Forearm bone mineral density as a predictor of adjacent vertebral refracture after percutaneous kyphoplasty in patients with osteoporotic vertebral compression fracture: a retrospective analysis

BACKGROUND: The incidence of adjacent vertebral body re-fracture after percutaneous kyphoplasty (PKP) is associated with a number of variables, of which decreased bone mineral density is one of the major risk factors. Forearm bone mineral density (BMD) measurements are gaining attention because of their convenience and validity, but there is a lack of systematic research on the specific relationship between forearm BMD and the risk of adjacent vertebral re-fracture after PKP. PURPOSE: To investigate the correlation between forearm BMD and the risk of adjacent vertebral re-fracture after PKP in osteoporotic vertebral compression fractures (OVCF) patients. METHODS: Retrospective evaluation of 198 OVCF patients receiving PKP was conducted in this study. The patients were divided into two groups: the no-fracture group and the re-fracture group, according to whether or not they had undergone vertebral re-fracture. Obtain basic information about the patient's age, sex, body mass index, bone cement leakage, smoking history, diabetes history, and surgical segmentation. Using computed tomography, the mean Hounsfield unit (HU) values for the BMD of the L1 lumbar spine were determined. For the dual-energy X-ray BMD test, the distal one-third lengths of the patient's nondominant forearm's radius and ulna were chosen. Receiver operating characteristic curves were utilized to evaluate the predictive value of forearm BMD versus lumbar CT values for vertebral re-fracture, and univariate and multivariate logistic regression analyses were employed to identify characteristics related with vertebral re-fracture following PKP. RESULTS: Re-fracture rate after PKP was 17.2% at a minimum 12-month follow-up. Significant differences were seen between the refracture and non-fracture groups in terms of hypertension, Cobb angle correction, vertebral height recovery rate, intradiscal cement leakage, forearm bone density, and vertebral HU values. In multifactorial logistic regression analysis, forearm bone density (OR 0.821; 95% CI 0.728-0.937, p = 0.008) and HU values (OR 0.815; 95% CI 0.733-0.906, p = 0.005) were independent risk factors for vertebral re-fracture. The area under the curve (AUC) for forearm BMD values and HU values predicting adjacent vertebral re-fracture were 0.956 and 0.967, respectively. CONCLUSIONS: Forearm BMD is an independent risk factor for re-fracture of adjacent vertebrae after PKP. In addition, forearm BMD, as a valid indicator of postoperative re-fracture after PKP in patients with OVCF, and the HU value of lumbar spine CT were both powerful tools for predicting re-fracture.