Identifying Incomplete Atypical Femoral Fractures With Single-Energy Absorptiometry: Declining Prevalence.

BACKGROUND: Atypical femur fractures (AFFs) are associated with long-term bisphosphonate (BP) therapy. Early identification of AFF prior to their completion provides an opportunity to intervene, potentially reducing morbidity associated with these fractures. Single-energy X-ray absorptiometry (SE) is an imaging method recently shown to detect incomplete AFF (iAFF) prior to fracture completion. METHODS: Between May 2013 and September 2014, we assessed 173 patients who had been prescribed BP therapy for >5 years for iAFF using SE at their presentation for routine bone mineral density testing. We compared these findings with those of our previously published prospective study (n = 257) in which the femur was imaged for iAFF using dual-energy X-ray absorptiometry. In addition, we estimated the yearly prevalence of complete AFF among patients with subtrochanteric fracture at our institution from 2006 to 2014, and we evaluated prescribing trends for BP in Ireland from 2009 to 2014. RESULTS: No patients had iAFF using SE femur compared with a prevalence of 2.7% in the earlier study. Between 2006 and 2014, we observed a rise and decline in AFFs at our hospital and a similar national trend in BP prescribing. CONCLUSIONS: AFFs appear to be decreasing. New customized scan modes of dual-energy X-ray absorptiometry systems, which visualize the entire femur at high image quality and take measurements, have the potential to identify iAFF prior to fracture completion and to ascertain those at highest risk of AFF.

Should Dual-Energy X-ray Absorptiometry Technologists Estimate Dietary Calcium Intake at the Time of DXA?

Adequate calcium intake is essential for bone health. Calcium is obtained from dietary sources and supplementation. Knowing the daily dietary calcium intake is helpful in deciding on the need for supplementation. Dietary calcium intake can be estimated quickly and accurately using an approach recommended by the National Osteoporosis Foundation. We sought to evaluate the usefulness of estimating dietary calcium intake by a technologist at the time of attendance for dual-energy X-ray absorptiometry (DXA) scanning. We conducted a retrospective survey of results on estimated dietary calcium intake in adults attending our DXA unit over 2 years (n=5569). We assessed intake with reference to the specifications of the Institute of Medicine according to sex and age. The average intake was 736 mg daily: Young adults had higher intakes than older adults (p<0.001), and men had higher intakes than women (p=0.017). According to Institute of Medicine's specification, we estimate that nearly 45% of Irish women need supplemental intake of 500 mg daily but <4% need supplemental intake of 1000 mg daily. Younger adults are apt to have intakes within, or higher than, the requirement. Having DXA technologists estimate dietary calcium intake at the time of DXA scanning may provide helpful information to the referring clinicians about the need for supplementation.

Incomplete atypical femoral fractures: assessing the diagnostic utility of DXA by extending femur length.

Atypical femoral fractures (AFFs) are associated with prolonged bisphosphonate therapy. A feature of incomplete AFF is a localized periosteal reaction. It has been suggested that extending the length of the femur image at the time of dual-energy X-ray absorptiometry (DXA) may diagnose an incomplete AFF. In patients older than 50 yr on bisphosphonate therapy for more than 5 yr, we extended femur length at the time of routine DXA. Abnormal DXA images were suggested in 19 of 257 patients (7.4%). On X-ray, 7 patients (2.7%) showed no abnormality, 7 patients (2.7%) showed evidence of AFF, and 5 patients (2.0%) showed an unrelated radiographic abnormality. Of the 7 cases with X-ray evidence of AFF, 5 had a periosteal flare and 2 had a visible fracture line, both of whom needed insertion of an intramedullary nail. We demonstrated that it is feasible to detect incomplete AFF early using extended femur length imaging with a prevalence in our sample of 2.7% (95% confidence interval: 1.7%-3.7%).