A 16-year-old female patient suffering from left hip pain and limping for 6 months was diagnosed with avascular necrosis of the left hip. An x-ray revealed left femoral head avascular necrosis (AVN) with cystic formation. A magnetic resonance image (MRI) showed femoral head collapse. Stage ⅢI AVN was the diagnosis. After admission, core decompression combined with a bone graft (Allomatrix) was performed under fluoroscopy. The postoperative care of this patient included restricted weight bearing and use of crutches for 3 months. She received monthly outpatient department follow-up. Her daily activities and ambulation were almost back to normal after 6 months. An x-ray revealed new bone formation over the superior region of the femoral head at 6 months of follow-up. An MRI showed less edema, increased vascularity throughout the previously necrotic region, and no further subchondral bone collapse.