title: The functional muscle-bone unit in subjects of varying BMD.
abstract: CONCLUSIONS
  This study used the "functional muscle-bone unit" concept to investigate muscle-bone interaction of the lumbar spine in subjects of varying bone mineral density. It was found that unit bone mass corresponded to a relatively more muscle mass in subjects with reduced bone mineral density, indicating a relatively higher mechanical load from muscles exerted on trabecular bone.
  
  
  BACKGROUND
  Bone is an architecturally adaptive tissue which responds to mechanical loading. This study is proposed to use "functional muscle-bone unit" to reflect this muscle-bone interaction at spine in subjects with different bone mineral density.
  
  
  METHODS
  The study was carried out in young normal subjects (21 females; age, 29 ± 3) and elderly subjects (155 females; age, 73 ± 3.9) with varying bone mineral density. Cross-sectional area of paravertebral muscle groups was measured in MR images to indicate the muscle mass, while the bone mineral content by dual X-ray absorptiometry was used to represent the bone mass. The functional muscle-bone unit was calculated as the ratio between the bone mass to muscle mass.
  
  
  RESULTS
  It showed that with aging, the muscle mass decreased with the bone mass losing. However, more pronounced reduction was found in bone mass than in muscle mass in the subjects with lower bone mineral density.
  
  
  CONCLUSIONS
  Muscle-bone interaction was changed in elderly, especially in those with osteoporosis. Unit bone mass corresponded to a higher muscle mass in subjects with reduced bone mineral density than those normal subjects. This may be contributory to the occurrence of nontraumatic vertebral fractures in elderly subjects with reduced bone mineral density.
authors.affiliation: Department of Electronic and Information Engineering, Harbin Institute of Technology Shenzhen Graduate School, Rm 205C, C Building, HIT Campus, University Town, Xili, Nanshan, Shenzhen, China, 518055, tma@hitsz.edu.cn.
authors.forename: H T
authors.initials: HT
authors.lastname: Ma
authors.forename: J F
authors.initials: JF
authors.lastname: Griffith
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.forename: P C
authors.initials: PC
authors.lastname: Leung
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000473:pathology / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D009929:Organ Size / Q000502:physiology; D015663:Osteoporosis, Postmenopausal / Q000473:pathology / Q000503:physiopathology*
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