Survival analysis and risk factors of new vertebral fracture after vertebroplasty for osteoporotic vertebral compression fracture

Abstract

BACKGROUND CONTEXTAlthough risk factors of new adjacent vertebral fracture (AVF) and remote vertebral fracture (RVF) after vertebroplasty may differ, research on this topic is lacking. PURPOSETo determine the natural course of new vertebral fractures after vertebroplasty for osteoporotic vertebral compression fracture (OVCF) and to analyze each risk factor for understanding the incidence of AVF and RVF. STUDY DESIGNRetrospective cohort study. PATIENT SAMPLEThe study subjects included 205 patients who received vertebroplasty for OVCF and were followed-up for at least 1-year. OUTCOME MEASURESData on factors that could affect the occurrence of vertebral fractures, such as age, body mass index, and bone density, were collected from the patients’ medical records. Fracture pattern, fracture location, sagittal imbalance, degree of segmental kyphosis after vertebroplasty, cement distribution, and cement leakage were radiologically examined. METHODSxDuring the follow-up period, any newly developed vertebral fractures were identified. We analyzed whether the time of occurrence differed between AVF and RVF by performing a survival analysis and each risk factor separately. RESULTSNew vertebral fractures occurred in 47 patients (22.9%) after vertebroplasty, AVF occurred in 21 patients (10.2%), and RVF occurred in 26 patients (12.7%). The onset time of AVF was 6.2±1.8 months after vertebroplasty, showing a significant difference from that of RVF, which was 15.2±1.8 months (p<.001). In the univariate analysis, the risk factors of AVF included severe osteoporosis (T-score<−3.0), vertebroplasty in the thoracolumbar junction, sagittal imbalance, and segmental kyphosis angle >15° (p=0.029, p=0.033, p=0.001, and p=0.021, respectively). The risk factors of RVF included severe osteoporosis (T-score <−3.0) and sagittal imbalance (p=0.013 and p=0.004). In the multivariate analysis, the risk factors of AVF included vertebroplasty in the thoracolumbar junction and sagittal imbalance (hazard ratio=3.34, p=0.032 and hazard ratio=4.05, p=0.008), and those of RVF included only sagittal imbalance (hazard ratio=2.66, p=0.024). CONCLUSONAfter vertebroplasty for OVCF, a significant difference in the meantime of occurrence was found; it took 6 months for AVF and 15 months for RVF to develop. Vertebroplasty in the thoracolumbar junction was identified as a risk factor for AVF, whereas sagittal imbalance was a risk factor of both AVF and RVF.