Association of QCT bone strength and soft tissue thickness with trochanteric and femoral neck fractures in Older Men

J Borggrefe; T de Buhr; S Shrestha; C Nielson; E Orwoll; LM Marshall; D Black; CC Glüer

doi:10.1055/s-0032-1329751

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, Table of Contents

Association of QCT bone strength and soft tissue thickness with trochanteric and femoral neck fractures in Older Men

J Borggrefe ¹, T de Buhr ¹, S Shrestha ², C Nielson ², E Orwoll ², LM Marshall ², D Black ³ CC Glüer ¹ for the Osteoporotic Fractures in Men (MrOS) Research Group

¹Medical Physics, Department of Diagnostic Radiology, University Clinic Schleswig Holstein, Kiel, Germany
²Bone and Mineral Unit, Oregon Health & Science University, Portland, Oregon, USA
³Department of Epidemiology and Biostatistics, University of California, San Francisco, California, USA

Abstract

Zielsetzung: We investigated the associations of biomechanically motivated strength indices of the proximal femur derived from quantitative computed tomography (QCT) with hip fracture risk among elderly men.

Material und Methodik: Using a case-cohort sampling design nested within the MrOS cohort, we evaluated QCT scans of 230 men (age 74.3±6 years, 65 with confirmed hip fractures) with Mindways' QCTPRO BIT software. New failure mode specific bone strength indices for the femoral neck (FN) and for the trochanteric (TR) regions were defined, both for the respective entire cross sections and their quadrants. Bending strength was estimated by minimum section modulus (Zmin) and quadrant bending index (QBI); buckling strength by buckling ratio (BR) and the local thinning index (LTI) of the quadrant of lowest strength. Integral and trabecular BMD were also derived for the two anatomic regions. Areal BMD (aBMD) of the total proximal femur from DXA is presented for comparison.

Ergebnisse: Men with hip fractures were older than non-fx cases (77.1±6.0 years vs. 73.3±5.7 years, p<0.0001). Hazard Ratios (HR) were significant for all indices tested except for TR LTI, with DXA aBMD being the strongest single predictor. In multivariate models, among QCT variables FN BR (HR=1.8;1.2–2.8), TR BMD trab (HR=2.3;1.4–4.0), and TR QBI (HR=2.4;1.4–4.0) contributed independently (joint AUC=0.80).

Diskussion: QCT derived biomechanical indices of hip fracture risk add predictive value independent of DXA aBMD. These strength indices permit insight into the biomechanics of fracture risk.

QCT - hip fractures - fracture prediction - men