This pilot study investigates whether walking training using cruro-malleolar casts (CMCs) - rigid leg splints extending from the thigh to the ankle - can safely improve gait quality in children with bilateral cerebral palsy (CP). CMCs are already used in routine clinical care at our center, but their biomechanical effects and therapeutic value have never been formally studied.Children aged 7 to 14 with bilateral spastic CP (diplegia or quadriplegia, GMFCS levels I-III) will participate in a 4-week treadmill walking program wearing CMCs, preceded by a 1-month observation baseline and followed by a 6-month follow-up. The investigators will use motion capture technology and surface electromyography to measure how the CMCs immediately change the way children walk - particularly at the hip and pelvis - and whether the training program leads to lasting improvements in walking speed, quality, and endurance.The study also carefully monitors pain and effort perceived by children during each training session, so that tolerance of the intervention can be rigorously assessed. Six participants will be enrolled. The study uses a Single-Case Experimental Design (SCED), which allows rigorous conclusions to be drawn from a small number of patients through repeated measurements over time.
Background and rationale Cerebral palsy is the most common cause of motor disability in children. Among its clinical forms, spastic diplegia is characterized by predominant lower limb involvement and progressive gait deterioration during growth, driven by musculotendinous contractures and secondary orthopedic complications. From Rodda and Graham's gait classification Group II ("jump gait") onward, hamstring overactivity plays a central role - contributing to excessive knee flexion and limited hip extension in late stance. Interventions targeting active hamstring stretching in a controlled gait pattern may therefore have significant clinical value. Cruro-malleolar casts (CMCs) are knee-extension orthoses molded over the child's walking ankle-foot orthosis. In current clinical practice at our center, they are used both for passive stretching postures and as a gait rehabilitation tool. The hypothesized mechanisms during CMC-assisted walking include: active hamstring stretch at initial contact; increased hip extensor (gluteus maximus) activation during loading response and mid-stance; improved pelvic belt mobility and trunk extension in the frontal plane; increased eccentric hip flexor activity and posterior step in late stance - effects that are expected to be amplified when training is performed on a treadmill. Despite their use in clinical practice, no published study has evaluated the biomechanical, muscular, or functional effects of CMCs during walking training. Study design This study uses a nested Single-Case Experimental Design (SCED), combining an A-B-Follow-up series with an Alternating Treatments Design (ATD) embedded within Phase B. Phase A (Baseline, 1 month): Three repeated measurement sessions (every 15 days), with no intervention. Establishes each participant's individual baseline trajectory. Phase B (Intervention, 1 month): Four weekly measurement sessions. Participants perform 4 sessions per week of treadmill walking training with CMCs (20 minutes per session, with verbal and/or manual guidance from a physiotherapist, and music chosen by the child to support motivation). At each of the 4 measurement time points within Phase B, participants are assessed in 4 randomized conditions: walking on ground with ankle-foot orthoses (AFO) alone; walking on ground with AFO + CMCs; walking on the instrumented treadmill (DIG) with AFO alone; walking on DIG with AFO + CMCs. Randomization of condition order is restricted by practical and safety constraints (ground assessments must precede treadmill assessments; treadmill speed is capped at ground walking speed). Phase FU (Follow-up, 6 months): Three measurement sessions at 1, 3, and 6 months post-intervention. The per-patient protocol lasts 8 months. Inclusion will span 30 months, for a total study duration of 3 years, starting from CPP approval.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
6
Cruro-malleolar casts (CMCs) are rigid bivalved knee-extension orthoses molded over the child's existing functional ankle-foot orthosis. Fabricated by a nurse-plaster technician and physiotherapist, they include protective padding, corrective felt inserts promoting knee extension, and supra-condylar fixation hooks. Windows are cut in the CMCs to allow surface EMG electrode and reflective marker placement during gait analysis. CMCs are worn during treadmill walking training (16 sessions over 4 weeks, 4 sessions/week, 20 minutes/session) on an instrumented treadmill (DIG system) with physiotherapist guidance. They are also worn during ground and treadmill gait analysis sessions. CMC walking is compared to walking with ankle-foot orthoses alone, both on ground and on the instrumented treadmill, within each participant across repeated assessment sessions.
Hip and Lumbopelvic 3D Kinematics during CMC-assisted Walking
Three-dimensional kinematic curves of the hip and lumbopelvic complex recorded by motion capture (Qualisys optoelectronic system, IOR Full Body Gait Model) during walking with and without CMCs, on ground and on treadmill (DIG). Mean joint angles are extracted at key gait cycle events (initial contact, loading response \~10%, mid-stance, terminal stance, peak swing \~70%).
Time frame: Assessed at each of the 4 weekly measurement sessions during Phase B (weeks 5, 6, 7, and 8 from study start).
Surface EMG Muscle Activation Timing
Activation timing (onset and offset, expressed as % of gait cycle) of hamstrings (semitendinosus), rectus femoris, vastus lateralis, and gluteus maximus, recorded by surface EMG (Cometa Pico) during walking with and without CMCs, on ground and on treadmill.
Time frame: Assessed at each of the 4 weekly measurement sessions during Phase B (weeks 5-8).
Walking Speed
Walking speed is defined as the velocity at which an individual walks, recorded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention).
Pain Perception during CMC Training
Child-reported pain perception related to CMC wearing, measured by the Faces Visual Analogue Scale (0-10, 0 = no pain, 10 = unbearable pain) after each training session.
Time frame: Recorded after each of the 16 training sessions during Phase B (weeks 5-8).
Hip Extensor and Flexor Muscle Strength
Isometric strength of hip extensor and flexor muscles measured by dynamometry, and active hip extension range of motion, assessed in prone position at the edge of the table.
Time frame: Assessed at all 10 measurement time points across Phase A (weeks 1-4), Phase B (weeks 5-8), and Phase FU (1, 3, and 6 months post-intervention).
Gait Quality - 3D Kinematic and Kinetic Curves without CMCs
Full lower limb 3D kinematic curves and joint moments/powers (hip, knee, ankle) recorded without CMCs, on ground and on treadmill., used to assess changes in overall gait pattern over time including sagittal plane locomotor profile, anterior knee vector positioning, and trunk/pelvic alignment.
Time frame: Assessed at all 10 measurement time points across Phase A (weeks 1-4), Phase B (weeks 5-8), and Phase FU (1, 3, and 6 months post-intervention).
Walking Endurance - 6-Minute Walk Test (6MWT)
Distance covered in 6 minutes (meters) on a 30-meter indoor corridor with standardized instructions and encouragements, performed with the participant's habitual walking aids and orthoses. A validated functional walking capacity test widely used in pediatric cerebral palsy populations.
Time frame: Assessed at all 10 measurement time points across Phase A (weeks 1-4), Phase B (weeks 5-8), and Phase FU (1, 3, and 6 months post-intervention).
Cadence
Cadence is a measure of speed calculated as the total number of full cycles (of both a right and left foot strike) taken within a given period of time, often expressed in steps per minute or cycles per minute recorded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention)
Step Length
Step length is the distance between the point of initial contact of one foot and the point of initial contact of the opposite foot. Recorded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention)
Stride Length
Stride length is defined as the distance between two points where the same foot strikes the ground sequentially, encompassing the sum of left and right step lengths. Recorded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention)
Step Width
The mediolateral space between the two feet (the difference between right and left heels during gait). Recorded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention)
Single Support Duration
The period of time when only one foot is in contact with the ground recoreded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention)
Double Support Time
The period of time when both feet are in contact with the ground recorded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention)
Stance ratio
The ratio between the entire gait cycle and stance phase recoreded with and without CMCs, on ground and on treadmill.
Time frame: Assessed at all 10 measurement time points: 3 baseline sessions (Phase A, weeks 1-4), 4 intervention sessions (Phase B, weeks 5-8), and 3 follow-up sessions (1, 3, and 6 months post-intervention)
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