The anatomy of Trans-Obturator Posterior Anal Sling (TOPAS) and dynamics of potential mechanism of action
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The aim of this study was to investigate the course of the transobturator posterior anal sling and its relationship to anatomical structures.
The transobturator anal sling procedure was performed in four fresh-frozen pelvises. The pelvises were dissected and the structures adjacent to the sling and the course of the sling were identified and measurements obtained.
The transobturator posterior anal sling was inserted 2 ± 0.5 cm posteriorly to the anus, and 2.5 ± 0.5 cm caudal to the coccyx under the levator plate at the level of the puborectalis muscle. The tape was 3.5 ± 0.5 cm from the pubic symphysis and 2.3 ± 0.3 cm from the obturator canal at entry into the pelvic cavity. The tape passed 2.3 ± 0.3 cm inferior–medial to the obturator canal. At entry, the sling passed lateral to the ischiopubic ramus through the following structures: gracilis, adductor brevis, obturator externus, obturator membrane, and beneath the obturator internus muscle. The sling traveled 2–3 ± 0.5 cm over the iliococcygeus muscle and perforated the iliococcygeus fibers 0–2 cm medial to arcus tendinous levator ani. The posterior division of the obturator nerve was 2.8 ± 0.7 cm from the tape. The anterior division of the obturator nerve was 3.4 ± 0.8 cm from the tape. The device passed 1.1 ± 0.4 cm from the most medial branch of the obturator vessels.
The transobturator posterior anal sling travels mostly in the avascular area of the ischiorectal fossa and posterior to the puborectalis muscle as intended.
KeywordsAnatomy Anal sling Transobturator posterior anal sling Fecal incontinence
We would like to acknowledge the assistance of the team at INOVA Advanced Surgical Technology and Education Center (ASTEC) and thank Mr. Larry Walker, the director of the program for his support of this study.
J. Alshiek: Project development, data collection, statistical analysis, manuscript writing. Peter Rosenblatt: Project development, manuscript review. S. A. Shobeiri: Project development, data collection, statistical analysis, manuscript writing.
Compliance with ethical standards
Conflict of interest
Dr. Peter Rosenblatt is the inventor of the transobturator posterior anal sling the other authors declare that they have no conflict of interest.
This was an anatomical observational study that was approved as an exempt study at Inova Fairfax Hospital.
For this type of the study, formal consent is not required.
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