Risk factors analysis of bone defect after surgery of thoracolumbar fracture/

English Keywords:Thoracolumbar fracture  Bone defects  Related factors  Receiver operating characteristic curve

English Abstract:

  【Abstract】 Objectives: To explore the related risk factors of bone defect after reduction and internal fixation of thoracolumbar fracture via posterior approach. Methods: Retrospective analysis of 74 patients(41 males and 33 females, aged 43.3±1.3 years) with single-segment thoracolumbar fractures treated with pedicle screw-rod system reduction and internal fixationvia posterior approach from January 2016 to March 2019 in our hospital. The mean follow-up period was 15.6±0.2 months. At 1 year after surgery, CT examination was performed. The complete preoperative and postoperative follow-up radiographic data were collected. The patients were divided into bone defect group(40 cases) and fracture healing group(34 cases) according to the presence of bone defects on the horizontal or sagittal CT images of the injured vertebra at 1 year after operation. Data of age, sex, body mass index(BMI), AO classification were recorded. Preoperative MRI was performed to evaluate the integrity condition of preoperative intervertebral disc. CT image data were used to measure the vertebral body compression before operation, sagittal cobb angle, postoperative fracture reduction status, and other related factors. Univariate analysis and multivariate logistic regression analysis were used to analyze the relationship between riskfactors and the occurrence of bone defects. The predicted relationship between the correlation of various factors and bone defects were verified through ROC curve. Results: Univariate analysis showed that the bone defect group had a higher rate of unscathed vertebral nails(27.50%) than the fracture healing group(8.82%), and the preoperative disc injury rate(35.00%) was higher than the fracture healing group(5.88%), the reduction rate (52.50%) was higher than that of fracture healing group(20.59%), the average degree of vertebral compression before operation was (3.49±1.87)%, higher than the average degree of compression of the fracture healing group (25.01±2.01)%, the difference was statistically significant(P<0.05). There was no significant difference in age, BMI, fracture AO classification, and preoperative sagittal Cobb angle between the bone defect group and fracture healing group(P>0.05). The preoperative disc injury, excessive compression of the vertebral body and excessive expansion of the fracture are independent risk factors for bone defect after thoracolumbar fracture reduction. The areas under the ROC curve were: 0.660, 0.706, 0.646(P<0.05), it suggests that the above research factors have good sensitivity and specificity for predicting the correlation of postoperative bone defects. Conclusions: The preoperative intervertebral disc integrity, preoperative vertebral body compression degree, fracture distraction status are independent risk factors for bone defects after thoracolumbar fracture reduction.