BoneKEy Reports | BoneKEy Watch
DXA plus measurement of bone strength predict fracture risk more accurately
DOI:10.1038/bonekey.2013.39
Several QCT-based Finite Element (FE) models of the proximal femur have been developed, validated and used for predicting hip fracture and monitoring drug treatment of osteoporosis. This study assessed 728 elderly women using dual-energy X-ray absorptiometry (DXA) in conjunction with determination of bone strength using FE analysis.
The 182 women who suffered a subsequent hip fracture had a significantly higher load-to-strength ratio compared to controls, with significantly lower femoral strength and bone mineral density (BMD) at the hip or femoral neck (FN). Even after adjusting for FN BMD, the odds ratio was significantly greater than 1: 1.7 (confidence interval (CI)1.2–2.4) for femoral strength and 1.4 (CI 1.1–1.7) for load-to-strength ratio.
Using a DXA-based FE model may therefore allow more accurate identification of elderly patients with a high risk of hip fracture who should be offered therapy to reduce their risk.
Editor’s comment: The FE model was validated on 56 cadaveric femoral specimens subjected to breaking that simulated a fall. Although the results showed that FE strength was moderately correlated to the experimental strength, this and other DXA-based models are restricted by the inherent limitations of DXA scans, which allow a 2-dimensional approach only. As the femur was modeled with constant thickness and uniform volumetric density in the anteroposterior direction, and the cortical bone’s material properties were not modeled separately, loading conditions were simulated in a sideways fall only.
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