The device is implantable in the living body for attachment and augmentation of tendons and/or reinforcement of bones. It comprises a substantially flat membrane having a rounded outer shape and at least two perforations. The membrane contains resorbable or degradable polymeric and/or polymeric-ceramic material, having a Young's modulus in the range of 1 to 50 GPa and a tensile strength in the range of 0.1 to 20.0 GPa. It allows a more secure fixation of transosseous sutures.