The present invention provides an improved orthopaedic system for the modification of the distance between the contralateral maxillary segments or halves. In a preferred embodiment, the system includes two metal bone plates fixed on the bony palatal shelves, with slotted extensions which opposite internal walls have concave indents into which disk-shaped wings of interchangeable distraction modules fit. The in the palatal plane concave female indent and the convex male wing prevent distraction module dislocation in case of oblique placement in the axial plane. In the frontal plane, the male wings are straight. The extension on the abutment plate has a slit like opening at the caudal side, to be fitted by a suture or a wire of any kind material, passing also in an opening in the male wing of the distraction module, to allow for assembling the units before fixation in the bony palatal shelve. The abutment plate is made partly malleable for an improved accommodation to the local alveolar bony anatomy. The opposing ends of the abutment plate have a shape allowing the anterior side to slip under the mucoperiosteum similar to a dissecting instrument, and the posterior end rounded and blunt in a way to protect the palatal arterioles. The abutment plates are provided by a slotted hole or slotted holes to accommodate the osteosynthesis screws or tacks in a preferred position related to the adjacent dental roots.