Comparison of single and dual growing rods in the treatment of early onset scoliosis: a meta-analysis

Background: The growing rod technique was applied in the treatment of early onset scoliosis (EOS) with promising outcomes and many complications at the same time. We reviewed data from literatures to compare the results of single growing rods with dual growing rods to achieve a clear understanding of this technique. Methods: PubMed, Embase, MEDLINE, ScienceDirect, CNKI, Wanfang Data, and CQVIP were searched electronically until March 2016 using "growing rod" and "early onset scoliosis" as major search terms. Also, we manually searched other relevant conference proceedings. Two reviewers independently finished methodological quality assessment, data extraction, and calculations. Results: Six retrospective trials were adopted in data analysis including 126 and 119 patients in the single and dual rod groups, respectively. Significantly better coronal correction rates were observed immediately after the initial operation (MD = -14.67; 95 % CI -20.97 to -8.37; P < 0.01; I-2 = 0 %) and at the final follow-up (MD = -23.70; 95 % CI -45.87 to -1. 52; P = 0.04; I-2 = 82 %) in the dual rod group. Similarly, better lengthening of the T1-S1 height occurred in the dual rod group immediately after the initial operation (MD = -1.74; 95 % CI -2.62 to -0.85; P < 0.01; I-2 = 0 %) and at final followup (MD = -3.8; 95 % CI -5.56 to -2.04; P < 0.001; I-2 = 36 %). There were more complications about the implant in the single rod group, while wound problems were common in the other group. Conclusions: The data of the current meta-analysis showed advantages in the coronal correction rate and lengthening by dual growing rods with fewer implant-related complications and more wound complications.