The intra- and inter-observer reliability of the Samilson and Prieto grading system of glenohumeral arthropathy

Severity of glenohumeral arthropathy following shoulder instability is ofte n graded radiologically on the basis of osteophyte size according to Samils on and Prieto. Intra- and inter-observer reliability of this popular gradin g system was determined using standard radiographs of 20 arthritic cadaveri c humeri. Using two observers on two occasions, reliability of the grading system using the antero-posterior radiograph varied between fair and poor ( kappa coefficients 0.07-0.33). This study shows that the Samilson and Priet o grading of glenohumeral arthropathy is unreliable and, in clinical use, w hen magnification and rotation is less easy to control, it is likely to be even more so. Another validated classification system must therefore be fou nd.