Cerebral palsy comprises a complex, multi-dimensional group of non-progressive movement disorders resulting from damage to the brain prenatally, perinatally, or early in childhood. Incidence of cerebral palsy has remained constant over the past two decades at 2.0 to 2.5 per 1000 live births [1, 2]. The long-term disability and costs to the health care system and society associated with cerebral palsy are significant. Cost of services to these children and their families is substantial, with health costs alone estimated at $1,406 per family per year (over $6 billion per year) . Non-reimbursed costs to families for services, equipment, and lost family income can amount to thousands of dollars each year . Honeycutt et al.  state that the extra economic lifetime costs associated with cerebral palsy is $800,000 per person.
From the viewpoint of the International Classification of Functioning, Disability and Health (ICF) , cerebral palsy presents with "impairments" in body function and structure such as muscle tone, strength, reflexes and range of motion. Significant "activity" limitations can also be present (e.g., dressing, feeding, functional mobility) as well as restricted "participation" (e.g., playing, participating in school) in social and community roles for the child.
This project, coordinated from CanChild Centre for Childhood Disability Research at McMaster University, Hamilton, Canada builds on research conducted by our research team over the past several years to develop and test a task/context-focused approach to treatment for young children with cerebral palsy.
The primary objective of this project is to conduct a multi-site randomized clinical trial to evaluate the efficacy of a task/context-focused approach compared to a child-focused remediation approach in improving performance of functional tasks and mobility, increasing participation in everyday activities, and improving quality of life in children 12 months to 5 years of age who have cerebral palsy.
In North America, neurodevelopmental treatment is the most commonly used treatment technique used by therapists in their care of children with a diagnosis of cerebral palsy . Although this approach acknowledges functional independence as an important goal of treatment [8, 9], the means to obtain function focuses on remediation of the child in the International Classification of Functioning, Disability and Health (ICF) component of body function and structure. The therapist attempts to inhibit abnormal posture and movement and to improve the child's quality and efficiency of movement by encouraging typical patterns of movement [10, 11]. It is assumed that "typical" patterns of movement will lead to functional improvements and reduce activity limitations and participation restrictions. Research to support this assumption is inconclusive .
Some therapists and researchers are questioning this emphasis on "normality" because it may not explore all options for functional success [13–17]. Compensatory movements and environmental adaptations may be more efficient solutions to the motor challenges encountered by children with cerebral palsy [18–20]. From this latter perspective, performing the functional task, rather than attainment of normal patterns of movement, is the important goal of treatment.
An array of factors has influenced this philosophical shift – including current models of health status, the perspectives of persons with disabilities, family-centered service delivery, and the application of dynamic systems theory (DST) to motor behavior. Each concept is discussed briefly here.
(a) Models of health status
Therapists are now using models of health status, such as the ICF , as frameworks to identify primary goals, and to evaluate treatment effects. These models have provided a framework by which to discuss and question the assumption of a cause and effect relationship between impairments and functional restrictions [6, 21, 22]. Functional performance is the result of the dynamic interaction of a myriad of factors, not just those at the level of impairment within the child. The new component of contextual factors in the ICF model encourages therapists to consider the influence of personal and environmental attributes on function simultaneously with the physical abilities of the person. The concept that many factors both internal and external to the child influence functional motor success has caused a re-evaluation of current treatment approaches based on a hierarchical neuromaturational model focused primarily on changing the child's abilities.
(b) Influence of persons with disabilities
Changing societal attitudes towards disability complement the health status frameworks used in this study. Traditionally, disability was viewed as a problem within the person and the goal was to fix, heal or prevent the problem . Persons with disabilities advocated for a change in this perspective, suggesting that disability is a political rather than a medical issue. The social construction model of disability put forward that society's values and beliefs artificially partition persons into 'disabled' and 'able-bodied' roles in society, and prevent the full participation of persons with disabilities in the community [23–27].
(c) Family-centered principles
The development of the family-centered philosophy in rehabilitation practice has also influenced attitude changes in the management of children with motor dysfunction. Family-centered service principles clearly articulate that parents know their children best. Family-centered service acknowledges that families are different and unique, and that optimal child functioning occurs within a supportive family and community context . Within this framework, the therapist is viewed as a collaborator, not an expert. Goals of treatment are identified collaboratively with input from the family, child and therapist. This change in service delivery has created an environment conducive to the identification of functional goals at the level of activity and participation rather than exclusively at the level of impairment. There is a need to explore all treatment strategies, including changes to the task and environment, in order to facilitate the achievement of these goals.
(d) Dynamic Systems Theory
Dynamic Systems Theory (DST) is a recent framework to explain motor development [29, 30]. DST suggests that the most efficient motor behavior results from the spontaneous self-organization and interaction of many subsystems to achieve a functional goal. These subsystems derive from three sources: the child, the task and the environment . Within the child, subsystems include not only the central nervous system, but also factors such as biomechanics, anthropometric measures (e.g., head size), temperament, and cognition. Examples of subsystems within the task (what the child is trying to do) which affect motor behavior, are the shape of an object being grasped, or the height of a table that the child uses to pull to stand. In the environment, diverse factors such as the surface on which the child is moving, the effect of gravity and the child's interaction with caregivers or therapists may contribute to the motor behavior that emerges.
The concept that spontaneous self-organization results in the best movement solution challenges therapists to reconsider the traditional therapeutic rejection of "abnormal" movement patterns such as "bunny-hopping" and "W-sitting" that many children with cerebral palsy spontaneously discover and use effectively. Historically, therapists have discouraged these "abnormal" movement patterns because of concern that they would prevent the emergence of more typical ways to move and sit and might result in decreased range of motion. Should these movement solutions be discouraged or accepted as innovative solutions? DST theory challenges traditional treatment perspective that "typical" patterns of movements are the optimal solution for all children. New treatment models are emerging that consider functional success the goal of treatment with less concern about the "normality" of the movement strategy [18, 20, 32, 33].
From a DST perspective, adaptation of the environment and/or task is acceptable as a solution to a motor problem rather than immediately focusing on changing the abilities of the child. Burton and Davis'  ecological task assessment is based on matching the task and environment with the abilities of the child in order for the child to achieve success, instead of trying to change the child to conform to an existing environment. For example, rather than viewing walking as the optimal mobility method, some therapists now advocate an array of movement options for children with cerebral palsy that represent the best fit with specific environments .
Integrating these themes – the Task/Context-Focused Approach
The following principles define the key components of the task/context-focused approach.
1. Promote Functional Performance
The goal of treatment is for the child successfully to achieve a specific functional goal that has been identified collaboratively by the family, child and therapist. Emphasis is placed on success with the task rather than the attainment of "normal" patterns of movement. The underlying principle is that there is no one right way to perform a task. Different solutions may be used in different environments. For example, if the goal is for the child to move independently in the home, the child may creep on his or her abdomen on the smooth surface of the kitchen floor but change to rolling on the carpet in the living room. This principle is derived from the DST tenet that movement is always goal-oriented and context specific.
2. Identify Periods of Change (Transition)
Treatment will be most successful if it is introduced at a time when the child is trying to do a new task or attempting to do an established task in a different way. This premise fits with the concept of a developmental, global readiness for performing a new motor task or changing the way an established task is accomplished. Parents (and child) will play an integral role in deciding when the child is ready to attempt a new skill. Transition is a concept of DST that is defined kinematically as the period when a child's movement patterns are more easily perturbed and take longer to return to a stable state. Clinically, the concept of transition is intriguing because it implies a "window of opportunity" when a child is most ready to achieve new functional goals. A study by Trahan & Malouin  provides evidence that short term intensive therapy at this "right time" may be as effective as longer term, regular therapy. In a multiple baseline design, five children with cerebral palsy who received short periods of intensive therapy (4 times/week for 4 weeks) followed by no therapy for 8 weeks maintained gains in their motor skills. Using transition as an indicator of readiness, treatment will be time-limited and aimed specifically at success on an identified functional goal.
3. Identify and Change the Primary Constraints
Constraints or rate-limiting factors that prevent achievement of a functional goal are identified. Treatment strategies will be based on the identification of both constraints and enablers of a specific goal by the parents, child and therapist. These constraints and enablers may be identified in the child, the task (goal) or the environment. For each constraint, the therapist must consider if the specific constraint can be changed or whether an adaptation is needed. Examples within the environment are the effects of gravity, space to move, floor surface etc. Examples of how the task may be changed are changing the size of the spoon for a feeding goal and modifying a walker for a mobility goal. Examples of constraints within the child are muscle strength, range of motion, motivation. Constraints/enablers associated with the task and/or the environment will be the first focus of treatment before attempts to change constraints within the child. If a specific changeable constraint is identified within the child, intervention may include changing this constraint through time-limited intervention but only at the level of activity and/or participation. This approach is different from a child-focused approach that centers on remediation of the abilities of the child, usually at the level of body structure and function. The aim of the task/context-focused treatment is to achieve success at the functional goal as soon as possible rather than emphasize the quality of a child's movement.
4. Provide Opportunities for Practice
Children will have opportunities to practice a new skill in the most appropriate environment. Sometimes skills will emerge spontaneously when an appropriate constraint has been changed, but typically in childhood, developmental skills require practice for refinement and to become more automatic. If necessary, practice will be incorporated into the treatment. Again, the emphasis will be on achievement of the functional goal in a natural setting. Practice focuses on the functional goal in the most appropriate environment .
The Child-Focused Approach
A review of the literature in children's rehabilitation in preparation for this project yielded 77 papers reporting research that involved children with cerebral palsy. A wide variety of treatment approaches are being used with this population including surgical treatments such as tendon transfers  and dorsal rhizotomy [39, 40] and pharmacological treatments, most typically, botulinum toxin injections and intrathecal baclofen [7, 41, 42].
Treatment approaches utilized by physical and occupational therapists focus primarily on remediation of body function and structure in children with cerebral palsy. These treatments include: maintaining range of motion and joint alignment through stretching, casting and splinting [43, 44], strength training [45–47], facilitation of normal movement patterns and postural control through physical handling and practice of functional activities [12, 48, 49], treadmill training  and electrical nerve stimulation [51, 52]. Adaptive equipment is frequently prescribed for seating, positioning, mobility and function [53, 54]. Only four articles were found that evaluated a functional therapy approach [33, 37, 55, 56].
The therapy literature describing treatment approaches continues to emphasize neurodevelopmental approaches, primarily aimed at changing body function and structure in the child. Treatment now embraces tenets of motor learning and systems theories applied to movement. For example, identification of functional goals and the importance of the child taking control of movements  are now both incorporated as important components. However, the means to attain these goals still emphasize changing the child's quality of movement, with typical movement patterns used as the "gold standard" [10, 11]. Improvements in functional performance are frequently cited as the desired outcome; however, the methods for achieving this outcome are primarily through changes in body function and structure within the child [57, 58].