Static Versus Expandable Cages in Minimally Invasive Lateral Lumbar Interbody Fusion

Abstract

Study Design: A meta-analysis approach to a systematic review. Objective: Perform a systematic review to identify all reports directly comparing outcomes of lateral lumbar interbody fusion (LLIF) using static versus expandable interbody cages. Specifically focusing on periprocedural complications, intraoperative morbidity, and fusion outcomes. Summary of Background Data: Minimally invasive surgical techniques, particularly LLIF, have gained popularity for their potential to reduce muscle and soft tissue dissection, leading to faster postoperative recovery. LLIF has been associated with fewer complications compared with open posterior approaches. The introduction of expandable lumbar interbody devices aims to further reduce surgical difficulty and potential complications. However, concerns include a small graft window due to the expansion mechanism and higher costs. Methods: The Web of Science, Scopus, and PubMed databases were systematically queried in accordance with PRISMA guidelines to identify articles comparing outcomes following LLIF using static and expandable interbodies. The Newcastle-Ottawa Scale (NOS) was employed to assess the risk of bias (ROB) in the selected studies. Extracted data underwent effect-size meta-analysis with the PyMARE library, using P<0.05 to define statistical significance. Results: Of the 77 identified articles, 4 studies comprising 283 patients (mean age: 67.1 y, 55.8% female) met the inclusion and exclusion criteria. A total of 150 patients (53%) were treated with static interbodies compared with 133 (47%) receiving expandable interbodies. The groups did not differ significantly with respect to operative time (P=0.59), blood loss (P=0.89), length of stay (P=0.78), subsidence (P=0.49), 24-month mean disc height (P=0.11), 24-month mean ODI (P=0.58), or 24-month mean visual analog scale (VAS) back pain (P=0.81). The expandable group saw a trend toward improved fusion rates (97% vs. 92%, P=0.06). Conclusions: The present meta-analysis suggests the use of expandable (vs. static) interbodies in LLIF surgery may result in similar surgical morbidity, subsidence, and decompression. Further prospective comparative studies are merited to validate these results.