An 18 month old boy was referred to the local child development centre because he was not walking independently. He walked around by holding on to furniture; he had first crawled at age 11 months.

We wanted to use an evidence based approach to guide our assessment and management, so before seeing him, we considered three issues. Firstly, we wanted to know whether, in an 18 month old child referred to a community paediatrician because he cannot walk independently, the most likely outcome is cerebral palsy, a primary muscle disorder, another neurological abnormality, or simply delayed motor development. Secondly, we wanted to know how many children with Duchenne muscular dystrophy present with delayed walking at 18 months. Thirdly, we wanted to know whether a creatine kinase level is a worthwhile screening test if there are no abnormal signs.