Article

Many individuals with cerebral palsy wear ankle foot orthoses during
daily life. Orthoses influence joint motion, but how they impact muscle remains
unclear. In particular, the gastrocnemius is commonly stiff in cerebral palsy.
Understanding whether orthoses stretch or shorten this muscle during daily life
may inform orthosis design and rehabilitation. This study
investigated the impact of different ankle foot orthoses on gastrocnemius
operating length during walking in children with cerebral palsy. STUDY DESIGN:
Case series, within subject comparison of gastrocnemius operating length while
walking barefoot and with two types of ankle foot orthoses. METHODS: We performed
gait analyses for 11 children with cerebral palsy. Each child was fit with two
types of orthoses: a dynamic ankle foot orthosis (Cascade dynamic ankle foot
orthosis) and an adjustable dynamic response ankle foot orthosis (Ultraflex ankle
foot orthosis). Musculoskeletal modeling was used to quantify gastrocnemius
musculotendon operating length and velocity with each orthosis. RESULTS: Walking
with ankle foot orthoses could stretch the gastrocnemius more than barefoot
walking for some individuals; however, there was significant variability between
participants and orthoses. At least one type of orthosis stretched the
gastrocnemius during walking for 4/6 and 3/5 of the Gross Motor Functional
Classification System Level I and III participants, respectively. AFOs also
reduced peak gastrocnemius lengthening velocity compared to barefoot walking for
some participants, with greater reductions among the Gross Motor Functional
Classification System Level III participants. Changes in gastrocnemius operating
length and lengthening velocity were related to changes in ankle and knee
kinematics during gait. CONCLUSION: Ankle foot orthoses impact gastrocnemius
operating length during walking and, with proper design, may assist with
stretching tight muscles in daily life. Clinical relevance Determining whether
ankle foot orthoses stretch tight muscles can inform future orthotic design and
potentially provide a platform for integrating therapy into daily life. However,
stretching tight muscles must be balanced with other goals of orthoses such as
improving gait and preventing bone deformities.

Langue : ANGLAIS