Abstract

Purpose
There is an increasing recognition of the clinical importance of the sagittal balance after lumbar fusion surgery. The purpose of this study to review the etiology of sagittal imbalance after lumbar fusion surgery and report the radiographic and clinical results of surgical treatment of these patients.
Materials and Methods
Retrospective review of revision spine surgery due to sagittal imbalance in 35 patients. Various surgical methods such as posterior–anterior–posterior (PAP) sequential approach, Smith–Peterson osteotomy (SPO), pedicle subtraction osteotomy (PSO), and vertebral column resection (VCR) were performed to restore lumbar lordosis. The outcome variables included preoperative, postoperative, and follow-up radiographic films, and a clinical assessment using Oswestry Disability Index (ODI), SRS 22, and a review of postoperative complications.
Results
The mean age of the patients was 62 years (age range, 49–74), and mean follow-up duration was 31 months (range, 24–37) for clinical and radiographic outcome variables. The mean preoperative LL/PI (lumbar lordosis/ pelvic incidence) ratio was different from postoperative value (P< 0.0001). Twenty one out of 35 patients showed perioperative complications including proximal junctional kyphosis or infection. All functional outcomes measures improved postoperatively (P < 0.0001).
Conclusion
Most common causes of revision spine surgery due to sagittal imbalance include failure to enhance lumbar lordosis, proximal vertebral collapse, and junctional kyphosis. LL/PI ratio was considered as one of the valuable spinopelvic parameter for evaluation of sagittal imbalance. Following surgical treatment, sagittal balance was generally improved with good to excellent clinical outcomes and high patient satisfaction, although the perioperative complication rates are high.

• Keywords: Sagittal imbalance, SPO, PSO and VCR