Outcome and complications of growing rods for correction of hyperkyphotic early-onset scoliosis

Abstract

Objective To evaluate the changes in sagittal profiles and complications during treatment with growing rods(GRs) in hyperkyphotic early-onset scoliosis (EOS). Methods From December 2009 to December 2016, a total of 32 EOS pa-tients who received growing rods treatment in our center, including 8 males and 24 females, were reviewed retrospectively. All the patients had minimum 2-year follow-up and over 2 lengthenings. Based on the reference value of thoracic kyphosis (TK) in T2-12 of normal children, the patients were categorized into an N group (20°≤TK≤50°, 15 cases, 4 males and 11 females) or K group (TK≥50°, 17 cases, 4 males and 13 females). The distribution of etiology was similar between the two groups. The average age was (6.2±2.0) years and (6.3±2.3) years respectively, curve flexibility was 34.6%±10.4% and 35.8%±11.2% before surgery. The precon-toured rods were tunneled submuscularly, connecting proximal and distal anchors, and tandem or domino connectors. The rods were then locked after applying direct distraction that allowed appropriate elongation. The connectors were all placed under the deep fascia. Results The mean follow-up in the N and K groups was (5.5±1.9) years and (5.5±2.1) years, respectively. The distri-bution of proximal and distal anchors was similar between the two groups. The N and K groups, respectively, had an average num-ber of lengthenings of 5.1±2.0 and 5.3±2.3, with mean lengthening intervals of (11.3±2.3) months and (10.9±1.9) months, respec-tively. In the N group, TK was decreased from 36.0°±9.4° to 30.6°±8.3° after surgery, and to 32.2°±7.8° at the last follow-up, dem-onstrating it was maintained within the normal range. In the K group, TK was markedly reduced from 67.6°±11.6° to 41.7°±8.7° af-ter the index surgery, with a correction rate of 38.3%±14.6%, and the difference was statistically significant. And then it slightly increased to 46.5°±8.4° at the last follow-up, with correction loss of 7.1%±4.2%, and the difference was not statistically significant compared with the postoperatiom. The complication rate in the K group was significantly higher than in the N group (76.5% vs. 33.3%, P=0.031). The most common implant- and alignment- related complication in both groups was rod fracture (15.6%) and proximal junctional kyphosis (21.9%), respectively. The incidence of rod fracture in the N group and K group was 6.7% and 23.5%, respectively. And the incidence of proximal junctional kyphosis was noted as 13.3% and 29.4% in the N group and K group, respectively. Proximal junctional angle (PJA) in the K group was greater than that in the N group preoperatively, postopera-tively and at the last follow-up. Moreover, the increasing amount of PJA was significantly greater in the K group compared to the N group (1.6°±1.0° vs. 0.7°±0.8°). Four and seven complication events in the N and K groups, respectively, were evaluated with GradeⅠ. Four and seven complication events in the N and K groups, respectively, were classified as GradeⅡA. Conclusion GRs can effectively restore the sagittal profile in hyperkyphotic EOS patients, but with a higher complication rate compared to the patients with normal kyphosis. Key words: Scoliosis; Orthopedic procedures; Postoperative complications