Vol.:(0123456789) 1 3 Aging Clinical and Experimental Research https://doi.org/10.1007/s40520-018-1024-8 ORIGINAL ARTICLE Quantitative analysis of modifed functional muscle–bone unit and back muscle density in patients with lumbar vertebral fracture in Chinese elderly men: a case–control study Yong Zhang 1  · Jin Guo 2  · Yangyang Duanmu 1  · Chenxin Zhang 1  · Wei Zhao 1  · Ling Wang 1  · Xiaoguang Cheng 1  · Nicola Veronese 3  · Francesco Pio Cafarelli 4  · Giuseppe Guglielmi 4,5 Received: 10 May 2018 / Accepted: 10 August 2018 © Springer Nature Switzerland AG 2018 Abstract Objectives Bone mineral density (BMD) is associated with muscle mass and quality, but little research has been done on functional muscle–bone unit and back muscle density in patients with lumbar vertebral fracture. This study used the “modifed functional muscle–bone unit” concept and measured back muscle density to investigate muscle–bone interaction diference between the fracture and control group. Methods This was a case–control study. A total of 52 elderly male patients (mean age 75 years) with lumbar vertebral frac- ture (cases) and 52 control healthy subjects were enrolled. Cross-sectional area (CSA) and density of paravertebral muscle were measured in quantitative computed tomography (QCT) images to represent the muscle mass, while the bone mineral density measured by QCT was used to represent the bone mass. The modifed functional muscle–bone unit was calculated as the value of volumetric BMD divided by muscle area. Results People with vertebral fractures reported signifcantly lower values in the cross-sectional area and density of paraverte- bral muscle compared to control group. In the multivariate analysis, BMD (odds ratio, OR = 0.929; 95% confdence intervals, CIs 0.888–0.971), erector muscle density (OR = 0.698; 95% CI 0.547–0.892), and summated muscle CSA (OR = 0.963; 95% CI 0.93–0.991) were independent protective factors for the presence of a fracture. BMD resulted signifcantly and moderately associated with cross-sectional area and density of paravertebral muscle (r = 0.329–0.396). Conclusions There were signifcant diferences between the modifed functional muscle–bone unit and back muscle density between the fracture group and control group in elderly men. Lower BMD, loss of muscle mass and density are associated with increased presence of the lumbar vertebral fracture. Keywords Functional muscle–bone unit · Muscle density · Lumbar vertebral fracture · Quantitative computed tomography Introduction The decrease in bone mineral density (BMD) and in skel- etal muscle mass and muscle force are closely related to the occurrence of fractures and are among the main reasons for the decline in physical function in the elderly [1–3]. Cur- rently, BMD, the most commonly used parameter in the quantifcation of bone property, can refect the bone strength and predict the incidence of fractures to a certain degree [4, 5]. Alone application of BMD in predicting the risk of fractures is relatively limited in that increasing studies have demonstrated that bone mass is associated with not only age but also the bone size and muscle function [6–8]. Degenera- tion of skeletal muscle is mainly characterized by decreased muscle mass or muscle cross-sectional area, reduced muscle * Giuseppe Guglielmi giuseppe.guglielmi@unifg.it 1 Department of Radiology, The Fourth Clinical Medical College of Peking University (Beijing Jishuitan Hospital), Beijing 100035, China 2 School of Public Health, Capital Medical University, Beijing 100069, China 3 National Research Council, Neuroscience Institute, Aging Branch, Padua, Italy 4 Department of Radiology, University of Foggia, Viale Luigi Pinto 1, 71100 Foggia, Italy 5 Department of Radiology, Scientifc Institute “Casa Sollievo della Soferenza” Hospital, San Giovanni Rotondo, Foggia, Italy