Safety evaluation of freehand lateral mass screw fixation in the subaxial cervical spine: Evaluation of 1256 screws

Hak Sun Kim, Kyung Soo Suk, Seong Hwan Moon, Hwan Mo Lee, Kyung Chung Kang, Sang Hun Lee, Jin Soo Kim

Research output: Contribution to journalArticle

Abstract

STUDY DESIGN.: Prospective study.

OBJECTIVE.: To evaluate the safety of the lateral mass screw (LMS) fixation.

SUMMARY OF BACKGROUND DATA.: LMS fixation has been known to have risk of injury to vertebral artery, nerve root, or facet joints.

METHODS.: A consecutive series of 178 patients undergoing planned LMS fixation were studied. Screw fixation was performed using the freehand technique. Entry point of screws was 2-mm medial from the center of the lateral mass. Planned divergent angle of the screw was 30. Bicortical fixation was tried in all cases. After the surgery, all patients underwent 3-dimensional computed tomographic scan of the cervical spine. We checked the number of screws in each level, divergent angle of the screws, and violation of foramen transversarium (FT), intervertebral foramen, or facet joint by screws. A reliability test was performed.

RESULTS.: Total 1256 screws were fixed with 269 at C3, 318 at C4, 331 at C5, and 338 screws at C6. Mean divergent angle of the screws were 34.7/33.1 at C3, 33.9 /32.1 at C4, 34.7/32.7 at C5, and 33.6/30.7 at C6. Incidence of FT violation was 0.876%. FT violation was most common at C6 (6/11 violations). Mean divergent angle in cases of FT violation was 15.0 and was significantly smaller than that of safe cases. There was no injury to vertebral artery. There was no violation of intervertebral foramen. Incidence of facet violation was 1.433%. Seventeen facet violations were within fusion segment. Only 1 screw violated healthy facet. Facet violation was most common at C3 (12/18 violations).

CONCLUSION.: LMS fixation is a safe stabilizing technique with very low incidence of violation of FT, intervertebral foramen, and facet. There is a possibility of FT violation if the divergent angle was small. FT violation was most common at C6. Facet violation was most common at C3.

Original languageEnglish (US)
Pages (from-to)2-5
Number of pages4
JournalSpine
Volume40
Issue number1
DOIs
StatePublished - Jan 1 2015
Externally publishedYes

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Zygapophyseal Joint
Spine
Vertebral Artery
Safety
Incidence
Wounds and Injuries
Prospective Studies

Keywords

  • cervical spine
  • complications
  • facet injury
  • freehand
  • lateral mass screw
  • nerve root injury
  • posterior surgery
  • safety
  • vertebral artery injury

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Clinical Neurology

Cite this

Safety evaluation of freehand lateral mass screw fixation in the subaxial cervical spine : Evaluation of 1256 screws. / Kim, Hak Sun; Suk, Kyung Soo; Moon, Seong Hwan; Lee, Hwan Mo; Kang, Kyung Chung; Lee, Sang Hun; Kim, Jin Soo.

In: Spine, Vol. 40, No. 1, 01.01.2015, p. 2-5.

Research output: Contribution to journalArticle

Kim, Hak Sun ; Suk, Kyung Soo ; Moon, Seong Hwan ; Lee, Hwan Mo ; Kang, Kyung Chung ; Lee, Sang Hun ; Kim, Jin Soo. / Safety evaluation of freehand lateral mass screw fixation in the subaxial cervical spine : Evaluation of 1256 screws. In: Spine. 2015 ; Vol. 40, No. 1. pp. 2-5.
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abstract = "STUDY DESIGN.: Prospective study.OBJECTIVE.: To evaluate the safety of the lateral mass screw (LMS) fixation.SUMMARY OF BACKGROUND DATA.: LMS fixation has been known to have risk of injury to vertebral artery, nerve root, or facet joints.METHODS.: A consecutive series of 178 patients undergoing planned LMS fixation were studied. Screw fixation was performed using the freehand technique. Entry point of screws was 2-mm medial from the center of the lateral mass. Planned divergent angle of the screw was 30. Bicortical fixation was tried in all cases. After the surgery, all patients underwent 3-dimensional computed tomographic scan of the cervical spine. We checked the number of screws in each level, divergent angle of the screws, and violation of foramen transversarium (FT), intervertebral foramen, or facet joint by screws. A reliability test was performed.RESULTS.: Total 1256 screws were fixed with 269 at C3, 318 at C4, 331 at C5, and 338 screws at C6. Mean divergent angle of the screws were 34.7/33.1 at C3, 33.9 /32.1 at C4, 34.7/32.7 at C5, and 33.6/30.7 at C6. Incidence of FT violation was 0.876{\%}. FT violation was most common at C6 (6/11 violations). Mean divergent angle in cases of FT violation was 15.0 and was significantly smaller than that of safe cases. There was no injury to vertebral artery. There was no violation of intervertebral foramen. Incidence of facet violation was 1.433{\%}. Seventeen facet violations were within fusion segment. Only 1 screw violated healthy facet. Facet violation was most common at C3 (12/18 violations).CONCLUSION.: LMS fixation is a safe stabilizing technique with very low incidence of violation of FT, intervertebral foramen, and facet. There is a possibility of FT violation if the divergent angle was small. FT violation was most common at C6. Facet violation was most common at C3.",
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T1 - Safety evaluation of freehand lateral mass screw fixation in the subaxial cervical spine

T2 - Evaluation of 1256 screws

AU - Kim, Hak Sun

AU - Suk, Kyung Soo

AU - Moon, Seong Hwan

AU - Lee, Hwan Mo

AU - Kang, Kyung Chung

AU - Lee, Sang Hun

AU - Kim, Jin Soo

PY - 2015/1/1

Y1 - 2015/1/1

N2 - STUDY DESIGN.: Prospective study.OBJECTIVE.: To evaluate the safety of the lateral mass screw (LMS) fixation.SUMMARY OF BACKGROUND DATA.: LMS fixation has been known to have risk of injury to vertebral artery, nerve root, or facet joints.METHODS.: A consecutive series of 178 patients undergoing planned LMS fixation were studied. Screw fixation was performed using the freehand technique. Entry point of screws was 2-mm medial from the center of the lateral mass. Planned divergent angle of the screw was 30. Bicortical fixation was tried in all cases. After the surgery, all patients underwent 3-dimensional computed tomographic scan of the cervical spine. We checked the number of screws in each level, divergent angle of the screws, and violation of foramen transversarium (FT), intervertebral foramen, or facet joint by screws. A reliability test was performed.RESULTS.: Total 1256 screws were fixed with 269 at C3, 318 at C4, 331 at C5, and 338 screws at C6. Mean divergent angle of the screws were 34.7/33.1 at C3, 33.9 /32.1 at C4, 34.7/32.7 at C5, and 33.6/30.7 at C6. Incidence of FT violation was 0.876%. FT violation was most common at C6 (6/11 violations). Mean divergent angle in cases of FT violation was 15.0 and was significantly smaller than that of safe cases. There was no injury to vertebral artery. There was no violation of intervertebral foramen. Incidence of facet violation was 1.433%. Seventeen facet violations were within fusion segment. Only 1 screw violated healthy facet. Facet violation was most common at C3 (12/18 violations).CONCLUSION.: LMS fixation is a safe stabilizing technique with very low incidence of violation of FT, intervertebral foramen, and facet. There is a possibility of FT violation if the divergent angle was small. FT violation was most common at C6. Facet violation was most common at C3.

AB - STUDY DESIGN.: Prospective study.OBJECTIVE.: To evaluate the safety of the lateral mass screw (LMS) fixation.SUMMARY OF BACKGROUND DATA.: LMS fixation has been known to have risk of injury to vertebral artery, nerve root, or facet joints.METHODS.: A consecutive series of 178 patients undergoing planned LMS fixation were studied. Screw fixation was performed using the freehand technique. Entry point of screws was 2-mm medial from the center of the lateral mass. Planned divergent angle of the screw was 30. Bicortical fixation was tried in all cases. After the surgery, all patients underwent 3-dimensional computed tomographic scan of the cervical spine. We checked the number of screws in each level, divergent angle of the screws, and violation of foramen transversarium (FT), intervertebral foramen, or facet joint by screws. A reliability test was performed.RESULTS.: Total 1256 screws were fixed with 269 at C3, 318 at C4, 331 at C5, and 338 screws at C6. Mean divergent angle of the screws were 34.7/33.1 at C3, 33.9 /32.1 at C4, 34.7/32.7 at C5, and 33.6/30.7 at C6. Incidence of FT violation was 0.876%. FT violation was most common at C6 (6/11 violations). Mean divergent angle in cases of FT violation was 15.0 and was significantly smaller than that of safe cases. There was no injury to vertebral artery. There was no violation of intervertebral foramen. Incidence of facet violation was 1.433%. Seventeen facet violations were within fusion segment. Only 1 screw violated healthy facet. Facet violation was most common at C3 (12/18 violations).CONCLUSION.: LMS fixation is a safe stabilizing technique with very low incidence of violation of FT, intervertebral foramen, and facet. There is a possibility of FT violation if the divergent angle was small. FT violation was most common at C6. Facet violation was most common at C3.

KW - cervical spine

KW - complications

KW - facet injury

KW - freehand

KW - lateral mass screw

KW - nerve root injury

KW - posterior surgery

KW - safety

KW - vertebral artery injury

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