Accuracy of computerized tomographic evaluation of canine radio-ulnar incongruence in vitro

Objective-To evaluate the accuracy of linear measurements obtained from computer tomography (CT) images of staged radio-ulnar incongruence in a canine cadaver forelimb model. Study Design-CT evaluation of induced progressive radio-ulnar incongruence in canine cadaveric forelimbs. Sample Population-Eight cadaveric canine left forelimbs. Procedure-A type 2 external skeletal fixator (ESE) with linear motors was attached to the radius in 8 cadaveric left canine forelimbs. Contiguous incremental and helical CT images of the proximal radio-ulnar articulation were acquired in the transverse, sagittal and dorsal planes. The radius was shortened by 1, 2, and 4 mm increments and scanning protocols were repeated at each increment. Digital caliper and CT image analysis measured the progressive change in distance between 2 marking spheres and the epiphyseal bone surfaces of the radio-ulnar articulation. Statistical analysis of measurements from incremental and helical CT acquisitions, and direct and reformatted images were compared with inter-sphere distance using Pearson product moment correlation coefficients. Results-The reformatted incremental acquisition series at the mid-coronoid in the oblique plane had the highest correlation coefficient (r-value) at 0.908. The mid-coronoid in the dorsal plane had the second highest r-value (0.856). The coronoid incisure in the sagittal plane had an r-value of 0.826. The reformatted incremental acquisition series at the coronoid incisure in the oblique plane had the lowest r-value, 0.592. Conclusion-Measurement of radioulnar incongruence may be best performed using reformatted incremental acquisition CT in the mid-coronoid region in an oblique plane. Clinical Relevance-Use of the technique reported in this study may enable determination of the association, if any, between radioulnar incongruence and developmental diseases of the canine elbow. (c) Copyright 2005 by The American College of Veterinary Surgeons