The Hephaistos-Orthosis was developed within the framework of the PhD-projects of Michel Ducos and Tobias Weber under the supervision of Prof. Dr. Jörn Rittweger and in cooperation with Prof. Dr. Gert-Peter Brüggemann of the German Sport University in Cologne. It unloads the muscles of the lower limb drastically while retaining the application of the body weight on the skeletal structure. Bone, muscle, tendon, vasculature and nerve adaptations to wearing HEPHAISTOS have been investigated in an ambulant interventional study (HEP-study).