Association Between Femoral Neck Bone Mineral Density and Lower Limb Fat-Free Mass in Postmenopausal Women

Abstract 

Aging is associated with several physiological changes that lead to increased disability and mortality. Examples of these changes are deteriorations in bone and muscle tissues, referred, respectively, as osteopenia and sarcopenia. Both have been linked to multiple morbid outcomes in older adults. The main purpose of this study was to determine the association between femoral neck and trochanter bone mineral density (BMD) and lower limb non-bone fat-free mass (MM) in postmenopausal women. One hundred eighty nine postmenopausal women volunteered to participate in the study (mean age 66.92±5.23yr). Subjects were divided into different groups according to lower limb MM, femoral neck, and trochanter BMD measurements using the 2-step cluster analysis. Pearson chi-square was used to analyze the correlation between the BMD and MM distributions. The 2-step cluster analysis leads to the formation of 3 groups according to the levels of lower limb MM (LMM—low values of MM, IMM—intermediate values of MM, and HMM—high values of MM), 2 groups according to the values of femoral neck BMD (LFN—low values and HFN—high values), and 3 groups for trochanter BMD (LTR—low values, ITR—intermediate values, and HTR—high values). The results of Pearson chi-square revealed a significant association between femoral neck BMD and lower limb MM, and trochanter BMD and lower limb MM, suggesting that individuals with reduced lower limb MM are prone to have decreased femoral neck and trochanter BMD. The present study supports the hypothesis of a relation between the incidence of low BMD and MM. It is recommended that dual-energy X-ray absorptiometry screening should be used to identify both BMD and MM in postmenopausal women to assess more accurately the risk of fractures and disability.

Key Words: Aging, fracture risk, osteopenia, osteoporosis, sarcopenia