A surgical method is provided, the method including the steps of: providing an artificial or allograft flexible planar structure; providing an implant, the implant including material liquefiable by mechanical oscillation, exposing a surface region of hard tissue or hard tissue substitute material; positioning the implant on an exposed area of the hard tissue or hard tissue substitute material; and fastening the implant to the hard tissue or hard tissue substitute material by impinging the proximal end of the implant with mechanical oscillation and simultaneously pressing the implant against the hard tissue or hard tissue substitute material while the distal end of the implant protrudes into a cavity of the hard tissue or hard tissue substitute material and regions of the liquefiable material are in contact with the hard tissue or hard tissue substitute material, and thereby liquefying at least a portion of the liquefiable material, and letting the liquefiable material resolidify.