Posterior instrumented fusion surgery for adult spinal deformity: Correction rate and total balance

Background: The primary radiological goal of surgery for adult spinal deformity (ASD) is the restoration of lumbar lordosis (LL). Radiological parameters were analyzed to determine the surgical indications for ASD using posterior side-loading spinal instrumentation system. Materials and Methods: This retrospective study included 31 patients of ASD who underwent posterior instrumented fusion surgery. Imaging parameters included spinal tilt angle (STA), LL, and thoracic kyphosis (TK). The ideal LL was estimated based on the normal value. Results: Of 16 patients with sagittal imbalance, 10 patients demonstrated sagittal balance postoperatively. All six patients with frontal imbalance showed frontal balance postoperatively. STA improvement well correlated with change of LL. On univariate analysis. preoperative TK was significantly associated with preoperative sagittal imbalance and postoperative lack of LL with postoperative sagittal imbalance. Conclusions: The surgical concept of ASD focusing on correction of LL was demonstrated. Although the surgery of ASD is still challenging, posterior instrumented fusion surgery using posterior side-loading system may be well applied for mild or moderate ASD without hyper-TK.The posterior side-loading system is practical and can be one of the surgical choices.