Do contiguous multilevel screws offer added curve correction compared with alternate level screw strategy in patients with adolescent idiopathic scoliosis when curve flexibility is taken into account?

Abstract

INTRODUCTION: With the use of each pedicle screw for surgical correction of adolescent idiopathic scoliosis (AIS), there is an increase in instrumentation-related costs, operative time, risk of neural injury, and overall health-care expenses. As such, alternate level screw strategy (ALSS) has been reported as a potential alternative to contiguous multilevel screw strategy (CMSS). Moreover, studies have shown the importance in accounting for the flexibility of the curve based on the fulcrum bending radiograph when assessing postoperative curve correction. Therefore, this study addressed a radiographic and cost analysis comparing CMSS with ALSS for the treatment of thoracic AIS with titanium screws and rod application. METHODS: 77 patients with AIS underwent surgery (range 6-15 levels). 35 patients received CMSS, which was characterised as bilateral screw fixation at every level. 42 patients underwent ALSS, which entailed bilateral screw fixation at alternate levels. Titanium rods were used in all cases. Preoperative and postoperative posteroanterior and fulcrum bending radiographic Cobb angles were obtained for all patients. The fulcrum flexibility and the fulcrum bending correction index (FBCI) were assessed. Cost analysis was also done. RESULTS: We recorded a statistically significant difference between screw strategy-type to that of preoperative and postoperative Cobb angles, and postoperative curve correction (p<0∙05). No statistically significant difference was noted between screw strategy-type and fulcrum flexibility (CMSS mean 66∙9%; ALSS mean 62∙7%; p>0∙05). The mean FBCIs of the CMSS and ALSS were 126∙1% and 122∙1%, respectively, and did not differ significantly (p=0∙734). Compared with CMSS, ALSS was associated with pedicle screw cost reductions of up to 46∙2%.