314. Distraction-based growth rods fixation vs active apex correction: what do the correction parameters say?

Abstract

BACKGROUND CONTEXT SHILLA and growth rods are two main surgical correction techniques for patients with early onset scoliosis. There has been a couple of comparative studies between the two techniques using myriads of deformity identifying characteristics such as, Cobb angle, apical vertebral translation, coronal balance, spinal length gain etc. However, SHILLA procedure suffers from loss of correction or reappearance of deformity through crankshafting or adding-on (eg, distal migration). The current study identifies a solution with a modified approach to SHILLA, which could help dynamically remodulate the apex of the deformity and mitigate loss of correction, and presents a comparative correction data against the long established traditional growth rod system. PURPOSE To determine if a modified SHILLA technique (active apex correction [APC]) would still compare favorably at follow ups, when compared to traditional growth rods procedures performed by the same team of surgical staff. STUDY DESIGN/SETTING A retrospective cohort PATIENT SAMPLE A total of 20 patients in APC group, 26 patients in growth rods group OUTCOME MEASURES Various spinal parameters, such as Cobb angle, kyphosis, lordosis, sagittal balance, coronal Balance, apical vertebral translation, spinal growth both preoperative and at follow ups. In addition all biomechanical, and correction related complications were presented. METHODS The APC group consisted of 20 patients with either scoliosis or kyphoscoliosis undergoing an index surgery or revision surgery and demonstrating a clear radiographic evidence of vertebral wedging at the apex. All patients were under 8 years of age with Risser less than or equal to 2, and the major Cobb's angle more than 40°. Following the same criteria, the growth rods group consisted of 26 patients. The surgical procedure involved was a modified version of to SHILLA, either using rod to screw (SHILLA screws from Medtronic) sliding mechanism or the analogous rod to domino (4.5 mm rod in 5.5 mm domino) sliding mechanism. In this modified technique, the most wedged vertebra was selected followed by insertion of pedicle screws in the convex side of the vertebrae above and below the wedged one. No screws were put on the concave side of the apex. For the growth rod surgery, the domino remained locked and distraction was applied every 6-9 months, and no apical screws were used. All surgeries were performed under intraoperative neuromonitor and C-arm. Additionally, no cast or brace were used for these patients postoperatively. The patients were followed up for an average period of 32 and 62 months in the APC and growth rods groups respectively. Statistical comparisons were made among different parameters between the two groups using t-test with unequal variances. RESULTS There was no statistical differences between the various spinal parameters, namely Cobb angle, apical vertebral translation, sagittal balance and spinal length gain between two groups. Whereas significant differences existed for coronal balance, which in part may have been due to differences in its preoperative value between the two groups. CONCLUSIONS The result of this study suggests clinical equivalency in regard to correction, between the two clinical procedures: APC and traditional growth rod system. However, growth rods showed higher complications compared to APC. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.