Abstract: A vertebroplastic cementitious composition includes a solid phase including Portland cement and a biocompatible additive which is a plasticizer and a hardening accelerant, wherein the amount of additive is between about 1% and about 15% by weight relative to the Portland cement; and an aqueous liquid phase, wherein the ratio of the solid phase to the liquid phase is between about 3 g/ml and about 6 g/ml. Methods of forming such compositions, treatment methods using such compositions and cementitious implants including such compositions are also described.