Cortical and trabecular deficits in patients with recent hip fractures assessed by DXA and 3D-DXA

Dual-energy X-ray absorptiometry (DXA) is the standard for osteoporosis assessment, but areal BMD (aBMD) does not fully capture volumetric or microstructural deficits associated with hip fractures. We aimed to characterize cortical and trabecular parameters using 3D-DXA in patients with hip fractures and assess whether these measures improve discrimination of prevalent fracture status beyond aBMD.

Descriptive analyses included 499 individuals: femoral neck fractures (FNfx, n=110), intertrochanteric fractures (ITfx, n=123), and controls (n=266). Patients were assessed within 15 days of fracture at the contralateral hip. DXA and 3D-DXA provided trabecular volumetric BMD (vBMD), cortical surface BMD (sBMD), and cortical thickness. TBS and FRAX were evaluated descriptively but excluded from penalized models. LASSO models were evaluated in 515 unique participants with complete predictor data.

Among fractured patients, 51% did not meet densitometric criteria for osteoporosis. In the low bone mass subgroup, fractured individuals showed lower trabecular vBMD, whereas osteoporotic subjects also exhibited reduced cortical sBMD. Exploratory comparisons suggested lower trochanteric trabecular measures in ITfx and lower femoral neck cortical thickness in FNfx, although most differences occurred between fracture groups and controls. Total hip aBMD alone yielded an AUC of 0.646. The LASSO λmin model improved discrimination modestly (AUC 0.692; p<0.001), while the λ1se model achieved an AUC of 0.663 (p=0.034).

3D-DXA identified cortical and trabecular deficits in patients with recent hip fractures, including those without densitometric osteoporosis, and provided complementary structural information beyond aBMD. However, the improvement in discrimination was modest and requires prospective external validation.