Radiographic, computed tomographic, and arthroscopic evaluation of experimental radio‐ulnar incongruence in the dog

Objective— To compare the diagnostic value of arthroscopy, computed tomography (CT), and radiography for evaluation of radio-ulnar incongruence (RUI). Study Design— Experimental evaluation of induced progressive RUI. Sample Population— Cadaveric Labrador forelimbs (n=11). Methods— The radius was shortened by 1, 2, and 3 mm with a surgical model of RUI. RUI was scored on radiographs, CT (2 radiologists), and arthroscopy (2 surgeons) before and after each modification. The sensitivity and specificity of each modality were compared. The effects of arthroscope and elbow position on arthroscopy observations were evaluated. Agreement between surgeons, radiologists, and each imaging technique and the known status of the elbow was calculated. Results— Complete arthroscopic sessions had an averaged sensitivity of 94% and specificity of 81.9%. The ability to detect mild incongruity (1 mm step) was greater at the incisure than other locations (P<.001). The average sensitivity and specificity of radiography were 99.3% and 42.4%, and for CT were 85.05% and 45.8%, respectively. The average agreement between imaging techniques and the known status of the elbows was greater with complete arthroscopic sessions (89.75%) than radiography (70.1%) and CT (76.85%). Inter-investigator agreement was greater between surgeons scoring arthroscopic examinations (88.6%) than radiologists scoring CT studies (43.9%). Conclusions— Evaluation of arthroscopic images allows sensitive and reproducible detection of experimental RUI, especially at the incisure. Arthroscopic evaluation of experimental RUI reached a higher diagnostic value than radiographs and CT images, because of its specificity and reproducibility. Clinical Relevance— The diagnostic value and reproducibility of arthroscopy may compare favorably with those of CT when evaluating RUI in dogs with elbow disease.