Subsequent fracture after percutaneous vertebroplasty can be predicted on preoperative multidetector row CT

Subsequent fractures after vertebroplasty in osteoporotic vertebral fractures: a meta-analysis

Percutaneous vertebroplasty (VP) provides substantial benefit to patients with painful osteoporotic vertebral compression fractures (OVCF). However, the reoccurrence of vertebral fracture after VP is a major concern. The purpose of this study is to conduct a meta-analysis on the incidence of subsequent fractures after VP in patients with OVCF. PubMed and EMBASE were searched. In addition, we scrutinized the reference list of all relevant articles to supplement the database search. We included original articles reporting on new fracture rates after VP in OVCF patients. Subsequent fracture rates were pooled across studies using a random-effects meta-analysis. Thirty-nine studies with a total of 8047 participants from 12 countries were included in this meta-analysis. Patients' age ranged from 64.2 to 94.6 years (reported by 31 studies). The median follow-up was 21 months (36 studies). Pooled estimate for subsequent fractures after VP was 23.4% (95% CI, 19.8-27.2%; I² = 93.0%, p < 0.01). New fractures after VP in 54.6% of cases occurred in the vertebral bodies adjacent to the treated vertebra (95% CI, 49.0-60.1%; I² = 66.0%, p < 0.01). A significant proportion of patients undergoing VP for OVCF experience new fractures after treatment, most of which are developed in the vertebral bodies adjacent to the treated vertebra.

Development and internal validation of a clinical prediction model for acute adjacent vertebral fracture after vertebral augmentation : the AVA score

AIMS

To develop and internally validate a preoperative clinical prediction model for acute adjacent vertebral fracture (AVF) after vertebral augmentation to support preoperative decision-making, named the after vertebral augmentation (AVA) score.

METHODS

In this prognostic study, a multicentre, retrospective single-level vertebral augmentation cohort of 377 patients from six Japanese hospitals was used to derive an AVF prediction model. Backward stepwise selection (p < 0.05) was used to select preoperative clinical and imaging predictors for acute AVF after vertebral augmentation for up to one month, from 14 predictors. We assigned a score to each selected variable based on the regression coefficient and developed the AVA scoring system. We evaluated sensitivity and specificity for each cut-off, area under the curve (AUC), and calibration as diagnostic performance. Internal validation was conducted using bootstrapping to correct the optimism.

RESULTS

Of the 377 patients used for model derivation, 58 (15%) had an acute AVF postoperatively. The following preoperative measures on multivariable analysis were summarized in the five-point AVA score: intravertebral instability (≥ 5 mm), focal kyphosis (≥ 10°), duration of symptoms (≥ 30 days), intravertebral cleft, and previous history of vertebral fracture. Internal validation showed a mean optimism of 0.019 with a corrected AUC of 0.77. A cut-off of ≤ one point was chosen to classify a low risk of AVF, for which only four of 137 patients (3%) had AVF with 92.5% sensitivity and 45.6% specificity. A cut-off of ≥ four points was chosen to classify a high risk of AVF, for which 22 of 38 (58%) had AVF with 41.5% sensitivity and 94.5% specificity.

CONCLUSION

In this study, the AVA score was found to be a simple preoperative method for the identification of patients at low and high risk of postoperative acute AVF. This model could be applied to individual patients and could aid in the decision-making before vertebral augmentation. Cite this article: Bone Joint J 2022;104-B(1):97-102.

Progression of Vertebral Compression Fractures After Previous Vertebral Augmentation: Technical Reasons for Recurrent Fractures in a Previously Treated Vertebra

It is well recognized that patients can develop additional vertebral compression fractures (VCF) in an adjacent vertebra or at another vertebral level after successful vertebral augmentation. Factors such as the patient's bone mineral density, post procedure activity, and chronic corticosteroid use contribute to an increased risk of re-fracture or development of new fractures in the first three months after the initial procedure. However, there is a very small subgroup of patients that have unchanged or worse pain after the vertebral augmentation that may indicate continued progression of the treated compression fracture or a recurrent fracture at the previously treated level. This review examines the clinical findings, radiologic signs, and intraprocedural technical failures that may occur during the initial vertebral augmentation that can lead to a progressive fracture in a previously treated vertebra. Causes of failure of the initial vertebral augmentation procedure include inadequate or incomplete filling of the fracture site, the cement missing the actual fracture allowing continued osteoporotic compression, and persistent or worsened intravertebral fluid-filled clefts. The existence of an unfilled intravertebral fluid cleft on preoperative diagnostic studies is the most important indicator of risk for progression as is the later development of fluid at the bone cement interface.

Analysis of Risk Factors for Secondary New Vertebral Compression Fracture Following Percutaneous Vertebroplasty in Patients with Osteoporosis

OBJECTIVE

The aim of this article was to analyze risk factors for secondary new vertebral compression fractures (SNVCFs) after percutaneous vertebroplasty in patients with osteoporosis.

METHODS

We investigated medical records and radiologic images of patients undergoing percutaneous vertebroplasty for osteoporotic vertebral compression fracture between October 2009 and September 2014. We assessed patients' age, past medical history, and bone mineral content using computed tomography. Procedure-specific outcomes were assessed, including ratio of injected bone cement to vertebral body volume, bone cement distribution in the vertebral body (to identify degree of consistency in bone cement injection), presence of bone cement leakage into adjacent disc space, segmental kyphosis, and time interval between first and second fracture events.

RESULTS

Percutaneous vertebroplasty was performed in 293 patients (60 men and 233 women) with 336 affected levels. Of this cohort, 34 (14.6%) patients sustained SNVCFs. We compared patients in 2 groups: patients who experienced SNVCFs, and patients who did not experience fractures. Significant differences were identified in bone mineral content (P = 0.000) and bone cement distribution (P = 0.000). Patients exhibiting bone cement leakage into disc space revealed a higher incidence of SNVCF than patients without leakage (P = 0.039).

CONCLUSIONS

Poor bone mineral content can be a predictive factor of SNVCFs. To prevent SNVCFs, bone cement should be injected as evenly as possible into the vertebral body. Bone cement leakage into the disc space should be avoided.

Risk Prediction of New Adjacent Vertebral Fractures After PVP for Patients with Vertebral Compression Fractures: Development of a Prediction Model

PURPOSE

We aim to determine the predictors of new adjacent vertebral fractures (AVCFs) after percutaneous vertebroplasty (PVP) in patients with osteoporotic vertebral compression fractures (OVCFs) and to construct a risk prediction score to estimate a 2-year new AVCF risk-by-risk factor condition.

MATERIALS AND METHODS

Patients with OVCFs who underwent their first PVP between December 2006 and December 2013 at Hospital A (training cohort) and Hospital B (validation cohort) were included in this study. In training cohort, we assessed the independent risk predictors and developed the probability of new adjacent OVCFs (PNAV) score system using the Cox proportional hazard regression analysis. The accuracy of this system was then validated in both training and validation cohorts by concordance (c) statistic.

RESULTS

421 patients (training cohort: n = 256; validation cohort: n = 165) were included in this study. In training cohort, new AVCFs after the first PVP treatment occurred in 33 (12.9%) patients. The independent risk factors were intradiscal cement leakage and preexisting old vertebral compression fracture(s). The estimated 2-year absolute risk of new AVCFs ranged from less than 4% in patients with neither independent risk factors to more than 45% in individuals with both factors.

CONCLUSIONS

The PNAV score is an objective and easy approach to predict the risk of new AVCFs.

Intervertebral disc degeneration induced by intradiscal poly(methyl methacrylate) leakage after spine augmentation in an in vivo rabbit model

Although intradiscal cement leakage is a common complication of spine augmentation, the effects of cement leakage into the intervertebral disc (IVD) have not been well investigated. This study aimed to determine the effects of cement leakage on IVD degeneration in rabbits. Poly(methyl methacrylate) (PMMA) particles were injected into lumbar discs of rabbits using 26 G needles. Tissue effects were assessed using disc height, sagittal T2-weighted images, histology and immunohistochemistry. The results showed that stimulation with PMMA particles significantly reduced disc height compared with that in the sham-operation group at 3 weeks after injection. The mean signal intensity of the operated discs showed little to no changes among all groups at 3 weeks post-operation. After 6 weeks, the signal intensity of the PMMA-injected group decreased by 22% compared with that in the sham-operation group. Histological and quantitative immunohistochemical examination indicated phenotypic tissue changes from cartilaginous tissue into fibrotic tissue, with apparent degeneration in the PMMA group. Additionally, more collagen type II-containing tissues, but fewer matrix metalloproteinase-7-positive cells or apoptotic cells, were detected in the sham-operation group. The PMMA particle-induced degeneration rate was slower than that of the degeneration group, whereas the histologic data showed no difference in the progression of degeneration between the two groups. These data suggest that PMMA particles can moderately accelerate disc degeneration compared with the 18 G needle puncture model. In conclusion, intradiscal injection of PMMA particles induced significant IVD degeneration in vivo. Therefore, further study of the adverse effects of PMMA leakage on IVD degeneration is required.

Risk factors for new vertebral fractures after percutaneous vertebroplasty in patients with osteoporosis: a prospective study

PURPOSE

To determine the risk factors for new vertebral compression fractures (VCFs) following percutaneous vertebroplasty (PV) in patients with osteoporosis.

MATERIALS AND METHODS

This prospective study included 132 consecutive patients with osteoporosis treated with PV in a single institution over 46 months from March 2005 to December 2008. Multivariable logistic regression and univariate analysis were employed to identify risk factors for new VCFs after PV, including patient demographic data, parameters of the initial and new fractured vertebrae, procedure-related information, and follow-up data.

RESULTS

During the follow-up period (22.4 months ± 12.1), 80 new vertebral fractures occurred in 36 (27.3%) patients. Multivariate analysis showed that number of VCFs per time frame, computed tomography (CT) value of nonfractured vertebrae (T11-L2), activity level after discharge, duration of follow-up, and cement distribution in the inferior part of the vertebral body or close to the endplate were statistically correlated with new fractures (odds ratios, 2.63, 0.96, 3.59, 1.00, 0.30, and 0.05; P = .006, P = .001, P = .007, P = .004, P = .021 and P = .029). Univariate analysis showed preexisting old VCFs were correlated with new VCFs (P = .045). Subsequent compression fractures in adjacent vertebrae (45 of 80) occurred more frequently and sooner than nonadjacent vertebral fractures (both P < .05).

CONCLUSIONS

The incidence of new VCFs after PV is relatively high and affected by several risk factors that are related to both the PV procedure and the natural course of osteoporosis.

Trabecular structure analysis using C-arm CT: comparison with MDCT and flat-panel volume CT

PURPOSE

This paper assesses interscan, interreader, and intrareader variability of C-arm CT and compares it to that of flat-panel volume-CT (fpVCT) and high-definition multi-detector-CT (HD-MDCT).

METHODS

Five cadaver knee specimens were imaged using C-arm-CT, fpVCT, and HD-MDCT. Apparent (app.) trabecular bone volume fraction (BV/TV), app. trabecular number (TbN), app. trabecular spacing (TbSp), and app. trabecular thickness (TbTh) of the proximal tibia were measured by three readers. Interreader, intrareader, and interscan variability for C-arm CT was expressed as coefficient of variation (CV), standard deviation (SD), and intraclass correlation coefficient (ICC).

RESULTS

With the exception of app.TbSp (CV: 7.05-9.35%, SD: 0.06-0.09, ICC: 0.89-0.94), the variability of C-arm CT was low (CV: 2.41-6.43%, SD: 0.01-0.048, ICC: 0.65-0.98). Its interreader reliability (CV: 2.66-4.55%, SD: 0.01-0.03, ICC: 0.81-0.95) was comparable to that of HD-MDCT (CV: 2.41-4.08%, SD: 0.014-0.016, ICC: 0.95-0.96), and fpVCT (CV: 3.13-5.63%, SD: 0.009-0.036, ICC: 0.64-0.98) for all parameters except app.TbSp.

CONCLUSIONS

C-arm CT is a reliable method for assessing trabecular bone architectural parameters with the exception of app.TbSp due to spatial resolution limitation.

Morphologic change in vertebral body after percutaneous vertebroplasty: follow-up with MDCT

OBJECTIVE

The purpose of this prospective study was to evaluate maintenance of spinal canal size and restoration of vertebral height and wedge angle after percutaneous vertebroplasty.

SUBJECTS AND METHODS

This study included 27 patients (19 women, eight men) with osteoporotic compression fractures (52 vertebrae). MDCT with multiplanar reformation was performed within 1 day before and 1 hour after the procedure and 1 year after the procedure on a routine or as-needed basis. The degree of retropulsion, smallest size of the spinal canal, and vertebral height and wedge angle were measured. Statistical analyses were performed with the paired Student's t and Mann-Whitney U tests.

RESULTS

There were no statistically significant differences in degree of retropulsion or size of the spinal canal before and after treatment and at the follow-up evaluation (p > 0.05). Even in the 36 vertebrae with spinal canal compromise before the procedure, there was no significant change in spinal stenosis (p > 0.05). Vertebral height and wedge angle were restored immediately after treatment (1.2 mm and 2.8 degrees , p < 0.05). These restorations were more prominent in vertebrae with fracture clefts than in those without clefts (p < 0.05). Restoration of vertebral height and wedge angle were diminished, but the preprocedure results were maintained in follow-up (0.4 mm and 1.1 degrees , p > 0.05).

CONCLUSION

Vertebroplasty can maintain vertebral height and wedge angle and spinal canal size at least 1 year after treatment.

The impact of preoperative magnetic resonance images on outcome of cemented vertebrae

Refracture of cemented vertebrae is often seen after percutaneous vertebroplasty. The purpose of this prospective study was to evaluate pre-procedural magnetic resonance images (MRI) for the prediction of further collapse and vertebral height loss after vertebroplasty. This study included 81 consecutive patients (73 women and 8 men) with osteoporotic compression fractures. MR studies were performed 1-5 days before vertebroplasty. Patients were followed to evaluate refracture for a minimum of 6 months after treatment. Cox proportional hazards model was used to evaluate relationships between clinical data, covariates on pre-procedural MRI, and the presence of cemented vertebrae refracture. The mean refracture rate was estimated with the Kaplan-Meier method. After a mean follow-up of 23.0 ± 8.2 months, 46 cemented vertebrae (57%) experienced refracture, and the mean loss of anterior vertebral height was 11.3%. The 1-year refracture rate after vertebroplasty was 7%, and rapid increased to 76% in the third year. Cox proportional analysis showed that any 1% decrease in signal intensity on T2-weighted images of the injured vertebra will increase the refracture rate by 0.74% (OR = 0.26, 95% CI 0.08-0.81, p = 0.02), and a 1% increase in the poorly enhanced volume ratio will increase the refracture rate by 4.3% (OR = 5.32, 95% CI 1.22-23.14, p = 0.03). Quantitative pre-procedural MRI appears to be useful in exploring vertebrae with poor bone marrow integrity, which effectively predicts the subsequent refracture of cemented vertebra.