Background. Lateral lumbar spine statistical shape models (SSM) have been used previously to describe associations with osteoarthritis and back pain. However, associations with factors such as osteoporosis, menopause and parity have not been explored. Methods and Results. A 143-point SSM, describing L1 to the top of L5, was applied to lateral spine iDXA scans from UK Biobank. Associations with self-reported osteoporosis, menopause, parity and back pain and the first 10 modes of variation were examined using adjusted binary logistic regression or linear regression (adjusted for age, height, weight and total spine BMD). We report odds ratios with 95% confidence intervals for each standard deviation change in mode. Complete data were available for 2494 women. Mean age was 61.5 (± 7.4) years. 1369 women reported going through menopause, 96 women self-reported osteoporosis and 339 women reported chronic back pain. 80% of women reported at least 1 live birth. Lumbar spine shape was not associated with back pain in this cohort. Two modes were associated with menopause (modes 1 & 2), 1 mode with parity (mode 1) and 2 modes with osteoporosis (modes 3 & 5). Mode 1 (43.6% total variation), describing lumbar curvature was positively associated with both menopause [OR 1.15 95% CI 1.00–1.33, p=0.05] and parity [OR 1.058 95% CI 1.03–1.0, p=0.01]. Mode 3, describing decreased vertebral height was positively associated with osteoporosis [OR 1.40 95% CI 1.14–1.73, p=0.001]. Conclusion. Menopause and parity were associated with a curvier lumbar spine and osteoporosis with decreased vertebral height. Shape was not associated with back pain. No conflicts of interest.  . Sources of funding. Wellcome Trust collaborative award ref 209233

The objective of this study was to assess the reliability and appropriateness of statistical shape modelling for capturing variation in thoracic vertebral anatomy for future use in assessing scoliotic vertebral morphology. Magnetic resonance (MR) images of the thoracic vertebrae were acquired from 20 healthy adults (12 female, 8 male) using a 1.5 T MR scanner (Intera, Philips). A T1 weighted spin-echo sequence (repetition time = 294 ms, echo time = 8 ms, number of signal averages = 3) was used. A set of slices (number = 27, thickness = 1.9 mm, gap = 1.63 mm, pixel size = 0.5 mm) were acquired for each vertebrae, parallel to the mid-transverse plane of the vertebral body. Repeated imaging, including participant repositioning, was performed for T4, T8 and T12 to assess reliability. Landmark points were placed on the images to define anatomical features consisting of the vertebral body and foramen, pedicles, transverse and spinous processes, inferior and superior facets. A statistical shape model was created using software tools developed in MATLAB (R2013a, The MathWorks Inc.). The model was used to determine the mean vertebral shape and ‘modes of variation’ describing patterns in vertebral shape. Analysis of variance was used to test for differences between vertebral levels and subjects and reliability was assessed by determining the within-subject standard deviation from the repeated measurements. The first three modes of variation, shown below (green = mean, red and blue = ±2 standard deviations about the mean), accounted for 70% of the variation in thoracic vertebral shape (Mode 1 = 44%, Mode 2 = 19%, Mode 3 = 4%). Visual inspection indicated that these modes described variation in anatomical features such as the aspect ratio of the vertebral bodies, width and orientation of the pedicles, and position and orientation of the processes and facet points. Variation in shape along the thoracic spine, characterised by these modes of variation, was consistent with that reported in the literature. Significant differences (p< 0.05) between vertebral levels and between some subjects were found. The reliability of the method was good with low relative error (Mode 1 = 5%, Mode 2 = 8%, Mode 3 = 19%). Statistical shape modelling provides a reliable method for characterizing many anatomical features of the thoracic vertebrae in a compact number of variables. This is useful for robustly assessing morphological differences between scoliotic and non-scoliotic vertebrae and in assessing entry points and trajectories for pedicle screws

Purpose. To investigate associations between sagittal thoracolumbar spine shape with sex and measures of adiposity throughout adulthood. Methods. Thoracolumbar spine shape was characterised using statistical shape modelling on lateral dual-energy x-ray absorptiometry images, recorded for vertebral fracture analysis, of the spine from 1529 participants of the MRC National Survey of Health and Development, acquired at age 60–64 years. Associations between spine shape modes (SM) and 1) sex, 2) contemporaneous measures of overall and central adiposity (indicated by body mass index and waist circumference, respectively), 3) changes in total and central adiposity during earlier stages of adulthood and age at onset of overweight, were investigated. Results. Four of the first eight spine modes (SM) describing lumbar spine shape differed by sex; on average, women had more lordotic spines than men with relatively smaller but caudally increasing anterior-posterior (a-p) vertebral diameters. Greater BMI and waist circumference and earlier onset of overweight were associated with uneven (or snaking) spinal curvatures (SM2) and larger a-p vertebral diameters (SM3). Central adiposity was also associated with larger caudal disc heights (SM4) in women, especially increases between 36–43 years. Conclusions. Sagittal spine shapes differed by sex and associations with overall and central adiposity also differed. Overweight and greater central adiposity earlier in adulthood were particularly important, and were associated with a straighter but more unevenly curved spine with larger vertebrae and caudal discs heights, possibly explained by a chronic effect of increased mechanical loading on the spine. Conflicts of interest: None. Funding received from MRC

Purpose and Background:. Healthy adults with a curvy (lordotic) lumbar spine were shown to lift a load from the floor by stooping, while straight (flat) spines squatted. Since skin-surface motion capture often misrepresents internal curvature this study calculated internal lumbar curvature during lifting in the same cohort and compared lumbosacral motion. Methods:. Magnetic resonance imaging (MRI) was performed in standing and bending forward to 30, 45 and 60°, with markers on the skin at L1, L3, L5 and S1. Lumbar spine shape was characterised using statistical shape modelling and participants grouped into ‘curvy’ and ‘straight’ spine sub-groups (N=8). On a separate day participants lifted a box (6–15 kg) from the floor without instruction while Vicon cameras tracked sagittal movement of L1, L3 and L5 skin markers. Sacral angle (to horizontal) was calculated from pelvic markers. Matching markers during MRI and lifting sessions allowed vertebral centroid positions (L1, L3, L5, S1) during lifting to be calculated using custom MATLAB code. Results:. The curvy group had more internal lumbar lordosis at pick up despite stooping to lift the load. From upright standing motion occurred earlier at the upper lumbar levels (L1–L3) compared with lower lumbar (L3–L5). During lifting straight spines had greater rigid-body motion of the entire lumbar spine compared with curvy spines who demonstrated more varied intersegmental motion with greater sacral flexion. Conclusion:. Individuals with very lordotic spines retained some degree of internal lordosis despite stooping when lifting. The lumbar spine appears more mobile at the upper levels, L1–L3, and constrained motion was seen in those with the least lordosis