Abstract
The aim of this study was to determine the influence of limb positioning on computed tomographic (CT) measurement of radio-ulnar incongruity (RUI) in canines. The sample population was comprised of twenty thoracic limbs harvested from ten adult canine cadaveric specimens of medium-size breeds without concurrent orthopedic disease. CT scans of each elbow were performed using two different flexion angles (90° and 135°) in combination with five different supination and pronation angles (-35°, -15°, 0°, 15° and 35°). The limbs were aligned using a custom-made fixation device. For each scan, RUI was measured at the apex (AMC) and base (BMC) of the ulnar medial coronoid process and compared with each elbow joint in the study. As the values followed a normal distribution and the one-factorial analysis of variance produced a significant result, a Dunnett post hoc test was performed to compare the individual test conditions pairwise for significant differences. The results show no significant differences in the measurement of RUI between 90° and 135° of elbow flexion. The RUI measured at the AMC showed significant maximum deviations (p < 0.001) of 18.14% at -15° and 15° and 31.31% at -35° and 35°. Measurement of RUI at the BMC showed no significant differences at 15° of pronation; 15° of supination resulted in small deviations of 5.51% (p < 0.001). Angulation of 35° resulted in average maximum deviations of 11.51% (p < 0.001). Supination resulted in greater changes in the RUI than pronation. This study concludes that pronation and supination affect the congruity of the radio-ulnar joint space, most evident at 35°. These findings should be considered during the positioning of the forelimbs for diagnostic purposes.