Multilevel standalone lateral interbody fusion: Radiographic and clinical outcomes at a high-volume institution

Introduction: Stand-alone lateral lumbar interbody fusion (SA-LLIF) without posterior instrumentation is increasingly being performed for various spine pathologies. There have been no studies to date regarding clinical and radiographic outcomes of patients who underwent multilevel SA-LLIF.

Methods: A retrospective review assessed patients undergoing multilevel SA-LLIF without posterior instrumentation between August 2017 to October 2021. Demographic information, comorbidities, and complications were collected. Clinical outcomes were characterized utilizing Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS). Spinopelvic parameters, subsidence rates, and re-operation rates were collected.

Results: Forty-three patients met inclusion criteria. Mean (SD) age was 70 years (8.1), and 31 (72.1%) of patients were male. Mean (SD) body mass index (BMI) was 28.2 (5.0). There were often multiple indications for surgery, with 37 (86%), 28 (65.1%), and 9 (20.9%) patients undergoing surgery for deformity correction, degenerative disc disease, and adjacent segment disease, respectively. Mean number of levels treated was 2.42 (range 2-4 levels, total 104 levels treated). Mean time to follow-up imaging was 2.01 years (range 30 days to 4.95 years). Mean difference in pre- and post-operative LL, PI-LL mismatch, PT, and SVA were 4.9 degrees increase (p < 0.001), 2.3 degrees decrease (p=0.08), 1.4 degrees decrease (p=0.08), and 0.94cm improvement (p=0.10). Fifteen patients (34.9%) had coronal deformity with largest cobb angle >20 degrees pre-op, and 11 (73.3%) had improvement in cobb angle postoperatively. Mean change in coronal cobb was 5.4 degrees improvement (28.6 degrees to 23.2 degrees postoperatively; p=0.01). Five of seven (71.4%) patients with spondylolisthesis had improved Meyer-Ding grade post-operatively. Fifteen patients (34.9%) experienced Grade 1 or more subsidence, with 23 of 104 levels (22.1%) affected. Three (7.0%) patients experienced symptomatic subsidence requiring re-operation. Five (11.6%) patients total required re-operation for progressive pain/radiculopathy and/or progressive deformity. There were significant improvements in ODI, VAS back, and VAS leg after surgery. Median (IQR) pre-operative ODI was 38 (28 to 48.5), compared to 25 (17.5 to 38.5) post-operatively (p < 0.001). Average pre-operative VAS were 7.0 and 6.0 for back and leg, respectively, compared to 3.5 and 0.0 post-operatively (p=0.002; p=0.001).

Conclusion : Multilevel standalone LLIF can be a safe and effective surgical option with good clinical and radiographic outcomes.