Abstract: A joint prosthesis comprising two co-operating prosthesis members fastening each to a different joint bone. At least one of the prosthesis members is formed by at least two prosthesis elements one surrounding the other, the one prosthesis element adjacent the bone being provided with fastening means distributed along the outer face and being located inside the outer face when the joint prosthesis is being applied, out of which outer face they can subsequently be moved in order to cause them to penetrate into the bone.The fastening means are formed by pins guided in passages of the prosthesis element. The tipform of these pins could be chosen in relation to the hardness of the bone to be penetrated.Furthermore, the contact faces of the two prosthesis elements could be provided with coating mimicing the elastic and/or resilient features of bone.