Autogenous bone grafting is widely used. In particular cancellous bone is osteoconductive, but the morbidity at donor sites is a reason to use bone substitutes.

In 5 years we have treated 64 patients affected by orthopaedic (arthrodesis of the ankle or the foot, THP revision) or traumatologic problems (acute fractures of tibial plateau, non-union or malconsolidation) with mineral bone substitutes (Pyrost or Osteoplantl). In a prospective clinical study, these substitutes were implanted as follows: the bone defect was filled by bone substitute (usually 5 ml)and we evaluated regeneration of bone defect by X-ray, MR and histological evaluation of osteogenic cells (at removal of osteosynthesis). In 85% of cases the regeneration of the bone defects was complete; in the other cases a partial or insufficient regeneration was found.

In different animal investigations Pyrost has been shown to have osteoconductive and osteostimulative effects: these substitutes have no antigenic propriety. In conditions of low osteogenetic potency, the combination of bone substitutes and autogenic bone marrow affects bone formation. In disadvantageous bone bed, bone substitutes must be augmented with bone marrow and in large segmental defects combination with autogenic bone grafts is recommended. A prerequisite for the application of bone substitutes in large defects is a sufficient primary stability of the bone bed. The application in infected tissue is not favourable.