One-way self-expanding rod for early-onset scoliosis: early results of a clinical trial of 20 patients

Abstract

Progressive early-onset scoliosis raises major challenges for surgeons, as growth must be preserved. With traditional growing rods, the need for repeated surgery is associated with numerous complications, high costs, and heavy psychosocial burden on the patient and family. We assessed the safety and efficacy of a new one-way self-expanding rod (OWSER). This prospective single-centre phase 2 study included two groups of children with progressive EOS treated by the OWSER in 2016-2017: Ten received a unilateral construct to treat progressive non-neuromuscular curves and 10 others a bilateral construct for neuromuscular scoliosis. Clinical and radiological data were assessed at surgery and 3, 6, 12, 18months later. The primary endpoint was success defined as the absence of repeated surgery at 12months. In the non-neuromuscular group, rod expansion occurred in 5 of 10 patients [95% CI 19-81]; in the five other patients, rotational conflict inside the domino prevented rod expansion, four of them required surgery within the first 12months. Rod expansion occurred spontaneously and during monthly traction sessions in all 10 neuromuscular patients [95% CI 69-100], without mechanical or device-related complications. Residual pelvic obliquity was improved by -3° [- 6.0 to 9.5] at 18months. Lung function improved in the non-neuromuscular group. In neuromuscular diseases, the OWSER bilateral construct seems to be safe and less aggressive. Used as unilateral construct in non-neuromuscular group, it was less effective. Accordingly, we recommend the bilateral construct for all aetiologies. That device could avoid further surgery and reduce the rate of complications after long follow-up.