The Relationship Between Global Sagittal Balance and the Incidence of Early Adjacent Vertebral Fractures Following Balloon Kyphoplasty

Background: Recently, it is widely known that global sagittal balance (GSB) influences the postoperative outcome of the spine. The purpose of this study was to investigate the relationship between GSB and the incidence of early adjacent vertebral fracture (AVF) following balloon kyphoplasty (BKP). Methods: This study included 96 patients (19 males, 77 females, mean age 77.4 ± 5.5 years) who underwent BKP for osteoporotic vertebral fracture and who were over 60-years-old. We investigated the effect of GSB on early AVF within 2 months after surgery. Of the 96 patients, 76 patients (16 males, 60 females, mean age 77.0 ± 5.4) underwent BKP at the thoracolumbar junction (T11-L2) and were investigated independently. After the two-group comparison, logistic regression analysis was performed. Results: During the observation period (18.3 ± 14.7 months), 27 of 96 patients (28.1%) suffered AVF after BKP, and 24 of 96 patients (25.0%) suffered early AVF. In the logistic regression analysis, spinopelvic parameters were not detected as significant risk factors. In cases of BKP at the thoracolumbar junction (T11-L2), 24 of 76 patients (31.6%) suffered AVF after BKP during the observation period (15.3 ± 19.5 months), and 21 of 76 patients (27.6%) suffered early AVF. Logistic regression analysis detected pelvic tilt (PT): odds ratio 1.087 (P = 0.046∗) and local kyphosis: 1.147 (P = 0.003∗) as risk factors for early AVF. The cutoff value was PT≥29° from the receiver operating characteristics curve. Conclusions: At the thoracolumbar junction (T11-L2), PT ≥29° is one of the risk factors of early AVF following BKP.