Quantitative computerized tomography of bone in relation to fracture status and lifelong physical activity: The AGES -Reykjavik study

Nahid J Rianon, The University of Texas School of Public Health

Abstract

Quantitative computerized tomography (QCT) provides an opportunity to create unique bone measurements for bone mineral density (BMD) (cortical and/or trabecular), and bone geometry (volume and cross-sectional area), which, in turn, allow for new assessments of bone characteristics for osteoporosis. Differences of the QCT bone attributes between groups with or without fractures, between young and old, and between men and women have been reported in the past. However, how these various QCT bone attributes might aggregate to affect bone health and whether a composite bone score (CBS) from constituent properties might prove to be a better correlate of fracture than traditional DEXA (Dual Energy X-ray Absorptiometry) BMD has not yet been explored. Half of the BMD variations up to age 65 years were attributable to peak bone mass. Inconclusive discussion about early life physical activity for accruing high peak bone mass versus lifelong physical activity for maintaining good bone health later in life have also been reported. A composite bone score was constructed with four properties (vertebral and femoral neck trabecular bone, femoral neck minimal cross sectional area, and femoral neck cortical thickness) fundamental to bone strength using the QCT bone measures from the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-Reykjavik) study. We examined the gender-specific relationship of the selected QCT measures and a combined score (CBS) with prevalent fractures for participants in the (mean age=76 ± 5 for 2110 men & 2682 women) AGES-Reykjavik study. The relationships of QCT measures and fracture status (fracture of hip, or spine or wrist) were then compared to that of the QCT-derived DEXA-like BMD of total hip (TOBD) and fracture status. We also examined the relationships of the single bone properties, representing different body sites and types of bone, with reported physical activity throughout life in the participants of the AGES-Reykjavik study. Fracture status demonstrated a negative association with the CBS (p<0.001 for both genders) as did all QCT measures (p<0.001 both genders) except femur neck minimal cross sectional area (MNCS). However, except for MNCS, the QCT measures did not differ significantly from each other in relation to fracture status. The combined QCT measure was not a stronger correlate of fracture status than TOBD. MNCS was not related to fracture status and had minimal impact on the composite bone score. While a CBS can be calculated using the four bone measurements used in our analysis, until reaching a clear understanding about MNCS, we recommend using individual bone attributes to be checked for investigating age related changes in bone strength and its relationship to fracture status in the elderly. Our results also emphasized the need for lifelong physical activity with continuation into old age for maintaining good bone health after 65 years of age. Vertebral BMD was the common bone characteristic affected by moderate-to-vigorous intensity physical activity reported by the elderly participants in our study.

Subject Area

Public health

Recommended Citation

Rianon, Nahid J, "Quantitative computerized tomography of bone in relation to fracture status and lifelong physical activity: The AGES -Reykjavik study" (2008). Texas Medical Center Dissertations (via ProQuest). AAI3315985.
https://digitalcommons.library.tmc.edu/dissertations/AAI3315985

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