Adjacent segment disease treated with stand-alone lateral lumbar interbody fusion: an analysis of domino adjacent segment revisions

OBJECTIVE: The aim of this study was to assess whether stand-alone lateral lumbar interbody fusion (LLIF) is a durable revision strategy for adjacent segment disease (ASD) in terms of risk for subsequent ASD revision surgery (i.e., domino ASD revision) compared with circumferential LLIF with posterior extension of fusion. METHODS: This was a single-center retrospective cohort study of patients who underwent revision and extension of fusion for ASD using either stand-alone LLIF or circumferential LLIF with posterior pedicle screw instrumentation between January 2008 and August 2023. Patients were included if they had undergone previous posterior lumbosacral fusion. Patients undergoing instrumentation across the thoracolumbar junction and those with incomplete radiographic data were excluded. Preoperative radiographs and MR images were reviewed to control for alignment and stenosis severity. The primary outcome was domino ASD revision. Secondary outcomes included cage subsidence and radiographic alignment, measured 1 year postoperatively. Kaplan-Meier survival analysis and multivariable Cox regression were performed. RESULTS: Of the 236 patients included, the mean age was 63.5 years, the mean BMI was 29.6 kg/m2, and 47.5% of patients were female. Baseline demographics, comorbidities, and spinal levels treated were similar to those treated with stand-alone LLIF (n = 131) and those treated with circumferential LLIF (n = 105). The median number of previous segments fused was 2 (IQR 2-3), and the median number of segments extended with LLIF was 1 (IQR 1-2). Stand-alone LLIF was associated with a significantly lower 5-year incidence of domino ASD revision (13.7% vs 28.6%, p = 0.005). On multivariable Cox regression analysis adjusting for preoperative alignment, stenosis severity, and the number of segments fused, stand-alone LLIF remained independently associated with fewer domino ASD revisions (HR 0.43, 95% CI 0.23-0.79, p = 0.007). Radiographic alignment was comparable between the groups. Cage subsidence occurred more frequently after stand-alone LLIF compared with circumferential LLIF (Marchi grade ≥ II: 22.9% vs 9.5%, p = 0.019) but was not associated with increased revision risk. Operative time and hospital stay were significantly shorter in the stand-alone LLIF group. CONCLUSIONS: The findings of this study support the use of stand-alone LLIF as a treatment option for ASD after previous posterior fusion. Compared with those treated with circumferential LLIF and posterior extension of fusion, patients treated with stand-alone LLIF had less domino ASD revision surgery, spent less time in the operating room, and had shorter hospital stays, with comparable radiographic outcomes except for a higher rate of cage subsidence.