The purpose of this study is to assess the clinical and x-ray results of patients who are treated with core decompression of the hip and the injection of a bone marrow concentrate and the use of the Bone Graft Substitute Genex®.

Avascular necrosis (AVN) or osteonecrosis (ON) of the femoral head refers to a condition in bone metabolism when cells of the trabecular bone (porous bone found at the end of long bones like the femur) in the hip spontaneously die. Depending on the amount of femoral head involvement, parts of the surface, like the articular surface that do not have blood vessels may collapse as the disease advances. Although the exact common occurrence of AVN or ON is unknown, the incidence is estimated to be between 20,000 to 30,000 newly diagnosed patients each year in the US.

Core decompression of the hip is a minimally invasive surgical technique performed to manage symptoms in early stages (precollapse) of the condition. The procedure involves drilling holes into the femoral head to relieve pressure and create channels for new blood vessels to nourish the affected areas. Multiple adjuncts to core decompression, such as structural bone grafts, bone marrow concentrates, and bone proteins have been developed to accelerate the healing process in these patients. In recent years, considerable research activity has also been expanded to find new bone substitutes with osteoconductive properties (where bone grows on a surface) for the use in the treatment of surgically created defects.

Genex® Bone Graft Substitute is a catalyst for bone healing. It complements the body's natural healing processes and encourages normal bone structure to be restored at a steady rate. Over 12 months, the graft matrix is completely absorbed and replaced by bone. No foreign artifacts are left behind to impair structural integrity.

Inclusion Criteria:

• Subject is at least 18 years or older with osteonecrosis of the femoral head
• Surgeon considers the patient appropriate for the core decompression procedure of the hip
• Subject provides voluntarily signature on the IRB approved Informed Consent Form
• Subject must be physically and mentally willing and able, in the Investigator's opinion at the time of enrollment, to be compliant with the protocol and complete the study protocol and follow ups

Exclusion Criteria:

• Subject is pregnant at the time of surgery
• Subject is incarcerated
• Subject is not comfortable with speaking, reading and understanding questions and providing responses in an available language for the questionnaires provided for the study

Patients who are 18 years or older with early osteonecrosis of the femoral head and meet the inclusion and exclusion criteria based on the protocol.