Utility and validation of bone mineral density measurements at forearm in predicting trabecular microarchitecture and central‐site osteoporosis in aging Indian postmenopausal women—a promising surrogate?

Abstract

Objective The objective of this paper was to present the results of our study of the utility of bone mineral density (BMD) measurements at various segments of distal forearm in predicting central‐site osteoporosis and deteriorated trabecular microarchitecture. Methods This was a cross‐sectional study and BMD at the femoral neck, lumbar spine, and distal forearm were assessed using the dual‐energy X‐ray absorptiometry (DXA) scanner and bone microarchitecture at lumbar spine by trabecular bone score (TBS). The utility of forearm BMD in predicting osteoporosis as well as the deteriorated TBS was assessed by a receiver operating characteristic analysis. Results A total of 352 postmenopausal women with mean (SD) age of 60.7 (6.8) years were included. The odds of having osteoporosis at femoral neck [odds ratio (OR) = 14.1, 95% confidence interval (CI): 7.8–25.2] and lumbar spine (OR = 7.5, 95% CI: 4.6–12.1) was highest with the mid‐distal radius. A derived T‐score cut off ≤ −1.6, −1.9, and −1.7 at any segment of the forearm was elucidated to predict osteoporosis at the central‐site, femoral neck, and lumbar spine, respectively, with sensitivity of 80%–88% and specificity of 60%–70%. The T‐scores at all three forearm segments ≤ −1.2 showed fair performance in predicting degraded trabecular microarchitecture. The T‐scores thus derived were further validated in cohort of 360 Bengali postmenopausal women. Conclusion BMD assessment at the forearm may be utilized in prediction of trabecular microarchitecture and central site osteoporosis at the femoral neck and lumbar spine in postmenopausal women.

Regional variation in bone mineral density of the distal radius

“…The regional changes in aBMD are perhaps intuitive when the anatomy of the distal radius is considered. Composition of the radius varies along its length, with the ultra-distal end containing predominantly trabecular bone, transitioning through the mid-distal and one-third zones where the bone structure contains predominantly cortical bone with fatty marrow [ 13 ]. Ghasem-Zadeh et al [ 9 ] report that the total bone mass can be expected to remain approximately constant along the distal third of the radius while the cross sectional area increases towards the ultra-distal end, resulting in decreased density of trabecular bone at the ultra-distal radius.…”

“…Cortical bone generally reduces in thickness with age and increases in porosity [ 14 ]. Gautam [ 13 ] also reports that trabecular bone loss starts earlier than cortical bone loss. It may therefore be expected that aBMD in the ultra-distal radius is particularly susceptible as an early fracture site due to inherently reduced cortical thickness and higher proportion of trabecular bone.…”