Choosing Minimally Invasive Versus Open Surgery in the Treatment of Adult Spinal Deformity (ASD): Analysis of a Prospective, Nonrandomized Multi-Center Study

Abstract

Abstract INTRODUCTION Surgical planning in adult spinal deformity is a key factor in achieving optimal outcomes. MIS approaches for deformity have been promoted to be an option that results in less postoperative morbidity. However, minimally invasive spine (MIS) surgery can have limitations in the degree of correction achievable. This study analyzes factors involved in determining whether a traditional open vs minimally invasive approach is selected in a prospective, nonrandomized multi-center trial. METHODS Enrollment criteria: only patients treated by surgeons who enrolled both open and MIS patients were included, age = 18 yr, and coronal curve (CC) = 20, SVA >5 cm, PT >25, or thoracic kyphosis (TK) > 60°. Surgical approach selection was at the discretion of the operating surgeon. Preoperative significant differences were included in a multi-variate logistic regression analysis to determine odds ratios for approach selection. RESULTS A total of 120 open and 148 MIS patients were available for analysis. Significant preoperative differences (P < .05) between open and MIS groups were noted for age (61.9 vs 66.7 yr), visual analog scale (VAS) back (7.8 vs 7), CC (36 vs 26.1), PT (26.4 vs 23), TPA (26.1 vs 21), and PI-LL (19.6 vs 14.9). No significant differences in Charlson index, frailty, body mass index (BMI) (29 vs 28.5), VAS leg (5.2 vs 5.7), ODI (48.4 vs 47.2), SRS-22 (2.7 vs 2.8), PI (58.3 vs 57.1), LL (38.9 vs 42.3), SVA (73.8 vs 60.3 cm). Multivariate analysis found that age (OR 1.06, P = .036), CC (OR 1.06, P = .001), and TPA (OR 1.17, P = .017) are significant factors in approach selection. For every 1-yr increase in age there was a 6% increase in MIS approach, and for every 1 degree increase in CC/TPA there was a 6% and 17% increased likelihood for an open approach respectively. CONCLUSION Pain, disability, and comorbidities were not factors in approach selection. Rather age and severity of mal-alignment as reflected by the CC and TPA appear to be the primary drivers for approach selection.