Assessment of hip fracture risk by cross-sectional strain-energy derived from image-based beam model

• Published in: Clinical biomechanics (Bristol) Vol. 63; no. NA; pp. 48 - 53
• Main Authors: Luo, Yunhua, Yang, Huijuan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2019
• Subjects: Absorptiometry, Photon; Accidental Falls; Aged; Aged, 80 and over; Allowable cross-section strain-energy; Bone Density; Cohort Studies; Cross-Sectional Studies; Dual energy X-ray absorptiometry (DXA); DXA-beam model; Female; Femur - diagnostic imaging; Femur Neck; Hip Fractures - diagnostic imaging; Humans; Impact force; Male; Pelvic Bones - diagnostic imaging; Risk Assessment; Stress, Mechanical; Impact force; Dual energy X-ray absorptiometry (DXA); Allowable cross-section strain-energy; DXA-beam model
• ISSN: 0268-0033; 1879-1271; 1879-1271
• DOI: 10.1016/j.clinbiomech.2019.02.016

Clinicians have been looking for a simple and effective biomechanical tool for the assessment of hip fracture risk. Dual-energy X-ray absorptiometry (DXA) is currently the primary bone imaging modality in clinic, and the engineering beam is the simplest model for a mechanical analysis. Therefore, we developed a DXA-based beam model for the above purpose. A beam model of the proximal femur was constructed from the subject's hip DXA image and denoted DXA-beam. Femur stiffness was calculated at cross-sections of interest using areal bone-mineral-density profile. Impact force induced in a sideways fall was applied as a critical loading. Fracture risk index at a cross-section was defined as the ratio of strain-energy induced by the impact force to the allowable strain-energy. A clinic cohort was used to study the discriminability of DXA-beam, which was measured by the area under the curve and odds ratio, both with 95% confidential interval. Fracture risk measured by DXA-beam model at the femoral neck [odds ratio 2.23, 95% confidence interval (1.83, 2.57)], inter-trochanter [2.49, (2.14, 3.25)] and sub-trochanter [2.82, (2.38, 3.51)] were strongly associated with hip fracture. The area under the curve by DXA-beam at the femoral neck [0.74, 95% confidence interval (0.70, 0.76)], inter-trochanter [0.77, (0.75, 0.82)] and sub-trochanter [0.76, (0.74, 0.81)] were higher than that by femoral neck bone mineral density [0.71, (0.65, 0.78)]. The DXA-beam model is a simple and yet effective mechanical model. It had promising performance in discrimination of fracture cases from controls. •An image-based beam model for assessment of hip fracture risk•A novel measurement of fracture risk based on cross-sectional allowable strain-energy•Validated by a cross-sectional study•Promising performance in discrimination of fracture cases from controls