Postoperative Radiological Improvement after Staged Surgery Using Lateral Lumbar Interbody Fusion for Preoperative Coronal Malalignment in Patients with Adult Spinal Deformity

This retrospective observational study evaluated improvement in coronal malalignment (CM) after anteroposterior staged surgery using lateral lumbar interbody fusion (LLIF) in patients with coronal lumbar curve adult spinal deformity (ASD). Sixty patients with ASD underwent surgery; 34 had SRS–Schwab type L lumbar curve. Patients with a coronal balance distance (CBD) ≥20 mm were diagnosed with CM. Using the Obeid CM classification, we classified the preoperative coronal pattern as concave CM (type 1) or convex CM (type 2). Demographic, surgical, and radiological parameters were compared. Whole-spine standing radiographs were assessed preoperatively and postoperatively. Twenty-three patients had type 1A, six had type 2A, five had no CM, and none had type 1B or 2B according to the Obeid CM classification. Compared with patients with Obeid type 1A, those with Obeid type 2A had significantly higher preoperative and postoperative coronal L4 tilts and a smaller change in corrected CBD (Δ|CBD|) (76.6 mm vs. 24.1 mm, p < 0.001). At the final follow-up, 58.6% (17/29 patients) of patients with SRS–Schwab type L CM showed improvement after corrective fusion using LLIF. Although the difference was not statistically significant, CM improved in 69.6% (16/23 patients) of patients with Obeid type 1A type but only 16.7% (1/6 patients) of those with Obeid type 2A type (p = 0.056). CM was more likely to remain after anteroposterior staged surgery using LLIF in patients with preoperative Obeid type 2A ASD.