Keyhole shoulder tendon surgery, illustration. This operation, named for the shape of the hole made in the bone, involves reattaching a tendon of the biceps to the upper part of the humerus (the upper arm bone). This is done to treat cases of shoulder instability, and is an example of the wider set of operations known as biceps tenodesis. It would typically be performed to treat severe cases of biceps tendonitis, where the biceps tendon is inflamed and swollen.