Defining a safe corridor for trans‐iliac pin placement in cats

Abstract

Objective To identify whether a theoretical predictable safe corridor is available in cats for placement of trans-iliac pins without the use of fluoroscopy.Methods Twenty-one cats with straight orthogonal normal pelvic radiographs were included. Two start points were evaluated: a midpoint and a dorsal point. The midpoint was defined as midway between the dorsal lamina of the sacral vertebral canal and the cranial dorsal iliac spine. The dorsal start point was 2 mm ventral to the cranial dorsal iliac spine. The pin was assumed to be driven at 90 degrees to the lateral face of the ilium, and considered surgeon accuracy was ±4 degrees from the perpendicular. The angular range and the distance between the iliac wings from the ventrodorsal radiograph were used to calculate the possible cross-sectional area and pin exit location if driven from one iliac wing to the other. The corridor was then evaluated for repeatability in six randomly selected cats.Results Vertebral foramina penetration risk was identified in some cats when using a 1.6 and 2 mm-diameter pin using the mid-iliac wing start point. The dorsal start point decreased the available pin placement area but reduced the risk of entering the hazardous zone for all pin sizes up to 2 mm. Conclusion and RelevanceA theoretical defined safe corridor is available for trans-iliac pin placement in cats between 2.0 and 5.5 kg. A 1.2-mm pin is the safest if using the mid-iliac wing start point. A more dorsal start point can accommodate up to a 2.0-mm pin if correctly aligned to the sacrum.

Outcomes for 15 cats with bilateral sacroiliac luxation treated with transiliosacral toggle suture repair

“…To overcome the risk of inadequate sacral drilling, the placement of the transiliac implant has been described with good clinical results reported for unilateral feline SILF treatment in one study. 30,34 In that study 2/6 cats were also treated for bilateral SILF, one of which suffered major implantrelated complications (biomechanical failure). In a series of 25 dogs with six bilaterally affected cases, transilial pinning was performed with a good overall outcome.…”

“…It can therefore easily lead to malpositioning of a screw, protruding into the sacral or pelvic canal, which could be associated with iatrogenic damage and/or reduced resistance to pull‐out forces. To overcome the risk of inadequate sacral drilling, the placement of the transiliac implant has been described with good clinical results reported for unilateral feline SILF treatment in one study 30,34 . In that study 2/6 cats were also treated for bilateral SILF, one of which suffered major implant‐related complications (biomechanical failure).…”