A Commentary on “Does Vertebral Cement Augmentation Reduce Postoperative Proximal Junction Complications in Spinal Deformity Corrective Surgery: A Systematic Review and Meta-analysis”
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Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) remain significant concerns following long-segment spinal deformity correction [1]. As a response to this challenge, vertebral cement augmentation (VCA) has been explored as a means to reinforce the upper instrumented vertebra (UIV) and adjacent levels. In the March issue of Neurospine, a special issue features a systematic review and meta-analysis consolidating current evidence on the impact of VCA on postoperative proximal junctional complications [2]. The authors’ efforts in synthesizing available data are commendable, as this topic remains debated among spinal deformity surgeons. While the findings suggest potential benefits, they also highlight limitations that warrant cautious interpretation more evenly.
While the meta-analysis highlights a reduction in PJF rates with cement augmentation, the risk of complications such as cement leakage must be carefully considered [3]. Cement extravasation, reported at rates approaching 48% in some studies, raises concerns about potential neural or vascular compromise. To mitigate these risks, several key strategies can be employed. Controlled injection pressure is crucial, with literature suggesting that maintaining a pressure of approximately 1.5–2.0 kgf (kilogram-force) optimizes cement interdigitation while reducing extravasation. Additionally, stepwise injection techniques and real-time fluoroscopic guidance allow for better control of cement flow, minimizing the risk of unintended leakage. Adjusting cement viscosity to a higher level before injection has also been shown to reduce extravasation by improving cohesion and reducing cement migration. Another important factor is cement volume optimization, as excessive cement fill increases leakage risk, while inadequate volume compromises mechanical stability [4]. By integrating these techniques, the safety profile of cement augmentation can be improved while preserving its biomechanical advantages in spinal fusion constructs [5].
Despite these potential benefits, VCA is not without its challenges. One major concern is the alteration of stress distribution at the cement-bone interface, which may inadvertently increase the risk of adjacent segment fractures. Computational modeling studies have demonstrated that while cement augmentation reinforces the immediate fixation strength of the UIV, vertebroplasty at the adjacent level may lead to stress concentrations at the cement-bone junction, particularly during lateral bending and axial rotation [6]. This raises the question of whether cement augmentation effectively mitigates PJK/PJF or, instead, alters the failure pattern to an adjacent level.
While cement augmentation has demonstrated benefits in select cases, it is not a universal solution. Although VCA offers mechanical advantages, it is not the only approach to mitigate PJK/PJF. Alternative strategies, such as hook fixation or biological augmentation, should be considered where applicable, particularly in patients with osteoporosis or high-risk profiles [7]. Biomechanical studies suggest that hook fixation may better distribute stress at the UIV, reducing hypermobility-related PJK, though implant loosening remains a concern. Comparative analyses indicate that VCA improves pullout strength, while hooks may provide greater stability against junctional motion [8]. Additionally, anabolic agents such as teriparatide and romosozumab have shown potential to enhance bone quality and reduce fracture risk, offering an adjunctive approach in osteoporotic patients [9]. These alternatives may provide a more tailored strategy for PJK/PJF prevention and warrant further investigation.
It may be beneficial in select patient populations such as those with osteoporosis or high PJF risk, but it should be applied with caution. Further prospective studies are needed to address key research gaps, including long-term outcomes of VCA, optimal patient selection criteria, and comparative effectiveness against alternative preventive strategies. Additionally, a cost-effectiveness analysis comparing VCA to revision surgery could provide valuable insights, as while VCA may reduce the need for costly reoperations, its upfront costs and potential complications must be weighed against long-term benefits. Until more robust clinical data is available, the decision to use VCA should be made on a case-by-case basis, weighing the potential benefits against known risks [3,10]. Ultimately, while the present meta-analysis offers valuable insights into VCA’s role in mitigating proximal junctional complications, further research is essential to refine its clinical application and establish evidence-based guidelines for optimal use. A multidisciplinary approach incorporating biomechanical, surgical, and patient-specific factors will be key in improving long-term outcomes.
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Conflict of Interest
The authors have nothing to disclose.