[The anatomy study of the frontal beak approach of Draf II b frontal sinusotomy]

To investigate the possibility and anatomy landmark of the frontal beak approach of endoscopic frontal sinusotomy to the frontal sinus lesions.

(1)Twenty cases of frozen cadaveric head underwent spiral computed tomography scans. Then data were transferred into the Mimics image workstation to reorganize CT images in the coronal, sagittal, and axial planes. The anatomic parameters related to surgical approach points were measured, such as the distance between vertical plate of the middle turbinate and lamina papyracea and the thickness of the frontal beak. (2) 3D visual model of the frontal cell and the drainage way of the frontal sinus was produced with the application of Sinuses Trachea I software. (3)The endoscopic frontal sinus surgery were performed on 20 cases of subjects (objects)to find out the anatomy landmarks of the frontal beak approach, measure the parameters such as the distance between middle turbinate and lamina papyracea, and evaluate the potential surgical complications during operation.

(1)The frontal beak is a white bony arcs located at the attachment point of middle turbinate front inserted to the skull base. Its position was relatively constant, before frontal sinus above. (2)The distance between the middle turbinate vertical plate and lamina papyracea was (7. 61 ± 1. 34) mm. The thickness of the frontal beak in surgical approach was (3. 27 ± 0. 91) mm. (3) 3D visual structure of the frontal sinus and its ventilation pathway: the shape of unilateral frontal sinus looked like the cone, which was transited by the drainage pathway of the frontal sinus. The front part of the frontal sinus ostium is surrounded by the frontal beak. The upper part the frontal beak connected to the floor of the frontal sinus. (4) Frontal beak can be used as an landmark of frontal beak approach in the endoscopic frontal sinus surgery. But the lateral view of frontal sinus still was limited in the operation.

The endoscopic frontal sinus surgery with the approach of the frontal beak is easy to operate and learn. In this area between the double "L", the operation is safe.