Comparison of Selective Anterior Versus Posterior Screw Instrumentation in Lenke5C Adolescent Idiopathic Scoliosis

Study Design. Retrospective review of anterior and posterior fusions for treatment of Lenke5C adolescent idiopathic scoliosis (AIS). Objective. To compare the clinical and radiographic results of anterior versus posterior pedicle screw instrumentation in Lenke5C AIS. Summary of Background Data. Anterior and posterior pedicle screw instrumentations are 2 established methods of correcting Lenke5C AIS. However, there are few reports that compare the 2 methods. Methods. Forty-six consecutive patients with Lenke5C AIS curves underwent selective lumbar or thoracolumbar fusion (1999-2005). Twenty-two patients had anterior surgery, and 24 patients had posterior surgery. Patients were evaluated at a minimum 2-year follow-up. Results. No complications occurred in either group. The number of levels involved in the major curve was similar for the anterior and posterior groups(5.5 vs. 5.7). Preoperative thoracic (24.13 degrees +/- 4.9 degrees vs. 22.88 degrees +/- 5.14 degrees) and lumbar/thoracolumbar (50.2 degrees +/- 7.52 degrees vs. 52.2 degrees +/- 6.40 degrees). Cobb values for the 2 groups were also similar. The percent correction of the lumbar curve was similar between the 2 groups at all stages of follow-up (56% vs. 57.7%), as was the percent of spontaneous correction of the unfused thoracic curve (25% vs. 27.2%). However, fusion levels were significantly shorter in the anterior group (mean, 5.09 vs. 6.13), and there were 8 patients (4 in the anterior group and 4 in the posterior group) whose thoracic curve became greater at the latest follow-up. The thoracolumbar/lumbar-thoracic Cobb ratio for these 8 patients was less than that for the other patients (1.34 vs. 2.43), and their curve flexibility was worse. Conclusion. Selective anterior and posterior screw instrumentation both achieved good surgical lumbar and subsequent spontaneous thoracic correction. There was no statistically significant difference between the 2 groups in lumbar correction or thoracic correction, but fusion levels were shorter in the anterior group. Patients with late thoracic curve decompensation had smaller thoracolumbar/lumbar-thoracic Cobb ratios and less preoperative flexibility than those who did not decompensate.