Technical Note - A patient-specific implant for orbital wall reconstruction with infraorbital rim extension: Accuracy and proof-of-principle evaluation of an “one-fit-only” design

Accurate intraoperative positioning of patient-specific implants (PSI) in orbital wall reconstruction remains challenging due to residual translational and rotational freedom. The aim of this proof-of-principle study was to introduce an orbital PSI design refinement incorporating infraorbital rim extensions based on the “one-fit-only” principle and to evaluate its positioning accuracy using a comprehensive 3D analysis. A patient with an unilateral and isolated left-sided orbital floor fracture underwent primary orbital reconstruction in a fully digital 3D workflow using a CAD/CAM-manufactured titanium PSI with three infraorbital rim extensions. Virtual surgical planning (VSP) was performed based on high-resolution computed tomography (CT). Accuracy assessment was performed using intraoperative cone beam computed tomography (CBCT) by superimposing the planned and achieved implant positions and analyzing them with open-source software 3D Slicer. Positioning accuracy was quantified using the Dice similarity coefficient (DSC), Hausdorff distance (HD), mean surface distance (MSD), rotational deviation (RD) and distance between centers (DBC). The PSI demonstrated high positional accuracy with low translational and rotational deviations. MSD was 0.63 mm and mean HD was 0.23 mm (maximum 0.79 mm) indicating close geometric congruence without clinically relevant focal malpositioning. Total RD was 1.53° and global translational deviation was 0.58 mm with submillimetric axis-specific components. At extended follow-up (4 months postoperatively), no implant-related complications and stable ophthalmological outcomes were observed. The presented orbital PSI design with infraorbital rim extensions demonstrates technical feasibility of accurate intraoperative positioning within a fully digital workflow. The proposed 3D outcome measures provide a framework for objective assessment of PSI positioning accuracy. Due to the single-case design, no conclusions can be drawn regarding workflow simplification, learning curve or equivalence to other techniques such as intraoperative navigation. This study should be interpreted as a proof-of-principle technical note based on a single-case.