Bivertebral pedicle-supralaminar autostable claw for proximal fixation of magnetic growing rods in early-onset scoliosis

Background: The various methods for the proximal fixation of magnetic growing rods in patients with early-onset scoliosis (EOS) are associated with high rates of mechanical complications related to material failure or proximal junctional kyphosis (PJK). The bivertebral autostable claw (BAC) has been proven reliable in adolescent idiopathic scoliosis but has not been assessed when used with magnetic growing rods. The objective of this study was to describe the operative technique and outcomes of BAC proximal fixation of magnetic growing rods in children with EOS.

Hypothesis: The BAC provides stable and effective proximal fixation in children with early-onset scoliosis.

Material and methods: This retrospective observational study included 24 patients who had surgery in 2015-2019 for early-onset scoliosis with magnetic growing rod implantation and BAC proximal fixation. Radiological variables were measured in the coronal and sagittal planes before surgery, during the early postoperative period (<3months) and at last follow-up (≥2years).

Results: No neurological complications were recorded. At last follow-up, four patients had radiological PJK, including one patient with clinical PJK due to material failure.

Discussion: BAC proximal fixation is both effective and sufficiently stable (4.2% pull-out) to withstand the forces applied during distraction sessions and daily activities in children with EOS. Moreover, the polyaxial connecting rods ensure better BAC adaptation to the local proximal kyphosis, which is often marked in this population.

Conclusion: The BAC is a reliable proximal fixation device that is well-suited to magnetic growing rod fixation in children with EOS.

Level of evidence: IV, retrospective observational cohort study.