The orbit first! A novel surgical treatment protocol for secondary orbitozygomatic reconstruction

Abstract

A novel surgical treatment sequence for secondary orbitozygomatic complex (OZC) reconstruction is described. Orbital reconstruction is performed before OZC repositioning. A surgical plan is made: the affected OZC is virtually osteotomized and aligned with a mirrored model of the unaffected OZC. A patient-specific implant (PSI) is designed for orbital reconstruction. Screw holes from the primary reconstruction are used for fixation. Primary screw hole positions at the repositioned OZC are embedded in the design, to guide OZC repositioning. A second patient-specific design is made for guidance at the zygomaticomaxillary buttress.

The workflow was utilized in two patients. The PSI was positioned using navigation feedback. After repositioning of the zygomatic complex, the screw hole positions at the infraorbital rim and zygomaticomaxillary buttress seemed to align perfectly: no screw hole adjustments were necessary. Minor deviations were seen between planned and acquired PSI position; the mean errors between planned and acquired OZC position were 1.5 and 1.2 mm.

Orbital reconstruction with a PSI before OZC repositioning ensures true-to-original orbital reconstruction. The use of old screw hole positions enables the PSI to be used as a static guide for OZC repositioning. The combination of static and dynamic guidance increases predictability in secondary OZC reconstruction.

Introduction

The goal of orbitozygomatic complex (OZC) fracture treatment is three-dimensional restoration of the disturbed anatomy and reconstruction of orbital volume (Kellman and Bersani, 2002, Buchanan et al., 2012, Liu et al., 2013). In case of a comminuted fracture or a combination of an OZC fracture with a naso-orbito-ethmoid fracture, accurate restoration of transversal dimensions and subsequent reconstruction of the orbit can be challenging (Kelley et al., 2007, Li et al., 2011, He et al., 2012, Liu et al., 2013). Possible sequelae of inaccurate repositioning of the zygomatic complex are hemifacial widening, malar flattening and enophthalmos (Westendorff et al., 2006, Kelley et al., 2007, Kaufman et al., 2008, Yu et al., 2010).

If secondary reconstruction is indicated, an osteotomy of the OZC may be performed in order to mobilize the OZC and move it to its anatomical position (Kellman and Bersani, 2002, Buchanan et al., 2012). Orbital reconstruction is generally performed after repositioning of the OZC and therefore depends on the realized position of the OZC. Secondary restoration of OZC architecture is acknowledged to be a difficult procedure: anatomical landmarks are frequently lost due to bone remodelling, an effort to reconstruct has already been undertaken and there is no guarantee of an optimal outcome of the secondary reconstruction (Watzinger et al., 1997, Kellman and Bersani, 2002, Westendorff et al., 2006, Kelley et al., 2007, Lu et al., 2012).

In this technical note, a treatment protocol is described for secondary orbitozygomatic reconstruction. The surgical sequence has been reversed: the orbital reconstruction is performed before repositioning of the OZC. A surgical plan is made, which utilizes patient-specific computer-aided designing. To perform orbital reconstruction and guide the OZC repositioning, a novel idea has been developed using the position of screw holes of the primary reconstruction. These screw holes are implemented in the design of a cutting guide, for accurate osteotomy, and two patient-specific implants. These modalities have been combined with intra-operative navigation.