These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: An anatomic study to determine the optimal entry point, medial angles, and effective length for safe fixation using posterior C1 lateral mass screws.
    Author: Hu Y, Dong WX, Spiker WR, Yuan ZS, Sun XY, Zhang J, Xie H, Albert TJ.
    Journal: Spine (Phila Pa 1976); 2015 Feb 15; 40(4):E191-8. PubMed ID: 25398038.
    Abstract:
    STUDY DESIGN: Anatomic study of the C1 lateral mass using fine-cut computed tomographic scans and Mimics software. OBJECTIVE: To investigate the optimal entry point, medial angles, and effective length for safe fixation using posterior C1 lateral mass screws. SUMMARY OF BACKGROUND DATA: Placing posterior C1 lateral mass screws is technically demanding, and a misplaced screw can result in injury to the vertebral artery, spinal cord, or internal carotid artery. Although various insertion angles have been proposed for posterior C1 lateral mass screw, no clear consensus has been reached on the ideal medial angle of the C1 lateral mass. METHODS: The C1 lateral masses were evaluated using computed tomographic scans and Mimics software in 70 patients. The effective width and effective screw length of posterior C1 lateral mass screws were measured at different medial angulations relative to the midline sagittal plane. The height (H) for screw entry point on the posterior surface of C1 lateral mass and the distance (D) between screw entry point and the intersection of the midline sagittal plane and the posterior arch of the atlas were also measured. RESULTS: The mean height (H) for screw entry on the posterior surface of the lateral mass was 4.25 mm, the mean distance (D) between screw entry point and the intersection of the midsagittal plane and the posterior arch of the atlas was 27.62 mm. The optimal medial angle was 20.86° with a corresponding effective width of 10.56 mm and effective screw length of 21.87 mm. CONCLUSION: This study helps to define the specific anatomy related to C1 posterior lateral mass screw placement in an effort to facilitate instrumentation. However, variation is seen in lateral mass anatomy, and this study must be combined with customized surgical planning that includes advanced imaging for safe and effective instrumentation. LEVEL OF EVIDENCE: 1.
    [Abstract] [Full Text] [Related] [New Search]