functional Mobility Scale.

The results were analyzed relative to the expanded and revised version of the

Gross Motor Function Classification System (GMFCS), neurological subtype and

age. Study IV was a cross-sectional study describing postural asymmetries and

ability to change position in 102 young adults with CP aged 19-23 years; and the

relation of posture to pain, range of motion, hip dislocation, scoliosis and ability to

change position. Study V evaluated the psychometric properties of the Posture and

Postural Ability Scale for adults with CP at GMFCS I-V.

The GMFCS is a good predictor of sitting and standing performance. Powered

wheelchairs provided independent mobility in most cases while few self-propelled

their manual wheelchairs. To achieve a high level of independent mobility,

powered wheelchairs should be considered at an early age for children with

impaired walking ability. The number of children who walked without aids

increased up to 7 years, but the proportion of children walking independently on

uneven surfaces was incrementally higher in each age group up to 18 years.

Postural asymmetries were associated with scoliosis, hip dislocation, hip and knee

contractures, and inability to change position. The Posture and Postural Ability

scale showed an excellent interrater reliability for experienced raters, a high

internal consistency and construct validity. It can detect postural asymmetries in

adults with CP at all levels of gross motor function.

6

Abbreviations

CP Cerebral Palsy

CPUP Cerebral Palsy follow-up Programme and National Quality Register

FMS Functional Mobility Scale

GMFCS Gross Motor Function Classification System

ICF International Classification of Functioning, Disability and Health

PAS Postural Ability Scale

PPAS Posture and Postural Ability Scale

ROM Joint Range of Motion

SCPE Surveillance of Cerebral Palsy in Europe

7

Definitions

Assistive devices Any product, instrument, equipment or technology

adapted or specially designed for improving the

functioning of a disabled person.

Cerebral palsy A group of permanent disorders of the development

of movement and posture, causing activity limitation,

that are attributed to non-progressive disturbances

that occurred in the developing fetal or infant brain.

The motor disorders are often accompanied by

disturbances of sensation, perception, cognition,

communication, and behavior, epilepsy, and

secondary musculoskeletal problems.

Environment The physical, social and attitudinal conditions which

are present in an individual’s life.

Hip dislocation Reimers’s migration percentage of 100%1.

Mobility Transferring from one place to another, by walking,

or by using various forms of transportation.

Performance What a person actually “does do” in a daily life

situation, and differs from what a person “can do”.

Posture The shape of the body i.e. the anatomical alignment

of the body segments in relation to each other and

the supporting surface and also the relationship

between the body and the environment.

Postural ability The ability to stabilize the body segments relative to

each other and to the supporting surface; to get into

the most appropriate body configuration for the

performance of the particular task and environment.

This means control of the center of gravity relative to

the base of support during both static and dynamic

conditions.

8

9

Original papers

This thesis is based on the following original papers referred to in the text by their

Roman numerals:

I Rodby-Bousquet E, Hägglund G. Sitting and standing performance

in a total population of children with cerebral palsy: a cross-

sectional study. BMC Musculoskeletal Disorders 2010,11:131

II Rodby-Bousquet E, Hägglund G. Use of manual and powered

wheelchair in children with cerebral palsy: a cross-sectional study.

BMC Pediatrics 2010,10:59

III Rodby-Bousquet E, Hägglund G. Better walking performance in

older children with cerebral palsy. Clinical Orthopaedics and

Related Research 2012, Vol.470(5), pp 1286-1293

IV Rodby-Bousquet E, Hägglund G, Westbom L. Postural asymme-

tries in young adults with cerebral palsy (Submitted)

V Rodby-Bousquet E, Ágústsson A, Jónsdóttir G, Czuba T, Johansson

A-C, Hägglund G. Interrater reliability and construct validity of the

Posture and Postural Ability Scale in adults with cerebral palsy, in

supine, prone, sitting and standing positions. Clinical Rehabilitation

(In press)

10

Thesis at a glance

Questions Methods Results Conclusions

I

How do children with CP usually sit, stand, and move between sitting and standing position? What is their use of assistive devices or external support?

Cross sectional study of a total population of 562 children with CP 3-18 years. Use of support or assistive devices to sit, stand, stand up and sit down was analyzed relative to GMFCS, CP subtype and age.

Standard chairs were used by 57%, 62-63% could stand and move between sitting and standing without support. Adaptive seating was used by 42%, support to stand by 31%, and to move from sit-to-stand and back by 18-19%.

Sitting, standing performance and the ability to move between these positions were highly correlated to GMFCS level. The GMFCS is age-related and seems to be a good predictor of sitting and standing performance.

II

What is the use of manual and powered wheelchairs and the degree of independent wheeled mobility in children with CP?

Cross sectional study based on data from the CPUP register of 562 children with CP, 3-18 years. Wheeled mobility was analyzed in relation to GMFCS, subtype and age.

Wheelchairs were used by 165 (29%) indoors, 61 for independent mobility and 104 were pushed by an adult. Wheelchairs were used by 228 child-ren (41%) outdoors; 66 for independent mobility and 162 were pushed.

Powered wheelchairs provided independent mobility in most cases (86%) while manual wheelchairs only did in 14%. To achieve independent mobility powered wheelchairs should be considered at an early age for children with impaired walking ability.

III

How does walking performance differ at different distances and environments, in children with CP?

Cross sectional study of 562 children with CP, 3-18 years. The Functional Mobility Scale (FMS) was used to rate mobility in relation to GMFCS, CP subtype, and age.

FMS correlated to GMFCS and varied between the subtypes. An increased proportion of children walked indepen-dently on all surfaces in each successive age group. 57- 63% walked without and 4-8% with walking aids.

The number of children who walked without walking aids increased up to 7 years, but the proportion of children walking independently on uneven surfaces was higher in each age group up to 18 years.

IV

What is the relationship between posture and the ability to change position, pain, contractures, hip dislocation and scoliosis in adults with CP?

Cross-sectional study of a total population of 102 adults with CP, 19-23 years. Analysis of the relationship between posture and joint range of motion, hip dislocation, scoliosis and pain.

Postural asymmetries were present at all GMFCS levels but more frequent at lower levels of motor function. Hip dislocation and scoliosis increase the odds ratio for an asymmetric posture.

Postural asymmetries were associated with scoliosis, hip dislocation, hip and knee contractures, and inability to change position.

V

How are the psychometric properties of the Posture and Postural Ability Scale for adults with CP?

Posture and postural ability was rated from photos and videos of 30 adults with CP, by three independent raters. Construct validity was evaluated based on known groups, GMFCS I-V.

Excellent interrater reliability (w kappa=0.85-0.99), high internal consistency (alpha=0.96-0.97, item-total correlation=0.60-0.91). Median values differed (p<0.02) between known groups.

The Posture and Postural Ability Scale showed an excellent interrater reliability for experienced raters, a high internal consistency and construct validity. It can detect postural asymmetries in adults with CP at all levels of gross motor function.

11

Introduction

Cerebral palsy

Cerebral palsy (CP) is a lifelong heterogeneous disorder affecting posture and

movement. It is the most common cause of motor disability in children and

adolescents with a prevalence of 2-3 children per 10002-8

. The children grow into

adults and the expected survival rate for people with CP is almost the same as for

the general population9. The severity of impairments varies greatly and the

mobility ranges from independent walking to totally dependent wheelchair

mobility4. The motor disorder is often combined with associated impairments such

as learning disability, epilepsy and visual impairment3; 10; 11

. CP was first described

by an orthopaedic surgeon in England, William Little 150 years ago (1862)12; 13

.

He described contractures and deformities resulting from spasticity and paralysis

due to brain damage during infancy, especially in children born pre-term or with

complicated births causing perinatal asphyxia. The condition was sometimes

accompanied by epilepsy and behavioral disorders. Little classified cerebral palsy

in children according to clinical symptoms into hemiplegia (one side more affected

than the other), paraplegia (legs more affected than arms) and generalized

rigidity12

.

Definitions

There have been several attempts to define CP throughout the years. In 1959 Mac

Keith et al14

defined CP as ‘a persisting qualitative motor disorder appearing

before the age of three years, due to a non-progressive interference with

development of the brain.’ Some years later Bax et al (1964)15

proposed the

following definition of CP; ‘a disorder of movement and posture due to a defect or

lesion of the immature brain.’ In 1992 Mutch et al16

defined CP as ‘an umbrella

term covering a group of non-progressive, but often changing, motor impairment

syndromes secondary to lesions or anomalies of the brain arising in the early

stages of development’. The most recent definition and the one used in this thesis

was presented by Rosenbaum et al in 200617

where CP is described as ‘a group of

permanent disorders of the development of movement and posture, causing

12

activity limitation, that are attributed to non-progressive disturbances that occurred

in the developing fetal or infant brain. The motor disorders are often accompanied

by disturbances of sensation, perception, cognition, communication, and behavior,

epilepsy, and secondary musculoskeletal problems’.

Prevalence

The prevalence of cerebral palsy in the western world, about 2-3/10002-8

, has not

decreased during the last decades in spite of improvements in maternal health and

neonatal care2; 18

. This could be explained by a decrease in perinatal mortality and

at the same time an increase in survival for children born preterm2; 18

.

The live birth prevalence of CP for the period of 1980 to 1990 was 2.08/1000 in a

study by the Surveillance of Cerebral Palsy in Europe network (SCPE) in 20024.

The prevalence of CP in southern Sweden (Skåne, Blekinge) was 2.4/1000 at 4-7

years of age and 2.8/1000 at 8-11 years of age in children born 1990-1993,

including children born abroad, and the mortality rate was low before 20 years of

age3; 6; 9

. The CP prevalence in adults is less well studied. Young people 17-20

years born 1988-1991 and living in Skåne, Blekinge the 1st

of Jan 2009 had a CP

prevalence of 2.3/1000 and formed the basis of study IV.

Classifications

There have been different classifications of CP since the first was proposed by

Little in 186212; 13

(Table I). Mac Keith et al14

suggested a more detailed

classification based on clinical signs into; spastic CP dived into hemiplegia

(unilateral, upper limb more affected than lower limb), diplegia (bilateral, lower

limbs more affected than upper limbs) and double hemiplegia (bilateral, upper

limbs more affected than lower limbs); dystonic CP (fluctuating tone, disorders of

static and dynamic postural control), choreoathetoid CP (presence of unwanted

movements), mixed forms of CP, ataxic CP (incoordination not due to dystonia,

weakness or choreic movements) and atonic diplegia (bilateral distribution of

weakness and hypotonia).

The Swedish classification of CP subtypes by Hagberg16; 19

has been widely used

and is based on clinical signs into spastic hemiplegia (involving one side of the

body), spastic diplegia (bilateral, lower limbs more affected than upper limbs),

spastic tetraplegia (bilateral involvement of upper more or equal to lower limbs),

ataxic CP (divided into ataxic diplegia and congenital ataxia), dyskinetic CP

(divided into dystonic CP and choreoathetotic CP) and mixed form. In

13

epidemiologic studies ataxic diplegia and spastic diplegia are usually grouped

together16

. The classification by Hagberg form the basis of the less detailed

classification of the Surveillance of Cerebral Palsy in Europe network (SCPE)20

.

The classification of subtypes according to SCPE is divided into unilateral spastic

29%, bilateral spastic 55%, ataxic 4%, dyskinetic CP 7% and non-classifiable 4%4.

The dyskinetic subtype can be further divided into dystonic and choreoathetotic

CP20

. The SCPE classification of subtypes shows substantial interrater reliability21

.

Table I Classifications of neurological subtypes in CP. In italics; subtypes further

divided into subgroups.

Little 1862 Mac Keith 1959 Hagberg 1975 SCPE 2000

SPASTIC Unilateral involvement

Hemiplegia Hemiplegia Spastic hemiplegia Unilateral spastic CP

Bilateral involvement, Legs more affected

Paraplegia Diplegia Spastic diplegia Bilateral spastic CP

Bilateral involvement, Arms more or equally affected

General rigidity

Double hemiplegia Spastic tetraplegia

ATAXIC Ataxia

Ataxic diplegia Congential ataxia

Ataxic CP

DYSKINETIC Fluctuating tone

Dystonic CP Dystonic CP

Dyskinetic CP

-Dystonic CP

-Choreoathetotic CP Increased activity, Unwanted movements

Choreoathetotic CP Choreoathetotic CP

HYPOTONIC Atonic diplegia Not CP Not CP

MIXED Mixed form Mixed form Non-classifiable

To describe CP in children the neurological subtype is usually combined with a

classification of gross motor function. The Gross Motor Function Classification

System (GMFCS) is a 5 level classification system describing gross motor

function of children and youth with CP on the basis of their self-initiated

movement with particular emphasis on sitting, transfers, and mobility22; 23

.

Although developed for children, the original version of the GMFCS for children

aged 2 to12 years has been evaluated for use in adults with CP24-26

. The expanded

and revised version of the GMFCS23

covers five age-bands from less than 2 years

up to18 years and has been used for all studies in this thesis (Figure 1).

14

Figure 1 Illustration of the expanded and revised version of the GMFCS, age-band 12-18

years, reprinted with permission from professor Kerr Graham.

15

Musculoskeletal problems

Children with CP are not usually born with deformities, and although the lesion of

the brain is non-progressive, many secondarily acquired clinical problems are

progressive, and musculoskeletal abnormalities tend to develop during

childhood27

. In both children with CP28

and typically developing children29

there is

a decline in joint range of motion as they grow older. Several studies24; 30-35

show a

decline in gross motor function in adults with CP such as reduced balance,

walking ability, range of motion together with increasing pain, physical fatigue,

and problems related to spasticity. A crouched standing posture leads to a reduced

hip and knee extension that worsens over time, due to gravity and the altered

position of the body segments in relation to each other36

. Contractures, bone and

joint deformities most commonly affect the spine and the lower extremities

leading to scoliosis, pelvic obliquity, hip dislocation, windswept deformity,

contractures of hips and knees, and foot deformities37; 38

. An asymmetric posture

increases the risk of tissue adaptation leading to these contractures and progressive

deformities39-42

. The time aspect is crucial for the development of contractures

making posture relative to time spent in these positions clinically important41; 43

.

Hip dislocations usually occur at an early age44

. In order to detect lateral migration

and prevent dislocation, children with CP should be followed with radiographs

from an early age45; 46

. Scoliosis is more frequent at lower levels of gross motor

function and the curve magnitude tends to increase with age even after bone

maturity47-49

. Severe scoliosis is associated with pelvic obliquity, windsweeping,

and hip dislocations50-52

affecting the sitting ability, but also to pain, pressure

ulcers, cardiopulmonary and gastrointestinal dysfunction51; 53

. A review of risk

factors for scoliosis by Loethers in 201054

revealed difficulties in interpreting data

since the cut-off for scoliosis on radiographs varied in different studies. In

addition, lateral migration of the hips ranging from 33-60 degrees was sometimes

defined as hip dislocation54

. However, contractures, scoliosis, hip dislocations, and

other fixed deformities can be reduced by early detection and preventive

treatment45; 46; 50; 51; 55; 56

.

The word “Orthopaedics” originates from the Greek words “orthos” (straight) and

“paideia” (children) and was introduced by the pediatrician Nicolas Andry de

Boisregard in 1741. His book “Orthopedia or the art of correcting and preventing

deformities in Children” (Figure 2) was published in English 174357

. Andry

suggested treatment that is still in use today such as early non-surgical treatment

with brace, bandages and shoes. He illustrated this as tying a tree to a pole to

straighten it out (Figure 2).

16

Figure 2 Nicolas Andry de Boisregard, Orthopedia, 1743, "http://creativecommons.org/ns#"

During the 19th century in Sweden, physiotherapy was a scientific treatment

called “mechanical medicine”, sanctioned by the Government58

. Physiotherapy

was complementary to the chemical treatment provided by the doctors. Today,

physiotherapy and orthopaedic interventions designed to prevent contractures and

deformities in people with CP are still focused on early detection and prevention.

CPUP - Cerebral Palsy follow up programme

CPUP is a National healthcare programme for people with CP in Sweden45; 55

. It

was initiated in southern Sweden in 1994 as a collaboration by the Orthopaedic

departments and the Habilitation Centres as an attempt to detect and prevent hip

dislocations, scoliosis and contractures in children with CP. The idea was to

improve and standardize the clinical assessment and the radiographic follow up of

the children’s hips and spine from an early age. Since 2005, CPUP is a National

healthcare programme approved by the National Board of Health and Welfare in

Sweden.

The associated registry includes all children with CP born after January 1, 1990,

living in the counties of Skåne and Blekinge, which have a total population of

approximately 1.3 million. The number of children with CP in the area

corresponds to a prevalence of 2.4/10003; 6

. A search is made regularly to identify

all children with cerebral palsy in the area and invite them to participate in CPUP,

and almost all families (98%) have agreed to participate6. The CPUP health care

programme includes a continuing standardized follow up with assessment of gross

and fine motor function, mobility, joint range of motion, clinical findings, and

treatment. The children are examined by their local physiotherapist and

17

occupational therapist twice a year until six years of age, then once a year. The

CPUP has been successful in reducing the incidence of hip dislocations in Sweden

to <1% compared to 15% in Norway46

(before Norway implemented the CPUP),

without increasing the number of operations. There has also been a reduction in

the number of severe contractures, scoliosis and windswept deformity45; 46; 50; 51; 55

.

Since 2009 CPUP is a National healthcare programme in Norway and the CPUP

programme is currently expanding to parts of Denmark and Iceland.

In 2009 a project was started to expand CPUP to include adults with cerebral

palsy. All people with CP born 1988-1991 living in the area of Skåne and

Blekinge were invited to participate in CPUP for adults. The place of living on 1st

of January 2009 was ascertained through the Swedish population register

(Statistics Sweden)59

. Adults born 1988-1989 were included in the inventory 2009.

The CP-prevalence was 2.3/1000 at the age of 17-20 years. Adults born 1990-

1991 were previously followed by the CPUP program for children, but before the

hip screening started. In order to assess the adults a form was developed which

included; clinical assessment of joint range of motion, scoliosis, posture, mobility,

gross and fine motor function, tone, and reports about pain, treatment, fractures,

use of orthosis, brace and assistive devices (www.cpup.se).

Sitting and standing

Physical therapy interventions include provision of postural support such as

adaptive seating and standing support to compensate for postural deficits and

increase function60-71

. Almost one third of children with CP are non-ambulant4 and

spend most of their lives in a sitting or lying position. The postural deficits

seriously affect the performance of daily activities in those with severe

impairments64; 72

. Difficulties in controlling voluntary movement and functional

performance can be traced to deficient postural ability73

. Adaptive seating reduces

the need for assistance from a caregiver74-76

and may facilitate daily activities and

functions such as playing77

, eating75-79

, breathing80

and arm and hand function69; 81;

82. A standing position requires more postural ability to keep the centre of gravity

within the base of support, while a sitting position provides a larger base of

support and less joints to stabilise66

. A crouched standing posture leads to a

reduced hip and knee extension that worsens over time, due to gravity and the

altered position of the body segments in relation to each other36

. Even healthy

children standing in a crouched posture show similar postural responses as

children with CP due to biomechanical changes in postural alignment83

.

18

Mobility

Mobility in terms of transferring from one place to another, is important for the

cognitive and psychosocial development of children. Children with CP usually

start to walk later than nondisabled children84

, and they walk with a slower speed

and higher energy cost85

. Normal walking is extremely efficient and advances the

body safely from place to place with a minimum of energy86

. In children with CP

there is a strong correlation between the energy cost of walking and the degree of

motor impairment87; 88

. The energy consumption is increased when walking with

assistive devices89-92

. Many children with CP walk in a crouched posture36; 83; 86; 93

.

The crouched gait often worsens over time as a result of increasing muscle

contractures, increasing body weight, and decreasing muscle strength compounded

by gravity94

. Thus, the achieved walking ability is not always maintained through

adolescence and adulthood32; 35; 95

.

Independent mobility is important for activity, participation, and self-sufficiency,

reducing the dependence on caregivers and the environment96-100

. Environmental

and personal factors influence a particular child’s performance in an everyday life

situation101; 102

. Safety and efficiency are important aspects when choosing

mobility methods in different environments100; 103

. Assistive devices for mobility

such as wheelchairs and walking aids can provide independent mobility to children

with disabilities, allowing them to explore their environment96-98; 104

, improving

activity, participation, satisfaction and quality of life105

. Powered wheelchairs

facilitate independent mobility while manual wheelchairs mainly ease the care

load106

. The single most important factor for the experience of participation in

adolescents with disabilities is the possibility to be ‘where it happens’107

, which is

closely related to independent mobility.

Systems theory and motor control

Two motor control theories have been used to describe development of posture

and movement in children with cerebral palsy108-110

. The reflex-hierarchical theory

from the early 1900s, where the nervous system was considered to be organized in

a top down vertical hierarchical structure where higher centres control lower

centres108-110

. Motor development was seen as a maturation of the central nervous

system with increasing corticalization, resulting in emergence of higher levels of

control over the lower levels of reflexes. Any damage to the higher levels of the

brain would result in persistent primitive lower reflexes. The treatment would

focus on techniques to facilitate normal motor patterns and inhibit reflexes and

abnormal motor patterns109

.

19

The systems theory which takes musculoskeletal and environmental factors into

account, was first described by Nicolai Bernstein (1967)109; 111

. He viewed the

body as a mechanical system consisting of several joints and muscles with

multiple degrees of freedom. To perform coordinated movements some body

segments need to be stabilized in order to allow mobility in other segments111

. The

specific segments to be stabilized will vary with the task111; 112

. The external forces

applied to the body are gravity and reaction forces from the supporting surface112

.

Internal muscular forces counteract the external forces, providing the stability

necessary to accomplish a task112

. This control of posture includes controlling the

body’s position in space with respect to both stability and orientation ensuring that

the line of gravity falls within the base of support and each body segment is

balanced relative to the segments below109

.

According to the systems theory, movement emerges from interaction between the

individual, the task and the environment, through coordination of many brain

structures and processes109

. This requires motor programmes, perception and

cognition109

. Postural control may also be affected by the attention required when

performing dual tasks113; 114

. The assessment and training of motor function

according to the systems theory focuses on both musculoskeletal and neural

aspects. The therapist should try to identify constraints within the person, the task

or environment that prevent the person from succeeding in functional tasks109; 115

.

Posture and postural ability

There is no universal definition of posture. In this thesis, the term ‘Posture’, relates

to the shape of the body i.e. the anatomical alignment of the body segments in

relation to each other and the supporting surface and also to the relationship

between the body and the environment109; 112; 116

. ‘Postural ability’ refers to the

ability to stabilize the body segments relative to each other and to the supporting

surface; to get into the most appropriate body configuration for the performance of

the particular task and environment. This means control of the centre of gravity

relative to the base of support during both static and dynamic conditions112; 116

.

CP is characterized by disorders of posture and movement4; 64; 66; 72; 83; 117; 118

.

Posture is the base from which movement occur so the ability to control posture is

an important prerequisite for all voluntary movements117; 119

. This requires muscle

tone predominantly in trunk, neck and antigravity muscles of the legs to produce

joint stiffness, in order to counteract the forces imposed by gravity and the ground

reaction forces73; 119

. The antigravity function (stability) provides the mechanical

support necessary for performing movements119

. Even a simple task such as

20

raising the arm requires complex control over numerous joints and muscles both to

stabilize posture and to perform the movement120

.

Normally postural responses such as righting, equilibrium and balance reactions

are controlled unconsciously by the brain stem, spinal cord and basal ganglia.

Damage in these areas may cause deficits of postural ability varying from being

unable to move within or change position to having limited ability necessitating

compensatory strategies that lead to asymmetry. Children with CP have difficulties

in fine-tuning postural adjustments64

. Typical characteristics are top-down

recruitment of postural muscles, antagonist co-activation and incomplete

modulation of muscular response64; 83

. These neuromuscular response patterns are

due to both neurological deficits and to biomechanical changes in their postural

alignment83

. Asymmetric postures have long been known to cause progressive

deformities in immobile people with CP due to the effect of gravity39-42

. Whenever

the body deviates from midline, a gravitational moment is produced which

compounds the deviation.

Assessment tools for posture

There are few tools for assessment of posture and postural ability in lying, sitting

and standing position which have been evaluated for people with severe physical

disabilities, and none of them has been evaluated for adults with CP.

For any measurement tool to be scientifically and clinically useful, it must meet

basic psychometric criteria regarding reliability and validity121

. For use in a

clinical setting the instrument should be relatively short and simple to complete

and not require expensive equipment. The Physical Ability Scale122

for assessment

of postural ability in children with severe disabilities was developed by Noreen

Hare during the 1970’s and 80’s. This inspired Pountney and co-workers to

develop the Chailey Levels of Ability61; 123

to describe stages of motor

development in typically developing infants and children with motor impairments.

Its’ validity has been evaluated for children and youth with CP124

. These

instruments form the basis of the Postural Ability Scale (PAS) developed by

Pauline Pope in the early 1990’s116

to assess both posture and postural ability in

people with severe physical disabilities regardless of age and diagnosis. This

assessment tool allows postural ability and posture to be assessed separately. It is

in clinical use for trained professionals but has not been evaluated for its

psychometric properties. During the years of 2009-2011, the PAS was developed

further by Pope and co-workers. The levels of ability were slightly modified and

items added to the quality of posture to allow assessment of posture from a sagittal

as well as a frontal view. This modified and expanded version of the PAS called

21

the Posture and Postural Ability Scale (PPAS) has not previously been tested for

reliability or validity.

The Posture and Postural Ability Scale

The Posture and Postural Ability Scale (Table 2) contains a 7-point ordinal scale

for the assessment of postural ability in standing, sitting, supine and prone and six

items for assessment of quality of posture in the frontal plane and another six

items in the sagittal plane. Postural symmetry and alignment gives 1 point for each

item while asymmetry or deviation from midline gives 0 points. The total score of

0-6 points is calculated separately for each position in the frontal and sagittal

plane.

Figure 3 Example of a supine and a standing posture when the person is unable to

maintain an aligned position independently.

The two lower levels of postural ability are in fact a rating of no ability, that is,

they are unable to maintain or change position by themselves (Figure 3). The

difference between those two levels is whether the person can (level 2) or cannot

(level 1) conform to the position when placed by another person, i.e in anatomical

alignment when supported. When a person cannot be placed in prone and standing

due to hip dislocation or severe contractures, especially of the hip flexors, postural

ability is scored as level 1= unplaceable and posture is scored 0.

22

Table 2 The Posture and postural ability scale (PPAS) with the 7-point ordinal scale for

assessment of postural ability in standing, sitting, supine and prone position; followed by

assessment of quality of posture. There are six items for assessment of posture in the

frontal plane and another six items in the sagittal plane.

PPAS Levels of postural ability

Level 1 Unplaceable in an aligned posture

Level 2 Placeable in an aligned posture but needs support

Level 3 Able to maintain position when placed but cannot move

Level 4 Able to initiate flexion/extension of trunk

Level 5 Able to transfer weight laterally and regain posture

Level 6 Able to move out of position

Level 7 Able to move into and out of position

Quality of posture , frontal view, (Yes = 1 point, No = 0 points)

Standing Sitting Supine Prone

Head midline Head midline Head midline Head to one side

Trunk symmetrical Trunk symmetrical Trunk symmetrical Trunk symmetrical

Pelvis neutral Pelvis neutral Pelvis neutral Pelvis neutral

Legs separated and straight relative to pelvis

Legs separated and straight relative to pelvis

Legs separated and straight relative to pelvis

Legs separated and straight relative to pelvis

Arms resting by side Arms resting by side Arms resting by side Arms resting (elevated, mid-position)

Weight evenly distributed Weight evenly distributed Weight evenly distributed Weight evenly distributed

Quality of posture , sagittal view, (Yes = 1 point, No = 0 points)

Standing Sitting Supine Prone

Head midline Head midline Head midline Trunk in neutral position

Trunk in neutral position Trunk in neutral position Trunk in neutral position Pelvis neutral

Pelvis neutral Pelvis neutral Pelvis neutral Hips extended

Legs straight, hips/knees extended

Hips mid-position (90°) Legs straight, hips/knees extended

Knees extended

Feet mid-position/flat on floor

Knees mid-position (90°) Feet resting in normal position

Arms resting (elevated, mid-position)

Weight evenly distributed Feet mid-position/flat on floor

Weight evenly distributed Weight evenly distributed

23

The Functional Mobility Scale

The Functional Mobility Scale (FMS)125

version 2 can be used for assessment of

the child’s walking performance at three different distances and environments: 5,

50 and 500 m representing the child’s mobility at home, at school, and in the

community, respectively (Table 3). The mobility is rated according to the need of

assistive devices and is assessed by questions put to the child or parent and not by

direct observation. The FMS has been evaluated for reliability, validity, and

sensitivity125

and shows substantial agreement between direct observation and

parental report126

.

Table 3 The Functional Mobility Scale (FMS) Version 2.

____________________________________________________________ Questions

How does your child move around for short distances in the house? (5 m) How does your child move in and between classes at school? (50 m) How does your child move around for long distances such as at the shopping center? (500 m)

Ratings 6. Independent on all surfaces 5. Independent on level surfaces 4. Uses sticks (one or two) 3. Uses crutches 2. Uses a walker or frame 1. Uses wheelchair C. Crawling N. Does not apply, eg, child does not complete the distance

__________________________________________________________________

24

Aims

The overall ambition of this thesis was to enhance knowledge of posture, postural

ability and mobility in individuals with CP, the use of assistive devices and also to

evaluate a clinical tool for assessment of posture and postural ability.

Study I: To describe how children with CP usually sit, stand, move between sitting

and standing position, and their use of support/assistive devices, related to age, CP

subtype and level of gross motor function.

Study II: To analyse the use of manual and powered wheelchair indoors and

outdoors, and the degree of independent wheeled mobility, in children with CP.

Study III: To describe walking performance and mobility in children with CP, and

to examine the association between walking performance and level of gross motor

function, CP subtype and age.

Study IV: To describe posture in supine, sitting and standing position, the ability

to change position, and also to analyse the association between posture and pain,

joint range of motion, hip dislocation, scoliosis and ability to change position in

young adults with CP.

Study V: To evaluate reliability, internal consistency and validity of the Posture

and Postural Ability Scale in adults with CP, in supine, prone, sitting and standing

position.

25

Methods

Design

Study I-III were cross-sectional studies of a total population of children with CP

describing their sitting and standing performance and the use of assistive devices

(study I), wheeled mobility (study II), and walking performance according to the

Functional Mobility Scale (study III). Study IV was a cross-sectional study

describing postural asymmetries and ability to change position in adults with CP,

and the relation of posture to pain, joint range of motion, hip dislocation, scoliosis

and ability to change position. Study V evaluated the psychometric properties of

the Posture and Postural Ability Scale for adults with CP from photos and videos

of adults at GMFCS level I-V.

Participants

Study I-III included all children with CP followed by the CPUP and living in

southern Sweden during 2008. There was a total of 562 children (326 boys, 236

girls) aged 3 to 18 years (mean age 10.9 years) born 1990-2005 (Table 4).

Study IV included all 102 adults with CP born 1988-1991 (63 males, 39 females)

examined within the CPUP program for adults in southern Sweden, from the start

in October 2009 until the end of 2011. The participants were 19-23 years at

examination (mean age 20.5 years) (Table 4). A total of 172 adults with CP were

identified through medical records. Ten were previously not informed about the

CP diagnosis and were excluded. Invitations to participate in the CPUP health care

programme for adults were sent to 162 persons, of which 26 declined, 20 did not

answer, and 116 accepted. Four of them were recently assessed in the child

rehabilitation services according to their CPUP program, and ten failed to appear.

In total 102 adults were examined before the end of 2011. There were no

statistically significant differences found between the characteristics of

participants and non-participants, except the proportion of unknown GMFCS

levels.

26

Study V included 30 adults with CP (15 males, 15 females) born 1988-1991 (age

range 19-22) (Table 4). The participants were recruited in October 2009-October

2010, during the project in the south of Sweden to expand CPUP and include

adults in the follow up program. The subjects who agreed to join the CPUP for

adults were invited to participate in this study until six persons at each GMFCS

level had accepted. One additional client with CP at GMFCS V was recruited from

the Rehabilitation Centre of Excellence in Kópavogur, Iceland. Written consent

was collected from all participants or by proxy where the participant was unable to

give such consent.

Table 4 Participants of study I-V

Participants Study I-III Study IV Study V

Age 3-18 19-23 19-22

Number 562 102 30

Female /Male 236/326 39/63 15/15

GMFCS I 264 38 6

GMFCS II 76 21 6

GMFCS III 64 13 6

GMFCS IV 84 10 6

GMFCS V 74 20 6

Unilateral spastic CP 163 26 -

Bilateral spastic CP 209 45 -

Dyskinetic CP 83 19 -

Ataxic CP 48 12 -

Unclassified/mixed CP 59 0 -

In all studies (I-V), cerebral palsy was defined according to Rosenbaum et al17

.

The CP diagnosis was confirmed and the neurological subtypes were classified by

a neuropaediatrician according to the Surveillance of Cerebral Palsy in Europe

network (SCPE)20

. Exclusion and inclusion criteria were in accordance with the

SCPE20

including motor impairment and specific neurological signs caused by

non-progressive brain dysfunction arising before the age of two. Gross motor

function was determined by the local physiotherapists according to the expanded

and revised version of the GMFCS23

.

27

Data collection

For study I-III data was extracted from the CPUP register, based on the latest

physiotherapy report for all children with CP born 1990-2005 in the south of

Sweden during 2008. Sitting, standing, wheeled mobility, walking performance

according to the Functional Mobility Scale, the degree of independence and use of

assistive devices were reported by client or by proxy. Data was analyzed in

relation to GMFCS level, CP subtype and age. To analyze data the children were

divided into different age groups according to the Swedish school system: 3 to 6, 7

to 9, 10 to 12, 13 to 15, and 16 to 18 years.

In study I the questions were: A. What kind of chair does the child usually sit in?

The options were: The child uses (1) a standard chair, (2) adaptive seating or (3)

does not sit. Adaptive seating was defined as any special seating, high chair or

seating system provided as an assistive device to those who cannot sit in a

standard chair due to postural deficit or physical disability.

B. How does the child usually maintain a standing position; get into a standing

position from sitting on a chair; sit down on a chair from a standing position? The

options were: The child (1) does it independently without external support; (2)

does it with external support or (3) cannot. External support denotes support from

the environment (wall, furniture, assistive devices) or from another person.

To obtain information on the child’s wheelchair performance (study II), the

children and their caregivers answered the following questions: Does the child

usually use a: (A) Manual wheelchair for mobility indoors? (B) Powered

wheelchair for mobility indoors? (C) Manual wheelchair for mobility outdoors?

(D) Powered wheelchair for mobility outdoors? The options were: (1) No, the

child does not use a wheelchair; (2) Yes, the child self-propels/operates

independently; (3) Yes, the child is pushed by an adult.

The Functional Mobility Scale (FMS)125

was used for assessment of walking

performance, mobility (study III), and need for assistive devices at home (5 m), at

school (50 m), and in the community (500 m) (Table 3).

In study IV data was extracted from the most recent assessment in the CPUP

register for adults born 1988-1991 in the south of Sweden. Posture was assessed

by a physiotherapist using items from the Postural Ability Scale (PAS)116

. Any

deviations from midline in head, trunk, leg, foot position or asymmetries in arm

position or weight bearing gives 0 point each and symmetric, neutral position

gives 1 point each with a total score of 0-6 points where a maximum score of 6

points indicates no postural asymmetry. Passive joint range of motion (ROM) was

assessed by goniometric measurement and classified as limited if extension of

hips, knees or elbows were less than 0 degrees on one or both sides, or inability to

28

reach 0 degrees of dorsiflexion of the feet. Scoliosis was defined as either having a

spinal curve at clinical examination by a physiotherapist or had a spinal fusion.

Hip dislocation was determined by an orthopaedic surgeon from radiographs and

defined as Reimers’s migration percentage of 100% in at least one hip1. Presence

of pain, use of assistive devices, ability to maintain and change position and

sleeping positions were reported by client or by proxy.

The psychometric evaluation of the Posture and Postural Ability Scale (study V)

was based on ratings from photos and videos of 30 adults with CP at GMFCS

level I-V. Photos of habitual posture of each individual were taken from a frontal

and sagittal view of the whole body in supine, prone, sitting and standing position.

Habitual refers to the posture customarily adopted by the individual when

instructed to sit, stand or lay down in prone or supine as straight as possible or, the

posture the body assumes when placed as straight as possible in any of these

positions and allowed to settle. The positions were supine lying on a plinth with

arms resting by side; prone lying on a plinth with the head to one side and arms

resting in an elevated position (flexion in elbows and abduction, external rotation

of shoulders); sitting on a plinth with feet on the floor; standing on the floor.

Those who were unable to maintain position independently were provided the

manual support needed to stay in position. Those who required total body support

in standing such as in GMFCS level V, were assessed in a standing brace or on a

tilt table. Videos recorded the participants’ postural ability while instructed to

assume and get out of the four positions. If unable to do this they were placed in

each position. Assessment of ability was then carried out sequentially

corresponding to the points on the Posture and Postural Ability Scale (Table 2) by

three experienced physiotherapists independently.

Statistical analysis

For all statistical analyses P-values less than 0.05 were considered significant. The

statistical analyses were performed using SPSS version17.0 (study I-III), SPSS

version 20.0 and Stata (study IV), and the R software environment (study V).

The chi-squared test for trend (the linear-by-linear association test) was used for

analyzing increasing or decreasing trends in ordinal data such as sitting, standing,

wheeled mobility and walking performance related to GMFCS level and age

(study I-III).

The Kruskal-Wallis test was used to analyze differences between nominal groups

such as CP subtypes (study I-III). Post hoc analyses were performed using the

Mann-Whitney U-test (study I-III). Z-test comparison of proportions with

Bonferroni adjusted p-values was used to analyze differences between participants

29

and non-participants (study IV). Pearson’s Chi square and Fishers exact test were

used to analyze differences in ordinal and categorical data.

Spearman’s rank correlation coefficient was used to estimate correlation

coefficients among ordinal variables (study I-IV), and to analyze relationship

between asymmetric postures and categorical variables such as pain, joint range of

motion, hip dislocation and scoliosis (study IV).

Binary logistic regression analysis with adjustment for CP subtype was used to

estimate the relationship between independent walking and age (study III). Ordinal

logistic regression was used to estimate the relationship between asymmetric

posture and joint range of motion, hip dislocation, scoliosis and pain (study IV).

Interrater reliability (study V) was calculated using weighted kappa scores which

takes the degree of disagreement into account127

. The magnitude of weighted

kappa indicates the agreement beyond chance and was interpreted according to

Fleiss 1981128

, where ≤ 0.40 signifies poor agreement, 0.40-0.75 fair to good

agreement and ≥ 0.75 signifies excellent agreement.

Internal consistency (study V) was evaluated using Cronbach’s alpha if item is

deleted and Corrected Item-total correlation based on averaged values for three

raters. Cronbach’s alpha if item is deleted corresponds to the value achieved if a

specific item is removed121

. The Corrected Item-total correlation shows the

correlation between each item and the total score of the measurement and any item

with a value <0.2 should be discarded121

.

For analysis of reliability and consistency all GMFCS levels were combined and

95% nonparametric bootstrap confidence intervals were generated based on a 1000

re samples129; 130

.

Construct validity (study V) was evaluated for known-groups based on GMFCS

I-V with median/range. The Jonckheere-Terpstra test was used when analyzing

arithmetic average values given by the raters.

Ethical considerations

Ethical approval was obtained from the Medical Research Ethics Committee at

Lund University for study I-IV (LU-443-99) and V (2009/361).

30

Results

Sitting and standing (study I)

The use of assistive devices and support to sit, stand and move between those

positions correlated to the GMFCS (Table 5), varied between the subtypes

(p<0.001), and was more frequent in pre-school children compared to school-

children (p<0.05).

Table 5 Correlations (p<0.001) between GMFCS levels and independence/use of support

to sit, stand, stand up (move from sit-to-stand) and sit down (move from stand-to-sit).

GMFCS Sit Stand Stand up Sit down

GMFCS 1.00 0.73 0.85 0.88 0.88

Sit 0.73 1.00 0.70 0.72 0.72

Stand 0.85 0.70 1.00 0.91 0.91

Stand up 0.88 0.72 0.91 1.00 0.99

Sit down 0.88 0.72 0.91 0.99 1.00

Of the 562 children 57% used standard chairs, 65% stood independently and 62%

moved between sitting and standing position without support. Adaptive seating

was used by 42%, 31% used support to stand and 18-19% to move between sitting

and standing position. Two children could not sit, 4% (21 children) could not stand

and 18% (102 children) could not move from sit-to-stand.

Adaptive seating was most frequent within the dyskinetic subtype and used by

89%. It was also used by 46% of those with bilateral spastic CP and by 40% of

those with ataxic CP. All children at GMFCS level V used adaptive seating, so did

95% at level IV, 54% at level III and 33% at level II.

Supported standing was used by 48% of the children with spastic bilateral or

dyskinetic CP. At GMFCS IV-V, 84% stood with support. The most frequent

standing device was a standing brace used by 130 children (3 of 4), in some cases

31

in combination with a standing frame or a tilt table. Standing frames or tilt tables

were used by 57 children, and standing wheelchairs by 23 children.

Most children who stood independently, also moved into a standing position

without support (Table 5). Of the 172 children who stood with support, half

required support to move from sit-to-stand, and the other half could not move from

sit-to-stand even with support. At GMFCS levels III and IV almost two thirds

(64%) required support to move from sit-to-stand. All children with unilateral

spastic CP could get from sit-to-stand and only 4% required support. Of the

children with ataxic CP 19% used support, as did 29% of those with bilateral

spastic CP while 16% could not move from sit-to-stand. In the dyskinetic subtype

only 17% moved from sit-to-stand independently while 55% could not move from

sit-to-stand even with support.

Wheeled mobility (study II)

Wheelchairs for mobility were used by 165 of the 562 children (29%) indoors, and

by 228 children (41%) outdoors. The use of wheelchairs varied between the

subtypes, and increased with age and GMFCS level. Wheelchairs were most

frequent in children with dyskinetic CP where 69% were pushed in manual

wheelchairs outdoors and 13% operated powered wheelchairs.

Manual wheelchairs were used by 163 children indoors (30% self-propelled and

70% were pushed), and by 219 children outdoors (14% self-propelled and 86%

were pushed). Powered wheelchairs were used by 35 children indoors and by 56

children outdoors. Of those using powered wheelchairs 83% operated

independently indoors and 86% outdoors while the remaining 14-17% required

assistance.

Indoors, wheelchairs were used by 4% at GMFCS level II, 48% at level III and

84% at levels IV-V. Outdoors, 39% at GMFCS level II used a wheelchair, so did

85-90% at levels III-V. Most powered wheelchairs were operated by children at

GMFCS level IV and only one child at level V operated a powered wheelchair

outdoors. All the 25 children at levels III-V who did not use a wheelchair for

outdoor mobility were aged 3-6 years. No child under the age of 4 had

independent wheeled mobility outdoors. In total 5 children under the age of 7

years used powered wheelchairs.

32

Walking performance (study III)

Walking performance was reported according to the Functional Mobility Scale

(FMS). Of the 562 children, 63% walked without aids at home, 60% at school,

and 57% in the community setting. Walking aids were used by 4-8% in different

environments. There was a high correlation (rs= -0.91) between the FMS and the

GMFCS at all distances. Most children at GMFCS levels I-II walked all distances

independently but with more difficulties on uneven surfaces and in longer

distances for those at GMFCS II. Walking aids were most frequently used by

children at level III, 33% at home and 52% at school. At GMFCS level IV 10-11%

used walking aids for shorter distances.

Almost all children with spastic unilateral CP walked all three distances without

aids. Walking aids were mostly used by children with ataxic or spastic bilateral CP

in the school environment. In children with ataxic CP 65-81% walked with or

without walking aids in different environments, the corresponding number was 52-

64% for children with bilateral spastic CP, and 16-24% of those with dyskinetic

CP.

The walking performance without aids (FMS 5 and 6) increased from preschool

children up to 7 years and then remained at that level. However, an increased

proportion walked on uneven surfaces (e.g. stairs, curbs) (FMS 6) in each

successive age group up to 18 years. Compared to preschool children the odds

ratio was 4.92 for 16-18 year-olds to walk on all surfaces at 500 m (Table 6). This

implies that an 18 year-old has a larger chance than a 7 year-old of walking

independently on all surfaces in the community.

Table 6 Binary logistic regression of independent walking in relation to age adjusted for

cerebral palsy subtypes. Odds ratios (OR) with 95% confidence interval (CI) and p values

for independent walking on all surfaces (FMS 6) and independent walking on level

surfaces (FMS 5) compared to all other categories; age was used as a categorical variable

with 3-6 years as reference category.

Category Age OR 5m (CI 95%) P-

value

OR

50 m (CI 95%)

P-

value

OR

500 m (CI 95%)

P-

value

FMS 6 3–6 ref

7–9 1.84 (0.94 3.57) =0.073 2.19 (1.12 4.29) =0.023 2.08 (1.05 4.10) =0.036

10–12 2.56 (1.34 4.89) =0.004 2.90 (1.51 5.59) =0.001 3.18 (1.64 6.17) <0.001

13–15 3.00 (1.54 5.85) =0.001 3.42 (1.74 6.74) <0.001 3.80 (1.91 7.53) <0.001

16–18 3.84 (1.94 7.60) <0.001 4.17 (2.08 8.33) <0.001 4.92 (2.45 9.88) <0.001

FMS 5–6 3–6 ref

7–9 1.53 (0.77 3.03) =0.227 2.01 (1.01 3.99) =0.047 2.17 (1.09 4.33) =0.028

10–12 1.82 (0.94 3.55) =0.078 1.81 (0.93 3.51) =0.081 2.05 (1.04 4.01) =0.038

13–15 1.53 (0.77 3.04) =0.225 1.86 (0.94 3.68) =0.077 2.34 (1.17 4.69) =0.016

16–18 1.83 (0.91 3.68) =0.089 1.87 (0.94 3.74) =0.076 2.55 (1.27 5.13) =0.009

33

Postural asymmetries (study IV)

Asymmetric posture, in terms of a low total score on the Postural Ability Scale

(PAS), was present at all GMFCS levels but more frequently at lower levels of

gross motor function. GMFCS correlated significantly (p<0.001) to PAS total

score for posture in supine (rs= -0.78), sitting (r

s= -0.72) and standing (r

s= -0.51).

At GMFCS level I-II head and trunk asymmetries were more common while

asymmetries varied more due to position at level III-V (Table 7). Postural

asymmetries were more frequent in standing compared to supine lying and sitting

for individuals at level I-III. The reverse was seen at GMFCS V with less

asymmetry in standing with support compared to supine lying and sitting.

Table 7 Distribution of postural asymmetries according to PAS in supine, sitting and

standing for each GMFCS level I-V. Results presented as number of people and fractions

(f) who scored 0 = No, at each item. Fisher’s exact test showed significant differences

(p<0.01) between GMFCS levels for all items marked *, (p>0.05) for remaining items.

I

N=38 II

N=21 III

N=13 IV

N=10 V

N=20

Position PAS items n (f) n (f) n (f) n (f) n (f)

Supine Head midline* 3 (0.1) 7 (0.4) 1 (0.1) 2 (0.2) 11 (0.6)

Trunk symmetrical * 3 (0.1) 7 (0.4) 3 (0.3) 2 (0.2) 15 (0.8)

Legs straight relative to pelvis* 2 (0.1) 6 (0.3) 7 (0.6) 7 (0.7) 19 (1.0)

Legs separated* 0 (0) 2 (0.1) 4 (0.3) 6 (0.7) 12 (0.6)

Arms resting by side* 3 (0.1) 3 (0.2) 1 (0.1) 7 (0.7) 18 (1.0)

Weight evenly distributed* 0 (0) 4 (0.2) 5 (0.4) 7 (0.7) 17 (0.9)

Sitting Head midline* 1 (0) 5 (0.3) 2 (0.2) 3 (0.3) 11 (0.7)

Trunk symmetrical * 4 (0.1) 8 (0.4) 5 (0.4) 6 (0.6) 12 (0.7)

Legs separated and in neutral position* 1 (0) 2 (0.1) 2 (0.1) 5 (0.5) 12 (0.7)

Arms resting by side* 2 (0.1) 1 (0.1) 2 (0.2) 6 (0.6) 16 (0.9)

Both feet flat on floor* 0 (0) 1 (0.1) 1 (0.2) 5 (0.5) 12 (0.7)

Weight evenly distributed* 2 (0.1) 3 (0.2) 3 (0.2) 6 (0.7) 14 (0.8)

Standing Head midline 7 (0.2) 7 (0.4) 3 (0.3) 2 (0.3) 3 (0.4)

Trunk symmetrical * 9 (0.3) 14 (0.8) 5 (0.5) 3 (0.6) 4 (0.6)

Legs straight hips and knees extended* 4 (0.1) 7 (0.4) 8 (0.7) 5 (0.8) 5 (0.7)

Legs separated* 0 (0) 2 (0.1) 5 (0.5) 4 (0.7) 2 (0.3)

Both feet flat on floor* 2 (0.1) 1 (0.1) 4 (0.4) 3 (0.5) 4 (0.5)

Weight evenly distributed 9 (0.3) 11 (0.6) 5 (0.5) 4 (0.7) 4 (0.6)

34

Some limitations of knee, foot and elbow extension were present at all GMFCS

levels while limited hip extension was found at GMFCS level II-V and dislocated

hips at GMFCS III-V (Table 8). Pain was reported by 63 of 102 individuals.

Table 8 Number of people and fractions (f) with hip dislocation, scoliosis, limited ROM,

and pain in relation to GMFCS level.

Asymmetric supine posture correlated (p<0.001) to limited knee extension

(rs=0.42), hip extension (r

s=0.52), hip dislocation (r

s=0.54), and scoliosis (r

s=0.45).

Asymmetric sitting posture correlated to hip dislocation and scoliosis (rs=0.46).

Asymmetric standing posture correlated to limited knee extension (rs=0.52).

Inability to put feet flat on floor in standing had a significant correlation to limited

knee extension (rs=0.40) but not to limited dorsiflexion of the feet. No correlation

was found between posture and pain.

The odds ratio for an asymmetric posture was 8 times higher in supine for those

with limited hip extension and 3 times higher for those with limited knee

extension. The odds ratio for an asymmetric posture was 2.5 times higher in

standing and 4 times higher in supine and sitting for those with scoliosis. It was 7

times higher in sitting and 19 times higher in supine for those with hip dislocation.

All adults at GMFCS levels I-III maintained lying position independently, while

10% of those at GMFCS IV and 60% at GMFCS V needed support to maintain

position. The correlation between GMFCS and ability to change position in lying

was rs=0.67 (p<0.001). Fifty percent of those at GMFCS level IV and V had only

one lying position, the other half used two or three positions. Only eight people, all

at GMFCS I-III, used all four positions; prone, supine, side lying left and right.

The ability to change position correlated to quality of posture in supine (rs= -0.60,

p<0.001). Seven out of nine adults with an asymmetric posture (0 points) could

I

N=38 II

N=21 III

N=13 IV

N=10 V

N=20 Total

N=102

n (f) n (f) n (f) n (f) n (f) n (f)

Hip dislocation 0 (0) 0 (0) 1 (0.1) 1 (0.1) 8 (0.4) 10 (0.1)

Scoliosis 12 (0.4) 7 (0.3) 6 (0.5) 6 (0.6) 17 (0.9) 48 (0.5)

Limited elbow extension 11 (0.3) 6 (0.3) 5 (0.4) 6 (0.6) 10 (0.6) 38 (0.4)

Limited hip extension 0 (0) 3 (0.2) 4 (0.3) 3 (0.3) 11 (0.6) 21 (0.2)

Limited knee extension 18 (0.5) 6 (0.3) 10 (0.8) 8 (0.8) 18 (0.9) 60 (0.6)

Limited foot dorsiflexion 7 (0.2) 8 (0.4) 3 (0.2) 3 (0.3) 4 (0.2) 25 (0.3)

Pain 23 (0.6) 13 (0.6) 7 (0.5) 8 (0.8) 12 (0.6) 63 (0.6)

35

not change position and required total assistance; six of them had only one

sleeping position.

All individuals at GMFCS IV and V used postural support to maintain sitting. The

ability to change position from sit-to-stand and stand-to-sit showed a high

correlation to GMFCS levels (rs= 0.88, p<0.001). The ability to move from sit to

stand also correlated with sitting posture (rs= -0.71, p<0.001).

All adults at GMFCS level I-II and 38% at level III stood unsupported, while

supported standing was used by 46% at level III, 90 % at level IV and 74 % at

level V. The remaining 26% at GMFCS V did not stand at all. The correlation of

standing ability to GMFCS was (rs= -0.60, p<0.001). Of the 26 adults using

standing support; seven stood 1-2 hours/day and the remaining 19 stood less than

1 hour/day.

Evaluation of the Posture and Postural Ability Scale (study V)

The Posture and Postural Ability Scale (PPAS) showed excellent interrater

reliability for three independent raters with weighted Kappa values of 0.85-0.99.

There was a high internal consistency for all items. Cronbach’s alpha if item

deleted was 0.96-0.97 with a 95% confidence interval of 0.93-0.98 for all items.

Corrected item-total correlation varied between 0.60-0.91 with the lowest

correlation for sitting posture in the sagittal view.

Table 9 Construct validity of the PPAS. Median values and range for GMFCS I-V and

p-values of averaged values for the three raters.

GMFCS

I II III IV V P

Supine Postural ability 7 (7-7) 7 (7-7) 7 (6-7) 4 (3-7) 1.5 (1-4) <0.001

Posture frontal 6 (2-6) 4 (2-5) 1 (0-6) 0 (0-1) 0 (0-1) <0.001

Posture sagittal 6 (4-6) 4 (1-6) 2.5 (0-6) 0.5 (0-3) 1 (0-3) <0.001

Prone Postural ability 7 (7-7) 7 (7-7) 6 (5-7) 4 (1-6) 1 (1-3) <0.001

Posture frontal 5 (2-6) 4 (2-5) 2 (0-5) 1 (0-3) 0 (0-3) <0.001

Posture sagittal 6 (2-6) 5 (2-6) 3 (0-6) 1 (0-4) 0 (0-4) <0.001

Sitting Postural ability 7 (7-7) 7 (7-7) 7 (2-7) 2 (2-6) 2 (1-2) <0.001

Posture frontal 6 (4-6) 4 (1-6) 3 (0-6) 0 (0-2) 0 (0-4) <0.001

Posture sagittal 3.5 (2-6) 2 (0-5) 3.5 (0-6) 0 (0-4) 1 (0-5) 0.019

Standing Postural ability 7 (7-7) 7 (7-7) 4 (1-7) 1.5 (1-2) 1 (1-2) <0.001

Posture frontal 6 (3-6) 3 (0-5) 0 (0-3) 0 (0-2) 0 (0-2) <0.001

Posture sagittal 5 (4-6) 2 (0-6) 1 (0-4) 0 (0-3) 0 (0-3) <0.001

36

The PPAS showed construct validity based on the ability of the assessment tool to

differ between known groups represented by the GMFCS levels I-V. Median

values and range in terms of min and max values are presented together with p-

values (p<0.02) calculated with Jonckheere-Terpstra for averaged values (Table

9). Distribution of scores at each level of gross motor function in all four positions

is provided for all three raters (Figure 4). The PPAS could not identify differences

in postural ability between individuals at levels I-II but was able to detect postural

asymmetries at all GMFCS levels.

Figure 4 Distribution of PPAS scores at GMFCS I-V in all four positions. All observations

are marked with different colours for each rater; red= rater A, blue= rater B, green=rater C.

The squared points connected with a line are means of each gross motor function level.

37

Discussion

The overall ambition of this thesis was to enhance knowledge of posture, postural

ability and mobility in people with CP; their use of assistive devices and also to

evaluate a clinical tool for assessment of posture and postural ability.

The samples of study I-IV represent a total population of children or young adults

with CP in the south of Sweden. Therefore the results are likely to give a true

picture of the performance in children and adults of all CP subtypes and all

GMFCS levels. However all participants of study I-III were included in the CPUP

health care programme which may have reduced the number of children who were

unable to sit, stand, walk or move and may also have affected their use of assistive

devices compared to children in areas without prevention programme. The results

show what the children usually do, i.e. their performance, not what they can do,

i.e. their ability. In children with disabilities, ability usually exceeds

performance102

. The discrepancy between ability and performance may relate to

differences in environmental factors102

. The cross-sectional design of study I-IV

can describe differences between groups at a specific moment, not changes over

time.

Sitting and standing

The number of children with CP using adaptive seating decreased with age,

increased with GMFCS levels and was most frequent in dyskinetic CP. Unilateral

spastic CP and ataxic CP were associated with a better sitting and standing

performance than bilateral spastic CP or dyskinetic CP. There was a high

correlation for all outcome measures related to the expanded and revised version

of the GMFCS. The GMFCS is age-related and as most children remain at the

same GMFCS level this classification system seems useful for prediction of the

individual child’s future sitting and standing performance.

Several studies show a significant improvement of sitting posture and postural

control in children with CP using adaptive seating such as seat inserts, external

supports and modular seating systems65; 68; 74; 131

. Adaptive seating also allows

parents to sit facing their child instead of holding them from behind, and this

38

facilitates feeding at mealtimes, play, communication and social interaction77

.

Pope et al.63

found improvements in both posture and mobility with the use of

adaptive seating over a three year period in children with CP aged 2.5-9 years who

were unable to sit independently. There is contradictory evidence regarding the

best position for sitting and the optimum inclination of seat surface132; 133

. Due to

the variability in people with CP, the particular task and environment, individual

assessment is required to provide appropriate support. Improvements in sitting

ability can also be achieved through training134; 135

. However it is vital to have

attainable, realistic goals depending on GMFCS level, bearing in mind that

postural ability and attention may be affected when performing dual tasks113; 114

.

The use of support to stand, and to move between sitting and standing position was

more frequent in preschool children than in schoolchildren and adolescents.

However it was not clarified whether this was due to natural development or to

environmental factors. Standing support such as tilt tables, standing frames and

standing braces can provide postural support to maintain upright position.

According to Pin et al.136

static weight bearing has been shown to increase bone

density in children with CP. A study by Kecskemethy et al.137

showed a wide

range of weight bearing loads in people with CP aged 6-21 years, with differences

of up to 29% of body weight between different standers. Gibson et al.138

showed a

significant lengthening of hamstrings in children with CP aged 6-9 years when

using a standing frame for 1 hour/day, 5 days per week.

In this study three of five children moved between sitting and standing position

independently, one of five used external support and one of five could not. Moving

between sitting and standing position requires more postural ability than

maintaining a static position, since the centre of gravity can move out of the base

of support while changing position120; 139

. People with CP have more difficulties in

recovering stability when exposed to balance threats117

. Musculoskeletal

constraints contribute to atypical postural patterns in standing such as a high

degree of antagonist co-activation83

. According to a review by dos Santos et al.140

there are several studies describing sit-to-stand movement in smaller samples of

children with spastic diplegic CP or hemiplegic CP, but our study is the first study

of a total population of children with CP including all subtypes and GMFCS

levels.

In Sweden, assistive devices such as adaptive seating, standing support,

wheelchairs and walking aids are provided free of charge by the Assistive

Technology Centres. This means that the results of these studies reflect the use of

assistive devices without regard to the economic situation of the families. The

opinions of the child and family, the rehabilitation team and the physical

surroundings influence the need for, or use of, assistive devices. Strategies to alter

the environment such as providing assistive devices in order to compensate for

functional impairments and enhance activity and participation have become more

39

accepted in paediatric rehabilitation76; 115; 141; 142

. Assistive devices enhance

function in children with CP and reduce the demand on caregivers76; 141

. It is

therefore important that different types of assistive device are carefully considered

for children with CP.

Wheeled mobility

The use of manual wheelchairs increased with GMFCS level, but the use of

manual wheelchairs for self-mobility was more frequent in children at GMFCS III.

The 25 children at GMFCS levels III–V who did not use a wheelchair for outdoor

mobility were all aged 3–6 years and were probably seated in a buggy outdoors.

Powered wheelchairs were most frequent in children at GMFCS IV. Children at

GMFCS levels III–IV achieved a higher degree of independent mobility using

manual and powered wheelchairs. Only one child at GMFCS level V had

independent wheelchair mobility outdoors using a powered wheelchair. This

corresponds to the results seen in the study by Östensjö et al.76

, where the largest

increase in wheeled mobility was seen at GMFCS level IV. Palisano et al.97

analysed the mobility methods in Ontario, Canada. In 360 children at GMFCS

level III–V aged 4–12 years, 67% were pushed in manual wheelchairs outdoors,

7% self-propelled a manual wheelchair and 12% operated a powered wheelchair.

The corresponding numbers for the same age group in the present study were

almost equal: 62% were pushed, 6% self-propelled in manual wheelchairs and

15% operated powered wheelchairs.

Postural instability restricts functional performance and upper extremity function

in children with CP64; 68; 132; 143

. Lacoste et al.143

found that in children with CP who

self-propelled their wheelchairs, 41% had difficulties in driving due to postural

instability. Of children using manual wheelchairs, 89% became unstable when

propelling, as did 61% when operating their powered wheelchairs. Providing a

stable sitting posture is an important prerequisite for improvement in function and

wheeled mobility.

The use of wheelchairs was most frequent in children with dyskinetic CP. Arner et

al.144

also reported difficulties with manual activities in 80% of children with

dyskinetic CP, in 41% of those with ataxic CP and in 39% of those with bilateral

spastic CP. The reduced hand function in combination with postural instability

may contribute to the fact that no child with dyskinetic CP self-propelled a manual

wheelchair outdoors, while 77% of those having a powered wheelchair operated

independently. The results indicate that children with dyskinetic CP need a

powered wheelchair to achieve independent wheeled mobility. However, powered

40

wheelchairs require more training and are not as easily transported in cars so

environmental factors must be considered.

Powered wheelchairs were only used by five children (4%) before the age of

seven, even though early self-produced mobility is crucial for the child’s cognitive

and psychosocial development98

. Wheelchairs are often used to symbolize

handicap or disability, so the stereotype of disability is easily reflected by them145

.

This may explain why some parents prefer buggies to wheelchairs hoping to avoid

drawing attention to the disability. However, children with motor impairments

may be at risk of developing learned helplessness if their development of

independence is not supported141

. Experience of self-produced mobility in healthy

infants as young as 8-9 months improves postural compensation to optic flow,

whether it is achieved through walkers, creeping or powered mobility146; 147

.

Powered mobility at an early age is not only a question of learning to drive but

rather a question of driving to learn148

.

Self-produced mobility can be obtained by powered wheelchairs at an early age149

,

but powered mobility still appears to be viewed as the last option for older

children when all other forms of mobility have failed97; 150

. This may be explained

by the traditional view of motor development as hierarchical where children were

expected to walk as much as possible to attain independent walking although it

may not have been the primary or goal of the child or the most functional method

for all environments104

. Fortunately this approach to modify the child rather than

the external factors has changed over the last decades104

. More attention is now

paid to alter the environment in order to facilitate efficient mobility and increase

participation in age-appropriate activities104

.

Bottos et al.149

showed that 21 of 27 children with severe motor disability aged 3–

8 years were able to operate a powered wheelchair with no or minimal adult

assistance. A majority of the parents were opposed to the idea of a power

wheelchair initially, but after provision almost all were positive. The driving skill

was related to the time spent in the powered wheelchair and not to IQ or motor

impairment149

. Butler151

reported improved self-initiated behaviours such as

interaction with objects, communication and changes in location in children aged

2-3 years provided with powered mobility. A randomized controlled study by

Jones et al.152

of 28 children with motor impairments aged 14-30 months, showed

significant improvements in functional mobility and receptive communication in

the children using powered wheelchairs compared to a control group. There was

also a reduction of caregiver assistance with mobility and self-care152

. In a study

by Tefft153

parents reported lower levels of stress, and increased satisfaction with

their child’s ability to move around and to interact, socialize and play with the

family when provided with a powered wheelchair. They also experienced a greater

acceptance by the general public to powered mobility for their children153

.

Powered mobility may also increase alertness and improve sleep/wake pattern148;

41

153. Participation and social interaction opportunities in the school environment

improved with the use of assistive devices in children with CP145

.

Östensjö et al76

reported improvements in independent mobility in children with

the use of powered mobility, while manual wheelchairs mainly eased the care

load for parents. Our study supports these results since a majority of children using

powered wheelchairs operated independently while only one child out of seven

attained independent wheeled mobility in a manual wheelchair.

Walking performance

Walking performance in children with CP varies due to personal and

environmental factors. This study shows the most frequent mobility method at

different distances and environments in an unselected total population of children

with CP, 3-18 years. The Functional Mobility Scale (FMS) was used to describe

walking performance at home (5 m), at school (50 m), in the community (500 m),

and its relation to GMFCS level, CP subtype and age.

A limitation to this study is that the ratings of the FMS only provide the child’s

most frequent mobility method. Some children may use several methods such as

both walking with devices and using a wheelchair.

In an analysis from the SCPE database comprising 10,042 children with CP in

Europe, Beckung et al154

reported that in 5-year-old children, 54% had unaided

walking and 16% walked with aids. Rumeau-Rouquette et al155

, in a French study

reported that in children aged 8-14 years, 38- 44% had unaided walking and 13-

28% walked with aids. The number of children with unaided walking in the

present study is similar to Beckung et al. but higher than Rumeau-Rouquette et al.

In the previous studies it is not clear at what distance or in which environment the

walking ability was recorded. The proportion of children using walking aids was

smaller in our study. The use of walking aids was most common in children at

GMFCS level III and in children with ataxic or spastic bilateral CP in the school

environment.

The walking performance increased with GMFCS level. A relationship between

the FMS and the GMFCS would be expected but has, to our knowledge, not

previously been examined. We found a high correlation between the two

classifications, indicating that GMFCS is a good predictor of walking

performance. FMS is developed to measure functional mobility in children

corresponding to GMFCS levels I to IV but does not discriminate between assisted

and independent wheelchair mobility. To overcome this problem a further level,

between FMS 1 and N, could be considered.

42

The number of children who walked without aids increased up to 7 years of age.

This is in agreement with the study by Bleck156

, who observed that walking ability

reached a plateau by the age of 7. It is also in agreement with longitudinal analysis

of motor growth curves showing peak motor performance at 6 to 7 years of age157-

159. The present study found, however, that the proportion of children walking

independently on uneven surfaces (FMS 6) was incrementally higher in each age

group up to 18 years. Hanna et al158

reported increased gross motor function (ie

capability) in adolescents at GMFCS I-II. Palisano et al.160

described improved

walking performance outdoors in adolescents at GMFCS II. Ability to walk on

uneven surfaces is important to achieve independent mobility and improve

accessibility in the community, where different surfaces, inclines, curbs, and stairs

are more common100

. This has clinical relevance because older children and

adolescents do more activities outside the home with friends than younger

children99

. Those at GMFCS I do more activities outside than those at levels II-

III99

. This result reflects their unrestricted walking performance.

Hanna et al.158

showed a decline in gross motor function in children at GMFCS

III-V from 8 years of age. Strauss et al.35

showed a decline in walking ability from

20 years and Jahnsen et al.24

reported a reduction in gross motor function in adults

at GMFCS II-III, mostly due to lack of balance, fear of falling, pain and

exhaustion. Several studies have shown increased energy consumption when

walking with assistive devices89-92

. Gibson et al.103

found that children with CP at

GMFCS III-IV consider walking as exercise rather than a functional ability, and

walking interventions were often associated with pain and fear103

. The children

were affected by normative ideas about walking as a moral good that must be

pursued frequently, contributing to negative self-identities in the children and

leading to angst and doubt in parents who feel they didn’t do enough if they let

their children use a wheelchair103

.

Raja et al.88

showed an increasing energy cost with each level of decreasing FMS

score when walking as well as a doubling in energy cost when walking outdoors

on uneven surfaces compared with even surfaces indoors88

. This may explain why

59% of the children at GMFCS level III walked 5 m at home, whereas only 16%

walked 500 m in the community. Franks et al.89

reported that mobility methods

affect school performance; the use of a wheelchair had a less negative impact on

visuomotor accuracy because the children were less tired than when walking with

assistive devices. Jahnsen et al.24

reported an increased experience of freedom,

speed of locomotion, and reduced energy cost in adults with CP at GMFCS III

when starting to use a wheelchair for mobility.

In the present study there was no decline in walking performance in adolescents.

As a result of the CPUP programme, the number of children who develop severe

contractures has been reduced55

. This improvement could result in a diminished or

delayed decrease in walking performance. In general, younger children with CP

43

get a more intense treatment and follow up by their physiotherapists than

adolescents and adults. A continuous treatment and training programme in order to

increase oxygen uptake, improve balance and strength, maintain joint range of

motion and reduce pain throughout adolescence may improve walking

performance or prevent a reduction in walking ability in those with a higher level

of gross motor function. The CPUP health care programme continues to monitor

the adolescents with CP as they grow into adults.

Postural asymmetries

Although the brain lesion in CP is non-progressive, many secondarily acquired

clinical problems are progressive, and musculoskeletal abnormalities may develop

continuously during the lifespan27; 37; 48; 49

. Asymmetric postures increase the risk

of tissue adaptation leading to contractures and progressive deformities39-42

which

most commonly affect the spine and the lower extremities37; 38

. Study IV is, to our

knowledge, the first study of postural asymmetries in a total population of adults

with CP.

A limitation of this study is the restricted number of participants when analyzing

the results for each GMFCS level separately. Although the proportion of

participants may seem low (63% of the 162 invited), it is compensated by the total

population approach; non-participants were known and compared to participants,

which is a strength of the study. The study group is a representative part of the

total population in this part of Sweden, with the CP prevalence 2.3/1000 at 17-20

years of age. The distribution of subtypes in the present study almost equals that of

the previous studies. According to the prevalence and distribution of gender,

subtypes and GMFCS levels, the study population is probably representative for

other areas and countries with similar development6.

Postural asymmetries were present at all GMFCS levels, but more frequently at

lower levels of gross motor function and varied in different positions. Normally a

standing position require more postural ability, and those at GMFCS levels I-III

demonstrated more asymmetries in standing compared to sitting and supine lying.

However the reverse was seen at GMFCS level V with a higher proportion of

postural asymmetries in supine and sitting compared to supported standing. This

indicates a lack of postural support in lying and sitting, while supported standing

corrects at least some of the asymmetry. Postural asymmetries can lead to

asymmetric weight bearing which affects the base of support within the center of

gravity can move161

. A crouched posture reduce the ability to recover balance117

.

The time spent in different positions has a great impact on the development of

contractures and deformities. In this study no one who used standing support stood

44

more than 1-2 hours/day. This implies that 22-24 out of the 24 hours/day were

spent in a more asymmetric position in sitting or lying for those at GMFCS level

V. In addition they are unable to change their position while lying or sitting. Of

those who were unable to change position in lying half had only one lying

position, indicating that they were not assisted in changing position. Porter42; 52

showed that preferred lying posture influence the direction of deformity with

windsweeping, hip dislocation and spinal curve in children with CP unable to

move out of their preferred posture. A study by Pountney56

on posture

management to prevent hip dislocation supports the importance of maintaining

symmetry without compromising function for those unable to change position.

This highlights the need for a proper assessment of posture, and provision of

postural support when needed, to prevent a sustained asymmetric posture.

Pain was reported by 63 of the 102 participants but no association between posture

and pain was found in this study. There was less reported pain compared to

previous studies by Jahnsen et al.31

(79%) and Andersson & Mattsson34

(82%). It

may be due to the older age of participants in their studies (mean age 34, 36 years

respectively). Limited range of motion was associated with postural asymmetries.

Andersson34

reported contractures in 80% of 221 adults with CP, where knee

contractures were most frequent. This corresponds to our findings where 60% of

all adults with CP had restricted passive knee extension in one or both knees. This

limitation was associated with postural asymmetries in both supine and standing

which requires extended legs. Supine posture was also affected by limited hip

extension, which was present in 22%. Previous studies39-42

indicate that a sustained

asymmetric posture predisposes to progressive deformities in people with CP. This

study has shown an association between posture and limited range of motion but

did not reveal if the contractures were caused by asymmetric posture or if the

limited range of motion caused the postural asymmetries. This illustrates the

importance of continuous monitoring of range of motion and posture in people

with CP.

Hip dislocations and scoliosis were associated with postural asymmetries in all

positions. The prevalence of hip dislocation (10 of 102) in this sample, not

included in the hip prevention programme, corresponds to reports from other

areas46; 162

. Hip dislocation, windswept-deformity and scoliosis are interrelated50

and can be reduced with a hip surveillance programme. Progression of scoliosis

increases with age even after skeletal maturity47-49

. Risk factors for progression are

early onset, large curve magnitude, thoracolumbar curve, total body involvement

and being confined to bed48; 49

. Since 1995 all children in the study area born in

1992 and later are included in a hip surveillance programme, which has reduced

the proportions of hip dislocations, windswept deformities and scoliosis45; 46; 50; 51;

55. The association between these deformities and postural asymmetries shows the

value of hip surveillance programmes. This study illustrates the importance of

45

monitoring range of motion and posture not only from an early age in children, but

also ongoing in adults with CP, to allow early identification and preventive

treatment of contractures and postural asymmetries.

Evaluation of the Posture and Postural Ability Scale

The Posture and Postural Ability Scale (PPAS) showed an excellent interrater

reliability, a high internal consistency and construct validity in a standing, sitting,

prone and supine position for adults with CP. Even though an asymmetric posture

is known to cause progressive deformities in people with CP there has been a lack

of clinical assessment tools for posture and postural ability evaluated for adults

with CP. This is, to our knowledge, the first study evaluating an assessment tool

for posture and postural ability in a lying, sitting and standing position for adults.

A limitation of the study is that all three raters participated in the development of

the PPAS; they have long clinical experience and are specialized in posture

management. Further research is needed to examine interrater reliability for

trained practitioners not involved in the modification of the assessment tool. A

further limitation is that the ratings were based on photos and videos. This

removes some variability that arises in clinical practise. Photos provide only a one

point in time reflection of the posture. However, the condition of people with

severe disabilities may alter during the day due to fatigue, pain etc. It may also

change over time making a measurement on different occasions such as test-retest

and intrarater reliability more difficult to interpret. Therefore we chose to evaluate

agreement between different raters and used photos and videos to standardize the

occasion and minimize disagreement due to different performances and

circumstances.

Internal consistency represents the average of the correlations among all items.

The scale demonstrated a high internal consistency for all items where Cronbach’s

alpha if item deleted was 0.96-0.97, which exceeds the 0.8 recommended by

Streiner Norman. Corrected Item-total correlation showed a slightly lower value

for sitting posture in the sagittal view compared to the other items. This is

probably explained by the fact that the height of the plinth was not optimal in

some photos which affected the ratings of hips and knees mid-position. An

adjustable plinth is not always available in clinical practice. If the plinth is not

adjustable or if using a chair it would be desirable to provide additional support for

the feet when needed.

Construct validity was evaluated through the PPAS’s ability to differ between

known groups in terms of the GMFCS levels in CP. According to this

classification, individuals at level I and II can walk and stand unsupported. The

46

highest level of the PPAS is to move into and out of position and therefore the

assessment tool was not expected to differ between GMFCS levels I and II in

postural ability. The basic level of postural ability is intact at GMFCS I-III, with

difficulties in fine-tuning muscle contractions to specific tasks and conditions72

.

The distribution of individuals at maximum and minimum score showed an

anticipated ceiling effect for postural ability in all four positions for adults at level

I-II, while the floor effect was higher for posture indicating a better quantity in

terms of ability than quality of posture. This indicates a need for assessing posture

and postural ability separately and as distinct from gross motor function, in order

to detect postural asymmetries and identify need for postural support. A strength

of the PPAS is that it identified postural asymmetries and deviations at all levels of

gross motor function in this study of adults with CP.

The PPAS was sufficiently sensitive to detect small postural asymmetries and

deviations even at GMFCS I and is likely to detect postural asymmetries at an

early stage. The assessment tool has no grading and cannot differ between a mild,

moderate or severe deviation. The rationale is that any deviation will increase by

forces imposed by gravity so it is clinically relevant to detect asymmetric posture

early in order to identify and apply the appropriate intervention to minimize

progressive deformities and contractures.

The PPAS does not require any special equipment and is easy to use in a clinical

setting. It provides important information of the need for postural support and

where it needs to be applied. Although the instrument has been used in clinical

practice for different client groups further research to evaluate its psychometric

properties for people with other diagnoses than cerebral palsy is desirable. All

assessment tools for posture and postural ability currently used in clinical practice

require additional training of the professionals intending to use them.

47

Conclusions

About 60% of children with CP, aged 3–18, used standard chairs, stood and

moved between sitting and standing position without external support. Adding

those using adaptive seating and external support, 99% of the children could sit,

96% could stand and 81% could move between sitting and standing position.

Unilateral spastic CP and ataxic CP were associated with a better sitting and

standing performance than the other subtypes. Sitting and standing performance

and the ability to move between these positions were highly correlated to the

expanded and revised version of the GMFCS. The GMFCS is age-related and as

most children remain at the same GMFCS level this classification system seems

useful for prediction of the individual child’s future sitting and standing

performance.

A majority of the children using manual wheelchairs were pushed while powered

wheelchairs provided independent mobility in most cases. Most children with

dyskinetic CP needed a powered wheelchair to achieve independent wheeled

mobility. To achieve as high a level of independent mobility as possible, powered

wheelchairs should be considered at an early age for all children with impaired

walking ability.

We found a variation in walking performance related to CP subtype and a high

correlation between the FMS and the GMFCS. The walking performance without

aids increased from preschool children up to 7 years and then remained at that

level, but the proportion of children walking independently on uneven surfaces

was incrementally higher in each age group up to 18 years. The improved

performance on uneven surfaces is important for achieving independent walking

and improves accessibility in the community. Continuous follow up and treatment

to improve and maintain walking performance is important both in children and

adolescents at higher levels of gross motor function.

Postural asymmetries were found at all GMFCS levels in young adults with CP,

but more frequently at lower levels of gross motor function. Postural asymmetries

were associated with scoliosis, hip dislocation, hip and knee contractures, and

inability to change position. It is important to monitor range of motion, hips, spine

and posture from an early age, but also continuously in adults with CP, to allow

early identification and preventive treatment of contractures and postural

asymmetries.

48

The Posture and Postural Ability Scale showed excellent interrater reliability for

experienced raters, high internal consistency and good construct validity. It

showed an anticipated ceiling effect for postural ability at GMFCS I-II while it

identified postural asymmetries at all GMFCS levels indicating a better quantity in

terms of ability than quality of posture in adults with CP. This indicates a need for

assessing posture and postural ability separately and as distinct from gross motor

function in order to detect postural asymmetries and identify need for postural

support. The PPAS was sensitive to detect postural asymmetries and deviations

even at GMFCS I and is likely to detect postural asymmetries at an early stage.

Further research

It is desirable to perform additional studies with longitudinal data based on the

CPUP quality register to enhance further knowledge of functional performance

and posture in a total population of children and adults with CP.

Further studies of postural stability in wheelchair seating are needed to evaluate,

its impact on wheeled mobility and postural asymmetries in people with CP.

Further research is planned to describe how long adults with CP remain in

different positions, their ability to maintain and change position and their use of

assistive devices.

Further research is needed to examine interrater reliability for trained professionals

not involved with the development of the Posture and Postural Ability Scale and

its application to other client groups. An evaluation of its responsiveness is also

desirable.

49

Sammanfattning

Summary in Swedish

Cerebral pares (CP) är den vanligaste orsaken till motorisk funktionsnedsättning

hos barn och ungdomar med en prevalens på 2-3/1000. CP innebär en livslång

funktionsnedsättning och den förväntade överlevnaden är nästan densamma som

för befolkningen i stort. CP karaktäriseras av svårigheter med rörelser och postural

förmåga och symtomen varierar från knappt märkbara till kraftigt begränsande.

Förmåga att kunna stabilisera kroppen mot tyngdkraften är en grundförutsättning

för alla viljemässiga rörelser. En asymmetrisk kroppsställning ökar risken för

vävnadsanpassningar som leder till utveckling av kontrakturer och felställningar.

Vid CP är det framför allt rygg och nedre extremiteter som drabbas, vilket kan

leda till skolios, bäckenasymmetri, windswept deformitet, höftluxation, höft- och

knäkontrakturer samt fotdeformiteter. Dessa felställningar kan delvis förhindras

genom tidig upptäckt och preventiv behandling. Eftersom vävnadsanpassningen

ofta sker succesivt över längre tid kan den vara svår att upptäcka utan

standardiserad mätning. Det finns ett fåtal bedömningsinstrument för position och

postural förmåga i liggande, sittande och stående, men inget av dem har

utvärderats för vuxna med CP.

Det övergripande syftet med denna avhandling var att öka kunskaperna kring

position, postural förmåga, förflyttning och hjälpmedelsanvändning hos personer

med CP och att utvärdera ett kliniskt instrument för bedömning av position och

postural förmåga.

Studie I-III var tvärsnittstudier av 562 barn med CP i åldrarna 3-18 år. De

beskriver sitt-, stå-, uppresningsförmåga, hjälpmedelsanvändning (I),

rullstolsanvändning (II) och gångförmåga (III) utifrån grovmotorisk funktionsnivå,

neurologisk subtyp och ålder. Grovmotorisk funktion klassificerades enligt Gross

Motor Function Classification System (GMFCS). Det är en 5-gradig skala där

personer i nivå I går tämligen obehindrat medan personer i nivå V har svårt att

stabilisera kroppen mot tyngdkraften och inte har någon självständig förflyttning.

Studie IV var en tvärsnittsstudie, av unga vuxna med CP i åldrarna 19-23 år, som

beskriver posturala asymmetrier och förmåga att ändra position relaterat till

smärta, rörelseinskränkning, höftluxation och skolios. Studie V var en utvärdering

50

av validitet och reliabilitet för bedömningsinstrumentet Posture and Postural

Ability Scale för vuxna med CP.

Omkring 60% av barnen med CP satt och stod utan stöd. Om man lägger till de

som använder hjälpmedel och externt stöd så klarade 99% att sitta, 96% att stå och

81% att resa sig och sätta sig. Det var högst andel barn med unilateral spastisk CP

och ataktisk CP som satt och stod utan stöd. Sitt och ståförmågan var starkt

korrelerad till GMFCS nivå. GMFCS är åldersrelaterad och eftersom de flesta barn

behåller sin GMFCS nivå förefaller denna klassificering användbar för att

prediktera sitt och ståförmåga hos barn med CP (studie I).

Rullstolar användes av 29% inomhus och 41% utomhus. Elrullstol möjliggjorde

självständig förflyttning i de flesta fall medan endast ett av sju barn körde sin

manuella rullstol själv. De flesta barn med dyskinetisk CP behövde elrullstol för

att kunna köra rullstolen själv. För att öka andelen barn med självständig

förflyttning bör elrullstol övervägas redan vid låg ålder för de barn som har nedsatt

gångförmåga (studie II).

Gångförmågan varierade mellan subtyper och korrelerade starkt med GMFCS

nivå. Det totala antalet barn som gick utan hjälpmedel ökade upp till 7 års ålder,

men andelen som gick själv på ojämna underlag var större i varje åldersgrupp ända

upp till 18 år. Att kunna gå på ojämna underlag är viktigt för en självständig gång i

samhället (studie III).

Posturala asymmetrier förekom vid alla GMFCS nivåer men var vanligare vid

lägre funktionsnivå. Asymmetrierna har ett samband med skolios, höftluxation,

höft- och knäkontrakturer samt oförmåga att ändra position. Det är viktigt att

kontinuerligt följa ledrörlighet, höfter, rygg och position från låg ålder men även

upp i vuxen ålder vid CP för att möjliggöra tidig upptäckt och preventiv

behandling av kontrakturer och posturala asymmetrier (studie IV).

Det kliniska bedömningsinstrumentet Posture and Postural Ability Scale visade

mycket hög interbedömarreliabilitet, goda interna mätegenskaper och

begreppsvaliditet. Det identifierade asymmetrier i liggande, sittande och stående

vid samtliga funktionsnivåer hos vuxna med CP och borde därför kunna

möjliggöra tidig upptäckt av posturala asymmetrier (studie V).

51

Acknowledgements

I wish to express my sincere gratitude to all people who in one way or another

have supported me and made this thesis possible. I especially want to mention:

Gunnar Hägglund, my main supervisor, for giving me this opportunity and for

believing in me before anyone else did. I am truly grateful for your never failing

support and encouragement from the very start and ongoing during these years.

Your open-minded attitude, strive for new knowledge, enthusiasm and instant

feedback has been vital. You have an extraordinary ability to know exactly what

kind of support I need and how to provide it, in order to step by step increase my

knowledge and independence. It is a true pleasure to work with you.

Lena Westbom, my co-supervisor, for your optimism, support and for sharing your

knowledge of CP, and epidemiology in spite of a busy schedule.

Ann-Christin Johansson, my co-supervisor, for your support and encouragement,

interesting discussions, good advice, and for your patience when introducing me to

statistics.

Jerzy Leppert and Mats Enlund, former and present head of CKF, for your endless

efforts to provide me with the time and resources necessary for my research. I

truly appreciate your support and ability to see possibilities and create

opportunities. Without you, I would not have been able to complete this thesis.

Pauline Pope, my friend and colleague, for introducing me to posture

management. Your passion, wisdom, skills and valuable work for people with

severe neurological disabilities is a great inspiration. I am grateful for your

encouragement, patience and enthusiasm in developing the PPAS and for all your

help in proof-reading my manuscripts and thesis.

Gudny Jónsdóttir and Atli Ágústsson, my friends and co-workers, you

continuously encourage, challenge and inspire me with your skills, open-minded

attitude, enthusiasm and concern for people with severe disabilities.

52

Tomasz Czuba, Jonas Ranstam, Rebecca Rylance and Philippe Wagner at RCSyd,

Jonas Björk RSKC, John Öhrvik KI, Kent Nilsson and Andreas Rosenblad CKF

for statistical advice.

All my colleagues and friends at the Centre for Clinical Research Västerås,

Uppsala University and at the Department of Orthopaedics, Lund University for

all your help, encouragement and support. Special thanks to my room-mates Lena

Burström and Magdalena Mattebo for sharing all the ups and downs in research.

All physiotherapists and occupational therapists in Skåne and Blekinge, who

contributed to this research with assessments and reports. With special thanks to

my colleagues Kerstin Arph-Hammargren, Sylvia Marcelius and Anette

Brantmark for all your work with the data collection for adults with CP.

Norbert Grentzelius, Thomas Ehmke and Rolf Hellström for sharing your

knowledge of customized seating and mechanics combined with humor and

concern for each client.

Susanne Hedberg and Henri Aromaa at the Hospital library, Västerås, for quick

and helpful services throughout the years.

My parents Håkan and Ulla-Britt for your unconditional love and never ending

support throughout my entire life. You have taught me that nothing is impossible;

it just takes a strong will, endurance, courage and creativity. Without your

extensive support I would not have been able to complete this thesis. My sister

Christina for being my best friend, supportive and boosting me with energy.

My family Pierre, Eric and Anna for being my greatest joy, and reminding me of

what is most important in life. You have not even once complained about the time

I’ve put into my research, and always encouraged me to continue. I especially

want to thank Anna for always helping me out whenever I’m struggling with

documents, illustrations or any computer problems.

The studies in this thesis were supported by grants from:

The Faculty of Medicine, Lund University,the Centre for Clinical Research

Västerås Uppsala University, Stiftelsen för bistånd åt rörelsehindrade i Skåne,

the Swedish Association of Local Authorities and Regions (SKL), the National

Association for Disabled Children and Youth (RBU), the Linnea and Josef

Carlsson Foundation, the Norrbacka-Eugenia Foundation, Promobilia, Region

Skåne, Landstinget Västmanland.

53

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