Balloon-assisted eggshell procedure via pedicle subtraction osteotomy for thoracolumbar kyphosis in ankylosing spondylitis: A randomized controlled trial

Objective To evaluate the feasibility of applying balloon dilation technique in the eggshell procedure via pedicle subtraction osteostomy (PSO) for thoracolumbar kyphosis secondary to ankylosing spondylitis (AS). Methods Prospective randomized controlled study. A total of 35 AS patients with thoracolumbar kyphosis admitted to the Department of Spinal Surgery, Changsha Central Hospital from October 2021 to October 2023 were enrolled and divided into two groups: the balloon group ( n = 16) and the non-balloon group ( n = 19). Both groups underwent spinal wedge osteotomy combined with pedicle screw fixation. The balloon group utilized balloon dilation to remove cancellous bone, while the non-balloon group employed the conventional eggshell technique. Surgical duration, intraoperative blood loss, complications, hospital stay, postoperative functional recovery, and degree of spinal deformity correction were assessed and compared. Results Significant differences were observed between the two groups in surgical duration, intraoperative blood loss, and hospital stay ( p < 0.001). No complications such as poor wound healing or surgical site infection occurred in either group. All 35 patients were followed up for an average of 18.5 months. Both groups showed significant improvements in VAS and ODI scores at 1 week postoperatively and final follow-up compared to preoperative values ( p < 0.05), with statistically significant differences between the two groups at 1 week postoperatively ( p < 0.05). Radiographic parameters (TLK, LL, SVA, PT) significantly improved in both groups at 1 week postoperatively and final follow-up ( p < 0.05), except for TK, which showed no significant change ( p > 0.05). No significant differences were found in radiographic parameters between the two groups at 1 week postoperatively or final follow-up ( p > 0.05). Conclusion The application of balloon dilation technique in PSO eggshell procedures offers advantages such as reduced intraoperative blood loss, shorter surgical duration, and enhanced safety. It represents a valuable surgical technique worthy of promotion in the correction of thoracolumbar kyphosis secondary to AS.