The advantages of tomosynthesis for evaluating bisphosphonate-related atypical femur fractures compared to radiography

Abstract

Objective: To investigate the advantages of using tomosynthesis (TS) compared to radiographs in the detection, characterization, and follow-up of bisphosphonate-related atypical femur fractures (BP-AFF).

Subjects and methods: Eight patients were identified retrospectively who underwent TS for radiographic findings suspicious for BP-AFF. Two radiologists independently interpreted 15 radiographs and 16 TS examinations, indicating the presence or absence of the following: (1) cortical "beaking" on radiographs, (2) radiolucent fracture line on radiographs, and (3) fracture lucency on TS corresponding to the site of radiographic abnormality. Radiation dose data were calculated for radiographs and TS using Monte Carlo analysis.

Results: There was agreement on 100 % of radiographs regarding the presence or absence of a cortical beak. Regarding the presence or absence of a fracture lucency, there was agreement on 100 % of TS examinations (Kappa = 1.0) and 73 % of radiographs (Kappa = 0.40 ± 0.24). For the 46 % of radiographs in which one or both radiologists did not visualize a fracture line, there was 100 % agreement for the presence of a fracture line on the corresponding TS. The interobserver agreement for fracture line detection was significantly higher for TS than for radiographs (p = 0.012). The effective radiation dose using TS was approximately 96 % lower compared to radiography.

Conclusion: TS outperformed radiographs in the detection and characterization of BP-AFF. TS may also have advantages over radiography for BP-AFF follow-up through its unique ability to visualize fracture healing with lower effective radiation doses to the patient.

Keywords: Atypical femur fracture; Bisphosphonate therapy; Cortical stress reaction; Insufficiency fracture; Osteoporosis; Subtrochanteric fracture; Teriparatide; Tomosynthesis.