Eleven patients with spastic cerebral palsy were evaluated preoperatively, and 3 and 9 months postoperatively after soft tissue surgery. Evaluation included clinical examination, the Functional Mobility Scale questionnaire, and instrumented gait and center of mass trajectory analysis. A decrease in time–distance parameters after 3 months was followed by progress in all parameters at 9 months postoperatively. Push-off range of ankle motion decreased after surgery and was not restored to preoperative level until 9 months later. The center of mass vertical displacement improved significantly. The Functional Mobility Scale showed gait improvement. Despite the normalization of range of motion after surgery, there is an obvious period of functional gait deterioration in the early postoperative period and the push-off range of motion at the ankle did not recover to preoperative level until 9 months later.