Fig. 2

A 24 year-old female patient (case 31): a-c Preoperative radiographs showed bilateral NONFH with right ARCO IIIa stage and left ARCO IIc stage. d-f Postoperative imaging at 1 week exhibited adequate filling of the osteonecrotic lesion by the beta-tricalcium phosphate (β-TCP). g-i At 8 weeks, the right head presented advanced collapse, and the β-TCP were gradually absorbed. Also, heterotopic ossification was observed in right side. j-l At 20 weeks, the right femoral head collapsed more than 4 mm and the contralateral collapsed less than 2 mm. In the meantime, the sparse remnants of grafting materials were almost entirely degraded