Analysis of the hemivertebra resection strategy in adolescent and young adult congenital scoliosis caused by double hemivertebrae.

Purpose: This study is to conduct a retrospective review of the selective resection strategies, their immediate efficacy and prognosis, using double hemivertebrae (DHV) as illustrative cases.

Methods: A total of 59 adolescent and young adult patients with DHV were enrolled from 2009 to 2021. They were categorized into sagittal kyphosis group (SKG), coronal takeoff group (CTG) and balanced group (BG). The selective resection strategies for each group were reviewed.

Results: Nineteen patients presented ipsilateral DHV, including 15 cases of continuous type (interval ≤ 3 vertebrae) and 4 cases of skipping type (interval ≥ 4 vertebrae), while 40 patients presented bilateral DHV, including 25 cases of continuous type and 15 cases of skipping type. The proportions of patients with 0, 1 and 2 HV resections were 26%, 58% and 16% in the ipsilateral group, and 45%, 48% and 7% in the bilateral group, respectively. The rate of HV resection in the SKG, CTG and BG was 77%, 61%, 33%, respectively. Kyphosis was the primary indicator for HV resection (60%), followed by coronal takeoff effect (21%) and coronal segmental scoliosis (19%). Significant curve progression due to misresection or mis-preservation of HV was recorded as 1.7% and 3.4%, respectively.

Conclusions: Kyphosis, coronal cervicothoracic or lumbosacral takeoff caused by hemivertebrae are primary indicators for selective hemivertebrectomy. For balanced DHV, the necessity of hemivertebrectomy is relatively low. Misresection or mis-preservation of HV may cause iatrogenic coronal imbalance and secondary severe curve progression.