Diminishing Clinical Returns of Multilevel Minimally Invasive Lumbar Interbody Fusion

Peter G. Passias, Cole Bortz, Samantha R. Horn, Frank A. Segreto, Nicholas Stekas, David H. Ge, Haddy Alas, Christopher G. Varlotta, Nicholas J. Frangella, Renaud Lafage, Virginie Lafage, Leah Steinmetz, Dennis Vasquez-Montes, Bassel Diebo, Muhammad B. Janjua, Mohamed A. Moawad, Chloe Deflorimonte, Themistocles S. Protopsaltis, Aaron J. Buckland, Michael C. Gerling

Research output: Contribution to journalArticlepeer-review

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Study Design.Single institution retrospective clinical review.Objective.To investigate the relationship between levels fused and clinical outcomes in patients undergoing open and minimally invasive surgical (MIS) lumbar fusion.Summary of Background Data.Minimally invasive spinal fusion aims to reduce the morbidity associated with conventional open surgery. As multilevel arthrodesis procedures are increasingly performed using MIS techniques, it is necessary to weigh the risks and benefits of multilevel MIS lumbar fusion as a function of fusion length.Methods.Patients undergoing <4 level lumbar interbody fusion were stratified by surgical technique (MIS or open), and grouped by fusion length: 1-level, 2-levels, 3+ levels. Demographics, Charlson Comorbidity Index (CCI), surgical factors, and perioperative complication rates were compared between technique groups at different fusion lengths using means comparison tests.Results.Included: 361 patients undergoing lumbar interbody fusion (88% transforaminal, 14% lateral; 41% MIS). Breakdown by fusion length: 63% 1-level, 22% 2-level, 15% 3+ level. Op-time did not differ between groups at 1-level (MIS: 233min vs. Open: 227, P=0.554), though MIS at 2-levels (332min vs. 281) and 3+ levels (373min vs. 323) were longer (P=0.033 and P=0.231, respectively). While complication rates were lower for MIS at 1-level (15% vs. 30%, P=0.006) and 2-levels (13% vs. 27%, P=0.147), at 3+ levels, complication rates were comparable (38% vs. 35%, P=0.870). 3+ level MIS fusions had higher rates of ileus (13% vs. 0%, P=0.008) and a trend of increased adverse pulmonary events (25% vs. 7%, P=0.110). MIS was associated with less EBL at all lengths (all P<0.01) and lower rates of anemia at 1-level (5% vs. 18%, P<0.001) and 2-levels (7% vs. 16%, P=0.193). At 3+ levels, however, anemia rates were similar between groups (13% vs. 15%, P=0.877).Conclusion.MIS lumbar interbody fusions provided diminishing clinical returns for multilevel procedures. While MIS patients had lower rates of perioperative complications for 1- and 2-level fusions, 3+ level MIS fusions had comparable complication rates to open cases, and higher rates of adverse pulmonary and ileus events.Level of Evidence: 3.

Original languageEnglish
Pages (from-to)E1181-E1187
Issue number20
StatePublished - Oct 15 2019


  • clinical outcomes
  • complication rates
  • fusion length
  • lumbar fusion
  • minimally invasive surgery
  • multilevel


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