Cadaveric morphometric analysis for atlantal lateral mass screw placement

Michael Y. Wang, Srinath Samudrala, Vincent C. Traynelis, Hoang N. Le, Daniel Kim, Edward C. Benzel, Volker K H Sonntag

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

OBJECTIVE: Atlantal lateral mass screws provide an alternative to C1/C2 transarticular screws and, in some cases, can obviate the need for extending a fusion to the occiput. For these reasons, C1 lateral mass screws are becoming increasingly popular. However, the critical local anatomy and unfamiliarity with this new technique can make C1 screw placement more challenging. METHODS: Morphometric analysis was performed on 74 cadaveric spines obtained from the Department of Anatomy at the Keck School of Medicine, University of Southern California. Critical measurements were determined for screw entry points, trajectories, and lengths for application of the technique described by Harms and Melcher. RESULTS: The mean height and width for screw entry on the posterior surface of the lateral mass were 3.9 and 7.3 mm, respectively. The maximum medialized screw trajectory ranged from 25 to 45 degrees (mean, 33 degrees). The mean maximal screw length to obtain bicortical purchase was 22.5 mm, and the mean minimum screw depth was 14.4 mm. Screw depths varied on the basis of the entry point, trajectory, and vertebral morphology. The overhang of the posterior arch averaged 11.4 mm (range, 6.9-17 mm). All specimens could accommodate 3.5-mm lateral mass screws bilaterally with proper preparation of the entry site. CONCLUSION: Significant variations in the morphology of C1 exist. However, the large size of the atlantal lateral mass makes screw placement forgiving. Preoperative computed tomographic scans and intraoperative fluoroscopy are useful in guiding proper screw placement. Close attention should be paid to preparation of the screw entry site.

Original languageEnglish
Pages (from-to)1436-1440
Number of pages5
JournalNeurosurgery
Volume54
Issue number6
StatePublished - Jun 1 2004
Externally publishedYes

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Anatomy
Fluoroscopy
Spine
Medicine

Keywords

  • Anatomy
  • Atlas
  • Cervical spine
  • Occipitocervical fusion

ASJC Scopus subject areas

  • Clinical Neurology
  • Surgery

Cite this

Wang, M. Y., Samudrala, S., Traynelis, V. C., Le, H. N., Kim, D., Benzel, E. C., & Sonntag, V. K. H. (2004). Cadaveric morphometric analysis for atlantal lateral mass screw placement. Neurosurgery, 54(6), 1436-1440.

Cadaveric morphometric analysis for atlantal lateral mass screw placement. / Wang, Michael Y.; Samudrala, Srinath; Traynelis, Vincent C.; Le, Hoang N.; Kim, Daniel; Benzel, Edward C.; Sonntag, Volker K H.

In: Neurosurgery, Vol. 54, No. 6, 01.06.2004, p. 1436-1440.

Research output: Contribution to journalArticle

Wang, MY, Samudrala, S, Traynelis, VC, Le, HN, Kim, D, Benzel, EC & Sonntag, VKH 2004, 'Cadaveric morphometric analysis for atlantal lateral mass screw placement', Neurosurgery, vol. 54, no. 6, pp. 1436-1440.
Wang MY, Samudrala S, Traynelis VC, Le HN, Kim D, Benzel EC et al. Cadaveric morphometric analysis for atlantal lateral mass screw placement. Neurosurgery. 2004 Jun 1;54(6):1436-1440.
Wang, Michael Y. ; Samudrala, Srinath ; Traynelis, Vincent C. ; Le, Hoang N. ; Kim, Daniel ; Benzel, Edward C. ; Sonntag, Volker K H. / Cadaveric morphometric analysis for atlantal lateral mass screw placement. In: Neurosurgery. 2004 ; Vol. 54, No. 6. pp. 1436-1440.
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