title: Geometric sensitivity of patient-specific finite element models of the spine to variability in user-selected anatomical landmarks.
abstract: Software to create individualised finite element (FE) models of the osseoligamentous spine using pre-operative computed tomography (CT) data-sets for spinal surgery patients has recently been developed. This study presents a geometric sensitivity analysis of this software to assess the effect of intra-observer variability in user-selected anatomical landmarks. User-selected landmarks on the osseous anatomy were defined from CT data-sets for three scoliosis patients and these landmarks were used to reconstruct patient-specific anatomy of the spine and ribcage using parametric descriptions. The intra-observer errors in landmark co-ordinates for these anatomical landmarks were calculated. FE models of the spine and ribcage were created using the reconstructed anatomy for each patient and these models were analysed for a loadcase simulating clinical flexibility assessment. The intra-observer error in the anatomical measurements was low in comparison to the initial dimensions, with the exception of the angular measurements for disc wedge and zygapophyseal joint (z-joint) orientation and disc height. This variability suggested that CT resolution may influence such angular measurements, particularly for small anatomical features, such as the z-joints, and may also affect disc height. The results of the FE analysis showed low variation in the model predictions for spinal curvature with the mean intra-observer variability substantially less than the accepted error in clinical measurement. These findings demonstrate that intra-observer variability in landmark point selection has minimal effect on the subsequent FE predictions for a clinical loadcase.
authors.affiliation: a Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology , Brisbane , Australia.
authors.forename: J P
authors.initials: JP
authors.lastname: Little
authors.forename: C J
authors.initials: CJ
authors.lastname: Adam
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001842:Bone and Bones / Q000033:anatomy & histology; D003198:Computer Simulation; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008875:Middle Aged; D008953:Models, Anatomic; D015588:Observer Variation; D066230:Patient-Specific Modeling; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012984:Software; D013131:Spine / Q000033:anatomy & histology; D014057:Tomography, X-Ray Computed
keywords: finite element; patient-specific; ribcage; scoliosis; spine; thoracolumbar