Fig. 1

Radiological findings of atypical femoral fracture. a X-ray images of Case 1. White arrow shows atypical femoral stress reaction (AFSR) on the right femur. X-ray of the left femur at the time of the AFF event and after intramedullary nail surgery. b X-ray images of Case 2. White arrow shows AFSR in the left femur. c X-ray and PET/CT images of Case 3. The upper images show bilateral AFSR and the middle image shows no metastasis in either femur. The lower images are x-rays obtained after prophylactic intramedullary nail fixation surgery. d X-ray images of Case 4. The upper images show left AFF and right AFSR. The lower images are X-rays after intramedullary nail fixation surgery on both sides. e X-ray, MRI and PET/CT images of Case 5. The upper left image is an x-ray showing left AFSR and upper right image is an MR image of the same region. The lower left image is a PET/CT image showing no evidence of malignancy and the lower right image is hematoxylin and eosin staining of fracture tissue from Case 5 (× 400). The section shows fragmented bone tissue, fibrous tissue, calcification, and a little bone marrow tissue