Abstract
To the Editor:
We read with great interest the recent article by Wang et al, “Effect of Intraoperative Image-Guided Spinal Navigation Technologies on Endoscopic Lumbar Spine Surgery: A Systematic Review and Meta-Analysis” (Global Spine Journal, 2025). 1 The authors are to be commended for addressing a timely and clinically relevant question in the field of minimally invasive spine surgery.
One methodological aspect, however, raises an important question that merits further discussion. The authors report a significant reduction in radiation exposure with intraoperative navigation, pooling results across 6 studies using a standardized mean difference (SMD) of −4.18. While this finding is impressive, the article does not specify which radiation metrics were reported in each included study (eg, fluoroscopy time, dose-area product, or cumulative air kerma), nor how such disparate measures were harmonized for meta-analysis.
This issue is critical because different radiation indices quantify distinct aspects of exposure—duration of fluoroscopy use, absorbed dose, or energy delivered per area—each with different clinical implications for both patients and surgical staff. Pooling them directly with SMD assumes they are interchangeable measures of the same construct, an assumption that may not be valid. High-quality methodological guidance on meta-analyses cautions that mixing physiologically distinct outcomes can lead to results that are difficult to interpret or even misleading.2-4
Our question, therefore, is whether the authors could clarify how they addressed this challenge. Were unit conversions performed before standardization? Or was SMD applied across studies reporting fundamentally different radiation outcomes? A brief explanation would enhance readers’ confidence in the validity and clinical applicability of the pooled estimate.
We believe this discussion is of high value to the spine community, particularly as navigation technologies continue to expand and comparative effectiveness research informs future practice.
