EXPRESS: Biomechanical evaluation of feline sacroiliac joint stabilization using a single short cannulated compression headless screw: A cadaveric study

OBJECTIVES: The aim of this study was to compare interfragmentary compression and rotational stability achieved with a single short cannulated compression headless screw (CCHS) with those obtained using longer CCHSs and cortical lag screws in a feline sacroiliac luxation (SIL) model. METHODS: In this experimental study, 12 cadavers of adult domestic short-haired cats with a simulated unilateral SIL were stabilized using a single 2.5 mm CCHSs engaging 40 % of the sacral width and mounted in a mechanical testing machine. To assess compressive forces, pressure-mapping sensors were inserted into the joint space before fracture reduction. Total force (N), area of compression (mm2), and total pressure (N/mm2) were recorded. For rotational mechanical testing, the pelves were subsequently loaded through the acetabulum to replicate hindlimb ground reaction forces. A constant displacement rate of 0.5 mm/s was applied until maximal failure. Yield and ultimate load, stiffness, and failure modes were recorded. Results were compared with previously obtained data for CCHSs and cortical lag screws engaging 60 % of the sacral width. Group comparisons were conducted using Fischer's ANOVA and Kruskal-Wallis tests. Post-hoc pairwise comparisons were conducted using Student's t-tests and the Dunn test. Statistical significance was set at p < 0.05. RESULTS: No statistically significant differences were identified among groups or in pairwise comparisons for total force (p=0.35), area of compression (p=0.76), total pressure (p=0.37), yield load (p = 0.55), ultimate load (p = 0.82), or stiffness (p = 0.57). All failures occurred due to screw loosening. CONCLUSIONS AND RELEVANCE: A single CCHS engaging 40 % of the sacral width provides interfragmentary compression and rotational stability comparable to that of screws engaging 60 % of the sacral width lengths under the specific ex vivo testing conditions used in the feline SIL model.