1. AFF: Bone Density and Structure with BP Use Based on Poster FR0030 “Bone Density and Structure of Patients on Bisphosphonates with Atypical Femur Fractures” Angela Cheung, Jonathan Adachi, Robert Josse, Robert Bleakney, Christian Viellette, Aliya Khan, Moira Kapral, Sophie Jamal, Heather McDonald-Blumer, Earl Bogoch Friday, October 15, 2010 ASBMR 2010 Toronto, Ontario

2. Method A cross-sectional study of 16 patients (15 female, 1 male) referred to the University Health Network Osteoporosis (OP) Clinic for assessment of atypical femoral fractures (AFFs) Each patient was assessed by an OP physician and all radiographs were independently reviewed by a musculoskeletal radiologist as well as an OP expert Areal BMD by DXA was performed at the lumbar spine, total hip and femoral neck HR-pQCT was also carried out at the distal radius and tibia HR-pQCT=High-resolution peripheral quantitative computed tomography

3. Patient Characteristics Mean age was 67.2 years (range 46.4 to 88.1) Mean serum 25-(OH)-D close to the time of fracture was 93 nmol/L (within the range felt to be sufficient) Mean duration of bisphosphonate (BP) use was 7.5 years (range 2 to 10.6) Chinese n=6, Indian n=2, European Canadian n=8 11 patients had comorbid conditions or medications (rheumatoid arthritis, pemphigus, liver transplant, diabetes, cancer, steroid or warfarin use

4. Results Mean BMD T-score at the lumbar spine, total hip and femoral neck were -0.68, -0.48 and -0.90, respectively On HRpQCT scans, there was decreased cortical thickness Marked cortical porosity and a lack of trabecular structure with empty “holes” on many of the scans These bone defects were not at the site of the fracture but at the wrist and the ankle On biopsy, there was low bone turnover but it was not adynamic bone disease per se

5. HRpQCT Scans of Patients on BPs with AFFs

6. Conclusions Patients on BP with AFFs have poor bone quality and structure as measured by HRpQCT Results suggest that low bone turnover and increased mineralization may not be the only explanation for AFFs