# The Intraoperative Fabrication of PMMA Patient-Specific Enophthalmos Wedges and Onlays for Post-Traumatic OZC Reconstruction

## TL;DR

This paper introduces a new surgical method using 3D-printed molds and PMMA to correct eye socket deformities caused by trauma.

## Contribution

A novel intraoperative technique using 3D-printed patient-specific molds and PMMA for reconstructing post-traumatic orbital deformities.

## Key findings

- PMMA wedges and onlays fabricated with 3D-printed molds effectively corrected post-traumatic enophthalmos and hypoglobus.
- Good subjective cosmetic results and functional improvements were reported by patients at a mean follow-up of 19.1 months.
- 3D-CT confirmed correct placement of implants in two patients.

## Abstract

Objective: Trauma is a leading cause of enophthalmos, typically resulting from an increase in the volume of the bony orbit. The general consensus is that post-traumatic primary deformity repair should aim to restore the premorbid volume, shape, and cosmesis of the orbitozygomatic complex (OZC). This study aims to utilise novel three-dimensional (3D) printed patient-specific moulds to intraoperatively fabricate enophthalmos wedges and onlays using polymethylmethacrylate (PMMA) bone cement to reconstruct the OZC. Methods: A total of seven patients underwent digital surgical planning using Freeform software to virtually correct orbitozygomatic complex deformities guided by a design algorithm. Three-dimensionally printed nylon patient-specific moulds were used intraoperatively to fabricate enophthalmos wedges and/or onlays using an industry-standard PMMA bone cement. Clinical examination and application of the proposed design algorithm determined that enophthalmos wedges were indicated for four patients, with one also requiring an onlay; and periorbital onlays were required for the three remaining patients. Results: Hertel exophthalmometry at a mean follow-up of 19.1 months demonstrated good outcomes in the correction of post-traumatic enophthalmos and hypoglobus and with patients reporting good subjective cosmetic results. Patients 5 and 7 had follow-up three-dimensional computed tomography (3D-CT) to confirm correct placement. Conclusion: The use of patient-specific PMMA wedges and onlays, fabricated intraoperatively with the aid of 3D-printed moulds, offers a reliable and effective approach for correcting post-traumatic enophthalmos and hypoglobus. This method allows for the restoration of orbital volume and anatomical contours, addressing both functional and aesthetic concerns. Our results demonstrate that this technique yields favourable outcomes.