Mesenchymal Stem Cells in Osteonecrosis of the Femoral Head

Inclusion Criteria: * 18 to 50 years of age (male and female) * Osteonecrosis of the hip ARCO grade I or II * Abscence of systemic or local infection * Laboratory tests with no relevant abnormal findings that contraindicate the surgery. * Informed Consent Form signed * The patient is able to understand the nature of the study Exclusion Criteria: * Osteonecrosis of the hip secondary to femoral neck fracture * Patients with no closed cartilage * Surgical implants in the femoral head * Septic arthritis * Patients with severe renal insufficiency * Patients expecting or with liver transplantation * Positive serology for HIV-1 or HIV-2, Hepatitis B (HBsAg), Hepatitis C (Anti-HCV-Ab) or Syphilis. * Pregnant woman or intended to become pregnant, or breath feeding * Neoplasia within the previous 5 years, or without remission * Immunosuppressive states * The patient is legally dependent * Participation in another clinical trial or treated with an investigational medicinal product the previous 30 days * Cardiac pacemaker, allergy to contrast or any other condition that contraindicates the MRI with contrast agents * Other pathologic conditions or circumstances that difficult participation in the study according to medical criteria * The patient does not accept to be followed-up for a period thar could exceed the clinical trial length