The purpose of this study was to prospectively compare the effect of orthopedic surgery (OS) and selective dorsal rhizotomy (SDR) on muscle tone, range of motion, gait and energy efficiency in ambulatory children with spastic diplegia. Twenty-five children with a diagnosis of spastic diplegia, with a mean age of 73 months, were evaluated prior to surgery and 1 and 2 years postoperatively; however, only the preoperative and 2-year postoperative data are reported here. Eighteen children received SDR and seven received OS. Children were evaluated with the Ashworth scale for muscle tone, passive range of motion (PROM), gait analysis and oxygen consumption for energy cost. Significant improvements were seen in PROM, muscle tone, gait kinematics and oxygen cost regardless of surgical intervention. Although OS and SDR interventions influence motor function through different mechanisms, the gait and energy outcomes 2 years following OS or SDR are similar.