Construction of a nomogram prediction model for adjacent vertebral fractures after percutaneous kyphoplasty

English Keywords:Osteoporosis vertebral compression fracture  Percutaneous kyphoplasty  Adjacent vertebral body fracture  Risk factor  Prediction model

English Abstract:

  【Abstract】 Objectives: To analyze the risk factors of new fractures of adjacent vertebrae after percutaneous kyphoplasty(PKP) in patients with osteoporotic thoracolumbar compression fractures(OVCF), and to construct a nomogram prediction model. Methods: Clinical data of patients with OVCF who underwent PKP in our hospital from March 2014 to March 2019 were retrospectively analyzed. The patients were divided into fracture group and non-fracture group(control group) according to whether a new fracture in the adjacent vertebrae occurred or not during follow-up. Clinical data of gender, age, location of fractured vertebral body, paravertebral muscle cross-sectional area(CSA), vertebral CSA, injection route(unilateral and bilateral), injection dose, post-injection morphology(lumps or spongy), bone cement leakage, operation time, the anterior height ratio of injured vertebrae and the Cobb angle of kyphosis before and after operation and during follow-up of both groups were collected. Single-factor and multi-factor regression were used to analyze the risk factors of adjacent vertebral fractures after PKP, and a nomogram prediction model was established by R software. Receiver operating characteristic(ROC) curve, calibration diagram and decision curve were used to verify the prediction efficiency, accuracy and clinical value of the model. Results: A total of 224 patients were enrolled, including 42 males and 182 females, with an average age of 65.19±8.62 years. Postoperative fractures of adjacent vertebrae occurred in 36 patients(45 vertebrae in total), with an incidence of 16.07%. Univariate analysis showed that there were significant differences in age, CSA value of paravertebral muscle/vertebral CSA value, location of fractured vertebral body, injection dose of bone cement, bone cement leakage and post-injection morphology between the fracture group and non-fracture group(P<0.05). Further multivariate logistic regression analysis showed that advanced age, decreased CSA value of paraspinal muscle/vertebral CSA, thoracolumbar fracture, injection dose of bone cement, bone cement leakage and agglomerate after injection were the risk factors for new fracture of adjacent vertebral body after PKP. The nomogram prediction model was constructed, and the AUC of the ROC curve of the model was 0.988. The calibration diagram showed that the calibration curve of the model was close to the standard curve. The decision curve indicated that the model was in the range of 1%-98%, and the predicted net benefit value of the model was high, indicating a high prediction efficiency of the model. Conclusions: The fracture of adjacent vertebrae after PKP in patients with OVCF is correlated with age, degree of paraspinal muscle degeneration, position of fractured vertebrae, dosage of bone cement injection, bone cement leakage, shape after injection and other factors. Based on this, the risk prediction model of adjacent vertebral fractures in patients with OVCF after PKP has good prediction efficiency and accuracy.