A study on atypical Kashin–Beck disease: an endemic ankle arthritis

BACKGROUND: To study the epidemiological characteristics of atypical Kashin–Beck disease cases without characteristic hand lesions such as interphalangeal joint enlargement and brachydactyly and the characteristics of ankle joint lesions. METHODS: We investigated Kashin–Beck in the endemic villages in Heilongjiang Province. The patients were judged according to the “Diagnosis of Kashin–Beck Disease” (WS/T 207–2010). The severity of foot lesions was judged based on the changes of X-ray images. Residents of non-Kashin–Beck disease area were selected as normal controls in Jilin Province. RESULTS: A total of 119 residents over 40 years old were surveyed in a natural village in the non-endemic area. A total of 1190 residents over 40 years old were surveyed in 38 endemic areas of Kashin–Beck disease. A total of 710 patients with Kashin–Beck disease were detected, including 245 patients with grade I, 175 patients with grade II, 25 patients with grade III, and 265 atypical patients. Among all investigated patients, 92.0% (653/710) had ankle joint changes, and it was 80.0% (196/245) in grade I patients and 95.4% (167/175) in grade II. Varying degrees of ankle joint changes were found in both grade III and atypical patients. The grade of Kashin–Beck disease was correlated with the degree of ankle joint change (P < 0.001), and the correlation coefficient r(s) = 0.376. Atypical Kashin–Beck disease patients in mild and severe endemic area of Kashin–Beck disease were younger than those with typical Kashin–Beck disease. CONCLUSIONS: We found a correlation between the degree of ankle joint change and the grade of Kashin–Beck disease. The higher the grade of Kashin–Beck disease, the more serious the change of the ankle joint.