RESUMEN
【Objective】 To investigate the feasibility of full-endoscopic posterolateral odontoidectomy through morphological analysis and cadaver specimen surgery. 【Methods】 We collected the DICOM data of 20 normal cervical CT patients （10 males and 10 females） from the PACS Image Library of our hospital. The Mimics software was used for cervical CT reconstruction and anatomical measurements were made to measure the maximum sagittal diameter， coronal diameter and height of the odontoid process. The C1 lateral mass could provide the maximum working height and width of endoscopic operation with a diameter of 7 mm， as well as the angle between the anchor point of C1 lateral mass and the notch on both sides of the odontoid process. The feasibility of endoscopic surgery was analyzed based on the measured data. The fresh frozen corpse was used for the operation in prone position under the guidance of C-arm. Kirschner wire was anchored at the midpoint of the lower surface of the C1 lateral mass. Part of the C1 lateral mass was removed by the grinding drill and endoscopic tools， and then the odontoid process and adjacent ligaments were removed. 【Results】 The maximum sagittal diameter， coronal diameter and height of the odontoid process were （11.73±0.74）mm， （10.97±0.71）mm and （14.51±0.91）mm， respectively. The working height and width of the C1 lateral mass were （13.53±0.57）mm and （10.00±1.27）mm， respectively. The angle between the anchor point and the double-edge notch of the odontoid process was （28.3±3.1）°， with no statistical difference between the male and female patients （P>0.05）. All the measurements met the requirements of 7 mm endoscopic implantation and surgical operation， and the space for swing could be provided for complete or partial removal of the odontoid process to meet the requirements of ventral spinal decompression. In cadaver surgery， a fully endoscopic posterolateral approach enabled complete removal of the odontoid process by grinding part of the C1 lateral mass. Postoperative cervical CT confirmed that the odontoid process had been completely resected， and there were no signs of dural sac or vertebral artery injury. 【Conclusion】 The odontoid process can be completely resected through a posterolateral endoscopic approach via the lateral mass approach of C1， providing a new surgical method for clinical odontoidectomy to decompress the spinal cord in craniovertebral junction.