34th Annual Scientific Meeting proceedings

Objectives:

The aim of this study was to compare plain radiographs and computed tomography (CT) in the evaluation of postoperative lag screw fixation of sacroiliac luxation (SIL) in cats and to determine the inter- and intra-observer variability of these two modalities for this purpose.

Methods:

The study included cats with unilateral or bilateral SIL without any conformational abnormalities. Bilateral SIL was treated as two separate cases. CT and radiographic images were obtained immediately following surgery and subsequently anonymised. Imaging assessment was performed by board-certified surgeons and radiologists and by surgical and radiology residents. The percentage of reduction and screw purchase, dorso-ventral and cranio-caudal screw angulation were measured. Based on these measurements, the quality of reduction and the need for surgical revision were recorded. Inter- and intra-observer variability was also assessed.

Results:

A total of 26 screws were included, comprising 10 unilateral and 8 bilateral SIL. The sensitivity and specificity of radiographic assessment for the necessity for revision surgery, were 66% and 76.47%, respectively. In bilateral cases, specificity increases to 88% while sensitivity decreases to 33%. Inter-observer agreement was found to be significantly low for radiographs and moderate for CT. Intra-observer agreement was significant for both radiographs and CT.

Conclusions:

Plain radiographs lack sensitivity and specificity compared to CT for the evaluation of postoperative lag screw fixation of sacroiliac luxation in cats, especially for bilateral SIL. CT should be considered as the reference exam. All observers, regardless of experience, were able to provide a reliable assessment of post-operative radiographs and CT.