A longitudinal study of trunk muscle properties and severity of thoracic kyphosis in women and men: the Framingham study

AL Lorbergs, BT Allaire, L Yang, DP Kiel… - The Journals of …, 2019 - academic.oup.com
The Journals of Gerontology: Series A, 2019academic.oup.com
Background Cross-sectional studies suggest that trunk muscle morphology in the lumbar
spine is an important determinant of kyphosis severity in older adults. The contribution of
age-related changes in muscle morphology in the thoracic and lumbar spine to progression
of kyphosis is not known. Our objective was to determine cross-sectional and longitudinal
associations of thoracic and lumbar muscle size and density with kyphosis. Methods
Participants were 1,087 women and men (mean age: 61 years) of the Framingham Heart …
Background
Cross-sectional studies suggest that trunk muscle morphology in the lumbar spine is an important determinant of kyphosis severity in older adults. The contribution of age-related changes in muscle morphology in the thoracic and lumbar spine to progression of kyphosis is not known. Our objective was to determine cross-sectional and longitudinal associations of thoracic and lumbar muscle size and density with kyphosis.
Methods
Participants were 1,087 women and men (mean age: 61 years) of the Framingham Heart Study who underwent baseline and follow-up quantitative computed tomography (QCT) scanning 6 years apart. We used QCT scans to measure trunk muscle cross-sectional area (CSA, cm2) and density (HU) at the thoracic and lumbar spine and Cobb angle (degrees) from T4 to T12. Linear regression models estimated the association between muscle morphology and kyphosis.
Results
At baseline, smaller muscle CSA and lower density of thoracic (but not lumbar) spine muscles were associated with a larger (worse) Cobb angle in women and men. For example, each standard deviation decrease in baseline thoracic paraspinal muscle CSA was associated with a larger baseline Cobb angle in women (3.7 degrees, 95% CI: 2.9, 4.5) and men (2.5 degrees, 95% CI: 1.6, 3.3). Longitudinal analyses showed that loss of muscle CSA and density at the thoracic and lumbar spine was not associated with progression of kyphosis.
Conclusions
Our findings suggest that kyphosis severity is related to smaller and lower density trunk muscles at the thoracic spine. Future studies are needed to determine how strengthening mid-back musculature alters muscle properties and contributes to preventing kyphosis progression.
Oxford University Press