There really is no set limit for age/weight on children with spina bifida in my experience. As children age, it does become a bit more challenging to properly place them in standing frames, especially if the frames do not assume a supine position. It is much easier to place children in frames when flat versus at an angle because gravity just makes a mess of things and you need more than one person to place the child in the frame. The older and larger they are and the higher the level of the lesion, the more you may find a need for extra bracing of the legs prior to standing to assist with proper alignment. Please don't let age/weight discourage attempts at standing; these kids need to be upright for a number of reasons: weight bearing through long bones for strengthening; digestion/elimination; respiratory/circulatory and maybe more importantly, socialization with their peers. Hope this helps.