Association between fresh osteoporotic vertebral fractures and muscle mass in patients with postmenopausal osteoporosis. — The International Society for the Study of the Lumbar Spine
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Association between fresh osteoporotic vertebral fractures and muscle mass in patients with postmenopausal osteoporosis. (#1072)

Arihisa Shimura 1 2 , Masaru Tanaka 2 , Masahiro Kanayama 1 , Fumihiro Ooha 1 , Toshiyuki Shimamura 1 , Takeru Tsujimoto 1 , Yuuchi Hasegawa 1 , Tomoyuki Hashimoto 1 , Hidetoshi Nojiri 2 , Muneaki Ishijima 2
  1. Hakodate Central General Hospital, Hakodate-shi,hon-cho, HOKKAIDO, Japan
  2. Orthopedics, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan

INTRODUCTION

Frailty and sarcopenia due to loss of muscle mass in the elderly has gained popularity in recent years.Previous studies have suggested an association between trunk muscle strength and osteoporotic vertebral fractures. However, it has remained unclear the relationship between trunk muscle mass measured by dual-energy X-ray absorptiometry (DXA) and vertebral fractures. The aim of this study was to investigate the association between muscle mass and incidence of fresh vertebral fractures in patients with postmenopausal osteoporosis.

METHODS

A total of 197 patients with postmenopausal osteoporosis between the ages of 65 and 84 were included in this study. They were divided into two groups based on the presence of fresh vertebral fracture during the follow-up period: annual year from the day of muscle mass measurement by DXA. We compared trunk muscle mass, lower limb muscle mass, and skeletal muscle index (SMI) between fracture group and non-fracture group. Trunk muscle mass and lower limb muscle mass were defined as the respective lean mass values measured by DXA, and they were normalized by body mass index (BMI). SMI was calculated by dividing the upper and lower limbs skeletal muscle mass by the square of the height, and the value was obtained by DXA. Additionally, lumbar bone mineral density also examined.


RESULTS

27 patients were in fracture group and 170 patients were in non-fracture group, trunk muscle mass (g/BMI) was 727.5 and 748.1 (p = 0.25), and lower limb muscle mass (g/BMI) was 408.8 and 442.1 (p = 0.02), with a significant difference in lower limb muscle mass. SMI was 5.79 in the fracture group and 5.68 in the non-fracture group (p = 0.44). Lumbar bone mineral density was 0.76 g/cm2  in the fracture group and 0.87 g/cm2 in the non-fracture group (p<0.01). There was no correlation between lower limb mass and lumber bone mineral density（r=-0.11）


DISCUSSION

Our retrospective review of 197 cases demonstrated that lower limb muscle mass, not trunk muscle mass was associated with fresh vertebral fractures. Although we did not examine the mechanism of injury, Ease of fall following to loss of lower limb muscle mass might be one of the risk factors of vertebral fractures. SMI: the value required for  diagnostic criteria of sarcopenia, was not associated with vertebral fractures; it may not be effective in assessing accurate muscle mass loss. The current study showed that lower limb muscle mass is an important factor in indicating vertebral fracture risk, as lumbar bone mineral density.

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