[From Marey to modern gait analysis. Advances in orthopedic surgery of motor disability]

Marey broke movement down into a series of stills. We still use this approach but technical advances, especially in computing, allow us to record cinematics, kinetics and electrical muscular activity simultaneously. We now have a better understanding of gait disorders in children with motor disabilities, challenging previous surgical indications and leading to the concept of single-procedure "multisite" surgery with spectacular improvements in outcome.