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How i do it: biportal endoscopic thoracic decompression for ossification of the ligamentum flavum

Abstract

Background

Currently, decompressive laminectomy with or without concomitant fusion is a standard treatment for ossification of the ligamentum flavum (OLF). However, conventional thoracic decompressive laminectomy is not free of the inevitable destruction of the posterior ligamentous complex, and facet injury may lead to various sequelae.

Method

We used the biportal endoscopic technique for posterior thoracic decompression (BE-PTD) and describe the steps with discussion regarding the indications, advantages, possible complications, and ways to overcome complications.

Conclusion

BE-PTD can obtain endoscopic visualizations of all the boundaries of the OLF lesion and achieve direct neural decompression of thoracic OLF.

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Abbreviations

LF:

Ligamentum flavum

OLF:

Ossification of the ligamentum flavum

bRFa:

Bipolar radiofrequency thermo-controlled ablator

SAP:

Superior articular process

BE-PTD:

Biportal endoscopic technique for posterior thoracic decompression

CSF:

Cerebral spinal fluid

References

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Acknowledgements

We would like to thank Editage (www.editage.co.kr) for English language editing.

Author information

Authors and Affiliations

Authors

Contributions

MSK, DHH, and HJP contributed to the conception of the study. MSK, KHY, and HJP wrote the manuscript. SYH, HJC, and HJP reviewed the manuscript. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

Corresponding author

Correspondence to Hyun-Jin Park.

Ethics declarations

Ethics approval

This study protocol was approved by the Hallym University Institutional Review Board (IRB FILE No. 2021–09-002) and adhered to the guidelines of the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Additional information

Key points

I. The posterior aspects of the thoracic vertebrae possess broad, sloping, and longer lamina, and most areas of the LF are covered by the vertebral lamina and inferior articular process of the superior vertebrae.

II. OLF begins from the capsular portion of the LF and extends to the interlaminar portion of the LF, eventually progressing to the dural side.

III. Occasionally, OLF lesions fuse with facet articular processes.

IV. Even if endoscopic visualization of the posterior aspects of the target vertebra is obtained, OLF lesions are often covered by the thoracic lamina of the superior vertebra.

V. The lack of clear surgical landmarks can be a major cause of difficulty in posterior thoracic decompression.

VI. The authors recommend performing sufficient laminotomy and partial medial facetectomy to safely identify all the boundaries of the OLF lesion.

VII. In particular, the medial border of the SAP of the inferior vertebra can be used as a landmark to identify OLF lesions.

VIII. The boundaries of OLF lesions can cause bleeding via nutritional vessels, and all the boundaries of OLF lesions can be identified through vascular cauterization using a bRFa.

IX. The OLF lesion is thinned like a paper-thin plate using a diamond drill, and OLF can be completely removed after adhesiolysis is performed.

X. BE-PTD can obtain endoscopic visualizations of all the boundaries of the OLF lesion and achieve direct neural decompression of thoracic OLF.

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Supplementary Information

Below is the link to the electronic supplementary material.

Video clip 1 After endoscopic visualization of the medial portion of the inferior articular process and lamina of the superior vertebrae, upper lamina of the inferior vertebrae, and interlaminar portion of the ligamentum flavum is achieved, unilateral laminotomy is performed using a small-head high-speed diamond drill until the superior articular process of the inferior vertebrae below the lamina of the superior vertebrae is identified. To identify the lesion of the OLF, many portions of the vertebral laminar and inferior articular processes need to be removed. However, OLF confined to the ligamentum flavum other than the fused type can be identified by partial resection of the inferior articular process by first identifying the medial boundary of the superior articular process of the inferior vertebrae and extending the laminotomy in the upper direction. When the spinal cord compressed by OLF is visible, OLF is decompressed using a drill until all the boundaries of the OLF are identified and only the paper-thin plate in contact with the dura mater remains. Finally, the adhesion of the OLF lesion and dura mater is released using a small nerve probe, and then OLF is completely removed and confirmed by dural pulsation restoration. OLF, ossification of ligamentum flavum (MP4 323651 KB)

701_2021_5031_MOESM1_ESM.mp4

Video clip 1 After endoscopic visualization of the medial portion of the inferior articular process and lamina of the superior vertebrae, upper lamina of the inferior vertebrae, and interlaminar portion of the ligamentum flavum is achieved, unilateral laminotomy is performed using a small-head high-speed diamond drill until the superior articular process of the inferior vertebrae below the lamina of the superior vertebrae is identified. To identify the lesion of the OLF, many portions of the vertebral laminar and inferior articular processes need to be removed. However, OLF confined to the ligamentum flavum other than the fused type can be identified by partial resection of the inferior articular process by first identifying the medial boundary of the superior articular process of the inferior vertebrae and extending the laminotomy in the upper direction. When the spinal cord compressed by OLF is visible, OLF is decompressed using a drill until all the boundaries of the OLF are identified and only the paper-thin plate in contact with the dura mater remains. Finally, the adhesion of the OLF lesion and dura mater is released using a small nerve probe, and then OLF is completely removed and confirmed by dural pulsation restoration. OLF, ossification of ligamentum flavum (MP4 323651 KB)

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Kang, MS., Chung, HJ., You, KH. et al. How i do it: biportal endoscopic thoracic decompression for ossification of the ligamentum flavum. Acta Neurochir 164, 43–47 (2022). https://doi.org/10.1007/s00701-021-05031-7

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  • DOI: https://doi.org/10.1007/s00701-021-05031-7

Keywords

  • Biportal endoscopic technique
  • Posterior thoracic decompression
  • Ossification of the ligamentum flavum
  • Thoracic compressive myelopathy