Abstract
Purpose::
The complex nature of bony orbital fractures and their impact upon orbital soft tissue structure and visual function presents a particular challenge to the orbital surgeon. Current orbital implants can be limited by their thickness, memory, tissue ingrowth or tissue cicatrisation.Based on the measurements of 40 cadaver orbits, we designed a custom-shaped, porous polyethylene-encased titanium mesh implant for use in internal orbital fractures with notches to respect the optic canal and nasolacrimal fossa.
Methods::
11 orbits with either combined orbital floor and medial wall fractures (8) or floor fractures with inadequate posterior support (3) underwent repair between 5/05 and 8/06. The patients were followed postoperatively for a minimum of three months. Ocular position and function were evaluated at each visit. CT of the orbits was obtained to verify implant position.
Results::
Each implant had to be trimmed and bent in order to conform to the unique bony fracture pattern and intact bony ledges. The porous polyethylene covering resulted in smoothly trimmed edges, and the titanium mesh had minimal structural memory. These two advantages facilitated the ease of placement.Postoperatively, none of the implants required removal or repositioning. CT verified correct implant placement in all cases. No globe dystopia or relative enophthalmos (>2 mm) was noted in any case postoperatively. No new ocular dysmotility developed postoperatively.
Conclusions::
Porous polyethylene-covered titanium mesh results in increased implant strength and decreased memory. The increased strength allows a thinner implant that minimizes abaxial displacement. The lack of memory associated with bending allows greater implant stability. The implant also has an impermeable barrier surface available on either or both sides. The barrier surface may inhibit adhesions from orbital soft tissue, while a barrier-free surface facing the sinus mucosa may vascularize, which offers additional implant stability. Finally, the titanium mesh allows postoperative imaging to verify implant placement.Uncomplicated, single orbital wall fractures may be successfully repaired with most currently available implant materials. However, in more complicated cases, such as combined orbital floor and medial wall fractures or floor fractures with inadequate posterior support, this custom-designed orbital implant provides a distinct advantage.
Keywords: orbit • trauma • anatomy