Differences in femoral neck and trochanteric structure in elderly women prior to hip fracture: Role in hip fracture prediction.

We examine the hypothesis that DXA structural variables measured at the femoral neck and trochanter cross sections will improve prediction of fractures at these sites in addition to areal BMD (aBMD). We present an analysis of the internal distribution of bone at the site of these fractures using baseline hip DXA measurement of 1,151 participants, mean age (SD) 75 (3), in the 15-year Perth Longitudinal Study of Aging in Women. Structural differences at the femoral neck (FN) and trochanter (TR) cross sections were compared in 69 participants who went on to sustain femoral neck fracture (FNF) and 59 participants who went on to sustain trochanter fracture (TRF), on average ten years later, to those who did not fracture. The new structural variables, in addition to aBMD and bone width (W), were Sigma (distribution of bone within scanned area) and Delta (distance between centre-of-mineral mass and geometric centre). At baseline, compared to Non-fracture cases, FNF cases had a FNaBMD 7% lower, a FNWidth 3% higher and a FNDelta 29% higher, associated with bone loss in superior segment. In Cox proportional hazard analysis for FNF, age (HR 1.39), THaBMD (0.79) and Delta (1.70) were significant. Addition of FN Delta to the base case of THaBMD and age improved the C statistic from 0.62 to 0.69, P =0.01. At baseline, TRF cases had a 15% reduction in TRaBMD with minor increases in Sigma (1%) and Width (2%). In Cox analysis for TRF neither addition of Sigma nor Width improved age and THaBMD as predictors and did not alter the C- statistic of 0.81. Adding measurement of FN Delta, which is an assessment of superior sector bone loss, to hip aBMD and age substantially improves clinical FNF prediction in older women. This article is protected by copyright. All rights reserved.