Intra- and interobserver reliability of classification scores in calcific tendinitis using plain radiographs and CT scans.

Calcific tendinitis is a common cause of shoulder pain; its treatment is based on the stage of the disease. Unfortunately the existing classification based on radiographs has low reliability. The aim of this study was to evaluate the contribution of CT scans to this matter. Fifty-six consecutive patients with calcific tendinitis were included in this study. Radiographs and CT scans were taken and were evaluated independently by six observers and classified according to the following systems: Gärtner, De Palma, Patte and Mole. After four months the same observers repeated their evaluation. The inter- and intraobserver reliability was calculated using Cohen's kappa analysis. The intraobserver reliability was sufficient using both CT and radiographs. Minimally better (not statistically significant) results were found for CT scans, especially for the Gärtner classification. Interobserver reliability was also better with CT scans but most of the time still hardly satisfactory. The classification scores for calcific tendinitis show insufficient reliability and reproducibility. This can be improved somewhat when using CT scans, but still remains unsatisfactory.