Surgical anatomy for pelvic external fixation.

Pelvic external fixators have a high rate of reported complications, most of which relate to pin placement. In this descriptive study, we analyzed the morphology of the ilium in cadaveric specimens and compared these with the measures obtained from normal human pelvic computer tomograph scans, and how these related to each of the three basic configurations of pin positioning for the external fixation of a pelvis: anterosuperior (Slätis type), anteroinferior (supra-acetabular), and subcristal. The irregular shape and size of the iliac wing and the abdominal wall overlying the pin's insertion site could hinder accurate placement of anterosuperior pins. Potential disadvantages of the use of anteroinferior pins was found related to the deep location of the anterior inferior iliac spine, interference with the hip flexion area, risk of hip joint penetration, and the variable obliquity of the ilium. As subcristal pins are positioned between two superficial bony landmarks of the iliac crest, our findings suggest that they are more likely to have a correct placement and avoid complications.