Children with cerebral palsy (CP) present a variety of motor impairments and activity limitations. Plastic ankle-foot orthoses (pl-AFO) are frequently prescribed to improve their gait. However, their use limit forward propulsion generation, which explains why children tend to remove their pl-AFO during recreational activities,including running and jumping. While the benefits of physical activity are proven for these children, there is no data about pl-AFO impact across a range of locomotor activities. Biomechanically optimized dynamic carbon fiber AFOs (c-AFO) are now available and may improve propulsion features in comparison with usual pl-AFOs. The investigators aim to compare the AFO-specific effects (pl-AFO vs c-AFO) on propulsion (during walking, running and jumping), to explore the consequences on social participation, as well as to evaluate the effect on the hemiparetic CP child's perception and adherence of wearing each AFO. In this prospective, multicenter, randomized controlled trial with a crossover design, 38 hemiparetic CP children from 8 to 15 years old will be evaluated with their usual pl-AFO and with a c-AFO. The pragmatic clinical approach of this study is expected to provide data to guide and optimize AFO prescription and use, while enhancing understanding of these devices and their adaptation to the actual physical activity of CP children.

This study is a randomized controlled trial with a crossover design. A total of 38 patients will be recruited from three different centers.

Each participant will be randomly assigned to one of two groups (Group c/pl or Group pl/c). Depending on the group allocation, each subject will test both types of ankle-foot orthoses (AFOs) in a different order.

• Group c/pl: Participants in Group A will first use the carbon AFO (c-AFO) for four weeks. Evaluations will be conducted before and after this period. After a washout phase, they will then use the plastic AFO (pl-AFO) for another four weeks, with evaluations conducted before and after this second phase.
• Group pl/c: Participants in Group B will follow the same protocol, but in reverse order: starting with the pl-AFO for four weeks (with pre- and post-evaluations), followed by a washout period and then four weeks with the c-AFO (again with evaluations before and after).

Each evaluation includes:

• A quantitative gait analysis including ground reaction force measurements, kinematic data, and spatiotemporal parameters.
• Clinical tests to assess functional mobility and endurance.
• Questionnaires to evaluate participation levels, satisfaction, and acceptance of the AFOs.

Inclusion Criteria:

• Children from 8 to 15 years old
• Spastic, hemiparetic cerebral palsy
• Level I or II on the Gross Motor Function Classification System
• Ability to walk and run 10 meters without assistance
• Ability to jump (simultaneous lift of both feet)
• Daily use of a plastic ankle foot orthosis allowing ankle mobility
• Affiliated to a social security scheme

Exclusion Criteria:

• Children with ataxic, dyskinetic, or mixed-type cerebral palsy
• Children with cognitive, intellectual, or behavioral disorders that may impair their understanding of instructions, the proper conduct of evaluations, or the use of assessment scales, as judged by the investigator.
• Children who have received botulinum toxin injections within 4 months prior to the inclusion visit
• Children or adolescents who have undergone surgical intervention:

within the past 6 months prior to inclusion if no bony procedure was performed, or within the past 12 months prior to inclusion if a bony procedure was performed, or who have a planned surgical procedure during the study period.

• Children who have participated in an intensive rehabilitation program within 4 months prior to the inclusion visit
• Children or adolescents participating in another interventional study that could interfere with the outcomes of the present study by altering the subject's physical abilities.