The ATA and its surgical importance: a newly described ligament lying between the dural sac and the ligamentum flavum at the L5 level.

Study Design: The anatomy of a new ligament in the human spine the ATA is described.

Objective: To describe a new ligament; the ATA, which lies between the dural sac and the ligamentum flavum at the L5 level and to discuss it's surgical importance.

Summary Of Background Data: Postoperative cerebrospinal fluid (CSF) leakage translates into longer hospital stays with significant implications for the patient, the health care system, and society as a whole. To avoid injury to the dural sac during lumbar surgery, it is crucial to know the surgical anatomy and its variations.

Methods: The length and the number of ATAs were examined in 14 consecutive patients, which underwent an L5 laminoflavectomy in our department. The ATA and its anatomic landmarks are described here for the first time in the literature. We named this ligament the ATA; reminding us to pay attention to the Terminal Attachment.

Results: The presence of the ATA is demonstrated in 10 patients (71%). There was a double ATA in four patients (40%). The mean length of the ATA was 7.7 ± 1.8 mm. The ATA originates from the dorsal surface of the dura mater at the level of the superior border of the superior facet of the S1 vertebra and projects toward the ligamentum flavum. Histologic examination of the ATA revealed fibrous connective tissue.

Conclusion: In this preliminary study, we have described a new ligament, the ATA, between the dural sac and the ligamentum flavum at the L5 level. The ATA is an important structure that creates a potential risk for inadvertent dural lacerations during flavectomy. Dissecting the ATA before the flavectomy may be an important step in reducing postoperative cerebrospinal fluid leaks, which may result in significant benefits for patients and health care organizations.