Comparing the Accuracy of Radiography and Sonography in Detection of Knee Osteoarthritis: A Diagnostic Study

BACKGROUND: Knee osteoarthritis (OA) is the most common degenerative disorder occurring in older people. Radiography and sonography are convenient techniques to detect diverse pathological features of knee OA. AIM: The aim of the present study was to evaluate the diagnostic efficacy of radiography and sonography in the detection of diverse features of knee OA. METHODS: In a prospective cross-sectional diagnostic accuracy study, 50 consecutive patients with suspected knee OA (40 women and 10 men, mean age 41.2 ± 6.1 years), referred to the rheumatology clinic of the Shohada Hospital of Khorramabad. All obtained magnetic resonance imaging (MRI), radiographic and sonography images were evaluated by two radiologists and rheumatologist with sufficient expertise in degenerative knee disorders. MRI has been considered as a gold standard test in evaluating other tests. The sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV) and accuracy with 95% confidence intervals of radiography and sonography in the diagnosis of knee OA were calculated. RESULTS: Prevalence of the marginal osteophyte, geode and decreased joint thickness were significantly higher in patients with age > 40 years compared to ≤ 40 years (P < 0.05). The incidence of diverse features of knee OA was not significantly different in terms of the patient’s gender, except for decreased joint space. The specificity of radiography was higher than its sensitivity. CONCLUSION: Our study showed that both radiography and sonography are useful imaging modalities, especially to diagnosis the positive cases of knee OA. The specificity of radiography is higher than to its sensitivity for all pathological features of knee OA. The sensitivity of sonography to detect some features of knee OA such as decreased joint thickness is considerably higher than radiography.