The potential of lower-limb exoskeletons and powered orthoses in gait assistance applications for patients with locomotive disorders would have a terrific impact in the society of the near future. This paper presents the development and main features of a lower limb exoskeleton being developed as an active orthosis to allow a quadriplegic child to walk. As the patient is not able to move any of her limbs, the device will produce her basic motions in everyday-life activities: stand up, sit down, and walk stably. Synergic biarticular actuation in the ankle, compliance controller based on the force measured by insoles at the feet and the definition of parameterized hip and foot trajectories that allow to choose the characteristics of gait are some of the new features included in this prototype. Experiments validate the improved performance of gait based on the proposed approach.