Is application of an internal anterior pelvic fixator anatomically feasible?

Abstract

Background: Spinal hardware has been adapted for fixation in the setting of anterior pelvic injury. This anterior subcutaneous pelvic fixator consists of pedicle screws placed in the supraacetabular region connected by a contoured connecting rod placed subcutaneously and above the abdominal muscle fascia.

Questions/purposes: We examined the placement of the components for anterior subcutaneous pelvic fixator relative to key vascular, urologic, bony, and surface structures.

Methods: We measured the CT scans of 13 patients after placement of the pelvic fixator to determine the shortest distances between the fixator components and important anatomic structures: the femoral vascular bundle, the urinary bladder, the cranial margin of the hip, the screw insertion point on the bony pelvis, the relationship between the pedicle screw and the corridor of bone in which it resided, and the position relative to the skin.

Results: The average distance from the vascular bundle to the pedicle screw was 4.1 cm and 2.2 cm to the connecting rod. The average distance from the connecting rod to the anterior edge of the bladder was 2.6 cm. The average distance from the screw insertion point to the hip was 2.4 cm; none penetrated the hip. The average screw was in bone for 5.9 cm. The pedicle screws were on average 2.1 cm under the skin. The average distance from the anterior skin to the connecting rod was 2.7 cm.

Conclusions: Components of this anterior pelvic fixator are close to important anatomic structures. Careful adherence to the surgical technique should minimize potential risk.

Level of evidence: Level IV, retrospective study. See Guidelines for Authors for a complete description of levels of evidence.

Figures

Fig. 1

Immediate postoperative AP of the pelvis with an internal anterior fixator in place for treatment of bilateral pubic rami fractures associated with a pelvic ring injury is shown.

Fig. 2A–C

(A) A CT slice tangential to the pedicle screw demonstrates the measurements for screw length and distance from the hip. (B) The distance from the skin to the tip of the pedicle screw, the tip of the pedicle screw to the bone, the maximal potential length of the screw in the bone, and the distance from the skin to the anterior aspect of the connecting bar are shown. (C) The distance from the connecting rod and pedicle screw to the external iliac bundle is demonstrated.