Selection of fusion levels in adolescent idiopathic scoliosis (AIS) using the fulcrum bending radiograph prediction: verification based on pedicle screw strategy

Abstract

INTRODUCTION: Selecting fusion levels based on the Luk et al (SPINE, 2008) criteria for operative management of thoracic AIS with hook and hybrid systems yields acceptable curve correction and balance parameters. However, it is unknown whether utilizing a purely pedicle screw strategy is safe and effective. MATERIALS AND METHODS: A prospective radiographic analyses (preoperative and postoperative 1 week and 1 year) of 25 operative thoracic AIS patients undergoing pedicle screw fixation. Radiographic measurement parameters entailed standing coronal/sagittal and FBR Cobb angles, FBR flexibility, fulcrum bending correction index (FBCI), truncal shift, radiographic shoulder height (RSH), and list. Fusion level selection was based on the Luk et al criteria and compared to conventional techniques. RESULTS: In the primary curve, the mean preoperative and final follow-up standing coronal Cobb angles were 60.6deg and 22.4deg, respectively (p<0.001). Mean immediate and final follow-up FBCIs were 124.2% and 111.3%, respectively. A mean 4.8deg loss of curve correction from immediate to final follow-up was observed (p<0.0001). Nineteen patients (76%) had distal levels saved (mean: 1.2 levels) in comparison to conventional techniques. A significant decrease in truncal shift was noted from preoperative to final follow-up (p<0.01). No statistically significant difference from preoperative to final follow-up was noted in RSH and list (p>0.05). CONCLUSIONS: This study suggests that pedicle screw fixation obtains greater deformity correction than hook and hybrid systems, and improves balance without compromising fusion levels.