[Musculoskeletal pathology in children with infantile cerebral palsy: a new classification system]

Cerebral palsy (CP) is one of the most common causes of physical disability in childhood. While the Gross Motor Function Classification System (GMFCS) describes motor abilities, a unified classification for musculoskeletal pathologies was lacking. The newly proposed four-stage system-based on the Mercer Rang model-describes the progression of lower limb pathology and supports diagnosis, treatment planning, and research. STAGE 1: Hypertonia: From birth to about 6 years, spasticity and delayed motor development predominate; contractures are rare. Early intervention and spasticity management (e.g., botulinum toxin) are the focus. STAGE 2: Contractures: Between the ages of 4 and 12 years, discrepancies between muscle-tendon length and bone growth cause a reduced range of motion. Surgical muscle or tendon lengthening may be indicated. STAGE 3: Bony deformities: Bony deformities such as increased femoral anteversion or pes valgus occur simultaneously with soft tissue contractures; rotational osteotomies and combined multilevel surgeries (SEMLS) are often required. STAGE 4: Decompensated pathology: After puberty, irreversible deformities and joint degeneration develop. Surgery usually aims at pain reduction or stabilization (e.g., arthrodesis).

This classification raises awareness of disease progression, helps select stage-appropriate treatments, and may prevent over- or undertreatment. Early recognition and intervention are crucial to avoid decompensation and improve long-term musculoskeletal and functional outcomes.