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Transpedicular screw violation of facet joint could lead to adjacent segment degeneration
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SAN DIEGO — Facet joint violation after transpedicular instrumentation is one of the risk factors for adjacent segment degeneration in patients undergoing lumbar fusion, according to a study presented here.
 Hyoung Yeon Seo |
Hyoung Yeon Seo, MD, presented his group’s findings at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons.
“We can find many possible reasons for the development of adjacent segment degeneration after lumbar spinal fusion, but a course is not yet clear,” Seo said.
A randomized, controlled study
Seo and his colleagues randomized 75 patients undergoing lumbar fusion into two groups. The adjacent segment degeneration group included 35 patients who received lumbar fusion in the superior segment because of adjacent segment degeneration after one- or two-segment fusions of the lower lumbar spine. Average interval between first surgery and superior segment surgery was 8.3 years. The control group for the study included 40 randomly selected patients who received lumbar fusion and had no complications for an average of 7 years.
To facilitate comparisons, the group reviewed the patients’ CT scans where both non-fused facet joints and proximal screws were visible. The investigators developed a point system wherein no points were given when the screw clearly avoided the facet joint, one point was given when the screw head was either in contact with – or suspected to have invaded – the facet joint, and two points when the screw had clearly invaded the facet joint. Left and right sides were evaluated, and a total sum of points was calculated.
Demographics known to increase the risk of adjacent segment degeneration were similar between the groups.
A potential factor
Seo reported that his group found the average degree of facet joint invasion at the superior adjacent segment after transpedicular instrumentation was 1.8 for the adjacent segment degeneration group — a result significantly higher than that of the control group, whose average was 1.1.
“The facet joint violation by transpedicular screw could be one of the factors for the development of adjacent segment degeneration after lumbar spinal fusion,” Seo concluded, adding that surgeons should be more cautious when utilizing the transpedicular screw.
Reference:
- Seo HY, et al. Does the facet joint violation by transpedicular screw cause adjacent segment degradation? Paper 257. Presented at the 2011 Annual Meeting of the American Academy of Orthopaedic Surgeons. Feb. 15-19, 2011. San Diego.
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