[Comparison of spontaneous correction in thoracic curves after anterior versus posterior selective fusion in Lenke type 5C adolescent idiopathic scoliosis].

To analyze the long-term results and the influence factors of spontaneous correction of unfused thoracic curves in anterior and posterior selective fusions in Lenke type 5C adolescent idiopathic scoliosis (AIS). From January 2005 to December 2011, 89 Lenke type 5C AIS patients with a minimum of 5-year follow-up who underwent thoracolumbar/lumbar (TL/L) selective fusion in Spine Surgery of Nanjing Drum Tower Hospital were reviewed.Forty-six patients underwent anterior fusion (anterior group), while 46 underwent posterior fusion (posterior group). The following radiological parameters were measured and analyzed at pre-operation, post-operation, and latest follow-up: curve magnitude of primary thoracolumbar/lumbar and secondary thoracic curve, trunk shift, thoracic apical vertebral translation, upper instrumented vertebra tilt, thoracic kyphosis, proximal junctional angle, sagittal vertical axis. Independent sample test was used to compare the above parameters between the two groups. Compared with those in posterior group, anterior group were found with less fusion levels (5.4±0.6 vs 5.9±0.8, =3.318, =0.001) and longer operation time[(276±28)min vs (186±36)min, =13.101, <0.001]. Immediately after surgery, the spinal deformity was significantly corrected in the two groups. The mean spontaneous correction rates of the minor curve were 50%±21% and 56%±20% in anterior and posterior groups, respectively (=1.489, =0.140). After a mean follow-up of (6.8±1.7) years in anterior group and (6.3±1.3) years in posterior group, the spontaneous correction rate of minor curve was maintained at 46%±22% and 49%±19%, respectively (=0.703, =0.484), with no significant correction loss. Other radiographic parameters were also stably maintained. According to the correlation analysis, the spontaneous correction rate was significantly correlated with upper instrumented vertebra (UIV) tilt in both groups (anterior: =-0.526, posterior: =-0.399, both <0.05). Both anterior and posterior selective fusion can achieve satisfactory spontaneous correction of unfused thoracic curves in Lenke type 5C AIS, with no significant difference between the two surgical approaches. UIV tilt is a key influence factor of spontaneous correction of thoracic curves.