Dynamic Foot Orthosis: Product Production vs Clinical Application vs. Documented Research
Valerie Wondra, MPT;
Kenneth H. Pitetti, Ph.D.; Rainbows United Inc., Wichita, Wichita State University
The past two decades have witnessed the production and clinical use (i.e., as a therapy device) of a relatively inexpensive foot orthotic that can be placed into the standard shoes of children with motor delays to improve their balance and motor capacities. The general term used to describe such an orthotic device is minimum controlled dynamic foot orthosis (DFO). An example of a DFO can be found in Figure 1
. The features of this DFO include, a) a thin layer of plastic on the bottom of dense foam (aliplast-like material) contoured and shaped to fit the plantar surface of the foot, b) construction with low-density polyethylene, and c) flexible at the toe, semi-flexible at the arch, and rigid around the heel. Additional features include an arch support, a metatarsal head depression, heel cup, and toe rise for toes 2 through 5.
Although the DFOs have been used clinically, little was known about "corrective" benefits. As pointed out in a 1989 article by Nancy Hylton,1 although there had been descriptive/observational/anecdotal reports about the benefits (e.g., improved balance) of DFOs in treating children with neurological/ developmental disorders, there was a paucity of scientific data regarding the effectiveness.
In an attempt to improve the limited scientific information on the affects of DFOs, we performed a study on the efficacy of DFOs as it relates to the locomotor skills of children with gross motor developmental delays.2 Results of this study suggest that DFOs could play a significant role in improving the locomotor skills of children with gross motor delays. Although this study 2 reported outcomes following only two months of wearing the DFO, we continued to follow a portion of the children from the original study and measured locomotor skills at 4 months and 12 months. The locomotor skills of these children continued to improve over this time period, and these results (i.e.., locomotor skills at 4 months and 12 months) were presented at the 2005 Combined Sections Meetings of the American Physical Therapy Association in New Orleans. 3
Although we felt that our studies represented an earnest exploratory attempt to report outcomes (i.e. measured improvements in gross motor skills) for children with gross motor delays who wear orthotics similar to the DFO, there were limitations to our findings. First, not all disability categories of the children (Down syndrome vs cerebral palsy vs developmentally delayed) showed improvement. Of interest, only the children that were classified as developmentally delayed (i.e., not with Down syndrome or cerebral palsy) showed significant improvements. Secondly, only those children with a Peabody Developmental Motor Scales Test-2 (PDMS-2) z score of -1.33 or lower demonstrated improvements. Those above this z score (i.e., z scores of -1.00 or –0.66) did not. The two other limitations were the small number of children in the studies (25 and 17, respectively) and there were no controls.
In the perfect world of "good science", we should have continued to collect data in order to address the short comings (i.e., limitations) of our initial studies. In the real world of pediatric rehabilitation, however, balancing "good science" with clinical needs or aspirations can be difficult. Before we could get to the "good science", the same company that made the original DFO(PattiBob, Cascade DAFO™, Inc, Ferndale, WA) developed what they considered to be a more supportive style of PattiBob, called the PollyWog (see Figure 2
). From a structural perspective, the obvious difference between the two DFOs was that the Polly-Wog's semiflexible plastic extended upward ˝ inch under the lateral and medial malleolus and supported all 3 cuneiform bones, the cuboid and navicular bones, and base of the metatarsals. But, did the structural changes of the PollyWog
result in locomotor improvements when compared to the Pattibob? In an attempt to address this question,
we compared two groups of 12 children matched in motor development diagnosis, chronological age, motor age equivalent, and motor locomotor capacities. Each group was fitted with either the PattiBob or PollyWog, allowed 7 days to wear the DFOs, then re-tested using the PDMS-2. Although significant gross motor improvements (i.e., raw scores for the PDMS-2) were seen for each group, significant improvements in age equivalent scores were seen only in the children wearing the Pollywog. These findings were presented at the Association of Children's Prosthetic-Orthotic Clinics, Orlando, Florida, 2005.4
From a clinicians point of view, these results suggest that: 1) both types of DFOs (PattiBob and PollyWog) could play a role in improving the gross motor skills (i.e., raw scores for the PDMS2) of children with motor delays; and 2) the Polly-Wog resulted in additional improvements (i.e., raw scores and age equivalent) within the first week.
However, from a researchers point of view, the limited number of participants in this study and in the above studies, as well as other methodogical limitations (i.e., types and classifications of gross motor disabilities) prevent definitive conclusions.
The point of this "editorial" is this. Prosthetic-Orthotic companies have their timetable in improving and marketing their products, but pediatric clinicians and researchers should have a timetable that is deliberate and cogent in determining the proper application of that product. For DFOs, clinicians and researchers still have work remaining on their agenda.
References:
- Hylton NM. Postural and functional impact of dynamic AFOs and FOs in a pediatric population. J. Prosthet Orthot. 1989;2:40-53.
- Pitetti KH, Wondra VC. Dynamic foot orthosis and motor skills of delayed children. J. Prosthet Orthot. 2005;1:21-24.
- Wondra VC, Pitetti KH. Effect of a dynamic foot orthosis on children with delayed gross motor locomotion skills: A 4- and 12-month follow-up. Pediatr Phys Thera. 2005;1:90.
- Wondra VC, Pitetti KH. Comparison of two dynamic foot orthoses on children with delayed gross motor skills. Association of Children's Prosthetic and Othotic Clinic; 2005, March, Orlando, FL.
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