Awareness of middle sacral artery pathway: A cadaveric study of the presacral area.

PURPOSE: To assess the anatomic path of the middle sacral artery (MSA) at the presacral area and its relationship to the spinal midline during an axial lumbar interbody fusion (AxiaLif) approach.

METHODS: Fifty human cadavers (25 males, 25 females) were used in this study. A transabdominal approach was used to expose the anterior aspect of the L5/S1 intervertebral disc and the presacral space. We measured the size and distance from the spinal midline at the following positions: (a) middle of the L5/S1 disc level, (b) 1 cm below the sacral promontory (SP), and (c) 2 cm below the SP. Each parameter was measured three times by two observers, and the mean value analyzed.

RESULTS: The MSA was present and originated from the left common iliac artery in all cadavers with a mean width of 2.14 mm. The position of the MSA in relation to the midline was most commonly on the left side (LS, 56%) followed by the right side (RS, 34%) and midline (ML, 10%). In the LS group, the distance from the midline is relatively constant in the three measured positions with a mean value of (a) 1.78 mm (range, 0-8.17 mm), (b) 2.08 mm (range, 0-7.10 mm), and (c) 2.06 mm (range, 0-9.76 mm). In the RS group, the distance from the midline increased from cephalad to caudad, with a mean value of (a) 1.44 mm (range, 0-9.64 mm), (b) 2.19 mm (range, 0-9.95 mm), and (c) 2.92 mm (range, 0-10.03 mm).

CONCLUSIONS: Our study found the presacral anatomic path of the MSA was most commonly at the left of midline. In addition, the right-sided MSA variant had increasing distance from the midline along its anatomic path from cephalad to caudad. Our findings suggest an AxiaLif approach at the left of midline may place the MSA at greatest risk.