Prediction of the 3D shape of the L1 vertebral body from adjacent vertebrae.

The aim of treatments of vertebral fractures is the anatomical reduction to restore the physiological biomechanics of the spine and the stabilization of the fracture to allow bone healing. However, the three-dimensional shape of the fractured vertebral body before the fracture is unknown in the clinical setting. Information about the pre-fracture vertebral body shape could help surgeons to select the optimal treatment. The goal of this study was to develop and validate a method based on Singular Value Decomposition (SVD) to predict the shape of the vertebral body of L1 from the shapes of T12 and L2. The geometry of the vertebral bodies of T12, L1 and L2 vertebrae of 40 patients were extracted from CT scans available from the VerSe2020 open-access dataset. Surface triangular meshes of each vertebra were morphed onto a template mesh. The set of vectors with the node coordinates of the morphed T12, L1 and L2 were compressed with SVD and used to build a system of linear equations. This system was used to solve a minimization problem and to reconstruct the shape of L1. A leave-one-out cross-validation was performed. Moreover, the approach was tested against an independent dataset with large osteophytes. The results of the study show a good prediction of the shape of the vertebral body of L1 from the shapes of the two adjacent vertebrae (mean error equal to 0.51 ± 0.11 mm on average, Hausdorff distance equal to 2.11 ± 0.56 mm on average), compared to current CT resolution typically used in the operating room. The error was slightly higher for patients presenting large osteophytes or severe bone degeneration (mean error equal to 0.65 ± 0.10 mm, Hausdorff distance equal to 3.54 ± 1.03 mm). The accuracy of the prediction was significantly better than approximating the shape of the vertebral body of L1 by the shape of T12 or L2. This approach could be used in the future to improve the pre-planning of spine surgeries to treat vertebral fractures.

An open source pipeline for design of experiments for hyperelastic models of the skin with applications to keloids.

The aim of this work is to characterize the mechanical parameters governing the in-plane behavior of human skin and, in particular, of a keloid-scar. We consider 2D hyperelastic bi-material model of a keloid and the surrounding healthy skin. The problem of finding the optimal model parameters that minimize the misfit between the model observations and the in vivo experimental measurements is solved using our in-house developed inverse solver that is based on the FEniCS finite element computational platform. The paper focuses on the model parameter sensitivity quantification with respect to the experimental measurements, such as the displacement field and reaction force measurements. The developed tools quantify the significance of different measurements on different model parameters and, in turn, give insight into a given model's ability to capture experimental measurements. Finally, an a priori estimate for the model parameter sensitivity is proposed that is independent of the actual measurements and that is defined in the whole computational domain. This estimate is primarily useful for the design of experiments, specifically, in localizing the optimal displacement field measurement sites for the maximum impact on model parameter inference.

Serological survey for antibodies to Encephalitozoon cuniculi in pet rabbits in Italy.

Pet rabbits (n = 125) from Southern Italy were submitted to a serological screening for Encephalitozoon cuniculi, using an enzyme-linked immunosorbent assay (ELISA) and a carbon immunoassay (CIA). Seventy-eight examined rabbits showed clinical signs suggestive of encephalitozoonosis (head tilt, ataxia, paralysis, cataracts, uveitis, polyuria and polydipsia), whereas 47 were healthy rabbits. Antibodies anti-E. cuniculi were found in 84/125 (67.2%) sera analysed. The results of the chi-squared test showed that sex and health status had no significant effect (P > 0.05) on E. cuniculi seropositivity; however, rabbits older than 4 months had a seropositivity for E. cuniculi significantly (P < 0.05) higher than that of rabbits aged up to 4 months. The results of the present survey reinforce the assumption that rabbit may be indicated as the main reservoir of E. cuniculi; therefore, routine screening examinations in pet rabbits are strongly advised considering the zoonotic potential of this parasite.