SUMMARY
The radiographic appearance of calcific tendinitis of the rotator cuff varies according to the stage of the disease. We compared currently used classification systems in a large group of observers to identify the most reliable classification system. Thirty-seven orthopaedic surgeons evaluated shoulder radiographs of 25 patients to classify the stage of the calcific tendinitis according to the classifications by (1) Gärtner and (2) Molé on a Web-based study platform. Inter and intraobserver agreement among observers was measured using the Siegel and Castellan multirater ?. Both classification systems had fair interobserver agreement: ? was 0.25 for the Molé classification and 0.34 for the Gärtner classification. The Gärtner classification was significantly more reliable than the Molé classification. Currently there is no radiographic classification that can serve the purpose of guiding the treatment in a reliable way. The Gärtner classification is the most reliable, although far from perfect, radiographic classification there is.