Page 13 - Maximizing the efficacy of ankle foot orthoses in children with cerebral palsy

Children with unilateral CP are affected on one side, while bilateral CP involves both sides of the body[5,13]. Third, the level of impaired overall motor functioning in children with CP can be categorized with the Gross Motor Function Classification System[14] (GMFCS). The GMFCS describes five levels of motor functioning, where lower levels indicate better motor function. Levels IV and V describe the group of children who are not able to walk independently. This thesis is focused on children with GMFCS levels I-III, i.e. referring to children who are able to walk independently with or without restrictions (level I and II respectively), or with a walking device (level III). Although the majority of children with CP (approximately 70%) are able to walk with or without assistive devices, motor impairments often lead to walking limitations[5]. In pediatric rehabilitation medicine, an important treatment goal is to acquire, maintain or improve walking ability of children with CP.
GaIt
The gait cycle
Gait is described by different phases of one leg (i.e. the leading leg) within a gait cycle. One gait cycle, or stride, starts with initial contact, which refers to the first contact of the foot with the ground and ends with the same leg hitting the ground again. Each stride is divided into a stance phase and a swing phase, where the stance phase accounts for approximately 60% of the gait cycle. These two main phases can be sub-divided into separate events, such as midstance (see Figure 1.1). Push-off describes the leg’s transition from the stance phase into the swing phase.
Normal gait
Each phase of the gait cycle is characterized by a specific position and orientation of the body’s segments and joints. In relation to these orientations, the ground reaction force, i.e. the force exerted by the ground on the body, acts on the joints. A close alignment of the ground reaction force to the joint rotation centers results in low net moments, and accordingly, in low muscle forces to maintain posture and balance. The course of the ground reaction force and its alignment to the joint rotation centers during normal gait are shown in Figure 1.1.
I
General introduction
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