An extreme movement osteotomy device includes an attachment plate suitable for being locked to the cortical substance of the bone to be treated, having a first proximal portion suitable for being attached to the inner cortical substance of the metatarsal diaphysis of the bone, a distal portion suitable for being attached to the outer cortical substance, next to the epiphysis of the metatarsus, and a central portion connecting the proximal and distal portions, each one of the proximal and distal portions of the plate being provided with at least one hole and orthopedic screws to pass therethrough; and a proximal intramedullary support system having a shank with a foam tip extending from the end of the proximal portion of the plate.