Use of a Low Profile Titanium Mesh in Orbital Reconstruction

Overview

In craniofacial trauma, the involvement of orbital structures is noted in up to 40% of cases (Ellis 1985). Post-traumatic orbital deformities caused by incorrect reconstruction of orbital dimensions are severe complications causing enophthalmos, diplopia and visual acuity disturbance. To prevent such complications, immediate repair of orbital injuries with the restoration of normal anatomy is indicated in orbital floor fractures. With the help of biodegradable implants small and medium-sized defects are easily managed (Büchel 2005, Lieger 2010). In extensive fractures however, only calvarian bone and titanium mesh considered to provide a sufficient support of the orbital content. Calvarial bone can be difficult to mould and to adapt to the form and size of the orbital lesion. In addition, donor site morbidity cannot be disregarded. Orbital reconstruction mesh on the other hand is always available and easier to apply. There are however important requirements for these meshes, such as biocompatibility, excellent stability, optimal adaptability and patient comfort. Recently, the company Medartis developed a titanium mesh featuring a low profile. In order to regain normal function, normal anatomy has to be re-established. It therefore seemed reasonable to assess an implant, which would facilitate orbital reconstruction without disturbing normal anatomy by its size, profile height or properties. The purpose of this study was to assess the use and accuracy of the low profile titanium mesh for primary internal orbital reconstruction.

Background Extensive bone loss after orbital trauma requires reconstruction to preserve ocular function and aesthetics. The optimal material for orbital reconstruction remains controversial. Today a multitude of both autogenous and alloplastic materials have been used for orbital reconstruction, including methylmethacrylate, Teflon, silicone, Supramid, Marlex, Silastic, gelatin film, bioactive glas, bone and cartilage (Haug 1999). The use of alloplastic materials has been tempered by complications such as infection, displacement and extrusion, fistula and cyst formation. During the past two decades, autogenous bone grafts have become increasingly popular for orbital reconstruction. Unfortunately, problems with bone grafts can occur and include unpredictable rates of bone resorption and the risk of subsequent dystopia or delayed enophthalmos, donor site complication, time consumption with harvesting and variable graft thickness and irregularities along with difficulty in graft contouring (Park 2001). These problems have revived interest in alloplastic alternatives, particularly in titanium and its alloys (Park 2001). Titanium shows a low infection rate, related in part to its excellent biocompatibility, which manifests as osseointegration. This circumstance is thought to lessen the rate of infection. During the past decade, different studies have examined a titanium meshes for orbital repair. Plates used in these studies demonstrate a minimum profile height of 0.25mm. Objective Assess the use and accuracy of the low profile titanium mesh for primary internal orbital reconstruction Methods Clinical assessment prior to operation by a maxillofacial surgeon with regards to bone and soft tissue lesions as well as concomitant injuries. An ophthalmologist then assessed eye lesions and quantified eye mobility (in mm), bulb positioning (Hertel's exophthalmometry, in mm) as well as the field of binocular vision (Goldmann perimetry, in % of the total). Preoperative 1mm CT-scans were obtained to analyse size and location of the defect as well as extend of muscle entrapment. The fractures were classified according to the scores introduced by Jaquiery(Jaquiery 2007). Follow up by at 2, 6 and 12 weeks after the operation (assessments see above), including postoperative CT-scan within 12 weeks. Volume analysis of CT comparing the two orbits (OsiriX Medical Image Software (Version 3.7.1, www.osirix-viewer.com).