Intraoperative Radiographs in Single-level Lateral Lumbar Interbody Fusion Can Predict Radiographic and Clinical Outcomes of Follow-up 2 Years After Surgery.

Retrospective cohort study The aim of this study was to evaluate whether the intraoperatively estimated parameters, as calculated on a cross-table lateral radiograph, are maintained in an upright position at discharge and at 2 years postoperatively and to identify the appropriate disc height (DH) to achieve substantial clinical benefit. The amount of correction retained following lateral lumbar interbody fusion (LLIF) surgery had not been reported. A single-center, consecutive series of patients who underwent single-level LLIF with at least 2 years of follow-up were retrospectively reviewed. Upright standardized preoperative, 1-week, and 2-year postoperative radiographs, as well as intraoperative lateral radiographs, were analyzed for DH, foraminal height (FH), and segmental lumbar lordosis (SLL) at the index level. Clinical outcomes were compared between preoperatively and 1 week and 2 years postoperatively. In total, 89 patients were evaluated (mean follow-up, 42.8 months [range, 24­83 months]). DH decreased from 12.5 ±â€Š2.7 mm intraoperatively to 11.7 ±â€Š3.1 mm at 1 week postoperatively, FH decreased from 15.9 ±â€Š3.6 mm to 15.1 ±â€Š3.6 mm, and SLL decreased from 13.6°â€Š±â€Š1.7° to 12.4°â€Š±â€Š1.7°. A linear correlation between intraoperative and 2-year postoperative parameters was found ( R2  = 0.552, 0.518, and 0.616, respectively). Clinical outcomes, including back pain, leg pain, and Oswestry Disability Index (ODI), significantly improved 2 years postoperatively. The optimal cutoff point for substantial clinical benefit thresholds for the ODI was a 4.18 mm increase in DH (sensitivity, 64.3%; specificity, 80.3%; area under the curve, 0.793; 95% confidence interval, 0.642­0.855). Some of the improvements in DH, FH, and SLL achieved intraoperatively during LLIF surgery were lost by the postoperative 1-week follow-up. An intraoperative radiograph can predict radiographic and clinical outcomes of the 2-year follow-up. The difference between preoperative DH and intraoperative DH should be >4.18 mm. Level of Evidence: 4.