Background: Selective fusions of the structural curve remain a common treatment strategy for adolescent idiopathic scoliosis, yet long-term outcomes are not well-understood. The purpose of this study was to report 10-year prospective radiographic and patient-rated outcomes of selective fusions of the main thoracic (MT) or thoracolumbar/lumbar (TL/L) curve, with particular attention to the behavior of the uninstrumented, compensatory curve. Methods: A prospectively collected multicenter database was used to identify patients who had been followed regularly for least 10 years after a selective MT or TL/L fusion for adolescent idiopathic scoliosis. Interval radiographs were evaluated for coronal and sagittal Cobb angles as well as overall coronal balance. Scores on the Scoliosis Research Society Questionnaire (SRS-24) were catalogued and evaluated. Radiographic outcomes and SRS-24 scores were compared between preoperative and postoperative time points using repeated-measures analysis of variance. Individual patient records were screened for recent curve progression of >5°, and these cases were methodically evaluated. Results: Fifty-one patients with selective fusions (21 MT and 30 TL/L) for adolescent idiopathic scoliosis who had been followed for at least 10 years were identified. The instrumented MT and TL/L curves were corrected by an average of 51% and 60%, respectively, at 10 years. The uninstrumented, compensatory curves had gradual spontaneous correction that approached the magnitude of the fused curve at 5 years postoperatively, with the correction maintained at 10 years. This led to excellent coronal balance. A subgroup of patients had recent progression of the primary curve adjacent to the prior fusion or within the instrumented segments, resulting in a compensatory progression of the uninstrumented curve. On the whole, SRS scores did not decrease during follow-up, and no patient had secondary operations. Conclusions: Selective fusion of a primary thoracic or lumbar curve in properly selected patients with adolescent idiopathic scoliosis will result in spontaneous correction of the uninstrumented curve and a durable result for at least 10 years. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Background: Anterior vertebral body tethering (AVBT) is a growth-modulation technique theorized to correct adolescent idiopathic scoliosis (AIS) without the postoperative stiffness imposed by posterior spinal fusion. However, data are limited to small series examining short-term outcomes. To assess AVBT’s potential as a viable alternative to posterior spinal fusion (PSF), a comprehensive comparison is warranted. The purpose of this meta-analysis was to compare postoperative outcomes between patients with AIS undergoing PSF and AVBT. Our primary objective was to compare complication and reoperation rates at available follow-up times. Secondary objectives included comparing mid-term Scoliosis Research Society (SRS)-22 scores, and coronal and sagittal-plane Cobb angle corrections. Methods: We performed a systematic review of outcome studies following AVBT and/or PSF procedures. The inclusion criteria included the following: AVBT and/or PSF procedures; Lenke 1 or 2 curves; an age of 10 to 18 years for >90% of the patient population; <10% non-AIS scoliosis etiology; and follow-up of ≥1 year. A single-arm, random-effects meta-analysis was performed. Deformity corrections, complication and reoperation rates, and postoperative SRS-22 scores were recorded. Results: Ten AVBT studies (211 patients) and 14 PSF studies (1,069 patients) were included. The mean follow-up durations were similar for both groups. Pooled complication rates were 26% for AVBT versus 2% for PSF, and reoperation rates were 14.1% for AVBT versus 0.6% for PSF with nonoverlapping confidence intervals (CIs). The pooled reoperation rate among studies with follow-up times of ≥36 months was 24.7% in AVBT versus 1.8% in PSF. Deformity correction, clinical outcomes, and mid-term SRS-22 scores were similar. Conclusions: Our study showed greater rates of complications and reoperations with AVBT compared with PSF. Reoperation rates were significantly greater in AVBT studies with longer follow-up (≥36 months). Deformity correction, clinical outcomes, and mid-term SRS-22 scores were similar. While a potential fusionless treatment for AIS merits excitement, clinicians should consider AVBT with caution. Future long-term randomized prospective studies are needed. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background: Thoracic anterior vertebral body tethering (TAVBT) is an emerging treatment for adolescent idiopathic scoliosis. Tether breakage is a known complication of TAVBT with incompletely known incidence. We aim to define the incidence of tether breakage in patients with adolescent idiopathic scoliosis who undergo TAVBT. The incidence of tether breakage in TAVBT is hypothesized to be high and increase with time postoperatively. Methods: All patients with right-sided, thoracic curves who underwent TAVBT with at least 2 and up to 3 years of radiographic follow-up were included. Tether breakage between 2 vertebrae was defined a priori as any increase in adjacent screw angle >5 degrees from the minimum over the follow-up period. The presence and timing of tether breakage were noted for each patient. A Kaplan-Meier survival analysis was performed to calculate expected tether breakage up to 36 months. χ² analysis was performed to examine the relationship between tether breakage and reoperations. Independent t test was used to compare the average final Cobb angle between cohorts. Results: In total, 208 patients from 10 centers were included in our review. Radiographically identified tether breakage occurred in 75 patients (36%). The initial break occurred at or beyond 24 months in 66 patients (88%). Kaplan-Meier survival analysis estimated the cumulative rate of expected tether breakage to be 19% at 24 months, increasing to 50% at 36 months. Twenty-one patients (28%) with a radiographically identified tether breakage went on to require reoperation, with 9 patients (12%) requiring conversion to posterior spinal fusion. Patients with a radiographically identified tether breakage went on to require conversion to posterior spinal fusion more often than those patients without identified tether breakage (12% vs. 2%; P=0.004). The average major coronal curve angle at final follow-up was significantly larger for patients with radiographically identified tether breakage than for those without tether breakage (31 deg±12 deg vs. 26 deg±12 deg; P=0.002). Conclusions: The incidence of tether breakage in TAVBT is high, and it is expected to occur in 50% of patients by 36 months postoperatively. Level of Evidence: Level IV