Implant (10) having a shaft which is adapted in use to be embedded in bone tissue and which has an outer surface provided with a circumferentially-oriented roughness. The circumferentially-oriented roughness has first and second axial sections (19, 21) with each section comprising a series of circumferentially-oriented peaks which have a crest and which are axially spaced apart by troughs. The axial spacing (d) between the crests of adjacent peaks in the first axial section (19) is less than the axial spacing (3d) between the crests of adjacent peaks in the second axial section (21). Although the axial spacing between the crests of adjacent peaks in the first and second axial sections of circumferentially-oriented roughness differs, the first and second axial sections of circumferentially-oriented roughness are adapted in use to provide the same or substantially the same pitch.