Between 2004 and 2007 he completed a further training at the Charité – University Medicine Berlin to become a medical specialist in orthopedics and trauma surgery.

[5] During his activities at the universities of Magdeburg, Leipzig and Berlin (Charité) Kayser contributed several important scientific works in this field.

[10] Of particular importance for Kayser in this field is an holistic assessment of the patients by means of a development of conservative and operative single-source therapy options.

Another focal point is the minimal-invasive spinal therapy, whereby the establishment of a combined treatment with intraoperative radiotherapy and cement augmentation[11] at the University of Greifswald as one of the two centers in Germany has to be emphasized.

Furthermore, he is a member of the National Disease Management "back-pain" as well as the working group "Skeletal and Kinetic Organs" of the German Society for Ultrasound in Medicine (DEGUM).