Accuracy of computed tomography in diagnosing temporomandibular joint osteoarthritis relative to histopathological findings - an ex-vivo study of 41 horses

Computed tomography (CT) is used to support the diagnosis of equine temporomandibular joint (TMJ) disease; however, its diagnostic accuracy remains unclear. This study aimed to evaluate the relationship between CT findings and histopathological manifestations of osteoarthritis (OA) in equine TMJs. 82 TMJs were CT-imaged, sampled, grouped into age-related and OA-related groups, and analyzed for frequency distributions, correlations, and CT-based TMJ OA diagnosis. CT findings were observed in 79% of joints, including CT anatomical variations considering to reflect age-related remodeling. Only 50% of joints showed co-occurrence of CT findings and histopathological manifestations of OA, confirming that not all CT findings are indicative of disease. Including all CT findings in the CT-based diagnosis of TMJ OA yielded a specificity of 0.41 (95% CI: 0.26-0.58), suggesting a high rate of false-positive diagnoses. Excluding all CT anatomical variations resulted in a sensitivity of 0.56 (95% CI: 0.40-0.72), indicating a substantial number of false-negative diagnoses. However, inclusion of specific CT anatomical variation - subchondral bone cysts - into the studied CT-based diagnosis increased sensitivity to 0.79 (95% CI: 0.62 to 0.89) while maintaining high specificity of 0.92 (95% CI: 0.80-0.98). Including this subset of CT findings in the diagnosis of equine TMJ OA may improve the accuracy of disease detection; however, the clinical relevance of the present cadaver investigation needs to be confirmed in in vivo studies.