Page 12 - Maximizing the efficacy of ankle foot orthoses in children with cerebral palsy

Chapter I
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Walking is one of the most important activities in daily life, as it enables participation in daily life activities. Although walking seems an easy task for most people, it is a delicate combination of movements of the different parts of the body. When a central neurological disorder such as cerebral palsy (CP) affects motor control, and consequently walking ability, the complexity of walking becomes apparent. In pediatric rehabilitation medicine, an important treatment goal is to acquire, maintain or improve walking ability of children with CP. To this end, one of the most common interventions in these patients is the use of an ankle foot orthosis (AFO). Evidence for the efficacy of these orthoses to improve gait in children with CP is however considered ambiguous, as both positive and negative effects have been reported. This thesis will focus on how efficacy of AFOs in CP might be improved.
cereBraL paLSY
With a prevalence of 2-3 per 1000 live births, CP is the most common cause of children’s disability in Western Europe[1-3]. It is described as “a group of permanent disorders of the development of movement and posture, causing activity limitations, that are attributed to a non-progressive disturbance that occurred in the developing fetal or infant brain”[1,4]. Several etiological factors could underlie CP and are typical for a particular time of onset: prenatal (e.g. intoxication), perinatal (e.g. infarction), and postnatal (e.g. infection)[3,5]. There are several risk factors for CP, such as prematurity, infection in the mother and/or child, and intrapartum asphyxia[6].
The term CP covers a broad variety of clinical presentations, which can be categorized
into groups or classes. First, CP can be described in terms of motor disorders, with spastic,
ataxic, and dyskinetic sub-types[5]. A mix of types may also occur, in which the dominant
type defines the motor disorder classification[4,7]. The type that will be discussed in this
thesis is the spastic CP, which is the most common type as it accounts for approximately
80 percent of the patients with CP[3]. Spastic CP is defined as a posture- and movement-
dependent muscle tone regulation impairment[5], which can be divided into impaired
muscle control and impaired biomechanical muscle properties[5,8]. Impaired muscle
control includes both deficit symptoms (e.g. muscle weakness and loss of selective
motor control), and excess symptoms, such as spasticity[9] and muscle co-contractions[5].
Impaired biomechanical muscle properties include increased muscle stiffness and
abnormal muscle length[10,11]. Consequently, children with spastic CP have a risk to
develop secondary impairments, such as joint contractures and bony deformities[12]. As
a second categorization, spastic CP can be classified based on disease distribution[5].