Optimizing orthotic management in children with cerebral palsy to improve mobility and participation

An ankle-foot orthosis (AFO) is a commonly prescribed rehabilitation
intervention in children with Cerebral Palsy (CP). AFOs have the purpose to
reduce gait deviations in order to enable or improve standing and walking,
thereby enhancing the child*s mobility and participation. Although AFOs in
children with CP are commonly prescribed, insight in underlying working
mechanisms and a clear concept of AFO design in relation to prescription goals
is largely lacking. At present, the decision-making process of AFO prescription
seems to rely primarily on current best available evidence and expert*s
experience and opinion, resulting in differences in AFO design. Literature
shows that AFO use is not always effective in children with CP and can even
have detrimental effects on the child*s functioning, e.g. by increasing energy
cost of walking or reducing walking speed. This suggests that AFO prescription
is inadequate in some patients, and underlines the importance and urgency of
acquiring more knowledge about the working mechanisms of AFOs. This requires a
extensive evaluation of AFO efficacy on a broad range of outcome measures, i.e.
using outcome measures that are related to both components of the International
Classification of Functioning, Disability and Health (ICF); *body functions and
structures* and *activities and participation*.

The primary objective of this study is to evaluate AFO efficacy in children
with spastic CP using outcome measures related to ICF the components of *body
functions and structures* and *activities and participation*. The secondary aim
is to identify prognostic factors for success of AFO treatment on outcome
measures related to the ICF component *activities and participation* in
children with spastic CP.

This is a pre-post experimental study. Baseline measurements (T0) will be done
while subjects wear their shoes. Additional measurements (energy cost of
walking and 3D gait analysis) will be performed with de subject's current (old)
AFO (if applicable). Then, the intervention AFO will be prescribed, of which
stiffness (K) will be varied (n=3, rigid, stiff and flexible). Sequence of AFO
stiffness will be blockrandomized (3x2x1=6 blocks). Subjects will accommodate
to each AFO stiffness for 4-8 weeks, after which AFO efficacy will be tested
(T1K1, T1K2 and T1K3). Then, the subject's optimal AFO will be selected and
subjects will wear this optimal AFO for 12-20 weeks. After this period,
follow-up measurements (T2) will be done.

Subjects will get an Floor Reaction Orthosis (FRO), composed out of pre-preg
material (e.g. impregnated carbon fibres), which will be fabricated with
integrated Neuro Swing® system ankle joint. This system has an adjustable
spring force, alignment, and range of motion of the ankle joint. This study
will investigate the effects of varying stiffness (spring force) of the AFO on
gait to select the subject*s optimal AFO.
The shaft of the new FRO will hold a small notch in which the @monitor will be
attached. Since the monitor will be merged within the shape of the FRO, it will
not cause any side effects or burden to the patient.

It is expected that AFO treatment will improve walking ability of the patient.
Furthermore, this extensive evaluation of AFO efficacy could contribute to
improving orthotic management in CP in the (near) future. It is therefore
assumed that relevance of the study is in balance with the burden for the
subjects.

Patients will enrol the study at the moment they are indicated to get new AFOs.
Consequently, patients are not asked to participate in an additional therapy on
top of their regular medical program. Participation in this study enables
selection of the subject*s optimal AFO, implicating the possibility of a more
beneficial AFO treatment compared to their usual care. Consequently, the
subject might experience direct benefits of his or her new AFO. Since the
intervention AFO will be custom made, it is assumed that the orthosis will not
cause greater burden or more pain compared to a conventional AFO.

Measurements of the study are non-invasive. Markers, sensors and cables might
somehow increase the burden during the measurements compared to normal walking
and fatigue or pain might occur. However, the risk of pain will be minimal and
subjects can quit the measurements if pain occurs. Subjects might get fatigued
during some of the measurements (e.g. fitness tests). The researcher will
therefore ensure that the subjects and parent(s) are completely informed before
starting the measurements and subjects will get sufficient time to recover from
all tests.

Considering the positive effects of optimizing AFOs as shown in preliminary
research, it can be concluded that the benefits outweigh the burden and the
minimal risk associated with this study.