Next generation of growth-sparing techniques: preliminary clinical results of a magnetically controlled growing rod in 14 patients with early-onset scoliosis.

STUDY DESIGN: Prospective nonrandomized study.

OBJECTIVE: To report the preliminary results of magnetically controlled growing rod (MCGR) technique in children with progressive early-onset scoliosis.

SUMMARY OF BACKGROUND DATA: The growing rod (GR) technique is a viable alternative for treatment of early-onset scoliosis. High complication rate is attributed to frequent surgical lengthening. The safety and efficacy of MCGR were recently reported in a porcine model.

METHODS: Multicenter study of clinical and radiographical data of patients who underwent MCGR surgery and at least 3 distractions. Distractions were performed in clinic without anesthesia/analgesics. T1-T12 and T1-S1 heights and the distraction distance inside the actuator were measured after lengthening.

RESULTS: Fourteen patients (7 girls, 7 boys) with a mean age of 8 years, 10 months (3 yr, 6 mo to 12 yr, 7 mo) had 14 index surgical procedures. Of the 14, 5 had single-rod (SR) surgery and 9 had dual-rod (DR) surgery, with overall 68 distractions. Diagnoses were idiopathic (N = 5), neuromuscular (N = 4), congenital (N = 2), syndromic (N = 2), and neurofibromatosis (N = 1). Mean follow-up was 10 months (5.8-18.2). The Cobb angle changed from 60° to 34° after initial surgery and 31° at latest follow-up. During distraction period, T1-T12 height increased by 7.6 mm for SR (1.09 mm/mo) and 12.12 mm for DR (1.97 mm/mo). T1-S1 height gain was 9.1 mm for SR (1.27 mm/mo) and 20.3 mm for DR (3.09 mm/mo). Complications included superficial infection in 1 SR, prominent implant in 1 DR, and minimal loss of initial distraction in 3 SR after index. Partial distraction loss observed after 14 of the 68 distractions (1 DR and 13 SR) but regained in subsequent distractions. There was no neurological deficit or implant failure.

CONCLUSION: Preliminary results indicated MCGR was safe and provided adequate distraction similar to standard GR. DR achieved better initial curve correction and greater spinal height during distraction compared with SR. No major complications were observed during the follow-up.