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. A total of 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.