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



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, 18 months later. The primary endpoint was success defined as the absence of repeated surgery at 12 months.


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 12 months. 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 18 months. 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.

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We thank the Assistance Publique Hôpitaux de Paris who sponsored the study protocol.

We thank Euros Company the manufacturer who donated the OWSER devices and contributed financially to the study. We thank Christophe Glorion and Vicken Topouchian for their participation in surgical procedures. We are grateful to the Clinical Research Unit team of Necker-Cochin Hospitals Group, especially Elodie Henry, Laure Choupeaux, and Loreto Naya Aquilue. We are also indebted to the rehabilitation team of Necker Hospital, for their help with managing the patients. We thank the patients and their families for their agreement and collaboration. We also thank Antoinette Wolfe for its help for manuscript redaction.


Euros Company (La Ciotat, France), the company that manufactures the device used in this clinical trial, funded the study. Euros Company had no role in designing the study, collecting the data, analysing or interpreting the findings, writing the study report, or deciding to submit the study report for publication. No authors of this paper received any financial or nonfinancial benefits in relation with this study.

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Correspondence to Lotfi Miladi.

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Conflict of interest

Lotfi MILADI has intellectual property rights with Euros Company. All other authors declare that they have no conflict of interest.

IRB approval

The Regional Ethics Committee (N° 2014-06-10) and National Drug Safety Agency (ANSM, DMTCOS/DMTCHIR/LAB/2014-A01043-44-A) approved the study. All parents or guardians provided written informed consent. The study was registred on (NCT02266667).

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Miladi, L., Khouri, N., Pradon, J. et al. One-way self-expanding rod for early-onset scoliosis: early results of a clinical trial of 20 patients. Eur Spine J (2021).

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  • Growing rods
  • One-way self-expanding rod
  • Neuromuscular scoliosis
  • Early-onset scoliosis
  • Bipolar technique