The Elusive Concept of Stability in Osteoporotic Vertebral Fractures: A Narrative Review.

Osteoporotic vertebral fractures (OVFs) are the most common fragility fractures, representing a substantial burden on healthcare systems worldwide. Although up to 30% of OVFs may be clinically silent, a subset of patients experiences an unfavorable course, developing painful pseudoarthrosis/nonunion, progressive vertebral collapse, and even neurological compromise. While initial OVF management is typically nonoperative, a considerable proportion of patients ultimately require surgical intervention. However, clear and universally accepted surgical indications are lacking, rendering clinical decision-making complex and highly individualized. In this context, evaluating the spine's ability to withstand physiological loads in the presence of potential instability is a critical step in the treatment algorithm. Nevertheless, spinal stability remains a dynamic and multifactorial concept that requires comprehensive assessment integrating both clinical and radiological parameters. This narrative review synthesizes the current state-of-the-art literature on the assessment of stability in OVFs, with particular clinical emphasis on clinical applicability. It revisits classical trauma-derived concepts and adapts them to the specific context of OVFs. We examine the respective roles of radiography, CT and MRI in evaluating fracture characteristics and spinal stability and summarize the main clinical and radiological markers. Furthermore, we distinguish between predictors of fracture progression and indirect indicators of established or evolving instability. Finally, we review current classification systems and outline general treatment considerations, focusing on how imaging findings may guide clinical decision-making in OVFs. Overall, this review provides a comprehensive framework of key imaging and clinical features that should be systematically assessed to estimate the risk of spinal instability.