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. 2016 Aug;10(4):705-10.
doi: 10.4184/asj.2016.10.4.705. Epub 2016 Aug 16.

Quantitative Anatomy of C7 Vertebra in Southern Chinese for Insertion of Lateral Mass Screws and Pedicle Screws

Michael Siu Hei Tse  1 , Chi Hin Chan  2 , Kam Kwong Wong  1 , Wing Cheung Wong  1
Affiliations

Quantitative Anatomy of C7 Vertebra in Southern Chinese for Insertion of Lateral Mass Screws and Pedicle Screws

Michael Siu Hei Tse et al. Asian Spine J. 2016 Aug.

Abstract

Study design: Retrospective study.

Purpose: To analyze the quantitative anatomy of C7 vertebra for insertion of lateral mass screws and pedicle screws in Southern Chinese patients.

Overview of literature: C7 lateral mass is smaller when compared to other subaxial cervical levels, which limits the length of lateral mass screws that can be used. Some studies have suggested pedicle screws for better fixation. But, this option is limited by the narrow pedicle width.

Methods: We have obtained computed tomography (CT) cervical spine data in 0.625 mm slices from our radiology department. The patients were adults. CTs were from May to August, 2015. The lateral mass screw length was measured using Margerl's technique and pedicle width and pedicle screw trajectory were determined in three-dimensional reformated images.

Results: CT scans of cervical spines of 94 patients were obtained and 188 lateral masses and pedicles of C7 vertebrae were measured. The mean lateral mass screw length was 13.2 mm (standard deviation [SD] 1.6 mm), mean outer pedicle width was 5.9 mm (SD 1.0 mm) and mean pedicle screw trajectory was 29.4 degrees (SD 3.6 degrees). Most (91.0%) of the pedicles had an outer diameter ≥4.5 mm.

Conclusions: The mean lateral mass screw length was longer when compared with other similar studies, while the mean outer pedicle width was narrower. Nearly 10% of the pedicles were unable to accommodate 3.5 mm screws. These findings favor the use of lateral mass screws to provide a safe and stable fixation for C7 vertebrae in Southern Chinese patients, while the final choice of fixation method should only be confirmed after careful preoperative planning with CT scan.

Keywords: Cervicalvertebrae; Instrumentation; Pedicle screws.

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Conflict of interest statement

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1
Fig. 1. (A–C) Measurement of lateral mass screw length.
Fig. 2
Fig. 2. (A, B) Measurement of pedicle width and trajectory.
See this image and copyright information in PMC

References

    1. Jeanneret B, Magerl F, Ward EH, Ward JC. Posterior stabilization of the cervical spine with hook plates. Spine (Phila Pa 1976) 1991;16(3 Suppl):S56–S63. - PubMed
    1. Abdullah KG, Nowacki AS, Steinmetz MP, Wang JC, Mroz TE. Factors affecting lateral mass screw placement at C-7. J Neurosurg Spine. 2011;14:405–411. - PubMed
    1. Karaikovic EE, Daubs MD, Madsen RW, Gaines RW., Jr Morphologic characteristics of human cervical pedicles. Spine (Phila Pa 1976) 1997;22:493–500. - PubMed
    1. Stemper BD, Marawar SV, Yoganandan N, Shender BS, Rao RD. Quantitative anatomy of subaxial cervical lateral mass: an analysis of safe screw lengths for Roy-Camille and magerl techniques. Spine (Phila Pa 1976) 2008;33:893–897. - PubMed
    1. Jang WY, Kim IS, Lee HJ, Sung JH, Lee SW, Hong JT. A computed tomography-based anatomic comparison of three different types of C7 posterior fixation techniques: pedicle, intralaminar, and lateral mass screws. J Korean Neurosurg Soc. 2011;50:166–172. - PMC - PubMed

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