Letter to Editor on “The Gantry Crane Technique: A Novel Technique for Treating Severe Thoracic Spinal Stenosis and Myelopathy Caused by Ossification of the Ligamentum Flavum and Preliminary Clinical Results” by Jian Zhu et al

To the editor:

We read with great interest the article by Jian Zhu et al. ¹ “The Gantry Crane Technique: A Novel Technique for Treating Severe Thoracic Spinal Stenosis and Myelopathy Caused by Ossification of the Ligamentum Flavum and Preliminary Clinical Results” recently published in the March 2023 issue of Global Spine Journal. The study presents an innovative operative method for treating severe thoracic spinal stenosis and myelopathy caused by ossification of the ligamentum flavum (OLF), and it can improve clinical outcomes and reduce the postoperative complications. We appreciate the authors’ efforts and innovations in spine surgery; however, we have a confusion that need to be clarified after reading this article.

In the article, the authors claimed their experience about the posterior elevation height of laminae and ossified ligament complex (LOC) was that elevation of 102 mm could ensure adequate decompression and avoid dural tears caused by excessive lifting in the eighth page of the fifth row. However, Sun J et al. ² reported the analogous bridge crane technique, in which they explained that a sufficient elevation height was 10.3 mm to treat severe thoracic spinal stenosis and myelopathy. Yan C et al. ³ reported using computer-based 3D simulations to formulate preoperative planning of bridge crane technique for thoracic ossification of the ligamentum flavum (TOLF). The posterior elevation height of LOC was about 7 mm. Furthermore, the above three articles are from the same unit and have co-authors. Their huge differences make us doubt the accuracy of the data.

The height of posterior suspension of LOC is the core of the gantry grane Technique, and it^’s decisive to the operation. If too high, it will lead to dural tears, and if too low, there will be insufficient decompression. In addition, as experienced spine surgeons, we have performed similar operations. And we know the elevation of the LOC is 10 mm approximately, which would not be 102 mm. So, might it be 10.2 mm in the artical?

Despite this confusion, the authors made a great contribution to this field. We once again gratitude the authors for their contributions.