Pelvic body composition measurements by quantitative computed tomography: Association with recent hip fracture
Introduction
Measures of proximal femoral bone mineral density (BMD) and structure from quantitative computed tomography (QCT) images are correlated in vitro to hip strength [4], [5], [6], [25] and are associated in cross-sectional studies with hip fracture [3]. In addition to the skeletal anatomy, the images also depict the muscle and adipose tissue surrounding the proximal femur. These images provide information about the total pelvic adipose and lean content as well information on the cross-sectional areas and Hounsfield Unit (HU) values (a measure of tissue X-ray attenuation) of the functional muscle groups in the field of view. CT measurements of the cross-sectional area (CSA) and mean Hounsfield Unit (HU) of the abdomen and mid thigh muscle bundle are well established measurements in epidemiologic studies of physical function in the elderly [13], [35], [36]. The CSA is a measure of overall muscle size and is strongly correlated to muscle strength and fall-related measures of physical function [14]. The HU value is a measure of the inter- and intra-cellular adipose content of the muscles [14], [27], with decreasing HU proportional to increasing fattiness [13]. In the thigh, the CSA and HU are independently correlated to knee extensor strength, and low mean HU is associated with reduced current physical function, lower strength, and with onset of disability [35], [36], [37].
We recently reported a cross-sectional analysis of the associations of QCT-derived measures of proximal femoral skeletal structure measures with hip fracture [3]. In this cohort, Cheng et al.showed that elderly Chinese women with hip fractures, imaged within 48 h of their fracture, differed from age-matched controls in multiple indices of proximal femoral bone density and geometry, even after adjustment for age and body size. In this study, we hypothesized that performance-related elements of body composition obtained from QCT scans of the hip, in particular the HU and CSA of the muscles surrounding the proximal femur, would be associated with hip fracture. We also hypothesized that combining these soft tissue indices with BMD would result in better discrimination between fractured subjects and controls than BMD measurements alone.
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Study subjects
Forty-five women with fractures of the hip (34 cervical, 11 trochanteric), aged 65 or older were recruited from the emergency room, Department of Traumatology and Orthopedic Surgery, Beijing Ji Shui Tan hospital. In order to minimize changes in BMD and body composition factors due to the fracture, only those subjects whose fractures had occurred within the last 48 h were accepted into the study. Potential hip fracture subjects were referred to the ER CT scanning service and to the study by
Descriptive statistics
Controls were not significantly different from fracture subjects in height but on average were 4 year s younger than subjects (p < 0.001) and 5% higher in BMI (p < 0.05). Descriptive statistics for each group are summarized in Table 2. BMD differed strongly between subjects with hip fractures and controls. Even after adjustment for age, height and BMI, subjects with fractures had 24% lower aBMD than controls in the total femur region (p < 0.0001,see Table 3).
Contribution of body fat measures
As shown in Table 3, subjects with hip
Discussion
Areal bone mineral density (aBMD) measured by DXA operates clinically as a surrogate measure for bone strength and is operatescommonly employed to select patients for preventive drug therapies [7], [34]. However, a growing number of studies have pointed out the limitations associated with using aBMD in isolation as an estimator of hip fracture risk, showing that considerable numbers of fractures occur in subjects who have higher aBMD than would normally be associated with osteoporosis [32], [38]
Acknowledgments
This patient study was funded by a grant from Eli Lilly. Development of the analytic technique was funded by NASA grant NNJ04HF78G.
References (42)
- et al.
Proximal femoral density and geometry measurements by quantitative computed tomography: association with hip fracture
Bone
(2007) - et al.
Femoral strength is better predicted by finite element models than QCT and DXA
J Biomech
(1999) - et al.
Bone density at various sites for prediction of hip fractures: the study of osteoporotic fractures
Lancet
(1993) - et al.
Body size and hip fracture risk in older women: a prospective study. Study of Osteoporotic Fractures Research Group
Am J Med
(1997) - et al.
Relation of body composition, fat mass, and serum lipids to osteoporotic fractures and bone mineral density in Chinese men and women
Am J Clin Nutr
(2006) - et al.
Age-related changes in hip abductor and adductor joint torques
Arch Phys Med Rehabil
(2004) - et al.
Reduced hip extension during walking: healthy elderly and fallers versus young adults
Arch Phys Med Rehabil
(2001) - et al.
Adipogenesis and aging: does aging make fat go MAD?
Exp Gerontol
(2002) - et al.
Volumetric quantitative computed tomography of the proximal femur: precision and relation to bone strength
Bone
(1997) - et al.
Age and gender differences in peak lower extremity joint torques and ranges of motion used during single-step balance recovery from a forward fall
J Biomech
(2001)
Assessment of fracture risk and its application to screening for postmenopausal osteoporosis. Report of a WHO Study Group
World Health Organ Tech Rep Ser
Bone quality: where do we go from here?
Osteoporos Int
Bone density distribution and gender dominate femoral neck fracture risk predictors
Skelet Radiol
Femoral structure and stiffness in patients with femoral neck fracture
J Orthop Res
Comparing the areas under two or more correlated receiver operating characteristic curves: a nonparametric approach
Biometrics
An Introduction to the Bootstrap
Accurate assessment of precision errors: how to measure the reproducibility of bone densitometry techniques
Osteoporos Int
Skeletal muscle lipid and its association with insulin resistance: what is the role for exercise?
Exerc Sport Sci Rev
Attenuation of skeletal muscle and strength in the elderly: The Health ABC Study
J Appl Physiol
Skeletal muscle attenuation determined by computed tomography is associated with skeletal muscle lipid content
J Appl Physiol
Effects of weight loss on regional fat distribution and insulin sensitivity in obesity
Diabetes
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2021, Experimental GerontologyCitation Excerpt :It is also apparent that the progression and severity of the CKD will differently compromise muscle mass, strength, quality, and function and disrupt the metabolism. Only two studies have examined the association between CT-derived muscle measurement (CSA and attenuation) and hip fracture in older adults (Lang et al., 2008; Lang et al., 2010). In the current study, we found a significant association between an accelerated decrease in quadriceps CSA, but not in density, and incident hip fracture risk.