Improvement of pulmonary function in children with early-onset scoliosis using magnetic growth rods

Case series.

To determine whether there is improvement in pulmonary function in children with early-onset scoliosis (EOS) using magnetic growth rods (MGRs).

EOS deformities have large impacts on lung function and volumes. Deterioration of pulmonary function in scoliosis is multifactorial, including severity, location of apex vertebra, and medical comorbidities. MGR insertion has benefits including reduction in operative procedures with repeated anesthetics, cost-effectiveness, and minimizing surgical and psychological distress. Pulmonary function tests provide objective and quantitative information about functional impairment caused by scoliosis. This is the first study that observes the MGR lengthening and changes in pulmonary function during a minimum period of 2.2 years.

Six cases of EOS secondary to neuromuscular disease were identified. Mean age at diagnosis was 2.8 year (2.1-4.9 yr), mean age at surgery was 7.5 year (5-10 yr), and mean follow-up was 2.5 year (2.2-2.8 yr). Pulmonary function test (forced vital capacity [FVC] + forced expired volume in 1 second [FEV1] both % predicted) was measured before and after insertion of MGR and at every lengthening clinic subsequently for a minimum 2 years. Coronal and sagittal Cobb angles were measured pre- and postoperatively as were length extension of growth rods. All except 1 patient had dual MGRs inserted (the other had a single rod). Lengthening was commenced and data was collected at 6-month intervals.

Average correction was 34° ± 18° and 36° ± 15° for coronal and sagittal Cobb angles, respectively. Mean lengthening achieved was 24.9 mm. Mean improvement in postoperative FVC and FEV1 was 14.1% and 17.2%, respectively. There was significant difference between the median preoperative and postoperative Cobb angle, P = 0.028.

This study demonstrates early intervention using MGR in patients with EOS is associated with significant improvement in postoperative pulmonary function tests; and significant improvement in deformity correction with use of MGR with added benefits of reduction in repeat anesthesia, reduction in surgical and psychological distress, and cost-effectiveness.

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