Primary Orbital Reconstruction with Selective Laser Melting (SLM) of Patient-Specific Implants (PSIs): An Overview of 96 Surgically Treated Patients

Abstract

Contemporary advances in technology have allowed the transfer of knowledge from industrial laser melting systems to surgery; such an approach could increase the degree of accuracy in orbital restoration. The aim of this study was to examine the accuracy of selective laser melted PSIs (patient-specific implants) and navigation in primary orbital reconstruction. Ninety-six patients with orbital fractures were included in this study. Planned vs. achieved orbital volumes (a) and angles (b) were compared to the unaffected side (n = 96). The analysis included the overlay of post-treatment on planned images (iPlan 3.0.5, Brainlab®, Feldkirchen, Germany). The mean difference in orbital volume between the digitally planned orbit and the postoperative orbit was 29.16 cm3 (SD 3.54, presurgical) to 28.33 cm3 (SD 3.64, postsurgical, t = 5.00, df = 95.00; p < 0.001), resulting in a mean volume difference (planned vs. postop) of less than 1 cm3. A 3D analysis of the color mapping showed minor deviations compared to the mirrored unaffected side. The results suggested that primary reconstruction in complex orbital wall fractures can be routinely achieved with a high degree of accuracy by using selective laser melted orbital PSIs.

Keywords: 3D mesh; customized implant; intraoperative navigation; orbital reconstruction; orbital wall fracture; selective laser melting.

Figure 1

A selective laser melted patient-specific implant designed for the left orbit, two wall reconstruction. A horizontal drainage system is incorporated throughout. Navigational landmarks and guides are provided to facilitate implant placement with intraoperative navigation. Screw holes are placed anteriorly for fixation to the inferior orbital rim.

Figure 2

Intraoperative navigation used to confirm correct implant position. (Upper left): pointer resting on a navigational landmark of the PSI. (Upper right, Lower right and left): screenshots showing position of pointer in axial, sagittal and coronal views (tip of pointer is represented by the centre of the green crosshairs).

Figure 3

(Upper left): screenshot showing pointer has reached the navigation landmark. (Upper right, Lower right and left): screenshots showing position of pointer in axial, sagittal and coronal views (tip of pointer is represented by the centre of the green crosshairs).

Figure 4

Bar graph showing the postoperative angular deviation from the unaffected orbit (planned reconstruction).