Secondary fracture prevention: review of recent American Society for Bone and Mineral Research multidisciplinary stakeholder consensus recommendations

[Comparison of refracture risk between sandwich vertebrae and ordinary adjacent vertebrae]

Objective

To compare the refracture risk between sandwich vertebrae and ordinary adjacent vertebrae, and to explore the risk factors related to refracture.

Methods

Retrospective analysis was performed on the data of patients who received percutaneous vertebral augmentation (PVA) and formed sandwich vertebrae between April 2015 and October 2019. Of them, 115 patients were enrolled in the study. There were 27 males and 88 females with an average age of 73.9 years (range, 53-89 years). Univariate analysis was performed to analyzed the patients' general data, vertebral augmentation related indexes, and sandwich vertebrae related indexes. Survival analysis was performed for all untreated vertebrae at T ₄-L ₅ of the included patients at the vertebra-specific level, and risk curves of refracture probability of untreated vertebrae between sandwich vertebrae and ordinary adjacent vertebrae were compared. Cox's proportional hazards regression model was used to analyze risk factors for refracture.

Results

The 115 patients were followed up 12.6-65.9 months (mean, 36.2 months). Thirty-seven refractures involving 51 vertebral bodies occurred in 31 patients. The refracture rate of 27.0% (31/115) in patients with sandwich vertebrae was significantly higher than that of 15.2% (187/1228) in all patients who received PVA during the same period ( χ ²=10.638, P=0.001). Univariate analysis results showed that there was a significant difference in the number of augmented vertebrae between patients with and without refractures ( Z=0.870, P=0.004). However, there was no significant difference in gender, age, body mass index, whether had clear causes of fracture, whether had dual energy X-ray absorptiometry testing, whether the sandwich vertebra generated through the same PVA, puncture method, method of PVA, number of PVA procedures, number of vertebrae with old fracture, whether complicated with spinal deformity, bone cement distribution, and kyphosis angle of sandwich vertebral area ( P>0.05). Among the 1 293 untreated vertebrae, there were 136 sandwich vertebrae and 286 ordinary adjacent vertebrae. The refracture rate of sandwich vertebrae was 11.3% which was higher than that of ordinary adjacent vertebrae (6.3%)( χ ²=4.668, P=0.031). The 1- and 5-year fracture-free probabilities were 0.90 and 0.87 for the sandwich vertebrae, and 0.95 and 0.93 for the ordinary adjacent vertebrae, respectively. There was a significant difference between the two risk curves of refracture ( χ ²=4.823, P=0.028). Cox's proportional hazards regression model analysis results showed that the sandwich vertebrae, thoracolumbar location, the number of the augmented vertebrae, and the unilateral puncture were significant risk factors for refracture ( P<0.05).

Conclusion

The sandwich vertebrae has a higher risk of refracture when compared with the ordinary adjacent vertebrae, and its 1- and 5-year fracture-free probabilities are lower than those of the ordinary adjacent vertebrae. However, the 5-year fracture-free probability of sandwich vertebrae is still 0.87, so prophylactic enhancement is not recommended for all sandwich vertebrae. In addition, the sandwich vertebrae, thoracolumbar location, the number of the augmented vertebrae, and the unilateral puncture were important risk factors for refracture.

Fracture-free probability and predictors of new symptomatic fractures in sandwich, ordinary-adjacent, and non-adjacent vertebrae: a vertebra-specific survival analysis

BACKGROUND

It is unclear whether the sandwich vertebra, is at higher risk of new symptomatic fractures (NSFs), and whether prophylactic augmentation might benefit patients with sandwich vertebrae.

OBJECTIVE

To compare fracture-free probabilities of sandwich, ordinary-adjacent, and non-adjacent vertebrae, and identify predictors of NSFs.

METHODS

Data were retrospectively analyzed for patients who had undergone vertebral augmentation resulting in sandwich vertebrae. NSF rates were determined and predictors were identified using Cox proportional hazard models.

RESULTS

The analysis included 1408 untreated vertebrae (147 sandwich, 307 ordinary-adjacent, 954 non-adjacent vertebrae) in 125 patients. NSFs involved 19 sandwich, 19 ordinary-adjacent, and 16 non-adjacent vertebrae. The NSF rate was significantly higher in the patients with sandwich vertebrae (27.2%) than among all patients (14.8%). At the vertebra-specific level, the NSFs rate was 12.9% for sandwich vertebrae, significantly higher than 6.2% for ordinary-adjacent and 1.7% for non-adjacent vertebrae. The corresponding fracture-free probabilities of sandwich, ordinary-adjacent, and non-adjacent vertebrae were 0.89, 0.95, and 0.99 at 1 year, and 0.85, 0.92, and 0.98 at 5 years (p<0.05). Cox modeling identified the following as predictors for occurrence of an NSF in a given vertebra: vertebra location, type of vertebrae, number of augmented vertebrae, and puncture method.

CONCLUSION

Sandwich vertebrae are at higher risk of NSFs than ordinary-adjacent and non-adjacent vertebrae, and several NSF risk factors were identified. Since 85% of sandwich vertebrae are fracture-free for 5 years and NSF risk increases with the number of augmented vertebrae, prophylactic augmentation of every sandwich vertebra may be unnecessary.