Inclusion Criteria:  Patient with a foot levator muscles impairment (single or bilateral drop foot) and / or instability of the back of the foot, associated with a deficit of the triceps Patient with inability to stand on tip-toe on one foot Patient having signed a free and informed consent Patient affiliated or entitled to a social security scheme  Exclusion Criteria:  Patient with fixed varus-equine foot Patient with an unstable skin condition (whether or not treated with additional treatment that may change the footwear) Patient with a a foot levator muscles impairment with a deficiency of the quadriceps and hamstrings (knee involvement) Patient with uncontrolled spasticity Patient for whom foot surgery is planned during the study Patient with one of the contraindications to the use of carbon medical device, indicated in the instructions for use Patient with one of the contraindications to the use of the standard plastic ankle foot orthosis, indicated in the instructions for use Patient with orthopedic comorbidities affecting the musculoskeletal system Pregnant woman Patient with major cognitive impairment incompatible with participation in a clinical trial Patient participating in another clinical investigation conducted to establish the compliance of a MD impacting the evaluation criteria Patient who cannot be followed for 12 weeks Vulnerable patient according to article L1121-6 of the public health code, persons subject to a measure of judicial protection or unable to consent freely