The invention relates to dry free-flowing filler (1) for forming a support structure in a bone cavity (4a). Said filler comprises a plurality of biocompatible support bodies (2) which are resistant to deformation or fracture under the physiological loads usually occurring in the bone cavity (4a). Said support bodies (2) have a size between 2 mm and 10 mm and an axis (A) and two opposite abutments (2g) spaced apart in the direction of the axis (A).