Multilevel stand-alone lateral lumbar interbody fusion: radiographic and clinical outcomes

Stand-alone lateral lumbar interbody fusion (SA-LLIF) without posterior instrumentation is increasingly being performed for various spine pathologies. There are few studies regarding clinical and radiographic outcomes in patients who underwent multilevel SA-LLIF. In this study, the authors aimed to explore these outcomes.

This is a retrospective review of patients who underwent multilevel SA-LLIF without posterior instrumentation between August 2017 and October 2021. Demographic information, comorbidities, and complications were collected. Clinical outcomes were measured using the Oswestry Disability Index (ODI) and visual analog scale (VAS). Spinopelvic parameters, subsidence rates, and repeat operations were recorded.

Forty-three patients met the inclusion criteria. The mean age was 70.1 years, and 31 (72.1%) patients were male. The mean BMI was 28.2. Patients often had multiple indications for surgery, with 39 (90.7%), 28 (65.1%), and 9 (20.9%) patients undergoing surgery for adult spinal deformity, degenerative disc disease, and adjacent segment disease, respectively. The mean number of levels treated was 2.42 (range 2-4 levels, total 104 levels treated). The mean time to follow-up imaging was 2.01 years (range 30 days-4.95 years). There were significant differences in pre- and postoperative lumbar lordosis (LL) (+4.9°, p = 0.001), pelvic incidence-LL mismatch (-4.5°, p = 0.003), and segmental LL at treated levels (+4.0°, p = 0.002). Fifteen (35%) patients had coronal Cobb angles > 20° preoperatively; 11 (73%) showed improvement in Cobb angle postoperatively (mean change -5.4°, p = 0.02). Fifteen (35%) patients experienced grade 1 or higher subsidence at 23 of 104 (22%) levels. Five (12%) patients required repeat operations for failure of indirect decompression, progressive deformity, symptomatic subsidence, or a combination thereof. Three (7%) of these patients had symptomatic subsidence. Subsidence was more common in patients with polyetheretherketone implants (n = 13) versus titanium implants (n = 2) (p = 0.002). Significant improvements were seen in median (IQR) pre- and postoperative ODI (38 [28-48.5] vs 25 [17.5-38.5], p = 0.001), VAS back (7.0 [4.8-8.0] vs 3.5 [0.8-6.2], p = 0.002), and VAS leg (6.0 [2.5-8.0] vs 0.0 [0.0-4.2], p = 0.001) scores.

In this small cohort, multilevel SA-LLIF was a safe and clinically effective surgical option for patients who required a shorter operative duration. Multilevel SA-LLIF had good clinical and radiographic outcomes but had a 7% reoperation rate for symptomatic subsidence. Further studies with longer clinical and radiographic follow-up are necessary to determine the durability of multilevel SA-LLIF.