This is called as malunion of the fracture i.e fracture union in wrong position. It is most common in upperlimb after fracture of humerus - cubitus varus or valgus. Since you haven't posted any details of fracture it's difficult to comment on the diagnosis but going by the limited information you have provided, the treatment lies in surgical correction of deformity by doing an osteotomy (Planned surgical fracture) and fixing it.