Single vs dual rod constructs in early onset scoliosis treated with magnetically controlled growing rods

Abstract

BACKGROUND: Non-invasive distractions of recently introduced magnetically controlled growing rods (MGCRs) spare multiple operations in the surgical treatment of early onset scoliosis (EOS). Since the costs of the implants are high, concerns have been raised regarding cost-effective, optimal but safe MGCR options: single or dual constructs. OBJECTIVES: To report deformity control, spinal growth and complication incidence in EOS patients treated with MCGR singleor dual-rod constructs. MATERIAL AND METHODS: The study involved 47 patients with MCGRs inserted at Great Ormond Street Hospital, London (UK) in 2013-2014, who were followed up for at least 1 year. In 32 patients, T1-S1 distances, and coronal and sagittal curves were measured on preoperative and postoperative X-rays, and at a one-year follow-up. All complications were recorded. The patients were analyzed in 2 groups: those with single-rod constructs (24 patients) and those with dual-rod constructs (23 patients). RESULTS: Comparing postoperative with one-year follow-up measurements, T1-S1 length increase was better in the dual-rod group (3.29%) than in the single-rod group (0.34%) (p = 0.031). In the whole series, mean scoliosis magnitude dropped by 27.5% at the one-year follow-up. The dual-rod group showed better mean curve correction: 36.5% compared to 15.3% in the single-rod group (p = 0.0076). Overall, 34.04% of the patients had complications: 45.8% in the single-rod group and 30.4% in the dual-rod group (p = 0.0413). Metalwork failure was observed in 8 patients, lengthening problems in 5 and wound infections in 2; there was also 1 case of proximal junctional kyphosis (PJK). Preoperative hyperkyphosis was associated with more complications (75%, p = 0.037), most of which were metalwork failure (41.6%). CONCLUSIONS: The MCGRs are efficient at controlling EOS; however, the complication rate is high, particularly in single-rod constructs. The use of dual-rod constructs allows for better curve control, greater T1-S1 length increase and a lower complication rate.