Background: Lateral mass screw fixation with plates or rods has become the standard method of posterior cervical spine fixation and stabilization for a variety of surgical indications. Despite ubiquitous usage, the safety and efficacy of this technique have not yet been established sufficiently to permit “on-label” U.S. Food and Drug Administration approval for lateral mass screw fixation systems. The purpose of this study was to describe the safety profile and effectiveness of such systems when used in stabilizing the posterior cervical spine.
Methods: A systematic search was conducted in MEDLINE and the Cochrane Collaboration Library for articles published from January 1, 1980, to December 1, 2011. We included all articles evaluating safety and/or clinical outcomes in adult patients undergoing posterior cervical subaxial fusion utilizing lateral mass instrumentation with plates or rods for degenerative disease (spondylosis), trauma, deformity, inflammatory disease, and revision surgery that satisfied our a priori inclusion and exclusion criteria.
Results: Twenty articles (two retrospective comparative studies and eighteen case series) satisfied the inclusion and exclusion criteria and were included. Both of the comparative studies involved comparison of lateral mass screw fixation with wiring and indicated that the risk of complications was comparable between treatments (range, 0% to 7.1% compared with 0% to 6.3%, respectively). In one study, the fusion rate reported in the screw fixation group (100%) was similar to that in the wiring group (97%). Complication risks following lateral mass screw fixation were low across the eighteen case series. Nerve root injury attributed to screw placement occurred in 1.0% (95% confidence interval, 0.3% to 1.6%) of patients. No cases of vertebral artery injury were reported. Instrumentation complications such as screw or rod pullout, screw or plate breakage, and screw loosening occurred in <1% of the screws inserted. Fusion was achieved in 97.0% of patients across nine case series.
Conclusions: The risks of complications were low and the fusion rate was high when lateral mass screw fixation was used in patients undergoing posterior cervical subaxial fusion. Nerve root injury attributed to screw placement occurred in only 1% of 1041 patients. No cases of vertebral artery injury were identified in 758 patients. Screw or rod pullout, screw or plate breakage, and screw loosening occurred in <1% of the screws inserted.
Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
1Silicon Valley Spine Institute, 221 East Hacienda Avenue, Suite A, Campbell, CA 95008
2The Rothman Institute, 925 Chestnut Street, 5th Floor, Philadelphia, PA 19107-4216
3Department of Neurosurgery, University of Utah, Health Science Center, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132
4Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, 601 North Caroline Street, JHOC 5244, Baltimore, MD 21287
5Indiana Spine Group, 13225 North Meridian Street, Carmel, IN 46032-5480
6Department of Orthopaedics, University of Maryland Medical System, 22 South Greene Street, Suite 11 SB, Baltimore, MD 21201
7Spectrum Research, Inc., 705 South 9th Street, Suite 203, Tacoma, WA 98405