Rupture of the rotator cuff tendon has a high prevalence and a very high impact on the quality of life. The ruptured cuff tendon is often surgically reconstructed using the long head of the biceps tendon of that same patient. However, it remains unknown what biological and biomechanical properties of the biceps tendon are required to fulfill this function. Therefore, in this study, surgical waste material of the biceps tendon and the ruptured cuff tendon from surgery is collected and analyzed for biological (inflammation) and mechanical properties. Ultimately, a strategy will be developed to patient-specific and non-destructively assess the quality of the biceps tendon and its suitability for reconstructing the torn cuff tendon. This project is performed in collaboration with dr. Okke Lambers Heerspink and dr. Freek Hollman of the VieCurie medical centre.