Biomechanical Morphing for Personalized Fitting of Scoliotic Torso Skeleton Models

Abstract

The use of patient-specific biomechanical models offers many opportunities in the treatment of adolescent idiopathic scoliosis, such as the design of personalized braces. The first step in the development of these patient-specific models is to fit the geometry of the torso skeleton to the patient’s anatomy. However, existing methods rely on high-quality imaging data. The exposure to radiation of these methods limits their applicability for regular monitoring of patients. We present a method to fit personalized models of the torso skeleton that takes as input biplanar low-dose radiographs. The method morphs a template to fit annotated points on visible portions of the spine, and it relies on a default biomechanical model of the torso for regularization and robust fitting of hardly visible parts of the torso skeleton, such as the rib cage. The proposed method provides an accurate and robust solution to obtain personalized models of the torso skeleton, which can be adopted as part of regular management of scoliosis patients. We have evaluated the method on ten young patients who participated in our study. We have analyzed and compared clinical metrics on the spine and the full torso skeleton, and we have found that the accuracy of the method is at least comparable to other methods that require more demanding imaging methods, while it offers superior robustness to artifacts such as interpenetration of ribs. Normal-dose X-rays were available for one of the patients, and for the other nine we acquired low-dose X-rays, allowing us to validate that the accuracy of the method persisted under less invasive imaging modalities.

Design of personalized scoliosis braces based on differentiable biomechanics—Synthetic study

“…For each subject, we captured biplanar radiographs of the trunk, as they are readily available as part of the regular check-up of scoliotic patients, using a DelftDI D2RS system with fluoroscopic exposure ( Wong et al, 2021 ). Then, we followed the procedure in ( Koutras et al, 2022 ) to morph a template trunk geometry and obtain personalized trunk biomechanical models. Table 1 provides the individual patient data, as well as the complexity of the simulation models, characterized by the number of triangles of the surface mesh (which dominates the cost of contact computations) and the number of tetrahedra of the soft-tissue mesh (which dominates the cost of deformation computations).…”

“…In our study, we use the trunk model to simulate the biomechanical response of different subjects suffering from AIS. To adapt the model to each subject, we start from a template geometry corresponding to a healthy (non-scoliotic) adolescent female, and then we apply the morphing method in ( Koutras et al, 2022 ), using as input low-dose radiographs of the subjects. Full personalization would also require estimating subject-specific mechanical parameters, but in this synthetic study we limit ourselves to the default mechanical parameters listed in ( Koutras et al, 2021 ).…”

“…We put the focus on modeling biomechanics elements that affect the deformation of the thoracolumbar spine under forces produced by a scoliosis brace. To this end, we largely rely on previous work for the development of the trunk model ( Koutras et al, 2021 ) and personalization of its geometry ( Koutras et al, 2022 ) (mechanical personalization is left as future work).…”

Thoughts and perspectives on biomechanical numerical models under impacts: Are women forgotten from research?

“…This conclusion is by the way clearly claimed by Kimpara et al, 52 even if recent works tend to adapt their initial male anthropometries to female ones. 58…”

“…This conclusion is by the way clearly claimed by Kimpara et al, 52 even if recent works tend to adapt their initial male anthropometries to female ones. 58 The abdomen segment was also of interest in scientific literature, for the understanding of injury criteria, 27,[60][61][62][63] also detailed in Table 2.…”