The invention relates to an orthopaedic positioning device especially for a wheelchair, comprising different wedges, especially pelvic wedges (1,2), adduction wedges (3,4), and abduction wedges (5), which are stackable and positioned in pre-defined areas on a seat or base (6), the assembly being positioned on a securing plate (7) that can be adjusted from the front to the rear, characterised in that said stackable elements allow good stability and a better distribution of pressure where the persons rear meets the seat.
