"M" line: New anatomical landmark for the maxillary sinus natural ostium.

OBJECTIVE

Describe a reliable anatomical landmark that can be used to locate the maxillary sinus natural ostium (MSNO) during endoscopic surgery, even if the uncinate process is preserved.

DESIGN

Descriptive anatomical.

SETTING

An anatomical and radiological study was performed to evaluate the consistency of the landmark, denominated "M" line.

SUBJECTS AND

METHODS

Dissections were performed in 57 cadaver heads (114 sides). In addition, 73 computerised tomography (CT) scans (146 sides) of patients with chronic inflammatory sinonasal disease were analysed using a three-dimensional (3D) reconstruction computer program.

RESULTS

The "M" line crossed the MSNO in 112 dissected sides (98.2%) and 140 sides at CT 3D reconstruction (95.9%).

CONCLUSION

The "M" line is a reliable anatomical landmark for predicting MSNO location. As such, it could improve and facilitate endoscopic sinus surgery, using traditional, minimally invasive or uncinate preserving techniques.