[Comparison of hybrid and traditional growing rod techniques in the treatment of early-onset congenital scoliosis]

Objective: To compare the surgical outcomes between hybrid and traditional growing rod (GR) techniques in the treatment of early-onset congenital scoliosis (C-EOS). Methods: A review was conducted of C-EOS patients who had undergone hybrid GR treatment at Department of Spine Surgery, the Affiliated Drum Tower Hospital of Nanjing University Medical School. Another group of patients who had undergone traditional GR were well matched to the hybrid GR group at a 1∶1 ratio in terms of main Cobb angle, age at initial surgery, and lengthening numbers. There were 5 boys and 8 girls with an age of (5.6±2.8) years in the hybrid GR group, and 6 boys and 8 girls with an age of (6.1±3.0) years in the traditional GR group, respectively. All patients had minimum 2-year follow-up and over 2 lengthening procedures. Radiographic data were compared with paired t tests in either group between each visit, and with independent t tests between the two groups. Results: On average, the hybrid group had a follow-up of (42.2±13.4) months (range:27-81 months), and had (4.0±1.8) lengthening procedures with a lengthening interval of (10.5±1.0) months; and the traditional GR group had a follow-up of (45.4±15.2) months (range: 24-76 months), and experienced (4.2±1.9) lengthenings with an interval of (10.8±1.1) months. After the index surgery, the major Cobb angle, C(7) translation, apical vertebral translation, and thoracic kyphosis (TK) had remarkable improvement in both groups. Notably, the hybrid GR group had significantly higher correction rates of major Cobb angle (t=2.348, P=0.027) and TK (t=3.768, P<0.001) than the traditional GR group. At the latest follow-up, the hybrid GR group had remarkably smaller Cobb angle of the major curve than the traditional GR group (t=2.790, P=0.010). At the same time, the hybrid GR group had higher T(1)-S(1) height gain than the traditional GR group (t=2.846, P=0.008) after the index surgery. Whereas, non-significant difference was noted between two groups with regards to the T(1)-S(1) growth rate during follow-up (t=0.516, P=0.610). Ten complications occurred during the follow-up period, including 2 in the hybrid GR group and 8 in the traditional GR group. The incidence of rod breakage and PJK in the traditional group was 3 and 4 times as high as that of the hybrid GR group, respectively. Conclusions: The hybrid growing rod can not only help to improve the correction of spinal deformity but also decrease postoperative complications during follow-up. Moreover, apical short fusion shows no significant influence on spinal growth.