Two-dimensional Distribution of Anterior Longitudinal Ligament Strength.

IMPORTANCE

Understanding the distribution of anterior longitudinal ligament (ALL) strength may guide graft fixation for sacrocolpopexy. However, variation in strength across the ligament's 2-dimensional surface has not been fully characterized.

OBJECTIVES

The objectives of this study were to evaluate the variation in ALL pullout strength along craniocaudal and mediolateral dimensions within the presacral space to inform the optimal location for sacrocolpopexy graft fixation.

STUDY

DESIGN

This was an anatomic study of 10 unembalmed female cadavers. A grid with 1-cm × 1-cm increments was superimposed atop the ALL surface centered on the midsacral promontory, extending 2 cm superiorly, 3 cm inferiorly, and 2 cm bilaterally. The pullout force required to avulse a high tensile-strength suture from a full-thickness purchase of ligament was assessed at each coordinate within the grid, then compared by mediolateral and craniocaudal location.

RESULTS

Pullout forces differed in the craniocaudal dimension (P<0.001). Relative to the sacral promontory (62.3±36.2 N), pullout strengths at 2 cm (31.9±20.7 N, P=0.003) and 3 cm (33.0±20.8 N, P=0.002) inferiorly were significantly weaker. Pullout forces also varied across mediolateral segments (P<0.001). Compared with midline (61.5±31.6 N), the most lateral segments 2 cm right (41.6±27.5 N, P<0.001) and 2 cm left (42.6±30.9 N, P=0.002) were significantly weaker.

CONCLUSIONS

The pullout strength of the ALL decreases with caudal and lateral deviation from the midsacral promontory but remains relatively preserved in the central portion surrounding the promontory. Understanding the distribution of ligament strength facilitates an efficacious sacrocolpopexy graft attachment and aids in navigating challenging presacral space anatomy.