Cadaveric Nerve and Artery Proximity to Sacrospinous Ligament Fixation Sutures Placed by a Suture-Capturing Device

To simulate sacrospinous ligament fixation on cadaveric specimens, describe the surrounding retroperitoneal anatomy, and estimate the risk to nerves and arteries for the purposes of optimizing safe suture placement.

Sacrospinous ligament fixation was performed on eight fresh-tissue female cadavers using a Capio ligature capture device. Distances from placed sutures to the following structures were measured: ischial spine; fourth sacral root; pudendal nerve; the nerve to coccygeus muscle; the nerve to levator ani muscle; inferior gluteal artery; and internal pudendal artery. Periligamentous anatomy was examined in an additional 17 embalmed cadaver dissections.

Sacrospinous ligament length was not seen to differ significantly between sides. The fourth sacral spinal nerve was seen most commonly associated with the medial third of the ligament, whereas the pudendal nerve and the nerves to coccygeus and levator ani muscles were associated with the lateral third. The inferior gluteal artery was seen leaving the greater sciatic foramen a median 15.8 mm (range 1.8-48.0, CI 14.9-22.3) above the ligament, whereas the internal pudendal artery exited just above the ischial spine. The two sets of sutures were placed 20.5 mm (range 9.2-34.4, CI 19.7-24.7) and 24.8 mm (range 12.4-46.2, CI 24.0-30.0) medial to the ischial spine, respectively. No structures were directly damaged by placed sutures. The nerves to coccygeus and levator ani were closest and arteries farthest from the placed sutures.

The middle segment of the sacrospinous ligament has the lowest incidence of nerves and arteries associated with it. This study confirms that the nerves supplying the pelvic floor muscles are at a higher risk from entrapment than the pudendal nerve.