Atypical Femoral Fractures: A Teaching Perspective Aliya A. Khan, MD, FRCPC, FACP, FACE, William D. Leslie, MD, MSc, FRCPC, Brian Lentle, MD, FRCPC, Sian Iles, MD, FRCPC, Stephanie M. Kaiser, MD, FRCPC, Heather Frame, MD, FCPC, Steven Burrell, MD, FRCPC, Angela M. Cheung, MD, FRCPC, PhD  Canadian Association of Radiologists Journal  Volume 66, Issue 2, Pages 102-107 (May 2015) DOI: 10.1016/j.carj.2014.01.002 Copyright © 2015 Canadian Association of Radiologists Terms and Conditions

Figure 1 A 75-year-old woman with rheumatoid arthritis and remote total knee replacement underwent a radiograph (A) for “knee” pain, which revealed thickening of the lateral cortex of the distal shaft of the femur (arrowhead). The pain persisted, and a technetium 99m–methylene diphosphonate bone scan was obtained 2 months later to exclude prosthesis loosening and revealed hyperemia (arrowhead) on the pool phase image (B) and intense uptake (arrowhead) on the bone phase image (C) in the lateral femoral cortex, which correlates with the finding on the radiograph. Mild uptake around the prosthesis is not in keeping with loosening. This was reported as suspicious for an atypical femoral fracture in this patient who had been on a bisphosphonate for >4 years. One week later, she completed the fracture (D). Canadian Association of Radiologists Journal 2015 66, 102-107DOI: (10.1016/j.carj.2014.01.002) Copyright © 2015 Canadian Association of Radiologists Terms and Conditions

Figure 2 A 68-year-old woman on bisphosphonates for many years developed right thigh pain, and a radiograph (A) was ordered to rule out an atypical femoral fracture (AFF); this revealed focal lateral cortical thickening (arrowhead), in keeping with an AFF. As a result, a contralateral radiograph (B) and a bone scan (C) were requested, which confirmed bilateral AFFs (arrowheads). A computed tomography scan was then obtained for further characterization (D, coronal; E, axial of the right leg; F, axial of the left leg), which demonstrated bilateral small focal areas of cortical thickening, with beaking of the lateral cortex (arrowheads). Canadian Association of Radiologists Journal 2015 66, 102-107DOI: (10.1016/j.carj.2014.01.002) Copyright © 2015 Canadian Association of Radiologists Terms and Conditions

Figure 3 A 76-year-old woman with osteoporosis had been on various bisphosphonates for many years. Back and left hip pain prompted radiographs (A), showing an ill-defined lucency and minimal cortical thickening in the lateral left subtrochanteric femur (arrowhead). Bone scan planar (B) and single-photon emission computed tomography/computed tomography (SPECT/CT) (C, coronal and axial slices from SPECT [upper] and CT [lower]), 4 months later showed intense uptake at the site in the left femur (arrowheads) but also moderate uptake in the same location in the right femur (arrows), in keeping with bilateral atypical femoral fractures. This diagnosis led, 6 weeks later, to prophylactic bilateral intramedullary nail fixation (D) to prevent completion of the fractures. Canadian Association of Radiologists Journal 2015 66, 102-107DOI: (10.1016/j.carj.2014.01.002) Copyright © 2015 Canadian Association of Radiologists Terms and Conditions

Figure 4 A 58-year-old woman was on bisphosphonates for 10 years because of increased fracture risk, which resulted from long-term steroid use for rheumatoid arthritis. She underwent a bone scan (A) because of left foot pain, which revealed a focus of uptake in the lateral cortex of the right femur (arrowhead). This led to a radiograph (B) and computed tomography (C), which demonstrated mild cortical thickening (arrowheads) and a subtle horizontal lucency (arrows), in keeping with an atypical femoral fracture (AFF). In response to minor trauma 2 years later, she completed the fracture (D). One year later, she underwent a bone scan (E) because she had developed left thigh pain. In addition to intense uptake at the fracture site in the right femur (which had been internally fixated), there now was a focus in the lateral cortex of the left femur (arrowhead), in keeping with an AFF. She proceeded to prophylactic intramedullary nail placement on the left. A subsequent radiograph (F) also demonstrates the AFF (arrowhead). Canadian Association of Radiologists Journal 2015 66, 102-107DOI: (10.1016/j.carj.2014.01.002) Copyright © 2015 Canadian Association of Radiologists Terms and Conditions