Physical therapists' perceptions of factors influencing the acquisition of motor abilities of children with cerebral palsy: implications for clinical reasoning. (Research Report).

Cerebral palsy is the sensory and neuromuscular deficit caused by a nonprogressive brain defect or lesion occurring during the prenatal, intrapartum, perinatal, or early postnatal periods. (1) At the time of diagnosis, most parents are concerned about their child's potential for motor development and, specifically, the prognosis for ambulation. (2-5) Knowledge of factors that can be used to predict motor outcomes in children with cerebral palsy is limited. (6) This prognostic information is essential, however, when making collaborative decisions with families about rehabilitation services for their children. (7) The clinical reasoning involved in this decision-making process has been suggested as being at the core of effective practice (8) and is therefore an important area for investigation.

"Clinical reasoning," as we use the term, refers to the many ways a practitioner thinks about and interprets an idea and incorporates knowledge, experience, problem solving, judgment, and decision making. (9) Experienced clinicians, especially those who practice in neurology, (10) are thought by at least one group to apply their knowledge of multiple factors influencing outcomes in an implicit way to arrive rapidly at decisions for a plan of care. (11, 12) In a review of research on clinical reasoning in pediatric physical therapy, Palisano and colleagues (13) argued that physical therapists largely use implicit thought processes and that the implicit knowledge might not be organized into an effective framework. (14) An explicit conceptual framework, therefore, might be useful for physical therapists to reflect on their perceptions of factors influencing motor outcomes of children with cerebral palsy and could optimize clinical reasoning.

Previously, we described a multivariate model of acquisition of motor abilities in infants and children with cerebral palsy up to the age of 7 years. (6) This model was developed to assist with decision making (Figure). We defined basic motor abilities as the child's capacity to perform movements such as rolling, sitting, crawling, and walking. This definition is consistent with Touwen's use of the term, which he differentiated from "motor skills" (eg, higher-level activities such as writing or playing sports or a musical instrument). (15) Recent research suggests that the acquisition of basic motor abilities plateaus by 6 or 7 years of age in children with cerebral palsy. (16) Accordingly, the focus of the model is on children younger than 7 years of age. Development of the model was guided by compatible theoretical frameworks (the disablement process using the International Classification of Functioning, Disability, and Health [ICIDH-2], (17) systems theory, and family-centered care), research on prognostic factors for motor outcome in children with cerebral palsy, literature on motor development of infants, and literature on the general health and developmental outcomes of children who are at risk for a developmental disability.

[FIGURE OMITTED]

The model contains 5 constructs (primary impairments, secondary impairments, child personality characteristics, family ecology, and health care services) that are proposed to interact to explain and predict the acquisition of basic motor abilities among children with cerebral palsy. Primary impairments were defined as organ- or system-level deficits that were apparent at the time of diagnosis. An example of a primary impairment is hypertonicity. Secondary impairments were defined as organ- or system-level deficits occurring over time. Contractures are an example of secondary impairments. Child personality characteristics were defined as any personality attributes that are largely independent of having a diagnosis of cerebral palsy (ie, relates to a description of children, regardless of diagnosis); temperament is an example of a personality attribute. Family ecology was defined as anything related to the environment of families, such as resources and supports.

Possible indicators identified in the literature for the 4 constructs in our study are presented in Table 1. As indicated in the Figure, primary impairments are hypothesized to be a major influence on the acquisition of motor abilities, both directly and by causing secondary impairments. Child personality characteristics are conceptualized by us as being independent of the primary impairments associated with cerebral palsy and as having an effect on motor abilities through an effect on secondary impairments. We viewed family ecology (ie, how families function) as being influenced, at least in part, by the personality characteristics of the child with cerebral palsy and, in turn, as influencing the acquisition of motor abilities through variations in opportunities for movement exploration.

The nature of a child's primary impairments and personality characteristics are hypothesized by us to have moderate and relatively minor influences, respectively, on the services provided by physical therapists. The nature of the secondary impairments might also influence services, which could affect the secondary impairments over time. The bidirectional arrows in the Figure indicate the relationship between the constructs of health care services and family ecology, in keeping with the philosophy of family-centered care. (18) As indicated by the dashed ovals and arrows in the Figure, the constructs of activity (as it applies to activities of daily living and play) and participation (eg, attendance at preschool or school) are not a part of the proposed model. They are included in the Figure to provide a perspective on how motor abilities relate to activity and participation. (6) Much of the evidence we used to develop the model came from literature on development rather than solely from the literature about children with cerebral palsy.

Streiner and Norman (19) contended that, in the absence of research-based evidence, clinicians with relevant experience are a valuable source of knowledge. One approach used to examine clinical reasoning and decision making is the nominal group technique (NGT). (20) The NGT is a method of obtaining group consensus that is designed to stimulate the generation of critical ideas, to increase the creative productivity of group action, to give guidance in the aggregation of individual judgments, and to arrive at a desirable group decision, while leaving participants with a sense of satisfaction. The NGT consists of a 6-step process that involves: (1) silent generation of items, (2) round-robin recording of items, (3) serial discussion of items, (4) preliminary ranking of items, (5) discussion of ranking, and (6) final ranking of items. According to Boyce et al, (21) when the NGT is used for planning a research agenda, clinicians' participation may increase because this method can provide a feeling of "ownership" of the results. The NGT has been used in rehabilitation research, including the development of a measure of quality of movement (15) and a classification system for children with cerebral palsy. (22)

The purpose of our study was to use a conceptual framework and the NGT consensus process to: (1) identify factors that physical therapists perceive are important in the acquisition of motor abilities in children with cerebral palsy, (2) discuss implications for clinical reasoning, (3) compare the results of the consensus process with current knowledge, and (4) discuss how the results can assist research. The focus of this work is not on interventions, but it is in line with the approach of clarifying prognostic factors before examining the effectiveness of interventions. (23) We did not include the construct of health care services in the consensus process.

Method

We studied pediatric physical therapists working in the Ontario Association for Children's Rehabilitation Services (OACRS) centers. The study had 3 phases: (1) consensus within focus groups, (2) compilation of potential determinants identified in the focus groups, and (3) consensus among all participants.

Selection of Participants

Physical therapist participants were recruited from 18 of the 19 centers affiliated with OACRS; one chief executive officer did not respond to an initial letter. The majority of children with cerebral palsy in Ontario receive services through these centers. Information packages were mailed to 75 physical therapists; 64 consents were returned after a second mailing, for a response rate of 85%. Of the 64 initial respondents, 57 physical therapists from 12 OACRS centers participated in the focus groups (phase 1). Group sizes ranged from 2 to 7 participants. Although 5 to 9 participants per group is recommended for the NGT, (20) groups were conducted with fewer participants because this represented the total number of eligible physical therapists at these centers. Four additional physical therapists consented to participate in the third phase of the study, which involved completion of a questionnaire. The questionnaire was mailed to the 68 physical therapists. After one reminder, 60 survey questionnaires were returned, for a response rate of 88%.

Fifty-six participants were women, and 4 participants were men; the majority worked full-time. As a group, these therapists had worked in pediatric rehabilitation for an average of 13.7 years (SD=7.4, range=1-35). Although the preferred interventions used by these participants cannot be stated with certainty, service providers in the OACRS centers usually provide family-centered services, particularly with respect to: enabling and partnership, providing specific information about the child, and providing respectful and supportive care. (24) There is, in our view, a trend among physical therapists working at centers similar to these to a move from a neurodevelopmental treatment approach to family-centered functional therapy (25) incorporating motor learning and cognitive strategies (26) when working with children with cerebral palsy.

Phase 1: Consensus Within Focus Groups

A package of information containing a description of the study, the agenda for the focus group, a 2-page introduction to the model and the definitions of the 4 constructs of interest, and a descriptive survey instrument was mailed to each physical therapist. Examples of determinants were described in very broad terms, so as not to constrain responses. (20) Participants were asked to think about what they believed influences the acquisition of basic motor abilities of young children with cerebral palsy relative to the 4 constructs. They were asked to record their ideas in the survey instrument provided in the information package in preparation for the meeting. The focus groups lasted 60 to 90 minutes, and the NGT was used. (20) Although the primary author (DJB) had not previously used this technique, the "Guidelines for Conducting NGT Meetings" (20) was used for the sessions. Each focus group began with an introduction of the facilitator (DJB), a review of the agenda, and a brief overview of the model. This introductory portion ended with the question "What are the important factors in the 4 constructs of child characteristics relating to the primary neurological impairments, child characteristics relating to the secondary impairments, child personality characteristics, and family ecology contributing to change in motor abilities of children with cerebral palsy?" Participants were assured that this was not a test. The facilitator reiterated the point that we were interested in learning from them and their experiences.

Step 1 was completed in 5 to 10 minutes. During this time, each participant independently generated a list of determinants of motor outcomes for the 4 constructs. Next, a round-robin format was used to generate a composite list of determinants of motor abilities. Each participant was asked to suggest one determinant at a time in an effort to ensure equal participation. Participants were encouraged not to repeat ideas, but to suggest variations that they thought were important. The group facilitator recorded ideas on a flip chart with a separate page for each construct. This process lasted 30 to 40 minutes. The round-robin format was conducted rapidly based the assumption that doing so would minimize ideas being attributed to individual participants. (20)

After all potential determinants were recorded for the 4 constructs, each determinant was reviewed for clarity and distinctiveness from other determinants through discussion guided by the facilitator. Although many of the determinants might be partially correlated, the main consideration was whether each determinant could potentially affect the acquisition of motor abilities in a unique way. Ideas were grouped together only if all members of the group agreed. The average number of determinants for each construct generated by the focus groups were: primary impairments=13.9 (SD=2.8, range=9-17), secondary impairments=10.8 (SD=3.1, range=6-16), child personality characteristics=11.6 (SD=4.2, range=6-20), and family ecology=14.8 (SD=3.5, range=9-21).

Each focus group ended with the participants identifying and ranking the 5 most important determinants for each of the 4 constructs. As recommended by experts on the NGT, (20) each participant first recorded the 5 most important determinants within a construct on 5 separate cards and then identified the most important determinant from the 5 cards (rank=5), the least important determinant from the remaining 4 cards (rank=1), the most important determinant from the remaining 3 cards (rank=4), and the least important determinant from the remaining 2 cards (rank=2). The last remaining card received a rank of 3. Consensus within each focus group was established by determining the average rank for each determinant generated by the participants.

Phase 2: Compilation of Determinants Identified by Focus Groups

Typically, the NGT includes steps 5 and 6 in which the results of the preliminary vote are discussed and a second vote is taken. In our study, the second vote was conducted by having all participants complete a questionnaire. In order to develop a questionnaire for completion by all participants (phase 3 of the study), the rank-ordered lists generated by the 12 focus groups were integrated into a single list. This task was accomplished using a strategy referred to as "the induction of categories using content analysis" (20) and was conducted first by the primary author and then independently by another pediatric physical therapist who had 10 years of clinical experience and a Master of Science degree (ie, research training beyond the entry-to-practice degree).

First, the rankings for each potential determinant generated by each focus group were written on paper, and the paper was cut into strips, with one determinant per strip. The primary author then sorted the determinants into groups, with each group capturing one set of ideas. For example, the determinants of "muscle tone" and "spasticity" were included in one group. Participants in some groups elected to combine some issues (eg, muscle contracture and skeletal malalignment); when this occurred, these ideas were pooled for all similar items. Through this process, redefinitions of categories and the development of new categories occurred. Thus, all potential determinants were categorized by new themes, and an average rank for each new theme was produced, reflecting input from the 12 groups. This average rank was determined by dividing the sum of the rankings provided by each individual focus group by 12 (ie, the number of groups).

Only those items with average ranks above 0.7 were selected for inclusion in the questionnaire. We arbitrarily selected this cut-point of 0.7 in order to get about 5 potential determinants for each construct. Although this cut-point seems low in the context of the scale of 1 through 5, many groups did not suggest some of the potential determinants. That effectively contributed zero points to the ranking for that determinant. Accordingly, the value cannot be considered an estimate of importance of the determinant; instead, this was simply the strategy that was used to identify variables ranked most highly for the next phase. Our strategy resulted in 5 potential determinants for primary impairments, 5 potential determinants for secondary impairments, 4 potential determinants for child personality characteristics, and 6 potential determinants for family ecology. The results of the average ranked values of these top 4 to 6 determinants for each construct are shown in Table 2.

To examine interrater reliability, a second pediatric physical therapist independently categorized the determinants generated from the focus groups (ie, she grouped the determinants into categories without knowledge of the primary author's categorization). Independent classification resulted in agreement on 17 of 20 determinants (ie, 85% item agreement). The 2 physical therapists were in agreement on 4 of the top 5 determinants for the construct of primary impairments, on all 5 determinants for the construct of secondary impairments, on 3 of the top 4 determinants for the construct of child personality characteristics, and on all except the fifth ranked of 6 determinants for the construct of family ecology. The questionnaire was constructed using the categorization by the primary author.

Phase 3: Consensus Among Participants

In the final phase, all participants completed a questionnaire that was developed for this study. The Appendix contains an example of one of the items under construct of family ecology. The potential determinants for each of the 4 constructs were presented in random order on the questionnaire. Questions were focused on the importance of each determinant in influencing the acquisition of motor abilities, an estimate of the feasibility of collecting data in a clinical setting, and an indication of what resources would be required before the data could be collected (eg, training, time, "other" [for example, financial reimbursement]). Participants were asked to rate the question about the importance of each item on a 10-point scale, with 10 being "very important" and 0 being "unimportant." Feasibility was rated on a 3-point scale, with 3 being "feasible" and 1 being "not at all feasible."

In order to identify a set of variables for future research to test the model, we selected a cut-point of greater than 7. The intent was to identify a relatively small number of variables that therapists perceived to be important in the acquisition of basic motor abilities by children with cerebral palsy. We did not aim to identify all possible variables. In the context of testing the model in the future with structural equation modeling, we believe in the principle of parsimony. (27-29) In addition, we believe that when doing research in a clinical setting, it is important not to burden families and service providers with data collection.

Results

The determinants that had ratings of importance of 7 or greater out of. 10 are shown in Table 3. The physical therapists identified the following 4 primary impairments as being potential determinants of motor abilities: muscle tone (which most groups referred to as "spasticity") and movement patterns, distribution of involvement, balance, and sensory impairment. The 4 highest ranked secondary impairments were: range of motion and joint alignment, muscle force, health, and endurance. Only one determinant (motivation) in the construct of child personality characteristics had an average rating of greater than 7. Finally, participants identified 3 items under the construct of family ecology: family's support to child, family expectations of their child, and the support a family receives.

All of the potential determinants listed in Table 3 (with the exception of sensory impairment) had median values for feasibility of 3 (top value). More than half of the respondents judged assessment of sensory impairment to be only "somewhat feasible" for young children with cerebral palsy.

Discussion

The 3-phase process of obtaining consensus among practicing pediatric physical therapists on factors that they believe influence the acquisition of motor abilities in children with cerebral palsy was successful. The high response rates (30) of 85% and 88% for 2 of the phases, in our opinion, attest to the enthusiasm of the physical therapists working in the OACRS centers in participating in this project. In this discussion, we elaborate on the potential implications of therapists' beliefs of prognostic factors on current clinical reasoning and decision making. We also discuss the similarities and differences between the results of this consensus project for each of the 4 constructs with the theory- and evidence-based model we previously developed. Finally, we state how these results will guide us in the next stage toward testing the model of determinants of motor abilities.

Implications for Clinical Reasoning

This consensus exercise was conducted with 60 physical therapists with an average of 13.7 years of experience in pediatrics. Although the participants neither developed the conceptual model illustrated in the Figure nor explicitly stated their assumptions about factors influencing the acquisition of motor abilities outside of this study, we contend that the results shown in Table 3 provide a rare glimpse of factors that physical therapists might use implicitly in practice when making clinical decisions. These determinants can be used in one of 2 ways. Determinants perceived as not likely to change have implications for prognosis, including establishment of realistic and attainable goals. In contrast, determinants perceived as amenable to change are potential areas for intervention. Although the therapists in this study were not asked to make this distinction, the results provide a foundation for further inquiry on how knowledge of determinants is applied in decision making.

Some of the primary impairments might be the factors that are least amenable to change through physical therapy intervention. Physical therapy intervention is not likely to change either the distribution of involvement or the nature of the sensory impairment. These factors, therefore, are unlikely to be the focus of intervention, but they could be taken into consideration when selecting intervention strategies and procedures for children with different attributes. Similarly, although muscle tone (ie, "the force with which a muscle resists being lengthened" (31)(p577)) has been a focus of physical therapy interventions in the past, (32) current rehabilitation practice favors medical or surgical interventions such as use of intrathecal baclofen, (33) use of botulinum toxin A, (34) or selective posterior rhizotomy (35) for the management of spasticity. From this study, it is difficult to speculate how physical therapists would use the factor they identified as "movement patterns" in decision making. Therapists using a neurodevelopmental framework based on the work of the Bobaths would likely target the quality of movement as an area for intervention, albeit in what they consider a functional context. (36-38) Conversely, therapists using what they call a functional approach (25) might use information from the assessment of movement patterns to assist in establishing realistic functional goals. Finally, little information was obtained with respect to balance or postural control; however, the consensus statements of a conference on the management of cerebral palsy concluded that physical therapy is effective in enhancing postural control, (39) supporting therapists' focus on enhancing balance and postural control during intervention.

In contrast to the mixed picture under the construct of primary impairments, physical therapists try to prevent secondary impairments through interventions. (7) The secondary impairments identified in our study as determinants of motor change are currently recommended as areas for intervention by health care practitioners working with children with cerebral palsy. These areas for intervention include prevention or minimization of muscle and joint contractures and skeletal malalignment and promotion of general health, muscle force, fitness, and endurance. (40, 41)

Motivation was the only child personality characteristic unrelated to the diagnosis of cerebral palsy that was identified as a determinant of change in motor abilities. Based on their experiences, participants might perceive that children who are motivated to achieve motor abilities are more likely to actively participate in intervention than children who are not motivated. That is, therapists might regard a child's "motivation" as important during the goal-setting process. In addition, some therapists might use strategies during intervention that are intended to enhance motivation. Some people believe that motivation can be increased if the child perceives the activity to have some type of intrinsic reward. (42) Campbell (43) related the concept of "flow" (defined as an optimal psychological experience) to a pediatric physical therapy session by suggesting that if a therapist is able to engage a child deeply in an activity, outcomes of therapy might be enhanced.

Finally, therapists identified a family's support to the child, expectations of the child, and the support that the family has as being important determinants of motor change for children with cerebral palsy. We believe that these ideas reflect a philosophical approach related to family-centered service. (44) Each of these determinants is a potential target for intervention or supportive care. Based on the assumption that optimal child functioning occurs within a supportive family and community context, service providers should support families and encourage the use of community supports, as necessary. (44)

In our study, therapists were not asked to describe how they perceived these factors to influence acquisition of motor abilities of children with cerebral palsy; however, we believe that this is a useful area for future inquiry. Campbell (43) recently emphasized the importance of using explicit decision-making paradigms in the context of a conceptual framework to improve physical therapy practice and optimize outcomes of children with neurological impairments. Conceptual models have been identified that influence daily practice by giving guidance on what to do, how to do it, and--most importantly--why to do it. (45) Thus, although it has been argued that clinical reasoning involves more than the ability to offer reasons justifying clinical decisions, (46) we believe that explicit acknowledgement of the content and process of clinical decision making will improve both the outcomes among children with cerebral palsy and the learning experiences of inexperienced physical therapists.

Comparison of Consensus Results With Current Knowledge

Primary impairments. Knowledge of factors used in predicting acquisition of motor abilities among children with cerebral palsy is limited to the type of involvement? distribution of involvement, (2-5, 47, 48) presence and intensity of primitive reflexes, (2-5, 48) and age of acquisition of earlier motor abilities such as independent sitting, (2, 4, 5, 47-49) with ambulation being the only motor outcome investigated. Historically, impairments in what people have called muscle tone have been thought of as a key contributor to limitations in motor function of children with cerebral palsy. (33) Recent experience with procedures such as selective dorsal rhizotomy suggest that muscle weakness (50) and other deficits associated with abnormal temporal organization of motor unit firing (51) persist following surgery. Consensus participants expressed the belief that alteration in muscle tone contributes to difficulties in acquiring motor abilities. We do not know, however, whether they shared a common definition of muscle tone. Many participants in phase 1 suggested that more than muscle tone is implicated. They referred to "movement patterns," a term incorporating other qualitative aspects of movement that included type of motor disorder (eg, dystonic or athetoid) and expression of the motor disorder (eg, presence and intensity of primitive reflexes). This fits with the description of the motor deficits of cerebral palsy as involving one or more of the following impairments: increased latency of movement onset, poor temporal organization of muscle contraction, poor force production, decreased speed of movement, and increased co-contraction. (52)

Although alterations in muscle tone and movement patterns emerged as most important in the preliminary "across focus groups" consensus, a second estimate of consensus across centers resulted in distribution of involvement being ranked as equally important. The physical therapists' views are supported by the research literature. For example, virtually all children with hemiplegia walk independently during the preschool years, (2-4) and children with diplegia have a much better prognosis for ambulation than children with quadriplegia. (3-5, 47, 48)

Participants identified both sensory impairment and balance as important in both first and final phases of our study. Little is known about the influence of sensory impairment on the acquisition of motor abilities in cerebral palsy, (53) in part, because of difficulties in measuring sensory impairments (including modulation and processing of sensory information) in young children. This difficulty was reflected in participants' rating of feasibility of collecting this information. Deficits in balance and postural control have long been described from clinical observations as fundamental problems among children with cerebral palsy. (32) More recently, researchers using kinetic and kinematic data collection methods have described postural control in children with cerebral palsy in greater detail. (54) Nonetheless, little is known about the relationship between balance and postural control (and the influence of intersensory conflict) and the acquisition of motor abilities in this group of children.

During phase 2, cognition emerged as a potentially important influence on the acquisition of motor abilities; however, participants did not identify it as a potentially important influence in the third phase. Cognitive ability has been identified as an unimportant determinant of ambulation, (55) although children with microcephaly (48) and children with very low scores on intelligence tests (4) have been shown to have poor motor outcomes. These results suggest that the relationship between cognitive ability and the acquisition of basic motor abilities is nonlinear, but cognitive abilities below a certain cut-point (but not above) clearly influence motor development. This nonlinear relationship might explain therapists' hesitancy to rank cognition as an important determinant for all children with cerebral palsy.

Secondary impairments. Impairments in range of motion and joint alignment were ranked as the most important secondary impairments in both parts of this consensus process. Many participants wanted to combine listings involving muscle and joint extensibility and bone alignment because impairments in these tissues were perceived to develop progressively. The research literature supports the observation that children with chronic hypertonicity are at risk for the development of muscle hypoextensibility, (56) joint contracture, (57) and skeletal malalignment. (58) Prevention of these secondary impairments is advocated to avoid long-term problems such as arthritis, (59) repetitive motion disorders, and bursitis. (40) Little is known about the influence of impairments in range of motion and joint alignment and the acquisition of motor abilities among children with cerebral palsy, although participants ranked these secondary impairments as most influential.

Children with cerebral palsy have been shown to have deficits in force production (60, 61) and endurance (as measured by the Energy Cost Index). (62, 63) Participants ranked these factors as potentially important determinants in the acquisition of motor abilities. Force production has been identified to be associated improved walking performance, (64, 65) but little is known about the influence of muscle force on the acquisition of other basic motor abilities or the influence of endurance on motor change.

Participants ranked general health as being an important determinant of motor abilities among children with cerebral palsy. To our knowledge, the role of general health in motor development of children with cerebral palsy has not been investigated. Finally, although participants initially identified pain (particularly postsurgical pain) as an important determinant, it did not remain listed as an important determinant in the second round of consensus across focus groups.

Child personality characteristics. Research involving infants developing typically has indicated that child characteristics of temperament, (66) motivation, (67) and risk taking (68) are potential influences on early motor development. Although the participants in our study of children with cerebral palsy initially identified several temperamental attributes that they believed to be particularly influential (eg, separation anxiety, sociability), upon reflection only motivation had an average importance rating of greater than 7. Although children with physical disabilities such as cerebral palsy have been shown to have lower levels of motivation than children without physical disabilities, (69) the role of persistence and motivation in the acquisition of motor abilities has not yet been explored.

Family ecology. Based on our literature review of aspects of families that support general child development, we identified global issues of family resources, quality of the home environment, family support, parental expectations, and family functioning as being potential important influences on motor development. (6) Only parental expectation has some evidence about its role on motor development. Specifically, caregiving practices that involve aggressive handling of infants and exposure of infants to frequent postural challenges are associated with motor advancement. (70) Although participants initially identified ideas similar to those we found in the literature, the final consensus revealed only 3 potential determinants that received an importance rating of greater than 7: the family's ability to support the child's motor development, the family's expectations of motor performance, and informal support available to the family (eg, extended family, friends, neighbors, church community). Currently, no research evidence exists regarding the role of these family attributes on the acquisition of motor abilities of children with cerebral palsy.

Informing Future Research

The determinants identified by the participants will be used, along with future research data, to test a multivariate model of determinants of motor change for children with cerebral palsy. Although practicing clinicians reached consensus about potential determinants, this does not mean that the identified factors are the most influential. We believe that their perceptions must be tested. Before this research can be conducted, measures of some of the variables will need to be operationally defined and developed, and the validity and reliability of data obtained with these measures will need to be examined.

Limitations

Several limitations of this work exist. First, participating clinicians might not have identified some critical factors that might influence the acquisition of basic motor abilities of young children with cerebral palsy. Some practicing clinicians do not keep up with the research literature, and they are not necessarily aware of the broader concepts being developed. However, many of the participants in this study are, in our view, reflective practitioners, (71) and make the most of their practice experiences.

Second, because the therapists generated lists of determinants and a common set of operational definitions was not used, the participants may actually have had differing views of the determinants. Muscle tone, for example, may have been tested by multiple therapists, but they may not all have had the same idea as to what the term means.

Third, the model and this consensus exercise focus on the acquisition of basic motor abilities such as rolling, crawling, and walking, and not motor skill acquisition, which relies on cognition to a greater extent. (15) Among children with cerebral palsy, these basic motor abilities are acquired by 7 years of age. (16) The combined effect of these 2 limitations might explain the lack of consensus about child characteristics. Variables such as cognition, attention, memory, anticipation, reasoning, and judgment are clearly important in acquiring new motor behaviors that are described as "skills" versus "basic abilities."

Summary and Conclusion

Physical therapists working in centers affiliated with the OACRS participated in a 3-phase consensus process to identify important determinants of acquisition of motor abilities in children with cerebral palsy. The primary impairments identified by the therapists were muscle tone and qualitative aspects of the movement disorder, distribution of involvement, balance, and sensory impairments. Important secondary impairments were deviations in range of motion and joint alignment, muscle force, health, and endurance. The only child personality characteristic thought to be influential in the acquisition of motor abilities was motivation. Finally, the family variables judged to be important were family support to the child, family expectations, and support to family. The results are compatible with current knowledge or address gaps in knowledge of determinants of motor abilities for children with cerebral palsy. The determinants identified by group consensus provide insight into contemporary perspectives on children with cerebral palsy and how physical therapists might use information to make clinical decisions.

The results of our study could provide knowledge for further investigation. As might be expected for a lifelong condition such as cerebral palsy that affects multiple systems, understanding of complex relationships among potential determinants of motor ability is a complex process. (23) Identification of prognostic factors has been identified as a priority for evaluating rehabilitation interventions (72, 73) and motor interventions for children with cerebral palsy. (74) Although this need was recognized over a decade ago, (74) knowledge of prognostic factors is limited. Clarification of determinants of motor abilities of children with cerebral palsy will provide knowledge that has direct implications for evidence-based decision making and outcomes research. (75)

Appendix.

Family Ecology

Family Expectations

Child Improvement Locus of Control: to be completed by a parent;
estimated time to complete is 10 minutes

a) Importance (0 is unimportant, 10 is very important-please circle)
               0 1 2 3 4 5 6 7 8 9 1 0

b) Feasibility (1 is not feasible at all, 3 is feasible--please circle)
                                  1 2 3

c) Additional resources required (circle all that apply)

1 training
2 time
3 other (please indicate)
Table 1.
Possible Determinants of Motor Change for Children With
Cerebral Palsy (a)

Construct                        Possible Determinant

Primary impairments
  Motor                          Aberrations in muscle tone
                                 Type of motor disorder
                                 Distribution of motor disorder
                                 Primitive reflexes
                                 Age of acquisition of motor
                                   abilities
  Sensory                        Visual impairment
                                 Sensorimotor integration (vision,
                                   somatosensation, vestibular)
  Cognitive                      Cognitive ability
                                 Epilepsy

Secondary impairments            Muscle hypoextensibility
                                 Joint contracture
                                 Skeletal malalignment
                                 Impaired force production
                                 Impaired endurance

Inherent child characteristics   Temperament
                                 Motivation
                                 Risk taking

Family ecology                   Family resources
                                 Quality of the home environment
                                 Family support
                                 Parental expectations
                                 Family function

(a) Adapted and reprinted with permission of the American Physical
Therapy Association from Bartlett DJ, Palisano RJ. A multivariate
model of determinants of motor change for children with cerebral
palsy. Phys Ther. 2000;80:598-614.
Table 2.
Average Ranking of Determinants for Each Construct Among 57
Physical Therapists From 12 Centers (a)

                                                            Average
Construct               Determinant                         Ranking

Primary impairments     Muscle tone/movement patterns       4.4
                        Cognition                           1.8
                        Distribution of involvement         1.6
                        Sensory impairment (all types)      1.4
                        Balance/postural reactions          0.8

Secondary impairments   Muscle and joint contractures/      5.4 (b)
                          skeletal malalignment
                        General health/respiratory status   1.5
                        Force production                    1.4
                        Endurance/fitness/efficiency        0.9
                        Pain/effect of surgery              0.7

Child personality       Motivation                          4.6
  characteristics       Temperament                         1.7
                        Separation anxiety                  1.2
                        Sociability                         0.9

Family ecology          Expectations/beliefs                3.5
                        Support to child                    2.3
                        Response to diagnosis               2.2
                        Family support                      1.7
                        Family functioning                  1.5
                        Family resources                    1.5

(a) Values range from 1 (least important) to 5 (most important).

(b) Values greater than 5 are possible as a result of independent
items being pooled in the content analysis strategy.
Table 3.
Determinants for Each Construct Rated as Most Important by 60
Physical Therapists in Phase 3 (a)

                                                        Estimate of
                                                        Importance

Construct               Determinant                     X     SD

Primary impairments     Muscle tone/movement patterns   9.4   1.0
                        Distribution of involvement     9.4   1.0
                        Balance                         8.7   1.4
                        Sensory impairment              7.5   2.0

Secondary impairments   Range of motion/joint
                          alignment                     9.0   1.2
                        Muscle strength/force
                          production                    7.9   1.6
                        Health                          7.5   1.9

Secondary impairments   Endurance                       7.0   2.0

Child personality
  characteristics       Motivation                      8.2   1.7

Family ecology          Support to child                7.9   1.8
                        Family expectations             7.3   2.1
                        Family support                  7.3   2.1

(a) Determinants were rated on a 10-point scale (1 = unimportant,
10 = very important).

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Both authors provided concept/research design and writing. Dr Bartlett provided data collection and analysis, project management, fund procurement, subjects, facilities/equipment, and institutional liaisons. Dr Palisano provided consultation (including review of manuscript before submission). The authors thank the physical therapists from the Ontario Association for Children's Rehabilitation Services Centres for participating in this project and Andrea Abbott for conducting the reliability portion of the content analysis. They also acknowledge the members of CanChild, Centre for Childhood Disability Research, McMaster University, for providing a forum for the development of this work.

Part of the information in this manuscript was included in a presentation titled "Prognostic Indicators in Cerebral Palsy: A Consensus Exercise" at the Tri-joint Congress; May 25, 2000; Toronto, Ontario, Canada.

This project was approved by the Review Board for Health Sciences Research Involving Human Subjects at The University of Western Ontario.

This project was funded through a research grant from the Vice President (Research) at The University of Western Ontario.

This article was submitted April 2, 2001, and was accepted September 26, 2001.

DJ Bartlett, PT, PhD, is Assistant Professor, School of Physical Therapy, Faculty of Health Sciences, 1588 Elborn College, The University of Western Ontario, London, Ontario, Canada N6G 1H1 ([e-mail]), and Associate Member, CanChild, Centre for Childhood Disability Research, McMaster University, Hamilton, Ontario, Canada. Address all correspondence to Dr Bartlett at the first address.

RJ Palisano, PT, ScD, is Professor, Programs in Rehabilitation Sciences, MCP Hahnemann University, Philadelphia, Pa, and Co-Investigator, CanChild, Centre for Childhood Disability Research, McMaster University.