Linda Probyn MD, Presenter: Nothing to Disclose

Angela Cheung, Abstract Co-Author: Speaker, Amgen Inc Speaker, Eli Lilly and Company Institutional Grant support, Amgen Inc Institutional Grant support, Eli Lilly and Company

Jonathan D. Adachi MD, Abstract Co-Author: Consultant, Actavis, Inc Consultant, Amgen Inc Consultant, Eli Lilly and Company Consultant, Merck & Co, Inc Consultant, Novartis AG Speaker, Actavis, Inc Speaker, Amgen Inc Speaker, Eli Lilly and Company Speaker, Merck & Co, Inc Speaker, Novartis AG Research Grant, Amgen Inc Research Grant, Eli Lilly and Company Research Grant, Merck & Co, Inc Research Grant, Novartis AG

Leon Lenchik MD, Abstract Co-Author: Nothing to Disclose

Aliya Khan MD, Abstract Co-Author: Consultant, Merck & Co, Inc Consultant, Amgen Inc Consultant, Eli Lilly and Company Consultant, Actavis, Inc Speaker, Merck & Co, Inc Speaker, Amgen Inc Speaker, Eli Lilly and Company Speaker, Actavis, Inc Research Grant, Merck & Co, Inc Research Grant, Amgen Inc Research Grant, NPS Pharmaceuticals

Robert Josse MD, Abstract Co-Author: Consultant, Actavis, Inc Consultant, Amgen Inc Consultant, Eli Lilly and Company Consultant, Merck & Co, Inc Consultant, Novartis AG Speaker, Actavis, Inc Speaker, Amgen Inc Speaker, Eli Lilly and Company Speaker, Merck & Co, Inc Speaker, Novartis AG Researcher, Amgen Inc Researcher, Eli Lilly and Company Researcher, Merck & Co, Inc Researcher, Novartis AG

Catherine Lang, Abstract Co-Author: Nothing to Disclose

Robert Bleakney MBBCh, FRCPC, Abstract Co-Author: Nothing to Disclose

Atypical Femoral Fractures (AFFs) are commonly bilateral. The purpose of this study is to evaluate bilateral AFFs and to determine if the imaging features of both fractures are similar.

Imaging studies of 76 patients with bilateral AFFs were retrospectively reviewed (3 male, 73 female, age range 31.1 to 91 years, mean age 67.3 years). The time interval between fracture diagnoses was determined. For each fracture, the following imaging features were evaluated: location of fracture, femoral angle, length of cortical thickening, comminution, medial spike (proximal or distal fragment), and fracture orientation (superior or inferior). Associations between imaging findings on pairs of bilateral fractures were assessed with Spearman’s correlation (rs) and the Kappa (κ) statistic.

Bilateral fractures (62 incomplete and 14 complete) occurred within 12 months of each other in 59/76 cases (77.6%). Average time between fracture diagnoses was 10.2 months. 90% of bilateral fractures occurred within 2.9 years of each other (range 0 to 120 months). There was a strong correlation between fracture location (rs=0.68) with 58/76 cases (76.3%) of bilateral fractures occuring within a distance of less than 5 cm. 41/76 cases (53.9%) had a distance of less than 2.5 cm between bilateral fractures. There was moderate correlation between femoral angles (rs=0.4) and weak correlation between length of cortical thickening (rs=0.28). There was substantial agreement for medial spike location (κ=0.67) and fracture orientation (κ=0.62), and moderate agreement for lack of comminution (κ=0.42). These findings were independent of the time between fractures.

Patients with unilateral AFFs are likely to be diagnosed with a contralateral AFF within the first year of presentation. Bilateral fractures are likely to have similar imaging findings and location along the femur, regardless of the time interval between fractures.

After diagnosing a unilateral AFF, surveillance of the contralateral femur is essential. Most contralateral fractures are similar in appearance and location to the index fracture.

Probyn, L, Cheung, A, Adachi, J, Lenchik, L, Khan, A, Josse, R, Lang, C, Bleakney, R, Bilateral Atypical Femoral Fractures: How Much Symmetry Is there on Imaging?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14014442.html