Anterior Column Realignment (ACR) has Similar Results to Pedicle Subtraction Osteotomy (PSO) in Treating Adults with Sagittal Spinal Deformity: A Multi-Center Study

Presented at SMISS Annual Forum 2013
By Gregory M. Mundis MD
With Behrooz A. Akbarnia MD, Nima Kabirian MD, Vedat Deviren MD, Robert K. Eastlack MD, Jeff Pawelek BS, Virginie LaFage PhD, Christopher Shaffrey MD, Shay Bess MD, Eric Klineberg MD, Christopher Ames MD,

Disclosures: Gregory Mundis MD A; ISSGF, Nuvasive. B; K2M, Medicrea, Misonix, Nuvasive. C; K2M, Nuvasive. F; Nuvasive. Behrooz Akbarnia MD A; Depuy Synthes Spine. B; NuVasive, K2M, Ellipse, Kspine. D; Alphatec Spine, NuVasive, Ellipse, Kspine, Nocimed., Nima Kabirian MD , Vedat Deviren MD A; AOSpine, Globus, Nuvasive. B; Nuvasive. F; Nuvasive., Robert Eastlack MD None, Jeff Pawelek BS None, Virginie LaFage PhD A; SRS, DePuy Synthes Spine. B; Medtronic. C; K2M, Medtronic, DePuy Synthes Spine. D; Nemaris Inc., Christopher Shaffrey MD None, Shay Bess MD A; DePuy Synthes Spine, Medtronic. B; DePuy Synthes Spine, Medtronic, Alphatec, Allosource, K2M. F; Pioneer., Eric Klineberg MD A; OREF, Depuy. C; Depuy, AO Spine., Christopher Ames MD A; Trans1. B; Medtronic, Stryker, Depuy. D; Trans1, Visualase, Doctors Research Group. F; Lanx, Stryker, Aesculap/B. Braun.,

Introduction: Anterior column realignment (ACR) has recently been described as a minimally invasive retroperitoneal lateral interbody fusion with anterior longitudinal ligament release for correction of adult sagittal plane deformity (ASD) in an effort to minimize the morbidity associated with pedicle subtraction osteotomy (PSO). This study aims to compare ACR with a PSO cohort from a retrospective consecutive multicenter database.

Methods: A consecutive series of 17 ACRs from a multicenter database was propensity matched (by pelvic incidence (PI), lordosis (LL) and thoracic kyphosis (TK)) to a retrospective consecutive multicenter PSO dataset (N=100). Inclusion criteria: Adult sagittal plane deformity requiring ACR or PSO and minimum 1-year follow-up. Differences between groups were investigated using unpaired t-test and change within groups using paired t-tests (N=17 in each group).

Results: All ACR underwent 2^nd stage open posterior instrumented fusion. There were no differences in baseline demographic or radiographic parameters (Table). Both groups were found to have significant improvement from pre- to final follow-up for LL, T1 spinopelvic inclination (T1SP) and T1 pelvic angle (TPA). PT did not improve in PSO (31 to 28) at 2-year but did improve in ACR (34 to 25; p<0.01). No differences were identified between ACR or PSO at 3-month or 2-year for LL (51° vs. 47°), PT (25° vs. 28°), and TPA (23° vs. 24°). PSO had more T1SP correction (8° vs. 1.9°). There was no difference in SRS-Schwab Classification modifier (PI-LL or PT) between groups at any time point. ACR saw significantly less blood loss (EBL: 1.6L vs. 3.6L; p<0.007) but no difference found in overall complication rates (41.2% vs. 47.1%).

Conclusion: ACR appears to achieve similar radiographic results as PSO in a propensity matched multicenter study with significantly less EBL and equal complication profile. While ACR has more PT correction, PSO patients have more trunk correction (T1SP). The lack of difference in TPA suggests equal spinopelvic correction and the difference is likely postural.