Illustrated Tips and Tricks for Intraoperative Imaging in Fracture Surgery by unknow

Author:unknow
Language: eng
Format: epub

Iliac Crest External Fixation Imaging Techniques

•• Iliac crest pins should be placed approximately 3 to 4 cm posterior to the anterior superior iliac spine (ASIS) and directed between the inner and outer tables of the ilium for depths as long as possible without penetration of the tables or acetabulum. It is customary to place at least two 5-mm Schanz pins per side through a small open incision to assure greater stability if one pin is poorly orientated. Right and left pin-to-bar constructs are secured anteriorly over the symphysis after reduction of pelvic volume. Multiplanar bars can be added for stability.

•• A common mistake is to place pins too vertically where they quickly penetrate the outer table with minimal bony purchase and risk impinging on the abdomen or chest wall. K-wires placed along the inner and outer tables help delineate the trajectory intraoperatively (slightly anterior and medial closely following the slope of the inner table) (Fig. 16-16).

Figure 16-16 This obturator-outlet fluoro view depicts a Schanz pin safely placed within the iliac tables and one with a vertical trajectory that leads to early outer table penetration and failure to engage the iliac crest with the working length of the pin.

•• Another common fault is failure to advance the pins within the iliac crest thereby resulting in a less powerful pin-bone interface for fracture reduction and stabilization; this yields a risk for pin loosening or iliac fracture. These fluoro images demonstrate shallow pin advancement in the iliac oblique view and an attempt looking “down” the pins through a modified obturator view (Figs. 16-17 and 16-18).

•• The ideal fluoroscopic image for iliac crest pin placement is the obturator-outlet view, which involves a combination of C-arm movements to efface the inner and outer tables of the ilium from a profile view (Fig. 16-19).7

•• Although the obturator-inlet view may “look down” a pin within the ilium, it does not yield any information about the pin working length within the bone (Fig. 16-20).

Figure 16-17 This iliac fluoro view shows a very short working length for pelvic external fixation pins.

Figure 16-18 This obturator-inlet fluoro view shoots down the short pins providing only proof that the pins have been placed into the iliac crest but offers no confirmation of the working length or penetration of the inner or outer table.

Figure 16-19 This obturator-outlet fluoro view depicts the safe placement of two iliac crest pins within the tables for a desired working length. A clinical demonstration of a right obturator-outlet view is shown.

Figure 16-20 This obturator-inlet fluoro view only depicts a proper starting point on the iliac crest (note the K-wires outlining the inner and outer tables).

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