The ethmo-frontal angle: a new anatomic and radiologic landmark for use in sinus surgery.

Objective: To identify anatomic and radiologic landmarks to assist with frontal sinus surgery.

Study Design: Retrospective review.

Subjects And Methods: Sinus CT scans of 50 patients were evaluated with respect to a new radiologic and anatomic landmark, the ethmo-frontal angle (EFA).

Results: Right-sided EFA ranged from 135 to 171 degrees. Left-sided EFA ranged from 136 to 167 degrees. Measurements of both sides displayed a normal distribution. When right and left sides within individuals were compared, there was no correlation to indicate a high degree of variation between any particular patient's right and left side EFA.

Conclusion: The EFA is a new landmark to assist otolaryngologists during surgery on and around the frontal sinus. Normal values for this angle have been presented. Surgeons should be aware that asymmetry in a patient's EFA is common, and each side should be examined individually.