Regional differences in bone mineral density biomechanically induce a higher risk of adjacent vertebral fracture after percutaneous vertebroplasty: a case-comparative study

Abstract

Background: Adjacent vertebral fracture (AVF) is a frequently observed complication after percutaneous vertebroplasty (PVP) in patients with osteoporotic vertebral compressive fracture. Biomechanical deterioration initially induces a higher risk of AVF. Studies demonstrated that the aggravation of regional differences in the elastic modulus of different components might deteriorate the local biomechanical environment and increase the risk of structural failure. Considering the existence of intravertebral regional differences in bone mineral density (BMD) (i.e. elastic modulus), it was hypothesized in the present study that higher intravertebral BMD differences may induce a higher risk of AVF biomechanically. Materials and Methods: The radiographic and demographic data of osteoporotic vertebral compressive fracture patients treated using PVP were reviewed in the present study. The patients were divided into two groups: those with AVF and those without AVF. The Hounsfield unit (HU) values of transverse planes from the superior to the inferior bony endplate were measured, and the differences between the highest and lowest HU values of these planes were considered the regional differences of the HU value. The data from patients with and without AVF were compared, and the independent risk factors were identified through regression analysis. PVP with different grades of regional differences in the elastic modulus of the adjacent vertebral body was simulated using a previously constructed and validated lumbar finite element model, and the biomechanical indicators related to AVF were computed and recorded in surgical models. Results: Clinical data on 103 patients were collected in this study (with an average follow-up period of 24.1 months). The radiographic review revealed that AVF patients present a significantly higher regional difference in the HU value and that the increase in the regional difference of the HU value was an independent risk factor for AVF. In addition, numerical mechanical simulations recorded a stress concentration tendency (the higher maximum equivalent stress value) in the adjacent vertebral cancellous bone, with a stepwise aggravation of the adjacent cancellous bony regional stiffness differences. Conclusions: The aggravation of regional BMD differences induces a higher risk of AVF after PVP surgery through a deterioration of the local biomechanical environment. The maximum differences in the HU value of the adjacent cancellous bone should, therefore, be measured routinely to better predict the risk of AVF. Patients with noticeable regional BMD differences should be considered at high risk for AVF, and greater attention must be paid to these patients to reduce the risk of AVF. Evidence grade: Level III b.

Association Between Abdominal Aortic Calcification and adjacent vertebral fracture after percutaneous kyphoplasty: a case control study.

“…Tao et al suggested that BMD <-3.45 would signi cantly increase the incidence of AVCF [7] . Furthermore, Li et al found that low BMD would cause the aggravation of regional BMD differences, which induces a higher risk of AVCF through a deterioration of the local biomechanical environment [21] . Similarly, in this study, it was found through univariate and binary logistic regression analyzes that low BMD also confers an increased risk of AVCF after vertebral kyphoplasty, as the lower the BMD-T score, the greater the risk.…”

Percutaneous lordoplasty for the treatment of severe osteoporotic vertebral compression fractures with kyphosis

“…Restoring the initial vertebral body height will decrease the risk of adjacent vertebral fractures (7). Recently, Li et al (22) had reported that aggravation of regional BMD differences induces a higher risk of adjacent vertebral fracture (AVF) after PVP surgery due to the deterioration of the local biomechanical environment. However, PLP technology reduces regional BMD differences by strengthening adjacent vertebral bodies, which may decrease AVF risks.…”

Increasing the angle between caudal screw and the transverse plane may aggravate the risk of femoral head necrosis by deteriorating the fixation stability in patients with femoral neck fracture

“…When comparing the difference between groups with and without femoral head necrosis, the independent samples Student’s t test was used for continuous variables, and the Chi-square test was used for the categorical variables [ 22 , 23 ]. We performed binary logistic regression to identify independent risk factors for femoral head necrosis.…”