Sagittal Alignment Correction in Single-Level Minimally Invasive Transforaminal Interbody Fusion with Unilateral vs. Bilateral Facetectomy

<b>Objective:</b> Bilateral facetectomy (BF) within minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) remains debated regarding its advantages over unilateral facetectomy (UF) in restoring segmental lordosis, addressing spondylolisthesis and decompressing both neural foramina. The evidence is limited. We sought to determine the benefits of contralateral facetectomy on radiographic and clinical outcomes. <b>Methods:</b> We conducted a single-center retrospective analysis on patients with lumbar degenerative disease who underwent single-level percutaneous instrumentation and MI-TLIF with either UF or BF. Plain radiographs, CT and MRI were utilized for comparative radiographic analysis. Various intraoperative and clinical parameters were evaluated to assess surgical effort and clinical outcomes. <b>Results:</b> We included 81 UF and 23 BF cases; complete radiological data were available for 27 and 13 patients, respectively. Both techniques demonstrated a comparable increase in segmental lordosis (UF 2.1° ± 5.3° vs. BF 4.3° ± 5.4°, <i>p</i> > 0.1), which is below the study's minimum detectable effect (MDE ≈ 5.1° at 80% power). Spondylolisthesis reduction was similar, with UF achieving a mean of 2.8 ± 2.2 mm and BF 2.4 ± 1.9 mm (<i>p</i> > 0.1). Mean posterior disc height did not differ significantly between groups (<i>p</i> > 0.1). The mean intraoperative blood loss was significantly higher with BF (803 ± 347 mL) compared to UF (437 ± 207 mL, <i>p</i> < 0.001). The mean duration of surgery was significantly longer for BF (240 ± 48 min) compared to UF (197 ± 37 min, <i>p</i> = 0.001). <b>Conclusions:</b> This study found no evidence of a large advantage of BF over UF in restoring segmental lordosis, spondylolisthesis and posterior disc height in monosegmental MI-TLIF surgery. Given the higher blood loss and longer operative time observed with BF, its use should be selective for specific indications.