Posterior Selective Fusion with Pedicle Instrumented Correction in Thoracic and Thoracolumbar Idiopathic Scoliosis

Abstract

Introduction To evaluate clinical and radiological outcome of selective fusion for adolescent idiopathic scoliosis (AIS) in thoracic and thoraco-lumbar curves i.e., Lenke 1C and 5C curves. Material and Methods 32 consecutive patients (22 females, 10 males) with 20 Lenke 1 C and 12 Lenke 5C were operated through posterior approach for AIS. Risser stage at the time of operation was 0–3 in 24patients and more than 3 in 4patients. Mean age was 13.5 years. Not every vertebra was instrumented with pedicle screws. Apical vertebral derotation and translation on the concave side were performed for correction. All patients underwent a selective fusion (1C only thoracic curve fused; 5C only thoracolumbar/lumbar curve fused). The data were prospectively collected preoperatively and at 6 weeks, 1year and 2 years post-operatively. Cobb angle, sagittal and coronal balance, and lowest fused vertebral tilt were documented at all time-points. Uninstrumented compensatory curves were measured at all time points. Results Lowest instrumented vertebra (LIV) was distal end vertebra in 15 patients and was one below distal end vertebra in 3 patients in Lenke1C curves. The main thoracic curve correction in Lenke1C was 66%, from 60° ± 12° preoperative to 20° ± 7° at 6 weeks. The Cobb angle was 20° ± 10° at 1 years and 24° ± 10° at 2 years. The apical vertebral rotation improved by 38%, the non-instrumented lumbar curves improved 50%. The last instrumented vertebral tilt decreased from 22° ± 8° preoperatively to 5° ± 5° postoperatively. The average thoracolumbar/lumbar (TL/L) preoperative Cobb angle in Lenke5C curves was 46° ± 8° which was corrected to 14° ± 7° (70% correction) at a 2-year follow-up. 25% of the uninstrumented thoracic curve had spontaneous correction. The coronal balance improved significantly ( p < 0.05) and remained stable from the first postoperative visit to the 2-year follow-up visit. The SRS-22 total scores improved significantly from before surgery to 2years after surgery ( p < 0.0001). No pseudarthrosis or reoperation was observed. One 12 girl with Lenke1C (65°) had intra-operative loss of neural monitoring signals who was paralysed postoperatively for a period of 2 weeks. She recovered completely by 2 months. Conclusion Posterior correction of thoracic and thoracolumbar AIS with pedicle screw instrumentation is safe and produces a long-term stable correction and high patient satisfaction. In Lenke 1C and 5C AIS deformity patterns fused selectively, the uninstrumented compensatory curves do not seem to progress. Selective fusions, when successfully performed, will optimize mobile segments of the spine in AIS patients.