- OBJECTIVE: To examine changes in mobility longitudinally following single-event multilevel surgery in ambulant children with cerebral palsy, focusing on those using assistive devices for functional mobility because they are most at risk of declining gross motor function. PARTICIPANTS: A consecutive sample of 156 ambulant children with cerebral palsy (99 males), 96 without devices (Gross Motor Function Classification System (GMFCS) I/II), 60 with devices (GMFCS III) who had single-event multilevel surgery at mean age 11 years 1 month. METHODS: GMFCS and Functional Mobility Scale (FMS) ratings were recorded pre-operatively and at 2 and 5 years post-operatively. A proportional odds logistic regression model was used for the GMFCS III group to predict the probability of assistive device requirements post-operatively conditional on baseline FMS. RESULTS: Children in GMFCS III showed more change than those in I/II at home and school. Those in GMFCS III using crutches pre-operatively at home and school were more likely to continue using them at 5 years, whereas those using walkers were more likely to change to crutches or wheelchairs. Wheelchairs were most commonly used in the community before and after single-event multilevel surgery. CONCLUSION: Mobility was generally stable or improved at 5 years after single-event multilevel surgery; however, a small number of children used more assistance to facilitate mobility.