Inclusion Criteria:

• UPenn (Steinberg) classification of osteonecrosis, inclusive of Stages IIB and IIC. Diagnosis will be based on magnetic resonance imaging (MRI).
• Modified index of necrotic extent < 40
• Idiopathic and non-idiopathic osteonecrosis.
• No infection in affected bones at the time of surgery.
• Patient competent to give informed consent.

• Normal organ and marrow function defined as:

  • Leukocytes ≥ 3000/µL;
  • Absolute neutrophil count ≥ 1500/µL;
  • Platelets ≥ 140,000/µL;
  • Serum AST (SGOT)/ALT (SGPT) < 2.5 X institutional standard range;
  • Serum creatinine within normal limits, based on clinical laboratory normal range.
• Female patients not pregnant or lactating.
• Patients with a history of corticosteroids or on active therapy, will only be eligible for enrollment if corticosteroid use is suspended for 1 month prior and 6 months after cell therapy and surgery.
• Patients who have been treated with oral bisphosphonates are eligible for the trial if treatment was stopped at least 6 months prior to enrollment.

Exclusion Criteria:

• Stages IA, IB, IC, IIA, IIIA or more severe femoral head osteonecrosis, primarily based on diagnosis by MRI.
• Flattening of the femur head (UPenn Stage IV) or articular cartilage collapse at the time of core decompression surgery.
• Septic arthritis; stress fracture, or non-osteonecrosis metabolic bone diseases (e.g., Paget's disease of bone, osteogenesis imperfecta, primary hyperparathyroidism, fibrous dysplasia [monostotic, polyostotic McCune-Albright syndrome] and osteopetrosis).
• Any active bisphosphonate treatment or any history of intravenous (IV) treatment
• HIV, syphilis, positive at time of screening.
• Active hepatitis B or hepatitis C infection at the time of screening
• Known allergies to protein products (horse or bovine serum, or porcine trypsin).
• Patients who will require continuous, systemic, high dose corticosteroid therapy (more than 7.5 mg/day) within 6 months after surgery.
• Patients in active treatment for cancer or blood dyscrasia, or have received chemotherapy, radiotherapy or immunotherapy in the past 2 years.
• Immunodeficiency diseases.
• Participation in another clinical study in the past 30 days or concurrent participation in another clinical trial.
• History of regular alcohol consumption exceeding 2 drinks/day (1 drink = 5 oz [150 mL] of wine or 12 oz [360 mL] of beer or 1.5 oz [45 mL] of hard liquor) within 6 months of screening and/or history of illicit drug use.
• MRI-incompatible internal devices (pacemakers, aneurysm clips, etc)
• Body mass index (BMI) of 40 Kg/m2 or greater
• Patients unable to tolerate general anesthesia defined as an American Society of Anesthesiologists (ASA) criteria of > 2
• Patients with poorly controlled diabetes mellitus (HbA1C > 8%), or with peripheral neuropathy, or known concomitant vascular problems.
• Patients receiving treatment with hematopoietic growth factors or anti-vasculogenesis or anti-angiogenesis treatment
• Traumatic osteonecrosis