The impact of direct vertebral body derotation on the lumbar prominence in Lenke Type 5C curves

Abstract

Object The thoracic rib hump, caused by axial rotation of the spine, is one of the most dissatisfying cosmetic features associated with adolescent idiopathic scoliosis (AIS). However, advances in instrumentation and surgical techniques, such as direct vertebral body derotation (DVBD), have allowed improved correction in the axial plane and the rib hump. In cases of thoracolumbar/lumbar curves (Lenke Type 5), the lumbar prominence can be equally disfiguring and is often associated with waist asymmetry, another cosmetic concern. Although DVBD has been evaluated in the thoracic spine, little is known about its impact on the lumbar spine. The authors investigated the outcomes of DVBD on the lumbar prominence. Methods A prospectively collected multicenter database was queried for pediatric patients with AIS and Lenke Type 5 curves. All patients who underwent thoracoplasty procedures were excluded. A total of 34 patients underwent surgical correction via a posterior-only approach using pedicle screw constructs. Nineteen patients underwent concurrent DVBD, and the remaining 15 patients served as a control group and did not undergo DVBD. All patients had a minimum of 2 years of follow-up. Results The mean age of the entire cohort was 14.9 ± 2.3 years, and the majority of patients were female (88%). All patients had Lenke Type 5C curves with a mean major curve of 46.0° ± 8.7°, which corrected to 13.7° ± 7.2° (70% correction). A mean of 10.7 ± 3.0 levels were fused. Only thoracic kyphosis was significantly different between the groups preoperatively. Similarly, postoperative radiographic parameters were comparable between the groups, with equivalent percentages of correction. Although improvement in the thoracic rib hump was comparable between the groups, the DVBD group had 56.2% correction of the lumbar prominence, and the control group had 76% improvement (p = 0.05). Conclusions Although DVBD has been a valuable tool in the management of AIS, the authors' results suggest that its application for thoracolumbar curves may be limited. Further analysis with a larger cohort is required to better ascertain the impact of DVBD on thoracolumbar curves.