Are models of disability useful in real cases? Pediatric case examples realized in research, clinical practice, and education: this perspective provides examples of the usefulness of models of disability in organizing research, educational materials, and measurement in clinical practice.

Conceptual models are useful devices for organizing complex material and examining interrelationships among variables. For example, speakers at the 1990 II STEP conference presented a systems model of motor control, (1) the dynamical systems model as used in studying infant motor development, (2) and the World Health Organization (WHO) model (3) as a systematic approach to measurement of impairments, functional limitations, and disability. (4)

In 1991 through 1995, I was privileged to be the first physical therapist to serve on the National Advisory Board for the newly created National Center for Medical Rehabilitation Research (NCMRR) of the National Institutes of Health (NIH). One of our tasks was to define the range of research to be funded by NCMRR, and we decided to use the Institute of Medicine model of disability (5) as the organizing framework for considering the dimensions of disability research that would be encouraged by NCMRR through its funding mechanisms. We added to the model the dimension of societal limitations because we believed that the inability of people with disabilities to achieve full participation in society was often seen as a failure of rehabilitation when, in fact, barriers created by attitudes, public policies, insurance coverage limitations, and so on were the more likely culprits. (6) Thus, the model incorporated the dimensions of pathophysiology, impairment, functional limitation, disability, and societal limitation. The definitions of these 5 dimensions of disability are shown in Appendix 1.

After reflection upon the model, we realized that research on the disability dimension was being funded by the National Institute on Disability and Rehabilitation Research in the US Department of Education and that NIH was already funding considerable work on the pathophysiology of disabling conditions. Thus, we determined that NCMRR should target a significant amount of funding toward research on understanding and reduction of impairments and functional limitations in people with disabilities and on revealing the relationships among the various dimensions of disability. As a result of my work on the National Advisory Board, I became interested in applying the NCMRR model of the disabling process to exploration of questions such as the following: (1) Does reduction of spasticity as defined by presence of excessive reflex activity in people with cerebral palsy (CP) improve motor function and reduce disability; that is, is there a hierarchical relationship among the dimensions of disability? and (2) How soon can the functional limitations characteristic of movement in infants with CP be recognized, and can we find a way to measure them before the usual age of medical diagnosis based on presence of abnormal postural tone and reflexes?

To illustrate the usefulness of models of disability, I will present the following cases exemplifying their application to questions such as those just posed in the areas of research, clinical practice, and education:

* A case report on a child with CP in which measures of impairment, function, and disability were used to assess outcomes of reduction of spasticity with intrathecally administered baclofen.

* The development of a test of functional motor performance for infants under 5 months of age for the purpose of early diagnosis of delayed motor development.

* Use of a conceptual model of health and disability as the organizing framework for a comprehensive reference book to guide the practice of pediatric physical therapy.

Case Example 1: Effects of Spasticity Reduction on Impairments, Functional Limitations, and Disability

As part of an unpublished double-blind, placebo-controlled clinical trial of the efficacy of intrathecally administered baclofen in reducing spasticity in people with CP, Almeida and colleagues (7) published a case report that used the NCMRR model for developing an outcome assessment plan. Outcome measures used were designed to assess changes in impairments (eg, spasticity, range of motion, isometric force generation), functional limitations (eg, mobility, and dressing), and disability in daily life activities such as recreation. The child was an 11-year-old boy with spastic diplegia who used a walker for household ambulation but a wheelchair in the community, had severe clonus in a standing posture that interfered with walking, needed assistance with transfers, and was unable to independently put on underwear and socks.

Baclofen reduced spasticity and clonus. (7) Associated changes in impairments observed during the period of double-blind control and masked assessment included decreased strength and muscle coactivation, increased hip and ankle range of motion, and faster upper-extremity reaching movements. In the functional limitations dimension, the Gross Motor Function Measure (8) showed small changes; nevertheless, independence in dressing and transfers improved, and orthoses were discarded. After the placebo-controlled part of the study, an open period of assessment was completed by investigators who were aware that the patient was continuing baclofen use. The patient won a "Most Improved in Physical Fitness Award" in school, and he was delighted that he was able to go out with friends while managing his toileting needs, car transfers, and seat belts without assistance. He loved being free of orthoses and reported great pleasure in having acquired upright stability such that he could stand at the refrigerator and open a can of "pop". Over the long term, however, range of motion decreased, and the wisdom of discarding his orthoses was questionable.

Overall, it appeared that spasticity reduction was associated with a much greater decrease in disability in daily life at school and in the community than would have been expected from the small changes measured in overall gross motor function. Had we measured only changes in impairments and functional limitations, we would have had no idea how large the perceived impact of baclofen use was in the patient's school and community activities. In summary, the outcomes of this case led us to support the belief of the NCMRR National Advisory Board that there is not necessarily a linear relationship among different dimensions of disability and to recommend that research measurement protocols should continue to relate changes in impairment to effects on functional limitations and disability in daily life in order to understand how interventions really work. I also am reminded of my presentation at the II STEP Conference in which I made a point of saying that interventions must be assessed for safety (ie, tested for unexpected negative effects). (4) In the case example described, freedom from clonus led the patient to discard his orthoses, but the likely result was an increase in muscle shortening that could lead to more serious orthopedic problems in the long run. One has to ask the question of whether improved cosmesis and freedom of movement associated with enhanced quality of life could lead to an increase in pain and the need for costly surgery in the future. Thus, this case example also supports the need for longitudinal follow-up of outcomes when using new types of interventions. When information regarding risks as well as benefits becomes available, health care professionals will be obligated to inform potential consumers of our services so that they can make informed decisions.

Case Example 2: Development of a Functional Motor Scale for Infants

A goal of my career has been finding a means for early detection of the movement dysfunction characteristic of CP, because I believe that early intervention can improve outcomes. At present, children with CP seldom receive intervention before 9 months of age, (9) and a definitive neurologic diagnosis is typically made only after 1 year of age or when children fail to walk on time. At the time I began my career, we believed that measurement of reflexes and muscle tone were the key to early diagnosis of central nervous system (CNS) dysfunction. Reflection on the unreliability of reflex and tone measures and the transient nature of some of the positive signs of CNS dysfunction, along with exposure to models of the disabling process, led to the mission of developing an alternative approach to testing (ie, an assessment of posture and movement needed for function in daily life). The aim was early identification of functional limitations resulting from negative signs of CNS dysfunction, such as poor postural control that might ensue from impaired muscle strength. In keeping with a systems and task-oriented model of motor control and motor development, the test also was designed to include items involving a variety of positions, handling, and types of tasks demanding participation of multiple sensory systems, as well as observations of spontaneous movement. (10) For example, the task of head control is presented in a variety of items in the test. In 1 item, the infant must demonstrate his or her ability to control movement of the head in the prone position in order to find a sound, while in other items visual or vestibular stimuli are used to elicit head control performance in other positions.

Test items that had been shown in a pilot study (11) to be responsive to intervention in premature infants receiving neurodevelopmental therapy (NDT) in a neonatal intensive care unit (NICU) were tested in large numbers of infants (12) and, of crucial importance, were compared with demands for movement placed on infants in daily life interactions with caregivers. (13) In the latter study, we were able to demonstrate that 98% of the items in the test were similar to performance demands placed on infants by their mothers during dressing, bathing, and play. This tool eventually became known as the Test of Infant Motor Performance (TIMP). (14) The power of this precise assessment approach to identifying functional limitations is demonstrated by the fact that the TIMP has been shown to be predictive at 3 months of age of school-age motor performance (15) and capable of diagnosing motor delay before hospital discharge in premature infants (16) and as early as 7 days postterm in infants with white matter injury. (17) The TIMP is also a responsive measure, having been used to demonstrate the effects on function of physical therapy in 2 clinical trials of early intervention. (11,16) In summary, concentrating on designing an assessment to measure infant motor function, rather than reflexes and tone, resulted in development of a test that proved to be a valid diagnostic (discriminatory) measure, predictive of future motor performance, and responsive to change with development or intervention.

The TIMP is currently in use in most US states to qualify infants for federally guaranteed early intervention and in at least 16 foreign countries, but use of the test is not yet a standard practice procedure for routine assessment of infants at risk for CNS dysfunction. Studies using the TIMP as an outcome measure showed that premature infants at risk for CNS dysfunction who were identified as delayed in the perinatal period can benefit from intervention, (11,16) but incorporating routine TIMP testing into nursery practice to a certain extent flies in the face of current recommendations to protect premature infants from stimulation. (18) Although we have no definitive evidence that intervention beginning earlier rather than later makes any difference in long-term outcomes, making it difficult to counter the argument for protection from stimulation, we do now possess the measures needed to investigate this question. In addition to the TIMP for assessment of early outcomes, longer-term outcomes can be assessed with other measures designed in conformity with models of disability, such as the Pediatric Evaluation of Disability Inventory (19) and the School Function Assessment. (20)

Case Example 3: Framework for a Comprehensive Reference for Pediatric Practice

The editors and authors of the 2000 edition of Physical Therapy for Children (21) used the hybrid disability model of the NCMRR along with the Guide to Physical Therapist Practice (22) as their organizational frame of reference. Thus, each condition discussed in the book was described in terms of common impairments, functional limitations, and disabilities, and assessment and intervention were described within the framework of the patient/client management model of the Guide to Physical Therapist Practice. As we planned the next edition of the book, however, we decided to alter our conceptual framework. Although the NCMRR model emphasizes societal barriers faced by people with disabilities and was demonstrated to be useful in the 2 previously described examples, it is essentially a negative model of the disabling process in its focus on pathology, impairment, and functional limitations. The maintenance of hope for a healthy and productive future is an essential component of work with the families of children with special needs, and, to that end, my co-editors, Darl Vander Linden and Robert Palisano, and I decided to use a different conceptual model to structure the third edition of Physical Therapy for Children. (23) Our conceptual model for organizing the material on childhood conditions in this edition is the newest version of the WHO model, the International Classification of Function, Disability and Health (ICF). (24) The ICF provides definitions of disability dimensions within the context of health. The model has 2 parts and emphasizes the components of health rather than the consequences of disease. The first part is "Functioning and Disability," which includes body functions and structures, and activities and participation (note the positive focus inherent in these terms). The second part of the ICF, "Contextual Factors," includes environmental and personal factors that impinge on health. Appendix 2 contains the definitions of terms used in the ICF model.

Using the ICF model to guide practice does not mean that pediatric physical therapists do not continue to measure and manage impairments and functional limitations. Impairments are assessed as part of an examination of body structures and function, and activity limitations can be quantified with standardized tests. The focus on positive outcomes provided by the ICF, however, means that we assess these physical aspects of health and function within the context of ascertaining family needs and goals in order to promote meaningful participation of the child in home, school, and community life. A focus on wellness and health promotion also fits well with the ICF model. (25)

How has Physical Therapy for Children changed as a result of the move to the ICF rather than the NCMRR model as its conceptual framework? As examples, videotaped cases of children with disabilities on a DVD that accompanies the book illustrate swimming activities for a child with osteogenesis imperfecta, community mobility for children with different types of disabilities, and assessment in the natural environment. Examinations and interventions described in the third edition also emphasize health-related physical fitness through activity and participation in the community. The Guide to Physical Therapist Practice, of course, continues to provide the model for presenting patient/client management in Physical Therapy for Children, and the editors do not find that to be incompatible with a switch to the terminology of the ICF model.

In summary, I have used the conceptual frameworks of the NCMRR and the WHO: (1) to plan and enrich the results of research on interventions for CP, (2) to develop a functional motor scale for infants that has excellent power to predict, discriminate, and be responsive to intervention effects, and (3) to frame a book to guide pediatric physical therapist education and practice.

Discussion

Keshner reminded us in a commentary in Physical Therapy (26) and in her presentation at the II STEP Conference (27) that we only provide intervention for things that we happen to think of measuring. Craik's II STEP Conference presentation (28) argued for the need for tests that provide a description of the relationship between abnormal motor behavior and functional ability and for standards that can be used for developing realistic intervention goals. In the area of pediatric physical therapy, we have perhaps come farthest in carrying out the recommendations of the II STEP Conference by moving beyond a focus on impairment to develop a host of new measures of function and disability in children.

At the time of the II STEP Conference, few tests were available that had been designed based on models of the dimensions of disability and validated for use in clinical practice by pediatric physical therapists. Now there are many tests available, of which the TIMP is only one. The Gross Motor Function Measure for children with CP was new at the time of the II STEP Conference but has recently been revised and is now a standard assessment used in both clinical practice and research. (29) In addition, the same group of researchers has published the Gross Motor Function Classification System for categorizing levels of functional ability in children with CP and has demonstrated its usefulness as a prognostic measure. (30) It is rapidly becoming the standard in pediatric neurology and rehabilitation for describing research sample characteristics in studies of children with CP. The Pediatric Evaluation of Disability Inventory was mentioned at the II STEP Conference but was only in press at the time. (19) A new version has been developed for use specifically in school settings. (20) In the area of infant testing, the TIMP, the Alberta Infant Motor Scale, (31) and the Harris Infant Neuromotor Test (32) did not exist, but the Movement Assessment of Infants, (33) a test that showed diagnostic promise but is now little used, in part, because of its length and lack of an overall quantitative score, was mentioned at the II STEP Conference.

Whether or not all of this creative activity on the part of pediatric physical therapists and other clinicians was a direct result of the II STEP Conference, it is clear that the move toward development of measurement tools to assess function and disability has resulted in outstanding capability to describe motor skills in children with disabilities across a wide range of age and ability levels. We now have the tools we need to measure function in research and clinical settings. In short, the tools are now at hand to diagnose CP early, (34) define the presence of functional limitations by 3 to 6 months of age, measure intervention effects on brain structure, (18) and classify motor outcomes of children with CP in ways that have functional and prognostic implications. The challenge remains that of getting all pediatric clinicians to use these excellent tools.

In addition to encouraging the development of new assessment devices, a hope of the organizers of the II STEP Conference was that new models of motor control, disability, and rehabilitation would be infused in the educational process of practitioner preparation. This was achieved, I believe, through major curricular revisions throughout the professional education system and through publication of books such as Physical Therapy for Children. (21) A third goal, however, was that the information presented at the II STEP Conference would guide the development of theory and translation of evidence into practice. This goal remains elusive. For example, the II STEP Conference attempted to wean us away from the idea that reducing spasticity as a means of normalizing movement can improve functional performance and to broaden our focus on multiple systems and levels of the organism. This idea became incorporated into education and practice with very little evidence behind it. Now I would ask whether the evidence in the case report by Almeida and colleagues (7) means that this question should continue to be raised through systematic study of effects across multiple dimensions of disability. The results of the baclofen study also demonstrated that disability models are not hierarchical, so one cannot assume that changing something at the impairment level will necessarily result in large changes in gross motor function. On the other hand, changing impairments could affect participation in daily life in astounding ways. To me it means that multidimensional assessment of outcomes is essential and that a great deal of research is still needed to test the various models and theories presented at the II STEP Conference. Of course, we also need to be sure that changes in function and disability perceived to be positive outcomes in the short term are not accompanied by creation of secondary impairments that might lead to major health issues in the long term. (35) In short, we must focus on the whole person and all dimensions of disability, including, via our advocacy activities, societal limitations that unnecessarily burden people with disabilities.

Second, as a more global review of the outcomes of the II STEP Conference, it seems to me that, despite the emphasis on rethinking the theories behind our interventions, few publications have resulted since the II STEP Conference in which the models presented have been tested. Thus, we remain at the mercy of theoretical knowledge, rather than hard evidence. Indeed, we are a long way from having the evidence needed to support clinical practice in neurologic rehabilitation. For instance, in a presentation at the 2005 Annual Conference and Exhibition of the American Physical Therapy Association, Svien and Anderson (36) presented a review of the types of publications that have appeared in the journal Pediatric Physical Therapy since its inception in 1989 through the final issue of 2003. Over the 15-year period, 32 (12%) of the studies described in the 262 articles that were published met the definition of experimental. Of those, only 4 were clinical trials, none of which were the type of large clinical trials presenting the strongest evidence about treatment efficacy. Furthermore, there has been no significant increase in the number of articles published that can be described as experimental across 4 successive periods of time studied in this review. Other outlets for research in pediatric neurologic rehabilitation exist, of course, but findings are likely to be similar.

Finally, one needs to ask whether the theories and intervention models presented at the II STEP Conference remain current today. A result of the II STEP Conference was promotion of a task-oriented and systems-based approach to intervention for people with neurologic disabilities. Yet, what we see in the evidence on effective approaches today seems rather different--specifically, data showing that highly focused, specifically targeted interventions such as treadmill training in nonfunctional environments and with passive assistance to structure movement patterns can be highly effective in improving locomotion in children with disabilities. (37-39) Where will we go from here with revision of our theory and approaches to intervention? Ultimately, large, hypothesis-driven clinical trials need to be designed to compare the effects of various theoretically based approaches, including task-oriented approaches and highly focused interventions. We should not continue to develop new theories and put them into practice without appropriate clinical research on efficacy and effectiveness. At the conclusion of the II STEP Conference, Barnes, with her usual style and wit perhaps said it best: "I do strongly urge that we get on with research that will help us to establish the efficacy of what we do." (40) Fifteen years later, we still need to heed her urging.

Appendix 1.

Definitions of the National Center for Medical Rehabilitation Research Model Dimensions of Disability (6)

Pathophysiology: Interruption of or interference with normal physiological and developmental processes or structures

Impairment. Loss or abnormality of cognitive, emotional, physiological, or anatomical structure or function, including all losses or abnormalities, not just those attributable to the initial pathophysiology

Functional Limitation: Restriction or lack of ability to perform an action in the manner or within the range consistent with the purpose of an organ or organ system

Disability: Inability or limitation in performing tasks, activities, and roles to levels expected within physical and social contexts

Societal Limitation: Restriction, attributable to social policy or barriers (structural or attitudinal), which limits fulfillment of roles or denies access to services and opportunities that are associated with full participation in society

Appendix 2.

Definitions of the International Classification of Function, Disability and Health (24) Components in the Context of Health

Body Functions: The physiological functions of body systems (including psychological functions)

Body Structures: Anatomical parts of the body such as organs, limbs, and their components

Impairments: Problems in body function or structure such as a significant deviation or loss

Activity: Execution of a task or action by an individual; activity limitations are difficulties an individual may have in executing activities

Participation: Involvement in a life situation; participation restrictions are problems an individual may experience in involvement in life situations

Environmental Factors: The physical, social, and attitudinal environment in which people live and conduct their lives

Personal Factors: Attributes of the person that include internal influences on functioning and disability

This article was received July 12, 2005, and was accepted January 23, 2006.

References

(1) Horak FB. Assumptions underlying motor control for neurologic rehabilitation. In: Lister MJ, ed. Proceedings of the II STEP Conference: Contemporary Management of Motor Control Problems. Alexandria, Va: Foundation for Physical Therapy; 1991:11-27.

(2) Heriza C. Motor development: traditional and contemporary theories. In: Lister MJ, ed. Proceedings of the II STEP Conference: Contemporary Management of Motor Control Problems. Alexandria, Va: Foundation for Physical Therapy; 1991:99-126.

(3) International Classification of Impairments, Disabilities, and Handicaps. Geneva, Switzerland: World Health Organization; 1980.

(4) Campbell SK. Framework for the measurement of neurologic impairment and disability. In: Lister MJ, ed. Proceedings of the II STEP Conference: Contemporary Management of Motor Control Problems. Alexandria, Va: Foundation for Physical Therapy; 1991:143-153.

(5) Pope AM, Tarlov AR. Disability in America: Toward a National Agenda for Prevention. Washington, DC: National Academy Press; 1991.

(6) Research Plan for the National Center for Medical Rehabilitation Research. Bethesda, Md: US Public Health Service, National Institutes of Health; 1993, NIH Publication No. 93-3509.

(7) Almeida GL, Campbell SK, Girolami GL, et al. Multi-dimensional assessment of motor function in a child with cerebral palsy following intrathecal administration of baclofen. Phys Ther. 1997;77:751-764.

(8) Russell D, Rosenbaum P, Gowland C, et al. Gross Motor Function Measure Manual. 2nd ed. Hamilton, Ontario, Canada: McMaster University; 1993.

(9) Weindling AM, Hallam P, Gregg J, et al. A randomized controlled trial of early physiotherapy for high-risk infants. Acta Paediatr. 1996;85: 1107-1111.

(10) Thelen E, Kelso JS, Fogel A. Self-organizing systems and infant motor development. Dev Rev. 1987;7:39-65.

(11) Girolami GL, Campbell SK. Efficacy of a neurodevelopmental treatment program to improve motor control of preterm infants. Pediatric Physical Therapy. 1994;6:175-184.

(12) Campbell SK, Kolobe THA, Osten ET, et al. Construct validity of the Test of Infant Motor Performance. Phys Ther. 1995;75:585-596.

(13) Murney ME, Campbell SIC The ecological relevance of the Test of Infant Motor Performance elicited scale items. Phys Ther. 1998;78: 479-489.

(14) Campbell SK. The quest for measurement of infant motor performance. In: Refshauge K, Ada L, Ellis E, eds. Science-Based Rehabilitation: Theories Into Practice. Philadelphia, Pa: Butterworth-Heinemann; 2005: 49-65.

(15) Kolobe THA, Bulanda M, Susman L. Predicting motor outcome at preschool age for infants tested at 7, 30, 60, and 90 days after term age using the Test of Infant Motor Performance. Phys Ther. 2004;84: 1144-1156.

(16) Lekskulchai R, Cole J. Effect of a developmental program on motor performance in infants born preterm. Aust J Physiother. 2001;47: 169-176.

(17) Barbosa VM, Campbell SK, Sheftel D, et al. Longitudinal performance of infants with cerebral palsy on the Test of Infant Motor Performance and on the Alberta Infant Motor Scale. Physical & Occupational Therapy in Pediatrics. 2003;23(3):7-29.

(18) Als H, Duffy FH, McAnulty GB, et al. Early experience alters brain function and structure. Pediatrics. 2004;113:846-857.

(19) Haley SM, Coster WJ, Ludlow LH, et al. The Pediatric Evaluation of Disability Inventory: Development Standardization and Administration Manual Boston, Mass: New England Medical Center Publications; 1992.

(20) Coster W, Deeney T, Haltiwanger J, Haley S. The School Function Assessment. San Antonio, Tex: The Psychological Corp; 2000.

(21) Campbell SK, Vander Linden DW, Palisano RJ, eds. Physical Therapy for Children. Philadelphia, Pa: WB Saunders Co; 2000.

(22) Guide to Physical Therapist Practice. 2nd ed. Phys Ther. 2001;81: 9-744.

(23) Campbell SK, Vander Linden DW, Palisano RJ, eds. Physical Therapy for Children. 3rd ed. Philadelphia, Pa: Elsevier; 2006.

(24) International Classification of Functioning, Disability and Health. Geneva, Switzerland: World Health Organization; 2001.

(25) Goodgold S. Wellness promotion beliefs and practices of pediatric physical therapists. Pediatric Physical Therapy. 2005;17:148-157.

(26) Keshner EA. Commentary on "Development of a Quality-of-Movement Measure for Children With Cerebral Palsy." Phys Ther. 1991;71: 828-829.

(27) Keshner EA. How theoretical framework biases evaluation and treatment. In: Lister MJ, ed. Proceedings of the II STEP Conference: Contemporary Management of Motor Control Problems. Alexandria, Va: Foundation for Physical Therapy; 1991:37-47.

(28) Craik RL. Abnormalities of motor behavior. In: Lister MJ, ed. Proceedings of the II STEP Conference: Contemporary Management of Motor Control Problems. Alexandria, Va: Foundation for Physical Therapy; 1991:155-164.

(29) Avery LM, Russell DJ, Raina PS, et al. Rasch analysis of the Gross Motor Function Measure: validating the assumptions of the Rasch model to create an interval-level measure. Arch Phys Med Rehabil. 2003;84:697-705.

(30) Rosenbaum PL, Walter SAD, Hanna SE, et al. Prognosis for gross motor function in cerebral palsy: creation of motor development curves. JAMA. 2002;288:1357-1363.

(31) Piper M, Darrah J. Motor Assessment of the Developing Infant. Philadelphia, Pa: WB Saunders Co; 1994.

(32) Harris SR, Megens AM, Backman CL, et al. Development and standardization of the Harris Infant Neuromotor Test. Infants Young Child. 2003;16:143-151.

(33) Chandler LS, Andrews MS, Swanson MW. Movement Assessment of Infants: A Manual. Rolling Bay, Wash: Movement Assessment of Infants; 1980.

(34) Einspieler C, Prechtl HFR, Bos AF, etal. Prechtl's Method on the Qualitative Assessment of General Movements in Preterm, Term and Young Infants. London, United Kingdom: Mac Keith Press; 2004.

(35) Campbell SK. Therapy programs for children that last a lifetime. Physical & Occupational Therapy in Pediatrics. 1997;17(1):1-15.

(36) Svien LR, Anderson SL. Published research in Pediatric Physical Therapy: an analysis of trends from first issue to present. Abstract PO-RR-117-TH_PT 2005 Boston. Available at: http://www.apta.org/ am/aptaapps/programming/pt/abstracts. Accessed July 10, 2005.

(37) Bodkin AW, Baxter RS, Heriza CB. Treadmill training for an infant born preterm with a grade III intraventricular hemorrhage. Phys Ther. 2003;83:1107-1118.

(38) Richards CL, Malouin F, Dumas F, et al. Early and intensive treadmill locomotor training for young children with cerebral palsy: a feasibility study. Pediatric Physical Therapy. 1997;9:158-165.

(39) Ulrich DA, Ulrich BD, Angulo-Kinzler RM, Yun J. Treadmill training of infants with Down syndrome: evidence-based developmental outcomes. Pediatrics. 2001;108:E84. Available at: http://www.pediatrics. org/cgi/content/full/108/5/e84. Accessed July 10, 2005.

(40) Barnes ML. Past, present, and future: the II STEP Conference. In: Lister MJ, ed. Proceedings of the II STEP Conference: Contemporary Management of Motor Control Problems. Alexandria, Va: Foundation for Physical Therapy; 1991:267.

SK Campbell, PT, PhD, FAPTA, is Professor and Head, Department of Physical Therapy, University of Illinois at Chicago, 1919 W Taylor St M/C 898, Chicago, IL 60612 (USA) ([e-mail]).

This article is a revised version of a presentation by the author at the III STEP Symposium on Translating Evidence Into Practice: Linking Movement Science and Intervention; July 16, 2005; Salt Lake City, Utah. Published research by the author described in this article was supported by the Foundation for Physical Therapy, the National Institutes of Health, Medtronic Inc (Almeida), and the Ministry of Education of Brazil (Barbosa). The author is the managing partner of Infant Motor Performance Scales, LLC (www.thetimp.com), the publisher of the Test of Infant Motor Performance (TIMP).