Case series of four complex spinal deformities: new frontiers in pre-operative planning.

BACKGROUND AND AIM: Osseous and medullar anomalies constitute a hard challenge for interpretation of complex vertebral deformities anatomy. To better frame these deformities three-Dimensional (3D) printing represents a new frontier in this field. The aim of this brief report is describing the use of 3D printed models for surgical planning in four complex vertebral deformity cases treatment. METHODS: Four cases of severe scoliosis were treated between December 2017 and January 2019; patients' mean age was 12,25 years. Two patients underwent neurosurgical intervention for myelomeningocele at the time of birth. Standard and dynamics X-Ray, Computed Tomography (CT) and Magnetic Resonance (MR) of the column were performed pre-operatively. CT files were implemented to build the 3D model of each spine and selected ribs. The models were 3D printed in thermoplastic material, then used to study the deformities and for surgical planning. A survey proposal about 3D models' utility and accuracy has been made to 15 residents and 6 main surgeons. RESULTS: Preparation of each 3D models required about 316.5 minutes and printing time was about 108 hours each. The average cost was 183.16 € to produce one 3D printed model, which resulted useful in surgical planning and educational. CONCLUSIONS: The manufacture of 3D models requires time, resources and multidisciplinary approach, it must be justified by complexity of the case. In this study 3D Printing allowed surgeons to carefully plan and simulate the surgery, ensuring for a better sizing of the implant.

Comparison of Three 3D Segmentation Software Tools for Hip Surgical Planning.

In hip arthroplasty, preoperative planning is fundamental to reaching a successful surgery. Nowadays, several software tools for computed tomography (CT) image processing are available. However, research studies comparing segmentation tools for hip surgery planning for patients affected by osteoarthritic diseases or osteoporotic fractures are still lacking. The present work compares three different software from the geometric, dimensional, and usability perspectives to identify the best three-dimensional (3D) modelling tool for the reconstruction of pathological femoral heads. Syngo.via Frontier (by Siemens Healthcare) is a medical image reading and post-processing software that allows low-skilled operators to produce prototypes. Materialise (by Mimics) is a commercial medical modelling software. 3D Slicer (by slicer.org) is an open-source development platform used in medical and biomedical fields. The 3D models reconstructed starting from the in vivo CT images of the pathological femoral head are compared with the geometries obtained from the laser scan of the in vitro bony specimens. The results show that Mimics and 3D Slicer are better for dimensional and geometric accuracy in the 3D reconstruction, while syngo.via Frontier is the easiest to use in the hospital setting.

Post-FSW Cold-Rolling Simulation of ECAP Shear Deformation and Its Microstructure Role Combined to Annealing in a FSWed AA5754 Plate Joint.

Friction stir welds are considered reliable joints for their lack of voids, cracks and distortions. When compared to the base material, friction stir welding (FSW) joints typically exhibit finer grain structured (especially at the nugget zone, NZ). Similarly, refined grain structure can also be obtained by severe plastic deformation (SPD) techniques, such as equal channel angular pressing (ECAP). In fact, the fine grain structures produced within the NZ of FSW or friction stir processed (FSP) materials are usually coarser than the ones achieved by ECAP. The former is characterized by lower dislocation density, higher high-angle boundary fraction and different mechanical strength, compared to what can be obtained by ECAP. In this study, a dedicated cold-rolling (CR) set-up, specifically designed to simulate an ECAP-equivalent shear deformation, was used to further refine the grain structure of FSW AA5754 sheets. The effect of ECAP-equivalent deformation induced by CR in a 2 mm-thick AA5754-H111 FSW joint was investigated. FSW was carried out at two different rotational (ω) and translational (v) welding speeds, 600 rpm, 200 mm/min and 1800 rpm, 75 mm/min, respectively. FSW sheets were then CR to obtain an equivalent shear strain of ε ~ 1.08, that is equivalent to 1-ECAP pass carried out with an internal die channels intersecting at an angle φ = 90° with a curvature extending over an angle Ψ = 20°. By CR, the sheet thickness reduced only by ~20%. The role of annealing on the FSW and CR plastically deformed AA5754 was also investigated. This was applied either prior or after FSW, and it resulted that whenever it follows the FSW, the mean volume fraction of dispersoids and Mg-rich particles is higher than the case of annealing preceding the FSW process. On the contrary, it was found that the annealing treatment had a minimal role on the dispersoids and particles mean size. The here reported post-FSW ECAP-simulated deformation, obtained by a customized CR process, showed sheet integrity and a significant concurrent grain size refinement.