title: Numerical evaluation of the correlation between the normal variation in the sagittal alignment of the lumbar spine and the spinal loads.
abstract: We present a numerical approach to reproduce various patterns of spino-pelvic organization. We wanted to predict the spinal loads in two static conditions (standing and holding a weight in the hands) based on parameters describing the shape of the lumbar spine: type following Roussouly classification, sacral slope, apex, inflection point and lumbar lordosis. Four hundred eighty finite element models including trunk muscles and representing the entire range of normal variability were created. The models predicted that, in the case of a moderate external load of 50 N, a lordotic and well balanced spine (e.g., type 3) could reduce the muscle activation in comparison with a more lordotic (type 4) spine, with negligible differences compared to a more straight spine (type 2). However, such a sagittal configuration was not correlated with a minimization of the loading state in the intervertebral discs, especially regarding anteroposterior shear loads. In the standing posture without any additional load, a less lordotic and more vertical spine (e.g., types 1 and 2) was sufficient to ensure a condition of minimal spinal loads. Despite a number of limitations, inverse statics numerical models of spine biomechanics including trunk muscles appear to be a promising tool to fill the knowledge gap between the clinical observations of the correlations between the spino-pelvic organization and the consequent spinal disorders.
authors.affiliation: IRCCS Istituto Ortopedico Galeazzi, Via Galeazzi 4, Milan, 20161, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Galbusera
authors.forename: Marco
authors.initials: M
authors.lastname: Brayda-Bruno
authors.forename: Francesco
authors.initials: F
authors.lastname: Costa
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Wilke
mesh_terms: D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology*; D008953:Models, Anatomic; D010384:Pelvic Bones / Q000502:physiology; D016474:Weight-Bearing
keywords: finite element; sagittal balance; spinal loads; spino-pelvic parameters; trunk muscles