Advanced surgical simulation processes in the correction of functional defects and musculoskeletal disorders in paediatric age

This thesis was developed through a collaboration between the Department of Industrial Engineering of the University of Bologna and the Paediatric Orthopedics and Traumatology Unit of the Rizzoli Orthopaedic Institute in Bologna, to integrate CAD and 3D printing technologies into a hospital-based point-of-care (POC) model for Virtual Surgical Planning (VSP) and in-house production of personalized surgical instruments using scalable and cost-effective technologies. The work focused on optimizing the VSP workflow for paediatric musculoskeletal deformities and bone tumours by combining structured deformity analysis, virtual simulation, and FDM 3D printing of Patient-Specific (PSI) and Graft-Specific (GSI) instruments in HTPLA. A standardized deformity analysis protocol was defined to formalize the planning process from geometric assessment to surgical simulation. The manufacturing phase was systematically investigated to improve dimensional accuracy and process stability. Printing optimization demonstrated that low fan speed combined with a 45° infill pattern minimized 3D deformation, with a standard deviation of 0.47 mm in 3D distance maps. A regression-based compensation model was developed to adjust fixation-hole diameters, according to the manufacturing process, ensuring reliable transfer from digital planning to physical surgical guides. The consolidated workflow was applied to 144 procedures in 114 patients, including 22 oncological cases. Angular correction was achieved in 91 procedures (mean 26.3°, range 3–151°), while bone grafts or massive allografts were used in 58 procedures, 22 of which were shaped using GSIs. Sterilizable PSIs were employed in 93 procedures, with a total of 199 guides produced (mean 2 per procedure). Complication rates were comparable to traditional surgery. Operative time was the only independent predictor of complications, while PSI-related technical issues were infrequent (6%) and mainly related to suboptimal imaging quality. Finally, an international research experience expanded the approach toward soft-tissue–aware and functional VSP models, outlining future developments toward prognostic applications in paediatric orthopaedics.