What Are Risk Factors for Adjacent Segment Disease?

Higher preoperative body mass index (BMI), floating fusion, superior facet joint violation and decompression outside fusion construct are all important risk factors for adjacent segment disease following lumbar fusion, according to a new study.

Adjacent segment disease is a known potential complication following lumbar spinal fusion, but still little is understood about the demographic, clinical and operative risk factors associated with it.

In the study, “Demographic, Clinical, and Operative Risk Factors Associated with Post-Operative Adjacent Segment Disease in Patients Undergoing Lumbar Spine Fusions: A Systematic Review and Meta-Analysis,” the researchers conducted a systematic review to determine what those risk factors may be.

The study was published online on December 8, 2021 in The Spine Journal.

The researchers identified 35 studies from PubMed, Embase, Medline, Scopus and Cochrane library databases with a total of 7,374 patients who had lumbar spine fusion. From these studies which were published up until December 2019, they analyzed all possible demographic, clinical and operative risk factors for adjacent segment disease after lumbar fusion.

The methodological index for non-randomized studies criteria was used to assess the methodological quality of the included studies.

Overall, 35 studies were included in the qualitative analysis and 22 in the meta-analyses. The mean quality score was 12.4 ±1.9 (range, 8-16) points.

The most significant risk factors were higher preoperative body mass index (mean difference [MD] = 1.97 kg/m2; 95% confidence interval [CI] = 1.49 to 2.45; p < 0.001), floating fusion (Odds ratio [OR] = 1.78; 95% CI = 1.32 to 2.41; p <0.001), superior facet joint violation (OR = 10.43; 95% CI = 6.4 to 17.01; p <0.001), and decompression outside fusion construct (OR = 1.72; 95% CI = 1.25 to 2.37; p <0.001).

“The overall level of evidence was low to very low. Higher preoperative BMI, floating fusion, superior facet joint violation, and decompression outside fusion construct are significant risk factors of development of adjacent segment disease following lumbar fusion surgeries,” the researchers wrote.

The study authors include Mohamed Kamal Mesregah, M.D., Brandon Yoshida, Nassim Lashkari, Aidin Abedi, M.D., Patrick Hsieh, M.D., Jeffrey Wang, M.D., Zorica Buser., and AO Spine Knowledge Forum Degenerative of Keck School of Medicine, University of Southern California.

Hans-Joerg Meisel, M.D., of Bermannstrost Hospital in Halle Germany, Ashish Divan, M.D., of St. George Hospital, University of New South Wales in Australia and S. Tim Yoon, M.D., of Emory Spine Center, Emory University in Atlanta, Georgia also were involved in the study.