Aim 2: Correlation of other parameters with postoperative healing: The investigator correlate other parameters with the postoperative healing. Following parameters are collected in preoperative MRI scans: tear size in cm, tear retraction in cm, central tendon length in cm, fatty infiltration with the classification of Goutallier I-IV. In preoperative x-rays we measure the critical shoulder angle in degree. Intraoperative measurement of: tendon quality in four stages and the tear pattern visual (see above, "Visit 2").