Iatrogenic Anteverted Pelvis After Adult Spinal Deformity Surgery: Is It a Risk Factor for Postoperative Mechanical...

Retrospective cohort study based on a multicenter prospectively collected database.

To determine whether postoperative anteverted pelvis (AP) in patients with preoperative normo- or retroverted pelvis (NRP) is associated with increased risk of mechanical or clinical complications after adult spinal deformity (ASD) surgery.

Pelvic anteversion is a rare spinopelvic morphology, typically considered physiological in young patients with low pelvic incidence. However, its occurrence after ASD correction-especially in patients with initially normo- or retroverted pelvic orientation-raises concerns about its potential impact on postoperative outcomes.

From a database of 2043 surgically treated ASD patients, 84 patients with postoperative AP were identified. Based on preoperative pelvic version, patients were categorized into two groups: preoperative AP (n=38) and preoperative NRP converted to postoperative AP (n=46). Demographic, surgical, radiographic, and health-related quality of life (HRQoL) parameters were analyzed at baseline and at 2-year follow-up.

There were no significant differences in age, BMI, or baseline HRQoL between groups. Both groups underwent similar surgical procedures, although the NRP group required more frequent decompression and pelvic fixation. At 2 years, both groups showed significant improvement in ODI and SRS-22 scores. Mechanical complication rates were not significantly different (10.5% in AP vs. 23.9% in NRP, P=0.154). Radiographic analysis showed that postoperative AP patients maintained a lumbar lordosis >60°, despite low or normal pelvic incidence. NRP patients exhibited greater changes in spinopelvic parameters postoperatively.

Postoperative AP does not appear to be associated with increased mechanical complications, even in patients who were normo- or retroverted preoperatively. These findings suggest that iatrogenic AP may represent a physiological adaptation rather than a pathologic outcome, particularly in younger patients without hip or neuromuscular comorbidities. Pelvic fixation is not necessary in cases of isolated AP when global sagittal balance is restored.