Pilot Study on the Validity, Tolerability, and Impact of a Walking Rehabilitation Intervention Using Cruro-Malleolar Cast in Children With Cerebral Palsy (RCMs)

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.