Abstract
Fatty infiltration of muscle, myosteatosis, increases with age and results in reduced muscle strength and function and increased fall risk. However, it is unknown if increased fatty infiltration of muscle predisposes to hip fracture. We measured the mean Hounsfield unit (HU) of the lean tissue within the midthigh muscle bundle (thigh muscle HU, an indicator of intramuscular fat), its cross-sectional area (CSA, a measure of muscle mass) by computed tomography (CT), bone mineral density (BMD) of the hip and total-body percent fat by dual X-ray absorptiometry (DXA), isokinetic leg extensor strength, and the Short Physical Performance Battery (SPPB) in 2941 white and black women and men aged 70 to 79 years. Sixty-three hip fractures were validated during 6.6 years of follow-up. Proportional hazards regression analysis was used to assess the relative risk (RR) of hip fracture across variations in thigh muscle attenuation, CSA, muscle strength, and physical function for hip fracture. In models adjusted by age, race, gender, body mass index, and percentage fat, decreased thigh muscle HU resulted in increased risk of hip fracture [RR/SD = 1.58; 95% confidence interval (CI) 1.10–1.99], an association that continued to be significant after further adjustment for BMD. In models additionally adjusted by CSA, muscle strength, and SPPB score, decreased thigh muscle HU but none of the other muscle parameters continued to be associated with an increased risk of hip fracture (RR/SD = 1.42; 95% CI 1.03–1.97). Decreased thigh muscle HU, a measure of fatty infiltration of muscle, is associated with increased risk of hip fracture and appears to account for the association between reduced muscle strength, physical performance, and muscle mass and risk of hip fracture. This characteristic captures a physical characteristic of muscle tissue that may have importance in hip fracture etiology. © 2010 American Society for Bone and Mineral Research
Highlights
Increases in the adiposity of skeletal muscle and other tissues have been linked at the cellular level to underlying age-related processes such as redox damage, which can result in mitochondrial dysfunction and impaired oxidative metabolism
To determine whether body composition measures predict hip fractures and to understand whether these measures act as surrogates for function-related hip fracture risk factors, we correlated measures of computed tomographic (CT) and dual X-ray absorptiometric (DXA) body composition, bone density, and physical function obtained at baseline with incident hip fracture in the cohort
Loss of muscle mass and increased fatty infiltration are manifested in midthigh CT images as loss of muscle bundle cross-sectional area (CSA) and decreased Hounsfield unit (HU) value of muscle tissue
Summary
Increases in the adiposity of skeletal muscle and other tissues have been linked at the cellular level to underlying age-related processes such as redox damage, which can result in mitochondrial dysfunction and impaired oxidative metabolism. Epidemiologic studies have correlated measurements of muscle and fat mass with fracture-related measures of bone mineral density (BMD), functional decline, and metabolic dysfunction in the elderly,(6–8) there is little information about the relationship of body-composition variables to incident hip fracture, the most serious consequence of osteoporosis. To address this issue, we analyzed data from the Health Aging and Body Composition (Health ABC) Study, a prospective cohort study of 3075 black and white men and women in Pittsburgh, Pennsylvania, and Memphis, Tennessee, designed to characterize changes in body composition as a pathway by which weightrelated health conditions contribute to disease and disability in the elderly. To determine whether body composition measures predict hip fractures and to understand whether these measures act as surrogates for function-related hip fracture risk factors, we correlated measures of computed tomographic (CT) and dual X-ray absorptiometric (DXA) body composition, bone density, and physical function obtained at baseline with incident hip fracture in the cohort
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
