Implant migration in growth-friendly constructs for early-onset scoliosis: a systematic review of reported patterns, associated factors, and clinical consequences.

PURPOSE: Implant migration is an incompletely characterised complication of growth-friendly treatment for early-onset scoliosis (EOS), with inconsistent terminology across the literature. This systematic review aimed to characterise reported patterns, study-specific frequency, associated factors, detection, and clinical consequences of implant migration and migration-related fixation failure in growth-friendly EOS constructs.

METHODS

PubMed, Embase, and CINAHL were searched from database inception to 27th November 2025 in accordance with PRISMA guidelines. Studies reporting implant migration or migration-related fixation failure in children with EOS treated with growth-friendly constructs were included. Findings were synthesised descriptively because migration definitions, constructs, outcome ascertainment, and reporting were heterogeneous. Risk of bias was assessed using Joanna Briggs Institute critical appraisal tools, and certainty of evidence was evaluated using GRADE.

RESULTS

Nineteen studies were included, predominantly retrospective cohorts and case series. Migration terminology was inconsistent and frequently overlapped with pull-out, dislodgement, loosening, and loss of fixation. For descriptive synthesis, reported events were organised into three recurring anatomical patterns: apical/ventral rod migration, proximal anchor migration/fixation failure, and distal or pelvic anchor migration/fixation failure. Ventral rod migration was represented by two publications, including one cohort in which CT-defined migration occurred in 3/90 patients (3.3%) and one case report. Proximal anchor-related events were represented across a greater number of studies. Candidate associated factors included deformity severity, repeated lengthening, patient morphology or bone quality, and construct characteristics; however, the available evidence did not permit identification of independent predictors.

CONCLUSION

Implant migration and migration-related fixation failure in growth-friendly EOS constructs are inconsistently defined and reported. The available evidence supports a proposed descriptive anatomical framework but does not permit reliable pooled incidence estimation or prediction of individual patient risk. Standardised definitions and prospective multicentre reporting are required to determine frequency, predictors, and clinically meaningful surveillance strategies.