Factors affecting Sandwich vertebral re-fracture after vertebral augmentation surgery for osteoporotic spine Sandwich fractures

Abstract

Objective To investigate the risk factors affecting Sandwich vertebral re-fracture after vertebral augmentation surgery for osteoporotic spine Sandwich fractures. Methods A retrospective case control study was conducted on the clinical data of 90 patients with osteoporotic spine Sandwich fractures treated with vertebral augmentation surgery from January 2004 to December 2015. There were 26 males and 64 females, aged (69.9±7.4)years. The patients were divided into fracture group (n=15) and non fracture group (n=75) according to the incidence of re-fracture after operation during follow-up. Gender, age, height, weight, bone mineral density, cumulative number of cemented vertebrae, location of the Sandwich vertebrae in the thoracolumbar segment, the preoperative kyphosis angle of the Sandwich fracture segment, surgical approach, cement injection approach (unilateral or bilateral), cement injection volume, cement leakage between the Sandwich intervertebral spaces, the postoperative kyphosis angle of the Sandwich fracture segment, and follow-up duration were used as independent variables. Chi-square test and multivariate logistic regression analysis were used to analyze the risk factors of vertebral Sandwich fracture. Results There were 97 Sandwich vertebrae in 90 patients, and 226 fractured vertebrae were treated with initial intensive treatment. The mean follow-up was 18.1 months. There were no significant differences in gender, age, height, weight, cumulative number of cemented vertebrae, whether the Sandwich vertebrae was located at the thoracolumbar segment, the preoperative kyphosis angle of the Sandwich fracture segment, the cement injection approach (unilateral or bilateral), the volume of cement injection, and the cement leakage between the Sandwich intervertebral spaces (P>0.05). There were significant differences in bone mineral density, surgical approach, and postoperative kyphosis angle of the Sandwich fracture segment between the two groups (P<0.05). Further logistic regression analysis showed that bone mineral density ≤ 3.5 SD and segmental kyphosis (≥10°) were risk factors for Sandwich fracture (P<0.05). Conclusions The low bone mineral density (T value ≤-3.5 SD)and postoperative kyphotic angle (≥10°) are risk factors for re-fracture of Sandwich vertebrae. Vertebroplasty itself does not increase the risk of recurrent vertebral fractures. Key words: Spinal fractures; Osteoporosis; Cement augmentation