Title
Fixation strength of unicortical versus bicortical C1-C2 transarticular screws
UMMS Affiliation
Department of Orthopedics and Physical Rehabilitation
Publication Date
2008-07-29
Document Type
Article
Subjects
*Bone Screws; Cadaver; Cervical Vertebrae; Equipment Design; Equipment Failure Analysis; Humans; *Materials Testing; *Shear Strength; Spinal Fusion; Stress, Mechanical
Disciplines
Orthopedics | Rehabilitation and Therapy
Abstract
BACKGROUND CONTEXT: The internal carotid artery and hypoglossal nerve lie over the anterior aspect of the lateral mass of the atlas and are at risk from bicortical C1-C2 transarticular screws. This has led to the recommendation for unicortical screws if the neurovascular structures are in close proximity to the proposed exit point. No data are available on strength of unicortical versus bicortical C1-C2 transarticular screws.
PURPOSE: To compare the biomechanical pullout strength of unicortical versus bicortical C1-C2 transarticular screws in a cadaveric model. STUDY DESIGN: Biomechanical study.
METHODS: Fifteen cervical spine specimens underwent axial pullout testing. A unicortical C1-C2 transarticular screw was placed on one side with a contralateral bicortical screw. Data were analyzed to reveal any significant differences in strength.
RESULTS: Mean pullout strength for the bicortical C1-C2 transarticular screws was 1,048.8 (+/-360.1) N versus 939.2 (+/-360.6) for unicortical screws (p=.22). There was no significant difference in the pullout strength of unicortical and bicortical screws.
CONCLUSIONS: In cases with satisfactory bone quality, it appears reasonable to use unicortical screws to avoid the risk of neurovascular injury from penetrating the anterior cortex of C1.
DOI of Published Version
10.1016/j.spinee.2007.02.008
Source
Spine J. 2008 Jul-Aug;8(4):661-5. Epub 2007 May 11. Link to article on publisher's site
Journal/Book/Conference Title
The spine journal : official journal of the North American Spine Society
Related Resources
PubMed ID
17526435
Repository Citation
Cyr, Steven J.; Currier, Bradford L.; Eck, Jason C.; Foy, Andrew; Chen, Qingshan; Larson, Dirk R.; Yaszemski, Michael J.; and An, Kai-Nan, "Fixation strength of unicortical versus bicortical C1-C2 transarticular screws" (2008). Orthopedics and Physical Rehabilitation Publications and Presentations. 50.
https://escholarship.umassmed.edu/ortho_pp/50