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22 February 2008 RESEARCH PROGRAM Jacques Riad
TITLE
Movement pattern, power generation and well being in ambulatory teenagers and young
adults with spastic hemiplegic cerebral palsy
BACKGROUND
General background.
Cerebral pares (CP) constitutes the largest group of children with neurological deficits, with a
prevalence around 2 of 1000 newborn in the western world .REF Hagberg The injury to the
immature brain occurs during pregnancy, around birth and up to 2 years of age. Depending on the
extent of the injury and where it is located, the children suffer from different symptoms. Many
different variables play a role in the expression of the static brain injury. The lack of neurological
control gives rise to impaired motor function and there is pronounced individual variety of
movement patterns in ambulatory children with CP.1-5
Although the brain injury is non-progressive, changes in movement patterns occur with further
growth, with maturation of the central nervous system and with the development of secondary
deformities and coping responses. Additionally, different treatment modalities influence the
changes and the ultimate ambulatory ability and efficiency, which set the outcome for the
individual’s final mobility and independence. 3,6 The treatment of children with CP generally
involves early identification with physiotherapy, orthotic treatment and surgical intervention during
the growth years. 7-10 It is generally assumed that the disability will remain static during adulthood.
Ideally the patient has received necessary treatment to optimize function when entering adulthood,
and will not need any further surgical interventions.
The identification and interpretation of the movement impairment and changes over time make
spastic cerebral palsy one of the most challenging disorders in pediatric orthopedic surgery.11-13
Background Study 1
Classification of spastic hemiplegic cerebral palsy in children.
Classification systems can be useful for prognostic reasons and to help in establishing treatment
strategies.12,14,15Winter´s classification of spastic hemiplegic CP, based on the sagittal kinematic
data from three-dimensional gait analysis (GA), is widely used.13However, it is not clear how
consistently and accurately children can be classified with this system.16 Also it is not established
when in childhood the pattern becomes clearly defined.4,17
Background Study 2
Power generation in children with spastic hemiplegic cerebral palsy.
The control of muscle activity is determined by the central nervous system. The degree and ability
of power generation from different muscles during gait can be considered to express motor control.
Power generation is the product of angular velocity and moments that together with momentum,
determines the propulsive forces of the body. From the gait analysis (GA), power generation from
the ankle, knees and hips can be calculated. Power generation in children with hemiplegic CP is
previously studied but the relationship between the hemiplegic and non-involved side in gait is not
well investigated.18-23
Background Study 3
Power generation during gait and muscle strength in relation to muscle volume and leg
length: a dynamic verses static assessment in teenagers and young adults with spastic
hemiplegic cerebral palsy.
The involved limb in the individual with hemiplegic CP is always shorter and smaller. It is not clear
if the brain injury determines the development of the leg or if it is the disuse that causes the
differences. It might be the relatively less force application to the involved limb that makes the
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difference in the development. Even if the non-involved leg is longer and bigger, it is not shown to
generate more power/work than the hemiplegic side during walking. REF polio,
If there is a difference between the hemiplegic side and the non-involved side regarding muscle
volume and maximal voluntary strength, is it reflected in the power generation during walking?
Differences between the hemiplegic and non-involved side and distal relative to proximal muscle
groups and power generation are of interest for comparison and to determine coping responses. It
could be of interest to learn if any specific muscle among the power generating muscles during gait
that should be exercised, by strength or co-ordination, to improve gait.
To our knowledge there are no studies correlating power generation during walking with static
muscle imaging by MRI, in children with CP. Neither could we find any studies correlating leglength to muscle volume assessed by MRI, in cerebral palsy.
Background Study 4
Quality of life, Self-esteem and Sense of coherence in teenagers and young adults with spastic
hemiplegic cerebral palsy.
It is well known that most adolescents with time develop an increasing awareness and concern
about their appearance. After puberty and the growth spurt individuals with spastic hemiplegic
cerebral palsy might have a very different view of their motor impairment than before. Additionally
with increasing growth increased leg length often causes relative tightness and an increased muscle
tone (spasticity) which makes changes in the movement pattern more apparent. The mild but
obvious asymmetry in gait and other movements may have developed into a problem. REF
Previous studies have investigated quality of life in relation to movement disorders and impairment.
The extent of physical impairment and the effect on gait/ambulation ability is however not clearly
defined. 42-56 A recent study of children with CP revealed that the child's physical function was not
correlated to psychosocial well-being. The children with mild cerebral palsy had greater effects on
their psychosocial well-being than would be predicted by their functional disability.57 Maybe the
relatively mild physical impairment is difficult to accept. There are very few studies in adolescents
and young adults with cerebral palsy regarding quality of life, self-esteem and self-concept in
relation to ambulatory capacity.
The teenager and young adult with spastic hemiplegic CP might be motivated to improve their gait
and movement and the goal would consists in less apparent deviations from normal. Physiotherapy
programs with co-ordination and muscle strengthening exercises could be suitable. However to be
able to provide rational and useful treatment recommendations, more knowledge in this field is
needed together with a better understanding of the patient’s concern.
GOAL / AIM
The overall goal of this study is to investigate the movement pattern during gait in teenagers and
young adults with spastic hemiplegic cerebral palsy. The emphasis is on the dynamic muscle power
generation during walking in relation to the static anatomical findings from MRI, on both the
hemiplegic and non-involved side. Additionally we wanted to assess quality of life, self-esteem and
self-concept in this physically high functioning group of individuals with cerebral palsy.
Specific aims:
1 To investigate how children with spastic hemiplegic CP can be classified using Winter’s
criteria and to investigate if patients move between groups over time and/or with surgical
intervention.
2 To investigate the hip and ankle power generation on both the hemiplegic and non-involved
side in children with spastic hemiplegic cerebral palsy during walking.
3 To study the correlation of power generation during walking and muscle strength in maximal
voluntary isometric contraction with muscle volume and leg-length.
4 To study differences in self reported quality of life, self-esteem and self-concept.
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METHODS
Physical examination by one physiotherapist will be performed including; passive range of motion
using a goniometer of the lower extremity using standardized positions, spasticity assessment
modified Ashworth scale, motorcontrol/selectivity.58 Measurements of weight and height will be
obtained. Classification of gross motor function (GMFCS).59
Patient medical history and records will be assessed concerning; ethiology of the diagnose
cerebral palsy if known, previous injury to the lower extremity, previous treatment with surgery,
botulinum-toxin, physiotherapy and orthotic device. Information concerning if the individual is
right or left handed, right or left footed (kicks a ball) and if the right or left side is the involved will
be collected.
Three-dimensional instrumented gait analysis (GA).
Three-dimensional gait analysis (GA) provides an objective quantitative dynamic measurement of
gait, and will be the main outcome tool in these studies.3,6 Gait will be recorded with a Vicon, 6-8
camera 3D motion analysis system (Vicon Motion System, Oxford England). Retroflective markers
is placed on bony landmarks or specific anatomical position (Plug-in-Gait model). Multiple gait
cycles will be collected and a mean cycle with standard deviation will be calculated. The patient
walks at a self-selected speed on a 10-meter walkway. The kinetic data will be collected using two
forceplates (Kistler). Generally 3 trials from each foot will be collected. The kinetic and kinematic
data will be collected from the same trials. The ground reaction force vectors will be collected
together with the kinematic data. Parameters of time and distance will be registered.
Power generation from the hip, knee and ankle joints with their corresponding muscle groups
during gait can be calculated from the kinematic and kinetic data collected. 3,6 The product of the
angular velocity and joint moment reflects the power generation at that very instant. The sum of all
the power, the total power generation, can be called the “work” produced. Thus the total power
generation from the hip extensors, mainly the gluteus muscles at early and middle stance phase will
be calculated as the positive area under the curve on the hip graph. On the ankle graph power
generation from the gastro-soleus muscle activity at late stance phase can be calculated. The third
main power generator during gait is from the hip, the iliopsoas muscle, at late stance and early
swing phase. Power absorption is calculated as the negative area under the curves.
Musclestrength, maximal voluntary muscle contraction.
A strength measuring chair (SMC) is used measuring isometric muscle strength. We measure
plantar flexion in the ankle joint and knee extension as the product of the compression force (N) of
the sensor and the moment arm (m).65 The degree of neurological involvement and the strength of
the subject influence the accuracy of the measurements over the knee and ankle joint. The joint
tested also determines the reliability when measuring voluntary muscle strength. The hip joint as an
example is difficult to measure since the adjacent body segments are difficult to isolate and
immobilise during the test.25-30Isometric muscle strength measurements have been shown to be
reliable in children with CP. By using a computerised dynamometer, a sensitive and valid testing
technique may be achieved.24
Magnetic resonance imaging ( MRI )
Magnetic resonance imaging (MRI) can without harmful radiation clearly visualise muscles and
other soft tissues with great detail. Individual muscles can be identified and measured. MRI is
frequently used to calculate muscle cross sectional area, which is highly correlated to muscle
strength. The MRI also provides information about leg and foot length.31-41
The MRI equipment used is Philips Intera 1.5 T (Philips Medical Systems, Best, the Netherlands).
The patient is placed supine with both legs stretched and parallel to the long axis of the body. The
feet are flexed 90 degrees relative to the legs. In order to measure muscle volume, consecutive
axial images, T2 weighted, are acquired from the highest insertion of the psoas muscle to the sole
of the feet. The slice thickness is 5 mm with a gap of 5 mm between slices. A typical TR/TE is
2400/80. The volume of individual muscle groups is measured by tracing the muscle outline in each
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slice and adding the number of slices. In order to measure the length of the lower extremities T2
weighted coronal images are acquired covering an area that include both the hip joint and the sole
of the feet. Slice thickness 5 mm with a 0.5 mm gap between slices, and the typical TR/TE the
same as above. As the practical field of view is approximately 40 cm, two or three separate (partly
overlapping) coronal series are needed to cover the lower extremity from the hip joint to the sole or
the foot. The length figures are calculated from the table position of the actual anatomical
landmarks. Care is taken to keep the patient in the same position during the whole examination by
using designed leg-feet rest splint with straps. A surface coil is used for the lower legs and feet and
a Q-body coil for the thigh and lower body.
Self reporting / questionnaires.
A, Quality of life, EQ 5D.
The general quality of life instrument EQ-5D is a standardised and validated instrument to describe
and measure health status. The test consists of three subscales. The first is a self-reporting
questionnaire where the individual classifies his/her health in five dimensions (physical movement,
hygiene, main activities, pain and anxiety and depression. The responses ranges from “no
problem”, “reasonable” and “with difficulties”. The second subscale is a visual scale (VAS).
Finally the third scale consists of questions about socio-economical and demographic
background.66-68
B, Self-esteem, “I think I am”.
The self-rating questionnaire “ I think I am” is used. It was developed from well established
international questionnaires on self-concept and self-image. REF It has shown good reliability with
a Cronbach alpha coefficient of 0.71-0.82, as internal consistency measure. REF “I think I am”
consists of five subscales, each one considering different aspects of the individual´s self-perception.
Physical characteristics, talents and skills, psychological well-being, relations with the family and
relations with others, are the different aspects. The questionnaire consists of 72 statements and the
subject is asked to choose one of four alternatives as an answer: “exactly like me”, “almost exactly
like me”, “not quite like me” or “not at all like me”. A score for each subscale is calculated as well
as a total score. 42,45,50-52,54-56
C, Sense of coherence.
Sense of coherence (SOC), implemented by Antovosky 1979, has been widely used among
researchers in health and caring sciences, and has been translated to several languages.
Antonovsky advocates a salutogenic view as opposed to a pathogenic view when health and disease
are being discussed. A person´s SOC is considered to be a major determinant of maintaining his or
her position on the health ease/dis-ease continuum and movement towards the healthy end. The
concept of SOC includes three components: the perception of comprehensively, manageability and
meaningfulness. The more comprehensively, manageably and meaningful a person view life, the
stronger the SOC. The individual´s SOC is developing during childhood and is influenced by all
aspects of life and feelings during growth. It is expected to be quite stable during adulthood with
only temporary fluctuations when serious events occur. The 29-item SOC scale has been found to
be reliable and valid. Each item has two anchoring responses ranging from 1-7 possible scores. An
example is; “Do you have the feeling that you are being treated unfairly?” The subject can answer
on the scale from “ very often” to “very seldom or never”. Thus the total score of the 29 items, with
7 possible scores on each, ranges from 29 to 203.43-49,52-54
PUBLISHED STUDIES
Study 1
Classification of spastic hemiplegic cerebral palsy in children.
Purpose: To investigate how children with spastic hemiplegic CP can be classified using Winter’s
criteria and to investigate if patients move between groups over time and/or with surgical
intervention.
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Material: One hundred and twelve patients with spastic hemiplegic CP with a mean age of 8.1 years
were included. . Independent ambulators without assistive devices or previous surgery were
included. In the second part of the study when comparing the Winter classification groups over
time with or without surgery, patients with two gait analysis were included. All children were fully
independent community ambulators graded as Gross Motor Function Classification System,
GMFCS, level one.
Methods: Medical records and the first three-dimensional gait analysis data were reviewed. Patients
were classified using the sagittal kinematics from the gait analysis, according to Winter’s criteria.
An independent sample t-test was used to compare groups.
Results: We found 26 patients (23%) that could not be classified according to Winter’s criteria. We
defined these patients as group 0. This group showed the least deviation from normal values. Each
of the five groups in our study showed a higher mean velocity of gait and were younger than any of
the groups from the Winter study. In regards to rotational alignment, kinetic variables, and to a
certain extent muscle tone, group 0 showed the least deviation from normal values, however most
differences were subtle. When re-classifying patients after a mean of 3 years, 8 of 15 had
deteriorated in the non-surgical group, moving to a higher numbered group, while 19 of 31
surgically treated patients had improved.
Conclusions: The Winter classification failed to classify 23 % (26/112) of our spastic hemiplegic
cerebral palsy children. We suggest that the classification be complemented with the less involved
group 0. In this way all patients can be classified and thus treatment plans can be established for all
patients. The classification can be divided into ankle, knee and hip joint involvement. The ankleinvolvement can be further divided into three separate groups. Treating physicians should be aware
of the possibility that patients may move into another classification group over time.
Significance: The classification system can be useful when considering expected goals achievable
and in considering the general movement prognosis.
Published in Journal of Pediatric Orthopaedics 2007.
Study 2
Power generation in children with spastic hemiplegic cerebral palsy.
Purpose: To investigate the hip and ankle power generation on both the hemiplegic and noninvolved side in children with spastic hemiplegic cerebral palsy during walking.
Material: Ninety-nine patients with spastic hemiplegic CP with a mean age of 8.4 years were
included.
Methods: Medical records and the three-dimensional gait analysis data were reviewed. Patients
were classified using Winter’s criteria and an independent sample t-test was used to compare
groups.
Results: The hip extensor power generation was higher in all Winter´s classification groups on both
the hemiplegic and non-involved side compared to age matched normal subjects. Comparing the
power generation from the ankle, all groups had less ankle power generation on both the
hemiplegic and non-involved side.
Conclusions: We found a major power generation shift from the ankle to the hips in children with
spastic hemiplegic cerebral palsy both on the hemiplegic and the non-involved side. This could be
interpreted, as symmetry in power generation from the hips is a way of compensating for decreased
ankle power generation on the hemiplegic side. The results could support that muscles
strengthening physiotherapy should be directed toward the hip power generators and co-ordination
exercises should be focused distally to the knee and ankle. This may also mean that power loss,
such as after tendon Achilles lengthening, at the ankle may be of less importance.
Published in Gait and Posture 2007.
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PLANNED STUDIES
Study 3
Power generation during gait and muscle strength in relation to muscle volume and leg
length: a dynamic verses static assessment in teenagers and young adults with spastic
hemiplegic cerebral palsy.
Purpose: To study the correlation of power generation during walking and muscle strength in
maximal voluntary isometric contraction with muscle volume and leg-length.
Material: study 3 and 4.
Approval from the ethic committee has been obtained.
The subjects will be recruited from the outpatient clinics in Skaraborg and Stockholm. Oral and
written information will be provided and a written consent obtained.
Approximately 50 individuals with spastic hemiplegic cerebral palsy and 20 normal for reference
will be included
Inclusion criteria:
Spastic hemiplegic CP, defined as unilateral neurological involvement registered on the physical
examination with the typical upper and lower extremity positioning, as well as gait deviations
found in the kinematics and kinetic data on GA. The cause for developing CP should have appeared
before 2 years of age.
Individuals between 13 and 23 years of age and independent ambulators are included. No assistive
device should be used. Generally this means independent community ambulators graded as Gross
Motor Function Classification System (GMFCS) level one and two.59
Another inclusion criteria is a mental and cognitive level that allows participation and co-operation
during the collection of data in the gait laboratory and ability to read and write and understanding
the questionnaires and with minimal assistance be able to answer the questions.
Exclusion criteria:
Patients with metal implanted in the body or for dental treatment can not be accepted since imaging
with the magnetic resonance camera would be difficult, but could also be harmful depending on the
strong magnetic field that is generated and possibly could move the metal installed.
Patients with previously fracture or extensive surgery on the lower extremity will be excluded.
Methods: Three-dimensional gait analysis, Magnetic resonance imaging, Strength muscle chair.
Significance: More knowledge of important power generators during gait and their correlation to
muscle volume and voluntary strength can help giving treatment recommendations.
Study 4
Quality of life, self-esteem and sense of coherence in teenagers and young adults with spastic
hemiplegic cerebral palsy.
Purpose: To study differences in self reported quality of life, self-esteem and self-concept.
Material: same as study 3.
Methods: Questionnaires; Quality of life EQ-5D, Self-esteem assessment “ I think I am” and Selfconcept assessment “Sense of Coherence.
Significance: Quality of life, self-esteem and self-concept assessments may reveal patient’s
concerns and constitute a base for better understanding.
IMPORTANCE
In cerebral palsy, spastic hemiplegia constitutes the group of individuals with the best walking
capacity. Not much attention has been directed toward this group of patients regarding ambulation,
partly because of their high function. The mild deviation in movement has been considered not
important and also very difficult to treat. Possible concern about appearance and movement pattern
from the individual’s point of view has therefore not been assessed.
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In the last decade or two, more sophisticated objective measurement tools regarding gait, muscle
strength and soft tissue imaging of the locomotion system has been developed. An increased
interest and awareness of objective measurement of well-being and quality of life assessment has
also evolved.
To better understand the complex mechanism of gait, in this relatively high functioning group of
patients, and direct treatment in improving function and appearance, there is need of more
knowledge. These studies might give more information on how to develop relevant treatment
programs and could also be useful in evaluating the effect of such programs.
TIMING OF STUDIES
Study 1 and 2 performed and published.
Study 3 and 4 data collection 2008.
Analysis, calculations and writing study 3 and 4, 2009-2010.
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