A physical therapist treats a five-year-old child immediately before having a new lower leg cast applied. The child has had a new cast each week for the last four weeks. Which medical condition would MOST likely warrant this type of intervention?

• A. Down syndrome
• B. Cerebral palsy
• C. Wilson's disease
• D. Phenylketonuria

Answer: (B)

Serial casting is used to progressively lengthen a tight muscle-tendon unit and improve range of motion when there is a fixed or dynamic contracture, especially in spastic conditions. In cerebral palsy, calf muscles often develop a plantarflexion (ankle equinus) contracture that limits dorsiflexion and contributes to toe-walking. Applying a cast that keeps the ankle in more dorsiflexion and changing it weekly allows the tissues to be gradually stretched over several weeks, improving ankle ROM and gait without surgery.

The other conditions don’t typically require this serial casting approach. Down syndrome may involve hypotonia and ligamentous laxity but not the pattern of progressive spastic contractures treated with weekly casts. Wilson’s disease and phenylketonuria are metabolic disorders with treatments not centered on serial casting for limb contractures.