The functional muscle–bone unit in subjects of varying BMD

• Published in: Osteoporosis international Vol. 25; no. 3; pp. 999 - 1004
• Main Authors: Ma, H. T., Griffith, J. F., Xu, L., Leung, P. C.
• Format: Journal Article
• Language: English
• Published: London Springer London 01.03.2014; Springer Nature B.V
• Subjects: Absorptiometry, Photon - methods; Adult; Aged; Aging; Aging - physiology; Bone density; Bone Density - physiology; Endocrinology; Female; Humans; Lumbar Vertebrae - pathology; Lumbar Vertebrae - physiopathology; Medicine; Medicine & Public Health; Muscle, Skeletal - pathology; Muscle, Skeletal - physiopathology; Muscular system; Organ Size - physiology; Original Article; Orthopedics; Osteoporosis; Osteoporosis, Postmenopausal - pathology; Osteoporosis, Postmenopausal - physiopathology; Rheumatology; Spine; Osteoporosis; Bone mineral density; Lumbar spine; Functional muscle–bone unit; Muscle mass
• ISSN: 0937-941X; 1433-2965; 1433-2965
• DOI: 10.1007/s00198-013-2482-7

Summary 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. Introduction 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.