The Clinical and Imaging Outcome of the Tandem Growing Rod Technique in Early-Onset Scoliosis With the Proximal Upper Thoracic Curve Progression: A Modified Technique of Growing Rod

Abstract

Study Design Retrospective cohort study. Objective The orthopaedic ability of traditional GR for severe EOS is limited. The proximal upper thoracic curve may progress during the lengthening procedure, which may lead to coronal imbalance and inhibit the longitudinal growth of the spine. In this retrospective cohort study, we investigated the clinical outcome of tandem GR. Methods We modified the traditional technique by using two groups of GR devices to control the major and the proximal upper thoracic curve, connected the two groups of GR in series, and named it tandem GR. The clinical and imaging outcomes of the new technique were evaluated and compared with traditional technique. Results Twenty one patients were enrolled in the tandem GR group, and 30 patients were treated with traditional GR as the control. The baseline parameters were consistent between the two groups. In the tandem GR group, the secondary curve progressed from 24.9 ± 3.9° to 31.4 ± 3.2° ( P = .006) in the procedure with the traditional GR and improved to 18.4 ± 4.5° ( P = .001) after the switch. Meanwhile, the clavicular angle aggravated from 1.6 ± 1.0° to 2.6 ± .7° ( P = .041), and improved to 1.7 ± .8° after changed to the tandem GR ( P = .033). At the final of the follow-up, the secondary curve was higher in the control group (27.1 ± 8.3° vs 18.4 ± 4.5°, P = .034), the clavicle angle was 2.4 ± 1.1° in control and 1.7 ± .8° in the tandem GR group ( P = .028), the T1-S1 height was 28.2 ± 4.8 cm in the control and 33.3 ± 3.0 cm in the tandem GR group ( P = .027). The average growth rate was 1.0 ± .3 cm/year in the control and 1.2 ± .4 cm/year in the tandem GR group ( P = .046). Conclusion Tandem GR can effectively improve the proximal upper thoracic curve progression during the treatment of EOS. Compared with the traditional GR, tandem GR can achieve better curve correction, better shoulder balance, and retains more capacity for longitudinal spine growth.