Sagittal Double-Hump Deformity of the Lumbosacral Spine: An Anatomical Risk Factor for Surgical Landmark Obscuration...

This prospective study evaluated the impact of the "double-hump" deformity-defined by anterior protrusions of the L4-L5 and L5-S1 disks-on L5-S1 angulation and laparoscopic sacrocolpopexy (LSC) outcomes. We hypothesized that this deformity is associated with reduced angulation and impaired sacral promontory visibility.

The L5-S1 intervertebral angle measured using sagittal computed tomography (CT) was the primary outcome. Intraoperative sacral promontory visibility, postoperative CT findings of mesh malposition, and perioperative surgical measures (operative time, blood loss) were key secondary outcomes. A total of 184 women scheduled to undergo LSC underwent preoperative CT. The double-hump deformity was defined as an L4-L5 angle > 15° and an L5-S1 angle < 50°. CT measurements of disk heights, disk angles, and sacral promontory location were obtained. For double-hump cases (n = 52), intraoperative videos were reviewed by a blinded surgeon who scored sacral promontory visibility. Postoperative CT was performed to assess mesh placement.

Compared with the control group, the double-hump group had a significantly smaller L5-S1 angle and greater L4-L5 angle (primary outcome). In 50% of double-hump cases (secondary outcome), sacral promontory visualization was rated as "difficult." Intervertebral fixation was not identified by postoperative CT. Estimated blood loss in the double-hump group was greater than that in the control group.

The double-hump deformity is associated with reduced L5-S1 angulation, spinal degeneration, and impaired landmark visibility during LSC. Preoperative recognition may facilitate surgical planning and improve intraoperative safety.