Preventing L5-S1 discitis associated with sacrocolpopexy

To further characterize the anatomy of the fifth lumbar to first sacral (L5-S1) disc space and to provide anatomic landmarks that can be used to predict the locations of the disc, sacral promontory, and surrounding structures during sacrocolpopexy.The lumbosacral anatomy was examined in 25 female cadavers and 100 computed tomography (CT) studies. Measurements were obtained using the midpoint of the sacral promontory as a reference. Data were analyzed using Pearson χ, unpaired Student's t test, and analysis of covariance.The average height of the L5-S1 disc was 1.8±0.3 cm (range 1.3-2.8 cm) in cadavers and 1.4±0.4 cm (0.3-2.3) on CT (P.001). The average angle of descent between the anterior surfaces of L5 and S1 was 60.5±9 degrees (39.5-80.5 degrees) in cadavers and 65.3±8 degrees (42.6-88.6 degrees) on CT (P=.016). The average shortest distance between the S1 foramina was 3.4±0.4 cm in cadavers and 3.0±0.4 cm on CT (P.001). The average height of the first sacral vertebra (S1) was 3.0±0.2 cm in cadavers and 3.0±0.3 on CT (P=.269).In the supine position, the most prominent structure in the presacral space is the L5-S1 disc, which extends approximately 1.5 cm cephalad to the "true" sacral promontory. During sacrocolpopexy, awareness of a 60-degree average drop between the anterior surfaces of L5 and S1 vertebra should assist with intraoperative localization of the sacral promontory and avoidance of the L5-S1 disc. The first sacral nerve can be expected approximately 3 cm from the upper surface of the sacrum and 1.5 cm from the midline.II.