Atypical femur fractures (AFF) have been associated with antiresorptive therapy. In a retrospective case-control study, we identified AFF using ASBMR 2013 criteria. Femoral shaft fractures were identified using ICD9 codes. We screened 1479 radiographs. Radiographs were excluded for high-energy trauma, tumor, or periprosthetic fracture. Two radiologists blinded to treatment scored 482 radiographs for AFF features, and jointly adjudicated discrepancies. The required AFF feature, low-energy trauma fractures between the lesser trochanter and supracondylar flare, occurred in 98 patients. These 98 had additional major AFF feature prevalence of: 64% lateral or uncertain origin; 98% complete/incomplete lateral fracture; 71% minimally comminuted/noncomminuted; 49% periosteal/endosteal reaction. A total of 57 (58%) of the femoral shaft fractures met AFF criteria (16% of the 98 having four major features, and 42% having five major features). Initial radiologist score agreement for AFF was 93%. All 11 patients with bilateral femoral shaft fractures had AFF (ten with bilateral AFF).
Fifty-four AFF cases were race- and sex-matched to 108 controls having non-AFF femoral fractures. Clinical variables were similar between controls having non-AFF fractures in the femoral shaft (n=29) and those with non-shaft control fractures (n=79). Drug use was determined primarily from dispensing records and augmented by chart review. AFF were associated with bisphosphonates within 5 years, glucocorticoid use at fracture occurrence, prodromal pain and lower alkaline phosphatase. Age, cortical thickness, prior osteoporotic fracture, other medical conditions and proton pump inhibitors were not associated with AFF.
|Cases (N=54)||Controls (N=108)||OR (CI)||P-value|
|Age (S.D.) years||72.8 (11.0)||74.0 (16.5)||1.00 (0.971.02)||0.67|
|Prodromal pain||39%||5%||13.04 (3.8743.88)||<0.0001|
|Bisphosphonates in 5 years||57%||8%||13.69 (4.8138.99)||<0.0001|
|Oral glucocorticoids||17%||3%||6.00 (1.6222.16)||<0.01|
Over half of the low-energy trauma femoral shaft fractures met the ASBMR 2013 AFF criteria. Though strongly associated with bisphosphonates, additional risk factors should be considered for AFF.
14 May 2016 - 17 May 2016