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The relationship between sagittal curvature and extensor muscle volume in the lumbar spine
Author(s) -
Meakin Judith R.,
Fulford Jonathan,
Seymour Richard,
Welsman Joanne R.,
Knapp Karen M.
Publication year - 2013
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/joa.12047
Subject(s) - sagittal plane , lumbar , lordosis , anatomy , medicine , low back pain , erector spinae muscles , magnetic resonance imaging , radiography , surgery , radiology , pathology , alternative medicine
A previous modelling study predicted that the forces applied by the extensor muscles to stabilise the lumbar spine would be greater in spines that have a larger sagittal curvature (lordosis). Because the force‐generating capacity of a muscle is related to its size, it was hypothesised that the size of the extensor muscles in a subject would be related to the size of their lumbar lordosis. Magnetic resonance imaging (MRI) data were obtained, together with age, height, body mass and back pain status, from 42 female subjects. The volume of the extensor muscles (multifidus and erector spinae) caudal to the mid‐lumbar level was estimated from cross‐sectional area measurements in axial T 1‐weighted MRIs spanning the lumbar spine. Lower lumbar curvature was determined from sagittal T 1‐weighted images. A stepwise linear regression model was used to determine the best predictors of muscle volume. The mean lower lumbar extensor muscle volume was 281 cm 3 ( SD = 49 cm 3 ). The mean lower lumbar curvature was 30 ° ( SD = 7 °). Five subjects reported current back pain and were excluded from the regression analysis. Nearly half the variation in muscle volume was accounted for by the variables age (standardised coefficient, B = −3.2, P = 0.03) and lower lumbar curvature ( B = 0.47, P = 0.002). The results support the hypothesis that extensor muscle volume in the lower lumbar spine is related to the magnitude of the sagittal curvature; this has implications for assessing muscle size as an indicator of muscle strength.