Breaking the "law of diminishing returns" with novel, staged, unilateral magnetically controlled growing rods to guided growth surgery for severe, progressive infantile scoliosis

PurposeInfantile scoliosis presents a significant challenge due to high risk of pulmonary complications and morbidity. While dual growing rod constructs are often utilized, they are not always feasible in a young patient with a severe curve. In this study, we present a series of eight patients treated with a unilateral magnetically controlled growing rod (uMCGR) construct later converted to guided growth surgery (GGS).MethodsA multicenter database was queried for patients with progressive infantile scoliosis treated with uMCGR before later conversion to GGS. A minimum of 2 year follow-up was required for inclusion. Curve magnitude, trunk growth, revisions, and complications were tracked at all time points.ResultsEight patients were included in the study. Mean age at index surgery was 4.1 years, while conversion to GGS occurred at average 7.9 years and final follow-up was at 10.5 years of age. At index procedure, major curve averaged 77.1 degrees, which improved to 45.4 degrees. Major curve increased to 48.4 degrees prior to conversion, then improved to 30.9 degrees. Major curve averaged 36.8 degrees at final follow-up, for a maintained curve correction of 52.3%. T1-12 height and T1-S1 height averaged 15.4 and 21.5 cm at index procedure and increased to 20.6 and 32.7 cm at final follow-up. Nine revisions were performed in 6 patients, and no patient showed evidence of premature fusion.ConclusionsTreatment of severe progression infantile scoliosis with this staged protocol provided excellent curve correction with continued trunk growth through treatment, without evidence of the "Law of Diminishing Returns".