Selection of posterior spinal osteotomies for more effective periapical segmental vertebral derotation in adolescent idiopathic scoliosis–An in vivo comparative analysis between Ponte osteotomy and inferior facetectomy alone

Background: Ponte osteotomy is a useful method in posterior spinal release. However, it is unclear whether Ponte osteotomy itself contributes to vertebral derotation in surgery for adolescent idiopathic scoliosis (AIS) patients compared to inferior facetectomy alone. This study aimed to assess the effect of Ponte osteotomy on the magnitude of periapical vertebral body rotation compared to inferior facetectomy alone. This study was a prospective collected data. Methods: The study included 63 patients with AIS (Thoracic curve type, 35; thoracolumbar/lumbar curve type, 27), who underwent surgery between August 2011 and January 2015. All AIS patients underwent posterior spinal fusion with uniplanar screws and Ponte osteotomies on three periapical intervertebral segments. We measured and analyzed the flexibility of periapical intervertebral rotation pre- and post-bilateral inferior facetectomy, and post-Ponte osteotomy with our device (three times). The difference in intervertebral rotation between pre- and post-Ponte osteotomy was analyzed. Results: The mean increase in angle was 5.6° for thoracic curves and 6.4° for thoracolumbar curves. The increase in angle for thoracolumbar curves was significantly larger than that for thoracic curves (P < 0.05). The more an apical region of the scoliosis was located at caudal side of spine, the more the flexibility due to Ponte osteotomy increased (P < 0.05). The significant differences of the increase in intervertebral flexibility between inferior facetectomies and Ponte osteotomies were recognized at middle thoracic and thoracolumbar regions (P < 0.005). Conclusions: Our data suggest that Ponte osteotomy has a loosening effect on periapical scoliotic curvature compared to inferior facetectomy alone. Ponte osteotomy is likely to be associated with an increase in loosening of the middle thoracic and thoracolumbar regions.