This study will be conducted at three different hospitals i.e. Turku University Hospital, Tampere University Hospital (Hatanpää hospital) and Kuopio University Hospital as a multicenter study. A total of 180 patients, 60 patients at each hospital, will be included in this study. The patients are clinically examined and a routine x-ray and MRI-investigation are performed. Patients must have an atraumatic degenerative supraspinatus tendon rupture comprising less than 2/3 of the tendon insertion, i.e. 1/3 of the tendon insertion must be intact. The rupture must be documented by MRI investigation. Patients must be willing and give a written informed consent. After recruitment the patients are randomized in one of three studied treatment modalities. The randomization is made after clinical and MRI investigation by neutral attendant using sealed envelopes. 60 identical envelopes (20 per group) are made in each center.