A method that induces bone regeneration with minimal surgical intervention is needed  for those young patients. Hernigou et al. first hit on the idea of cell therapy for osteonecrosis of the femoral head. They added bone marrow aspirate concentrate to core decompression. A series of publications reported positive results  of bone marrow aspirate concentration implantation for treatment  of ostenecrosis of the femoral head. As mentioned previously, bone marrow aspirate concentration is a mixture of various mononuclear cells, of which a very small fraction (0,01%) comprises mesenchymal stem cells. Furthermore, the number of stem cells in the final preparation various among patients, and thus cannot be standardised. Following studies, using ex vivo expanded autologous mesenchymal stem cells, yielded similar success to bone marrow aspirate concentration.