Does Sinus Surgery Increase the Risk of Orbital Fractures in Patients?

Abstract

IntroductionThe orbit is bounded by thin bony walls that are prone to fracture in facial trauma. Despite its thin nature, the medial orbital wall, or lamina papyracea, is less likely to fracture than the orbital floor. This may be due to the uncinate process of the ethmoid bone, as well as the ethmoid bulla, acting as buttresses for the medial orbital wall. What is not understood is how functional endoscopic sinus surgery (FESS), and its associated uncinectomy and ethmoidectomy, affect the fragility of the bony orbit. Resection of the uncinate process and ethmoid bulla, as well as skeletonization of the lamina papyracea, may predispose a patient to post‐surgical fractures. We hypothesize that FESS will decrease the force required to induce a fracture in the medial orbital wall.Objectives/MethodsThe objective of this study was to establish the force required to induce orbital fractures in cadaveric specimens, while evaluating the occurrence, severity and pattern of post‐surgery fractures. Using fixed (n=4) cadaveric heads, a pilot study was conducted to test the protocol and narrow the range of force required to produce orbital fractures. Subsequent studies will be performed using fresh‐frozen (n=8) cadaveric heads. FESS has been performed on one side of the head for each fresh‐frozen specimen, while the other side serves as control. Pre‐operative CT scans have been performed on all heads. Heads will be potted in 4″ PVC pipes, with dental cement, for stability during testing. Globes will be reinflated with a viscous sodium hyaluronate injectable for standardization of pressure, confirmed with a tonometer. An impactor mass of 1.356 kg will be dropped from varying heights onto the orbit to induce fractures. The force of impact will be measured, via accelerometer, to compare operated and non‐operated sides. Post‐operative fractures within the orbital wall will be detected via cone‐beam CT.ResultsPilot study results indicate that the force required to fracture the orbital floor is lower than the force required to fracture the medial orbital wall and these forces are in line with published values (orbital floor: ≥ 2.08 J; medial wall: ≥ 4.90 J). The post‐surgical force testing and scanning has not been completed at this time.Discussion/Future DirectionsThis is the first study to look at the effect of sinus surgery on orbital fracture risk in patients. Subsequent studies will analyze whether FESS decreases the force required to induce fractures of the medial orbital wall. As the prevalence of post‐FESS patients increases, it is important to understand how the bony alterations of sinus surgery affect the stability of the orbit in order to counsel patients appropriately and obtain informed consent.