Incongruity between the radius and ulna, the radius and humerus, and/or the ulna and humerus can be an important component of elbow pain and subsequent dysplasia. A short radius increases pressure on the coronoid process of the ulna and can lead to fragmentation, which can be diagnosed via radiography or CT. Rotation between the humerus and ulna during weight-bearing can also increase pressure on the coronoid process.
In this systematic review, the authors summarize the current knowledge on elbow incongruity and its assessment. When radiographic signs of both radioulnar and humeroulnar incongruity were used for assessment, radiography yielded an 88.8% sensitivity and 91.7% specificity for diagnosis of elbow incongruity. Arthroscopy has also been shown to be useful for diagnosis; several studies have found sensitivity using this modality to be 94% to 98% and specificity to be 81% to 89%. MRI and joint ultrasonography, however, were not found to be as useful in the evaluation of elbow incongruity. The gold standard for diagnosis is CT with 1-mm slice thickness.