Management of severe adult spinal deformity with circumferential minimally invasive surgical strategies without posterior column osteotomies: a 13-year experience.

Objective: To evaluate the mid- to long-term clinical outcomes of circumferential minimally invasive surgery (CMIS) without posterior column osteotomies for severe adult spine deformity (ASD) correction.

Methods: All patients with a minimum of 2-year follow-up undergoing staged CMIS correction of ASD from January 2007 to July 2018 were identified. All included patients had fusion of 3 or more interbody levels that spanned the L5-S1 junction. Only patients with severe deformity, Coronal Cobb > 50° or at least one SRS-Schwab ++ sagittal modifier (SVA > 95 mm, or PI-LL > 20, or PT > 30) were included. All complications were noted. Result: 136 patients met inclusion criteria; mean age of patients was 63.6 years (21-85, SD 13.7). The mean follow-up was 82.8 months (24-159, SD 36.6). The mean number of levels fused was 7 (3-16, SD 3). A total of 40 (29.4%) major complications were noted at final follow-ups: 2 (1.4%) intra-operative, 12 (8.9%) peri-operative (≤ 6 weeks from index), 26 (19.1%) post-operative (> 6 weeks from index). There was a total of 53 (40.0%) minor complications. Seven (5.1%) patients who developed radiographic proximal junctional kyphosis. Three patients (2.2%) developed proximal junctional failure. There were 8 (5.9%) cases of pseudarthrosis. Five of these occurred in patients undergoing AxiaLIF. All patients experienced improvements in patient-perceived outcomes (VAS, TIS, ODI, and SRS-22) and radiographic parameters at last follow-up when compared to pre-op (p < 0.05).

Conclusion: Rates of complications with CMIS correction of severe ASD are lower than published rates of complications seen with open ASD correction. Specifically, the incidence of catastrophic complications is lower. Furthermore, CMIS is associated with significant improvements in clinical and functional outcomes, low rates of pseudarthrosis and proximal junctional kyphosis. Therefore, in the appropriately selected patient, CMIS may be an excellent alternative approach to addressing severe ASD.