Are Sandwich Vertebrae Prone to Refracture After Percutaneous Vertebroplasty or Kyphoplasty? A Meta-Analysis

Background: The formation of sandwiched vertebrae (SDVs) after percutaneous vertebroplasty (PVP) or percutaneous kyphoplasty (PKP) has become a common phenomenon. Whether SDVs are more likely to fracture is still controversial. Therefore, we conducted a meta- analysis to provide medical evidence for whether SDVs are more prone to refracture than nonSDVs (NSDVs) after PVP or PKP. Methods: This study was conducted in accordance with the criteria of the Preferred Reporting Items for Systematic Reviews and Meta- Analyses. Several databases, including PubMed, Embase, Medline databases, China National Knowledge Infrastructure, Wanfang, and Weipu, were thoroughly searched for relevant studies included from any point up until June 2022. Statistical analyses were performed using Revman 5.4. Results: A total of 4052 individuals from 9 studies were enrolled. Overall, patients with SDV presented more risk to have refracture than patients with NSDV (OR = 1.57, P = 0.04). The incidences of refracture were comparable between the 2 cohorts in studies with a follow- up time less than 3 years (OR = 1.28, P = 0.49). However, patients with SDV were more prone to have refracture than patients with NSDV in studies with a follow- up time longer than 3 years (OR = 1.92, P = 0.009). Moreover, patients with SDV were more likely to have refracture than patients with NSDV in studies that involved both PVP and PKP (OR = 1.62, P = 0.002). In addition, age, low bone density, and postoperative kyphosis angle of sandwich fracture segments >10 degrees were independent factors to predict refracture. Conclusions: Patients with SDV were more likely to have refracture after PVP or PKP, especially when the follow- up time was longer than 3 years.