A Randomized Controlled Trial Assessing the Safety and Efficacy of a Novel Superelastic Rod In Comparison to Conventional Titanium Rod for Scoliosis Correction

Introduction:  Current implant technologies only correct scoliosis at the time of surgery but cannot fully correct the deformity.  A novel superelastic nitinol rod than can maximize curve correction by gradually correcting the scoliosis after surgery has been developed.  This is a parallel, double-blinded, randomized controlled trial comparing the safety and efficacy of these nitinol rods (Group 1) to conventional titanium rods (Group 2).

Methods:  Twenty-three adolescent idiopathic scoliosis (AIS) subjects, mean age 15 years, were recruited.  All subjects had single thoracic curves and were randomized at the time of surgery to receive either nitinol rods or conventional rods.  Assessments were carried out based on preoperative anteroposterior and lateral standing and fulcrum bending radiographs, postoperative standing radiographs, and serum nickel levels.  All assessments were made by two blinded observers. 

Results:  Eleven subjects were in Group 1 and 12 in Group 2.  All subjects were followed for a minimum of 6 months.  Mean preoperative Cobb angles in Group 1 and Group 2 were 58.18° and 53.51° respectively, while mean post-operative Cobb angles at 6 months were 17.79° and 16.70° respectively.  Balance parameters, nickel levels, and complication rates did not differ significantly.  Based on the fulcrum bending correction index (FBCI), group 1 subjects demonstrated better correction and gradually increasing correction over 4 weeks post-operatively.

Conclusion:  This is the first study to demonstrate that the novel superelastic rods are safe, can gradually correct curves, ultimately resulting in better coronal and sagittal alignments compared to traditional rods.  However, larger multi-center trials are needed to further substantiate these findings.