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L5/S1 Fusion Rates in Degenerative Spine Surgery: A Systematic Review Comparing ALIF, TLIF, and Axial Interbody Arthrodesis

Study Design:Systematic review. Objective:To determine the fusion rate of an anterior lumbar interbody fusion (ALIF), transforaminal lumbar interbody fusion (TLIF), and axial arthrodesis at the lumbosacral junction in adult patients undergoing surgery for 1- and 2-level degenerative spine conditions. Summary of Background Data:An L5/S1 interbody fusion is a commonly performed procedure for pathology such as spondylolisthesis with stenosis; however, it is unclear if 1 technique leads to superior fusion rates. Materials and Methods:A systematic search of MEDLINE was conducted for literature published between January 1, 1992 and August 17, 2014. All peer-reviewed articles related to the fusion rate of L5/S1 for an ALIF, TLIF, or axial interbody fusion were included. Results:In total, 42 articles and 1507 patients were included in this systematic review. A difference in overall fusion rates was identified, with a rate of 99.2% (range, 96.4%–99.8%) for a TLIF, 97.2% (range, 91.0%–99.2%) for an ALIF, and 90.5% (range, 79.0%–97.0%) for an axial interbody fusion (P=0.005). In a paired analysis directly comparing fusion techniques, only the difference between a TLIF and an axial interbody fusion was significant. However, when only cases in which bilateral pedicle screws supported the interbody fusion, no statistical difference (P>0.05) between the 3 techniques was identified. Conclusions:The current literature available to guide the treatment of L5/S1 pathology is poor, but the available data suggest that a high fusion rate can be expected with the use of an ALIF, TLIF, or axial interbody fusion. Any technique-dependent benefit in fusion rate can be eliminated with common surgical modifications such as the use of bilateral pedicle screws.