How Does Hyperkyphotic Early-Onset Scoliosis Respond to Growing Rod Treatment?

Abstract

BACKGROUND: Growing rods (GRs) pose a higher risk of kyphosis gain while improving coronal deformity with intermittent distractions in early-onset scoliosis (EOS), but in turn, increased kyphosis may also affect GR correction outcomes. However, there is a paucity of data regarding the effect of GRs on the sagittal spinal profiles in hyperkyphotic EOS. Thus, we aim to demonstrate how hyperkyphotic EOS responds to GRs treatment. METHODS: Forty patients treated with GRs for EOS were included and categorized into a normal kyphosis (N) group [20 degrees≤thoracic kyphosis (TK)≤50 degrees] or hyperkyphosis group (K) group (TK≥50 degrees). Radiographic measurements were performed before and after the index surgery and at the last follow-up. The complications were identified and classified using the surgical complications grading system. RESULTS: The N group included 13 patients with dual GRs and 6 patients with a single GR. The K group consisted of 17 patients with dual GRs and 4 patients with a single GR. The mean age at surgery in the N and K groups was 6.2±1.8 and 6.4±2.1 years, respectively. The N and K groups, respectively, had an average number of lengthenings of 4.2±2.0 and 4.3±2.3, with an average follow-up of 4.7±1.9 and 4.6±2.1 years, respectively. In the K group, TK was markedly reduced after the index surgery and slightly increased during follow-up, whereas changes in TK in the N group were not significant. The complication rate in the K group was significantly higher than in the N group (81.0% vs. 47.4%, P=0.046). The most common implant-related and alignment-related complication in both groups was rod fracture (17.5%) and proximal junctional kyphosis (22.5%), respectively. The complication events in the N group were 5 with grade I and 5 with grade IIA, whereas in the K group there were 8 with grade I and 11 with grade IIA. CONCLUSIONS: GRs can effectively correct hyperkyphotic EOS, with the sagittal profile being successfully restored to normal range. However, hyperkyphotic EOS tends to experience more complications such as rod fracture and PJK. LEVEL OF EVIDENCE: Level III.