This study aims, by means of a randomized control trial, to investigate which treatment method (corticoid injection + physiotherapy with a focus on manual therapy and home-exercises versus corticosteroid injection + physiotherapy with focus on education and supported home exercises) gives better results on clinically relevant outcomes (range of glenohumeral motion, psychological factors, pain, shoulder function, quality of life) and on parameters derived from arthroscopic glenohumeral investigation by means of MRI.