Systems for reducing a fracture in a bone, comprising a bone plate and a polyaxial fastener. In some examples the head of the polyaxial fastener has a deformable portion. As a fastener is inserted into an opening of a bone plate, threads located within the opening deform the deformable portion to secure the fastener in place at a desired angle within the opening. The head of the fastener also includes a bottom portion that bears against a portion of the opening to move the bone plate relative to the underlying tissue. A securing member or other structure may be included at the interface of the head and the deformable portion to secure the deformable portion to the head. At least one flute may be included on the deformable portion that provides a lead-in for the threads within the opening to cut into the deformable portion.