A usability-driven workflow for virtual fracture reduction using an open platform with ICP

Virtual surgical planning can support fracture reduction, but its routine use remains limited by the time and interaction burden associated with manually manipulating fragments in six degrees of freedom. This work presents a CBCT-based workflow designed to minimise user interaction by replacing continuous manual manipulation with a small number of point-based initialisation steps.

Fragment alignment through a sequential rigid registration strategy based on the iterative closest point (ICP) algorithm. The largest fragment is initialised manually. Subsequent fragments inherit the transformation estimated in the previous step and are refined automatically through ICP, although additional initialisation may be required in unfavourable configurations. Reduction accuracy was assessed using surface-to-surface distance analysis. The workflow is implemented using fully open-source tools ensuring reproducibility and accessibility without proprietary dependencies.

The workflow was evaluated on experimentally induced bovine femur fractures comprising two to four fragments by users with heterogeneous backgrounds. Compared to manual alignment, the proposed approach significantly reduced reduction time (Wilcoxon signed-rank paired test, p = 0.022), corresponding to an average reduction of approximately 63%. Surface-to-surface analysis showed mean alignment errors of approximately 1.5-1.8 mm, with consistent results across users.

A usability-driven workflow that constrains interaction to a limited number of discrete steps can substantially improve the efficiency of virtual fracture reduction while maintaining user control. The open-source pipeline provides an accessible solution for preoperative fracture reduction planning and should be regarded as a foundation for further developments in usability-driven virtual fracture reduction.